Merge pull request #3 from gilardh/master

paper librustzcash sync

.github/workflows/ci.yml

@@ -0,0 +1,120 @@
+name: CI checks
+
+on: [push, pull_request]
+
+jobs:
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: 1.37.0
+          override: true
+
+      # cargo fmt does not build the code, and running it in a fresh clone of
+      # the codebase will fail because the protobuf code has not been generated.
+      - name: cargo build
+        uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: --all
+
+      # Ensure all code has been formatted with rustfmt
+      - run: rustup component add rustfmt
+      - name: Check formatting
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check --color always
+
+  test:
+    name: Test on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macOS-latest]
+
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: 1.37.0
+          override: true
+      - name: cargo fetch
+        uses: actions-rs/cargo@v1
+        with:
+          command: fetch
+      - name: Build tests
+        uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: --verbose --release --all --tests
+      - name: Run tests
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --verbose --release --all
+      - name: Run slow tests
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --verbose --release --all -- --ignored
+
+  codecov:
+    name: Code coverage
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v1
+      # Use stable for this to ensure that cargo-tarpaulin can be built.
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+      - name: Install cargo-tarpaulin
+        uses: actions-rs/cargo@v1
+        with:
+          command: install
+          args: cargo-tarpaulin
+      - name: Generate coverage report
+        uses: actions-rs/cargo@v1
+        with:
+          command: tarpaulin
+          args: --release --timeout 600 --out Xml --packages "librustzcash,zcash_client_backend,zcash_primitives,zcash_proofs"
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v1.0.3
+        with:
+          token: ${{secrets.CODECOV_TOKEN}}
+
+  doc-links:
+    name: Nightly lint
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          override: true
+      - name: cargo fetch
+        uses: actions-rs/cargo@v1
+        with:
+          command: fetch
+
+      # Ensure intra-documentation links all resolve correctly
+      # Requires #![deny(intra_doc_link_resolution_failure)] in crates.
+      - name: Check intra-doc links
+        uses: actions-rs/cargo@v1
+        with:
+          command: doc
+          args: --all --document-private-items
+
+      # Build benchmarks to prevent bitrot
+      - name: Build benchmarks
+        uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: --verbose --all --benches

.travis.yml

@@ -1,6 +1,6 @@
 language: rust
 rust:
-  - 1.36.0
+  - 1.37.0
 
 cache: cargo
 
@@ -8,5 +8,12 @@ before_script:
   - rustup component add rustfmt
 
 script:
+  - cargo build --verbose --release --all
   - cargo fmt --all -- --check
   - cargo test --verbose --release --all
+  - cargo test --verbose --release --all -- --ignored
+
+before_cache:
+  - rm -rf "$TRAVIS_HOME/.cargo/registry/src"
+  - cargo install cargo-update || echo "cargo-update already installed"
+  - cargo install-update -a # update outdated cached binaries

Cargo.toml

@@ -6,6 +6,7 @@ members = [
     "librustzcash",
     "pairing",
     "zcash_client_backend",
+    "zcash_history",
     "zcash_primitives",
     "zcash_proofs",
 ]

bellman/Cargo.toml

@@ -1,28 +1,29 @@
 [package]
 authors = ["Sean Bowe <ewillbefull@gmail.com>"]
 description = "zk-SNARK library"
-documentation = "https://github.com/ebfull/bellman"
+readme = "README.md"
 homepage = "https://github.com/ebfull/bellman"
 license = "MIT/Apache-2.0"
 name = "bellman"
 repository = "https://github.com/ebfull/bellman"
-version = "0.1.0"
+version = "0.2.0"
+edition = "2018"
 
 [dependencies]
 bit-vec = "0.4.4"
 blake2s_simd = "0.5"
-ff = { path = "../ff" }
+ff = { version = "0.5.0", path = "../ff" }
 futures = "0.1"
 futures-cpupool = { version = "0.1", optional = true }
-group = { path = "../group" }
+group = { version = "0.2.0", path = "../group" }
 num_cpus = { version = "1", optional = true }
-crossbeam = { version = "0.3", optional = true }
-pairing = { path = "../pairing", optional = true }
+crossbeam = { version = "0.7", optional = true }
+pairing = { version = "0.15.0", path = "../pairing", optional = true }
 rand_core = "0.5"
 byteorder = "1"
 
 [dev-dependencies]
-hex-literal = "0.1"
+hex-literal = "0.2"
 rand = "0.7"
 rand_xorshift = "0.2"
 sha2 = "0.8"
@@ -36,3 +37,6 @@ default = ["groth16", "multicore"]
 name = "mimc"
 path = "tests/mimc.rs"
 required-features = ["groth16"]
+
+[badges]
+maintenance = { status = "actively-developed" }

bellman/README.md

@@ -1,12 +1,23 @@
 # bellman [![Crates.io](https://img.shields.io/crates/v/bellman.svg)](https://crates.io/crates/bellman) #
 
-This is a research project being built for [Zcash](https://z.cash/).
+`bellman` is a crate for building zk-SNARK circuits. It provides circuit traits
+and primitive structures, as well as basic gadget implementations such as
+booleans and number abstractions.
+
+## Roadmap
+
+`bellman` is being refactored into a generic proving library. Currently it is
+pairing-specific, and different types of proving systems need to be implemented
+as sub-modules. After the refactor, `bellman` will be generic using the `ff` and
+`group` crates, while specific proving systems will be separate crates that pull
+in the dependencies they require.
 
 ## License
 
 Licensed under either of
 
- * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+   http://www.apache.org/licenses/LICENSE-2.0)
  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
 
 at your option.

bellman/src/domain.rs

@@ -1,14 +1,15 @@
-//! This module contains an `EvaluationDomain` abstraction for
-//! performing various kinds of polynomial arithmetic on top of
-//! the scalar field.
+//! This module contains an [`EvaluationDomain`] abstraction for performing
+//! various kinds of polynomial arithmetic on top of the scalar field.
 //!
-//! In pairing-based SNARKs like Groth16, we need to calculate
-//! a quotient polynomial over a target polynomial with roots
-//! at distinct points associated with each constraint of the
-//! constraint system. In order to be efficient, we choose these
-//! roots to be the powers of a 2^n root of unity in the field.
-//! This allows us to perform polynomial operations in O(n)
-//! by performing an O(n log n) FFT over such a domain.
+//! In pairing-based SNARKs like [Groth16], we need to calculate a quotient
+//! polynomial over a target polynomial with roots at distinct points associated
+//! with each constraint of the constraint system. In order to be efficient, we
+//! choose these roots to be the powers of a 2<sup>n</sup> root of unity in the
+//! field. This allows us to perform polynomial operations in O(n) by performing
+//! an O(n log n) FFT over such a domain.
+//!
+//! [`EvaluationDomain`]: crate::domain::EvaluationDomain
+//! [Groth16]: https://eprint.iacr.org/2016/260
 
 use ff::{Field, PrimeField, ScalarEngine};
 use group::CurveProjective;
@@ -26,15 +27,19 @@ pub struct EvaluationDomain<E: ScalarEngine, G: Group<E>> {
     minv: E::Fr,
 }
 
-impl<E: ScalarEngine, G: Group<E>> EvaluationDomain<E, G> {
-    pub fn as_ref(&self) -> &[G] {
+impl<E: ScalarEngine, G: Group<E>> AsRef<[G]> for EvaluationDomain<E, G> {
+    fn as_ref(&self) -> &[G] {
         &self.coeffs
     }
+}
 
-    pub fn as_mut(&mut self) -> &mut [G] {
+impl<E: ScalarEngine, G: Group<E>> AsMut<[G]> for EvaluationDomain<E, G> {
+    fn as_mut(&mut self) -> &mut [G] {
         &mut self.coeffs
     }
+}
 
+impl<E: ScalarEngine, G: Group<E>> EvaluationDomain<E, G> {
     pub fn into_coeffs(self) -> Vec<G> {
         self.coeffs
     }
@@ -64,9 +69,9 @@ impl<E: ScalarEngine, G: Group<E>> EvaluationDomain<E, G> {
         coeffs.resize(m, G::group_zero());
 
         Ok(EvaluationDomain {
-            coeffs: coeffs,
-            exp: exp,
-            omega: omega,
+            coeffs,
+            exp,
+            omega,
             omegainv: omega.inverse().unwrap(),
             geninv: E::Fr::multiplicative_generator().inverse().unwrap(),
             minv: E::Fr::from_str(&format!("{}", m))
@@ -87,7 +92,7 @@ impl<E: ScalarEngine, G: Group<E>> EvaluationDomain<E, G> {
             let minv = self.minv;
 
             for v in self.coeffs.chunks_mut(chunk) {
-                scope.spawn(move || {
+                scope.spawn(move |_scope| {
                     for v in v {
                         v.group_mul_assign(&minv);
                     }
@@ -99,7 +104,7 @@ impl<E: ScalarEngine, G: Group<E>> EvaluationDomain<E, G> {
     pub fn distribute_powers(&mut self, worker: &Worker, g: E::Fr) {
         worker.scope(self.coeffs.len(), |scope, chunk| {
             for (i, v) in self.coeffs.chunks_mut(chunk).enumerate() {
-                scope.spawn(move || {
+                scope.spawn(move |_scope| {
                     let mut u = g.pow(&[(i * chunk) as u64]);
                     for v in v.iter_mut() {
                         v.group_mul_assign(&u);
@@ -142,7 +147,7 @@ impl<E: ScalarEngine, G: Group<E>> EvaluationDomain<E, G> {
 
         worker.scope(self.coeffs.len(), |scope, chunk| {
             for v in self.coeffs.chunks_mut(chunk) {
-                scope.spawn(move || {
+                scope.spawn(move |_scope| {
                     for v in v {
                         v.group_mul_assign(&i);
                     }
@@ -161,7 +166,7 @@ impl<E: ScalarEngine, G: Group<E>> EvaluationDomain<E, G> {
                 .chunks_mut(chunk)
                 .zip(other.coeffs.chunks(chunk))
             {
-                scope.spawn(move || {
+                scope.spawn(move |_scope| {
                     for (a, b) in a.iter_mut().zip(b.iter()) {
                         a.group_mul_assign(&b.0);
                     }
@@ -180,7 +185,7 @@ impl<E: ScalarEngine, G: Group<E>> EvaluationDomain<E, G> {
                 .chunks_mut(chunk)
                 .zip(other.coeffs.chunks(chunk))
             {
-                scope.spawn(move || {
+                scope.spawn(move |_scope| {
                     for (a, b) in a.iter_mut().zip(b.iter()) {
                         a.group_sub_assign(&b);
                     }
@@ -291,7 +296,7 @@ fn serial_fft<E: ScalarEngine, T: Group<E>>(a: &mut [T], omega: &E::Fr, log_n: u
 
     let mut m = 1;
     for _ in 0..log_n {
-        let w_m = omega.pow(&[(n / (2 * m)) as u64]);
+        let w_m = omega.pow(&[u64::from(n / (2 * m))]);
 
         let mut k = 0;
         while k < n {
@@ -331,18 +336,18 @@ fn parallel_fft<E: ScalarEngine, T: Group<E>>(
         let a = &*a;
 
         for (j, tmp) in tmp.iter_mut().enumerate() {
-            scope.spawn(move || {
+            scope.spawn(move |_scope| {
                 // Shuffle into a sub-FFT
                 let omega_j = omega.pow(&[j as u64]);
                 let omega_step = omega.pow(&[(j as u64) << log_new_n]);
 
                 let mut elt = E::Fr::one();
-                for i in 0..(1 << log_new_n) {
+                for (i, tmp) in tmp.iter_mut().enumerate() {
                     for s in 0..num_cpus {
                         let idx = (i + (s << log_new_n)) % (1 << log_n);
                         let mut t = a[idx];
                         t.group_mul_assign(&elt);
-                        tmp[i].group_add_assign(&t);
+                        tmp.group_add_assign(&t);
                         elt.mul_assign(&omega_step);
                     }
                     elt.mul_assign(&omega_j);
@@ -359,7 +364,7 @@ fn parallel_fft<E: ScalarEngine, T: Group<E>>(
         let tmp = &tmp;
 
         for (idx, a) in a.chunks_mut(chunk).enumerate() {
-            scope.spawn(move || {
+            scope.spawn(move |_scope| {
                 let mut idx = idx * chunk;
                 let mask = (1 << log_cpus) - 1;
                 for a in a {

bellman/src/gadgets.rs

@@ -1,3 +1,5 @@
+//! Self-contained sub-circuit implementations for various primitives.
+
 pub mod test;
 
 pub mod blake2s;

bellman/src/gadgets/blake2s.rs

@@ -1,12 +1,10 @@
-use pairing::Engine;
+//! The [BLAKE2s] hash function with personalization support.
+//!
+//! [BLAKE2s]: https://tools.ietf.org/html/rfc7693
 
+use super::{boolean::Boolean, multieq::MultiEq, uint32::UInt32};
 use crate::{ConstraintSystem, SynthesisError};
-
-use super::boolean::Boolean;
-
-use super::uint32::UInt32;
-
-use super::multieq::MultiEq;
+use ff::ScalarEngine;
 
 /*
 2.1.  Parameters
@@ -81,7 +79,7 @@ const SIGMA: [[usize; 16]; 10] = [
        END FUNCTION.
 */
 
-fn mixing_g<E: Engine, CS: ConstraintSystem<E>, M>(
+fn mixing_g<E: ScalarEngine, CS: ConstraintSystem<E>, M>(
     mut cs: M,
     v: &mut [UInt32],
     a: usize,
@@ -166,7 +164,7 @@ where
        END FUNCTION.
 */
 
-fn blake2s_compression<E: Engine, CS: ConstraintSystem<E>>(
+fn blake2s_compression<E: ScalarEngine, CS: ConstraintSystem<E>>(
     mut cs: CS,
     h: &mut [UInt32],
     m: &[UInt32],
@@ -339,7 +337,7 @@ fn blake2s_compression<E: Engine, CS: ConstraintSystem<E>>(
         END FUNCTION.
 */
 
-pub fn blake2s<E: Engine, CS: ConstraintSystem<E>>(
+pub fn blake2s<E: ScalarEngine, CS: ConstraintSystem<E>>(
     mut cs: CS,
     input: &[Boolean],
     personalization: &[u8],
@@ -382,7 +380,7 @@ pub fn blake2s<E: Engine, CS: ConstraintSystem<E>>(
         blocks.push(this_block);
     }
 
-    if blocks.len() == 0 {
+    if blocks.is_empty() {
         blocks.push((0..16).map(|_| UInt32::constant(0)).collect());
     }
 
@@ -404,12 +402,13 @@ pub fn blake2s<E: Engine, CS: ConstraintSystem<E>>(
         )?;
     }
 
-    Ok(h.iter().flat_map(|b| b.into_bits()).collect())
+    Ok(h.into_iter().flat_map(|b| b.into_bits()).collect())
 }
 
 #[cfg(test)]
 mod test {
     use blake2s_simd::Params as Blake2sParams;
+    use hex_literal::hex;
     use pairing::bls12_381::Bls12;
     use rand_core::{RngCore, SeedableRng};
     use rand_xorshift::XorShiftRng;
@@ -433,7 +432,7 @@ mod test {
         let expected = hex!("c59f682376d137f3f255e671e207d1f2374ebe504e9314208a52d9f88d69e8c8");
 
         let mut out = out.into_iter();
-        for b in expected.into_iter() {
+        for b in expected.iter() {
             for i in 0..8 {
                 let c = out.next().unwrap().get_value().unwrap();
 
@@ -554,4 +553,145 @@ mod test {
             }
         }
     }
+
+    #[test]
+    fn test_blake2s_256_vars() {
+        let data: Vec<u8> = hex!("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").to_vec();
+        assert_eq!(data.len(), 256);
+
+        let mut cs = TestConstraintSystem::<Bls12>::new();
+
+        let mut input_bits = vec![];
+
+        for (byte_i, input_byte) in data.into_iter().enumerate() {
+            for bit_i in 0..8 {
+                let cs = cs.namespace(|| format!("input bit {} {}", byte_i, bit_i));
+
+                input_bits.push(
+                    AllocatedBit::alloc(cs, Some((input_byte >> bit_i) & 1u8 == 1u8))
+                        .unwrap()
+                        .into(),
+                );
+            }
+        }
+
+        let r = blake2s(&mut cs, &input_bits, b"12345678").unwrap();
+
+        assert!(cs.is_satisfied());
+
+        let expected = hex!("0af5695115ced92c8a0341e43869209636e9aa6472e4576f0f2b996cf812b30e");
+
+        let mut out = r.into_iter();
+        for b in expected.iter() {
+            for i in 0..8 {
+                let c = out.next().unwrap().get_value().unwrap();
+
+                assert_eq!(c, (b >> i) & 1u8 == 1u8);
+            }
+        }
+    }
+
+    #[test]
+    fn test_blake2s_700_vars() {
+        let data: Vec<u8> = hex!("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").to_vec();
+        assert_eq!(data.len(), 700);
+
+        let mut cs = TestConstraintSystem::<Bls12>::new();
+
+        let mut input_bits = vec![];
+
+        for (byte_i, input_byte) in data.into_iter().enumerate() {
+            for bit_i in 0..8 {
+                let cs = cs.namespace(|| format!("input bit {} {}", byte_i, bit_i));
+
+                input_bits.push(
+                    AllocatedBit::alloc(cs, Some((input_byte >> bit_i) & 1u8 == 1u8))
+                        .unwrap()
+                        .into(),
+                );
+            }
+        }
+
+        let r = blake2s(&mut cs, &input_bits, b"12345678").unwrap();
+
+        assert!(cs.is_satisfied());
+
+        let expected = hex!("2ab8f0683167ba220eef19dccf4f9b1a8193cc09b35e0235842323950530f18a");
+
+        let mut out = r.into_iter();
+        for b in expected.iter() {
+            for i in 0..8 {
+                let c = out.next().unwrap().get_value().unwrap();
+
+                assert_eq!(c, (b >> i) & 1u8 == 1u8);
+            }
+        }
+    }
+
+    #[test]
+    fn test_blake2s_test_vectors() {
+        let mut rng = XorShiftRng::from_seed([
+            0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06,
+            0xbc, 0xe5,
+        ]);
+
+        let expecteds = [
+            hex!("a1309e334376c8f36a736a4ab0e691ef931ee3ebdb9ea96187127136fea622a1"),
+            hex!("82fefff60f265cea255252f7c194a7f93965dffee0609ef74eb67f0d76cd41c6"),
+        ];
+        for i in 0..2 {
+            let mut h = Blake2sParams::new()
+                .hash_length(32)
+                .personal(b"12345678")
+                .to_state();
+            let input_len = 1024;
+            let data: Vec<u8> = (0..input_len).map(|_| rng.next_u32() as u8).collect();
+
+            h.update(&data);
+
+            let hash_result = h.finalize();
+
+            let mut cs = TestConstraintSystem::<Bls12>::new();
+
+            let mut input_bits = vec![];
+
+            for (byte_i, input_byte) in data.into_iter().enumerate() {
+                for bit_i in 0..8 {
+                    let cs = cs.namespace(|| format!("input bit {} {}", byte_i, bit_i));
+
+                    input_bits.push(
+                        AllocatedBit::alloc(cs, Some((input_byte >> bit_i) & 1u8 == 1u8))
+                            .unwrap()
+                            .into(),
+                    );
+                }
+            }
+
+            let r = blake2s(&mut cs, &input_bits, b"12345678").unwrap();
+
+            assert!(cs.is_satisfied());
+
+            let mut s = hash_result
+                .as_ref()
+                .iter()
+                .flat_map(|&byte| (0..8).map(move |i| (byte >> i) & 1u8 == 1u8));
+
+            for b in r {
+                match b {
+                    Boolean::Is(b) => {
+                        assert!(s.next().unwrap() == b.get_value().unwrap());
+                    }
+                    Boolean::Not(b) => {
+                        assert!(s.next().unwrap() != b.get_value().unwrap());
+                    }
+                    Boolean::Constant(b) => {
+                        assert!(input_len == 0);
+                        assert!(s.next().unwrap() == b);
+                    }
+                }
+            }
+
+            assert_eq!(expecteds[i], hash_result.as_bytes());
+        }
+    }
 }

bellman/src/gadgets/boolean.rs

@@ -1,5 +1,6 @@
-use ff::{BitIterator, Field, PrimeField};
-use pairing::Engine;
+//! Gadgets for allocating bits in the circuit and performing boolean logic.
+
+use ff::{BitIterator, Field, PrimeField, ScalarEngine};
 
 use crate::{ConstraintSystem, LinearCombination, SynthesisError, Variable};
 
@@ -31,7 +32,7 @@ impl AllocatedBit {
         must_be_false: &AllocatedBit,
     ) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         let var = cs.alloc(
@@ -60,7 +61,7 @@ impl AllocatedBit {
 
         Ok(AllocatedBit {
             variable: var,
-            value: value,
+            value,
         })
     }
 
@@ -68,7 +69,7 @@ impl AllocatedBit {
     /// boolean value.
     pub fn alloc<E, CS>(mut cs: CS, value: Option<bool>) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         let var = cs.alloc(
@@ -93,7 +94,7 @@ impl AllocatedBit {
 
         Ok(AllocatedBit {
             variable: var,
-            value: value,
+            value,
         })
     }
 
@@ -101,7 +102,7 @@ impl AllocatedBit {
     /// an `AllocatedBit`.
     pub fn xor<E, CS>(mut cs: CS, a: &Self, b: &Self) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         let mut result_value = None;
@@ -153,7 +154,7 @@ impl AllocatedBit {
     /// an `AllocatedBit`.
     pub fn and<E, CS>(mut cs: CS, a: &Self, b: &Self) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         let mut result_value = None;
@@ -191,7 +192,7 @@ impl AllocatedBit {
     /// Calculates `a AND (NOT b)`.
     pub fn and_not<E, CS>(mut cs: CS, a: &Self, b: &Self) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         let mut result_value = None;
@@ -229,7 +230,7 @@ impl AllocatedBit {
     /// Calculates `(NOT a) AND (NOT b)`.
     pub fn nor<E, CS>(mut cs: CS, a: &Self, b: &Self) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         let mut result_value = None;
@@ -265,7 +266,7 @@ impl AllocatedBit {
     }
 }
 
-pub fn u64_into_boolean_vec_le<E: Engine, CS: ConstraintSystem<E>>(
+pub fn u64_into_boolean_vec_le<E: ScalarEngine, CS: ConstraintSystem<E>>(
     mut cs: CS,
     value: Option<u64>,
 ) -> Result<Vec<Boolean>, SynthesisError> {
@@ -296,16 +297,16 @@ pub fn u64_into_boolean_vec_le<E: Engine, CS: ConstraintSystem<E>>(
     Ok(bits)
 }
 
-pub fn field_into_boolean_vec_le<E: Engine, CS: ConstraintSystem<E>, F: PrimeField>(
+pub fn field_into_boolean_vec_le<E: ScalarEngine, CS: ConstraintSystem<E>, F: PrimeField>(
     cs: CS,
     value: Option<F>,
 ) -> Result<Vec<Boolean>, SynthesisError> {
     let v = field_into_allocated_bits_le::<E, CS, F>(cs, value)?;
 
-    Ok(v.into_iter().map(|e| Boolean::from(e)).collect())
+    Ok(v.into_iter().map(Boolean::from).collect())
 }
 
-pub fn field_into_allocated_bits_le<E: Engine, CS: ConstraintSystem<E>, F: PrimeField>(
+pub fn field_into_allocated_bits_le<E: ScalarEngine, CS: ConstraintSystem<E>, F: PrimeField>(
     mut cs: CS,
     value: Option<F>,
 ) -> Result<Vec<AllocatedBit>, SynthesisError> {
@@ -367,7 +368,7 @@ impl Boolean {
 
     pub fn enforce_equal<E, CS>(mut cs: CS, a: &Self, b: &Self) -> Result<(), SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         match (a, b) {
@@ -412,24 +413,24 @@ impl Boolean {
     }
 
     pub fn get_value(&self) -> Option<bool> {
-        match self {
-            &Boolean::Constant(c) => Some(c),
-            &Boolean::Is(ref v) => v.get_value(),
-            &Boolean::Not(ref v) => v.get_value().map(|b| !b),
+        match *self {
+            Boolean::Constant(c) => Some(c),
+            Boolean::Is(ref v) => v.get_value(),
+            Boolean::Not(ref v) => v.get_value().map(|b| !b),
         }
     }
 
-    pub fn lc<E: Engine>(&self, one: Variable, coeff: E::Fr) -> LinearCombination<E> {
-        match self {
-            &Boolean::Constant(c) => {
+    pub fn lc<E: ScalarEngine>(&self, one: Variable, coeff: E::Fr) -> LinearCombination<E> {
+        match *self {
+            Boolean::Constant(c) => {
                 if c {
                     LinearCombination::<E>::zero() + (coeff, one)
                 } else {
                     LinearCombination::<E>::zero()
                 }
             }
-            &Boolean::Is(ref v) => LinearCombination::<E>::zero() + (coeff, v.get_variable()),
-            &Boolean::Not(ref v) => {
+            Boolean::Is(ref v) => LinearCombination::<E>::zero() + (coeff, v.get_variable()),
+            Boolean::Not(ref v) => {
                 LinearCombination::<E>::zero() + (coeff, one) - (coeff, v.get_variable())
             }
         }
@@ -442,17 +443,17 @@ impl Boolean {
 
     /// Return a negated interpretation of this boolean.
     pub fn not(&self) -> Self {
-        match self {
-            &Boolean::Constant(c) => Boolean::Constant(!c),
-            &Boolean::Is(ref v) => Boolean::Not(v.clone()),
-            &Boolean::Not(ref v) => Boolean::Is(v.clone()),
+        match *self {
+            Boolean::Constant(c) => Boolean::Constant(!c),
+            Boolean::Is(ref v) => Boolean::Not(v.clone()),
+            Boolean::Not(ref v) => Boolean::Is(v.clone()),
         }
     }
 
     /// Perform XOR over two boolean operands
     pub fn xor<'a, E, CS>(cs: CS, a: &'a Self, b: &'a Self) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         match (a, b) {
@@ -474,7 +475,7 @@ impl Boolean {
     /// Perform AND over two boolean operands
     pub fn and<'a, E, CS>(cs: CS, a: &'a Self, b: &'a Self) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         match (a, b) {
@@ -508,7 +509,7 @@ impl Boolean {
         c: &'a Self,
     ) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         let ch_value = match (a.get_value(), b.get_value(), c.get_value()) {
@@ -615,7 +616,7 @@ impl Boolean {
         c: &'a Self,
     ) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         let maj_value = match (a.get_value(), b.get_value(), c.get_value()) {
@@ -1740,4 +1741,72 @@ mod test {
             }
         }
     }
+
+    #[test]
+    fn test_alloc_conditionally() {
+        {
+            let mut cs = TestConstraintSystem::<Bls12>::new();
+            let b = AllocatedBit::alloc(&mut cs, Some(false)).unwrap();
+
+            let value = None;
+            // if value is none, fail with SynthesisError
+            let is_err = AllocatedBit::alloc_conditionally(
+                cs.namespace(|| "alloc_conditionally"),
+                value,
+                &b,
+            )
+            .is_err();
+            assert!(is_err);
+        }
+
+        {
+            // since value is true, b must be false, so it should succeed
+            let mut cs = TestConstraintSystem::<Bls12>::new();
+
+            let value = Some(true);
+            let b = AllocatedBit::alloc(&mut cs, Some(false)).unwrap();
+            let allocated_value = AllocatedBit::alloc_conditionally(
+                cs.namespace(|| "alloc_conditionally"),
+                value,
+                &b,
+            )
+            .unwrap();
+
+            assert_eq!(allocated_value.get_value().unwrap(), true);
+            assert!(cs.is_satisfied());
+        }
+
+        {
+            // since value is true, b must be false, so it should fail
+            let mut cs = TestConstraintSystem::<Bls12>::new();
+
+            let value = Some(true);
+            let b = AllocatedBit::alloc(&mut cs, Some(true)).unwrap();
+            AllocatedBit::alloc_conditionally(cs.namespace(|| "alloc_conditionally"), value, &b)
+                .unwrap();
+
+            assert!(!cs.is_satisfied());
+        }
+
+        {
+            // since value is false, we don't care about the value of the bit
+
+            let value = Some(false);
+            //check with false bit
+            let mut cs = TestConstraintSystem::<Bls12>::new();
+            let b1 = AllocatedBit::alloc(&mut cs, Some(false)).unwrap();
+            AllocatedBit::alloc_conditionally(cs.namespace(|| "alloc_conditionally"), value, &b1)
+                .unwrap();
+
+            assert!(cs.is_satisfied());
+
+            //check with true bit
+            let mut cs = TestConstraintSystem::<Bls12>::new();
+            let b2 = AllocatedBit::alloc(&mut cs, Some(true)).unwrap();
+            AllocatedBit::alloc_conditionally(cs.namespace(|| "alloc_conditionally"), value, &b2)
+                .unwrap();
+
+            assert!(cs.is_satisfied());
+        }
+    }
 }

bellman/src/gadgets/lookup.rs

@@ -1,5 +1,6 @@
-use ff::Field;
-use pairing::Engine;
+//! Window table lookup gadgets.
+
+use ff::{Field, ScalarEngine};
 
 use super::boolean::Boolean;
 use super::num::{AllocatedNum, Num};
@@ -7,7 +8,7 @@ use super::*;
 use crate::ConstraintSystem;
 
 // Synthesize the constants for each base pattern.
-fn synth<'a, E: Engine, I>(window_size: usize, constants: I, assignment: &mut [E::Fr])
+fn synth<'a, E: ScalarEngine, I>(window_size: usize, constants: I, assignment: &mut [E::Fr])
 where
     I: IntoIterator<Item = &'a E::Fr>,
 {
@@ -28,7 +29,7 @@ where
 
 /// Performs a 3-bit window table lookup. `bits` is in
 /// little-endian order.
-pub fn lookup3_xy<E: Engine, CS>(
+pub fn lookup3_xy<E: ScalarEngine, CS>(
     mut cs: CS,
     bits: &[Boolean],
     coords: &[(E::Fr, E::Fr)],
@@ -118,7 +119,7 @@ where
 
 /// Performs a 3-bit window table lookup, where
 /// one of the bits is a sign bit.
-pub fn lookup3_xy_with_conditional_negation<E: Engine, CS>(
+pub fn lookup3_xy_with_conditional_negation<E: ScalarEngine, CS>(
     mut cs: CS,
     bits: &[Boolean],
     coords: &[(E::Fr, E::Fr)],

bellman/src/gadgets/multieq.rs

@@ -1,9 +1,8 @@
-use ff::{Field, PrimeField};
-use pairing::Engine;
+use ff::{Field, PrimeField, ScalarEngine};
 
 use crate::{ConstraintSystem, LinearCombination, SynthesisError, Variable};
 
-pub struct MultiEq<E: Engine, CS: ConstraintSystem<E>> {
+pub struct MultiEq<E: ScalarEngine, CS: ConstraintSystem<E>> {
     cs: CS,
     ops: usize,
     bits_used: usize,
@@ -11,10 +10,10 @@ pub struct MultiEq<E: Engine, CS: ConstraintSystem<E>> {
     rhs: LinearCombination<E>,
 }
 
-impl<E: Engine, CS: ConstraintSystem<E>> MultiEq<E, CS> {
+impl<E: ScalarEngine, CS: ConstraintSystem<E>> MultiEq<E, CS> {
     pub fn new(cs: CS) -> Self {
         MultiEq {
-            cs: cs,
+            cs,
             ops: 0,
             bits_used: 0,
             lhs: LinearCombination::zero(),
@@ -58,7 +57,7 @@ impl<E: Engine, CS: ConstraintSystem<E>> MultiEq<E, CS> {
     }
 }
 
-impl<E: Engine, CS: ConstraintSystem<E>> Drop for MultiEq<E, CS> {
+impl<E: ScalarEngine, CS: ConstraintSystem<E>> Drop for MultiEq<E, CS> {
     fn drop(&mut self) {
         if self.bits_used > 0 {
             self.accumulate();
@@ -66,7 +65,7 @@ impl<E: Engine, CS: ConstraintSystem<E>> Drop for MultiEq<E, CS> {
     }
 }
 
-impl<E: Engine, CS: ConstraintSystem<E>> ConstraintSystem<E> for MultiEq<E, CS> {
+impl<E: ScalarEngine, CS: ConstraintSystem<E>> ConstraintSystem<E> for MultiEq<E, CS> {
     type Root = Self;
 
     fn one() -> Variable {

bellman/src/gadgets/multipack.rs

@@ -1,15 +1,16 @@
+//! Helpers for packing vectors of bits into scalar field elements.
+
 use super::boolean::Boolean;
 use super::num::Num;
 use super::Assignment;
 use crate::{ConstraintSystem, SynthesisError};
-use ff::{Field, PrimeField};
-use pairing::Engine;
+use ff::{Field, PrimeField, ScalarEngine};
 
 /// Takes a sequence of booleans and exposes them as compact
 /// public inputs
 pub fn pack_into_inputs<E, CS>(mut cs: CS, bits: &[Boolean]) -> Result<(), SynthesisError>
 where
-    E: Engine,
+    E: ScalarEngine,
     CS: ConstraintSystem<E>,
 {
     for (i, bits) in bits.chunks(E::Fr::CAPACITY as usize).enumerate() {
@@ -49,7 +50,7 @@ pub fn bytes_to_bits_le(bytes: &[u8]) -> Vec<bool> {
         .collect()
 }
 
-pub fn compute_multipacking<E: Engine>(bits: &[bool]) -> Vec<E::Fr> {
+pub fn compute_multipacking<E: ScalarEngine>(bits: &[bool]) -> Vec<E::Fr> {
     let mut result = vec![];
 
     for bits in bits.chunks(E::Fr::CAPACITY as usize) {

bellman/src/gadgets/num.rs

@@ -1,5 +1,6 @@
-use ff::{BitIterator, Field, PrimeField, PrimeFieldRepr};
-use pairing::Engine;
+//! Gadgets representing numbers in the scalar field of the underlying curve.
+
+use ff::{BitIterator, Field, PrimeField, PrimeFieldRepr, ScalarEngine};
 
 use crate::{ConstraintSystem, LinearCombination, SynthesisError, Variable};
 
@@ -7,12 +8,12 @@ use super::Assignment;
 
 use super::boolean::{self, AllocatedBit, Boolean};
 
-pub struct AllocatedNum<E: Engine> {
+pub struct AllocatedNum<E: ScalarEngine> {
     value: Option<E::Fr>,
     variable: Variable,
 }
 
-impl<E: Engine> Clone for AllocatedNum<E> {
+impl<E: ScalarEngine> Clone for AllocatedNum<E> {
     fn clone(&self) -> Self {
         AllocatedNum {
             value: self.value,
@@ -21,7 +22,7 @@ impl<E: Engine> Clone for AllocatedNum<E> {
     }
 }
 
-impl<E: Engine> AllocatedNum<E> {
+impl<E: ScalarEngine> AllocatedNum<E> {
     pub fn alloc<CS, F>(mut cs: CS, value: F) -> Result<Self, SynthesisError>
     where
         CS: ConstraintSystem<E>,
@@ -66,7 +67,7 @@ impl<E: Engine> AllocatedNum<E> {
     /// order, requiring that the representation
     /// strictly exists "in the field" (i.e., a
     /// congruency is not allowed.)
-    pub fn into_bits_le_strict<CS>(&self, mut cs: CS) -> Result<Vec<Boolean>, SynthesisError>
+    pub fn to_bits_le_strict<CS>(&self, mut cs: CS) -> Result<Vec<Boolean>, SynthesisError>
     where
         CS: ConstraintSystem<E>,
     {
@@ -75,10 +76,10 @@ impl<E: Engine> AllocatedNum<E> {
             v: &[AllocatedBit],
         ) -> Result<AllocatedBit, SynthesisError>
         where
-            E: Engine,
+            E: ScalarEngine,
             CS: ConstraintSystem<E>,
         {
-            assert!(v.len() > 0);
+            assert!(!v.is_empty());
 
             // Let's keep this simple for now and just AND them all
             // manually
@@ -132,7 +133,7 @@ impl<E: Engine> AllocatedNum<E> {
                 current_run.push(a_bit.clone());
                 result.push(a_bit);
             } else {
-                if current_run.len() > 0 {
+                if !current_run.is_empty() {
                     // This is the start of a run of zeros, but we need
                     // to k-ary AND against `last_run` first.
 
@@ -183,13 +184,13 @@ impl<E: Engine> AllocatedNum<E> {
         cs.enforce(|| "unpacking constraint", |lc| lc, |lc| lc, |_| lc);
 
         // Convert into booleans, and reverse for little-endian bit order
-        Ok(result.into_iter().map(|b| Boolean::from(b)).rev().collect())
+        Ok(result.into_iter().map(Boolean::from).rev().collect())
     }
 
     /// Convert the allocated number into its little-endian representation.
     /// Note that this does not strongly enforce that the commitment is
     /// "in the field."
-    pub fn into_bits_le<CS>(&self, mut cs: CS) -> Result<Vec<Boolean>, SynthesisError>
+    pub fn to_bits_le<CS>(&self, mut cs: CS) -> Result<Vec<Boolean>, SynthesisError>
     where
         CS: ConstraintSystem<E>,
     {
@@ -208,7 +209,7 @@ impl<E: Engine> AllocatedNum<E> {
 
         cs.enforce(|| "unpacking constraint", |lc| lc, |lc| lc, |_| lc);
 
-        Ok(bits.into_iter().map(|b| Boolean::from(b)).collect())
+        Ok(bits.into_iter().map(Boolean::from).collect())
     }
 
     pub fn mul<CS>(&self, mut cs: CS, other: &Self) -> Result<Self, SynthesisError>
@@ -238,7 +239,7 @@ impl<E: Engine> AllocatedNum<E> {
         );
 
         Ok(AllocatedNum {
-            value: value,
+            value,
             variable: var,
         })
     }
@@ -270,7 +271,7 @@ impl<E: Engine> AllocatedNum<E> {
         );
 
         Ok(AllocatedNum {
-            value: value,
+            value,
             variable: var,
         })
     }
@@ -359,12 +360,12 @@ impl<E: Engine> AllocatedNum<E> {
     }
 }
 
-pub struct Num<E: Engine> {
+pub struct Num<E: ScalarEngine> {
     value: Option<E::Fr>,
     lc: LinearCombination<E>,
 }
 
-impl<E: Engine> From<AllocatedNum<E>> for Num<E> {
+impl<E: ScalarEngine> From<AllocatedNum<E>> for Num<E> {
     fn from(num: AllocatedNum<E>) -> Num<E> {
         Num {
             value: num.value,
@@ -373,7 +374,7 @@ impl<E: Engine> From<AllocatedNum<E>> for Num<E> {
     }
 }
 
-impl<E: Engine> Num<E> {
+impl<E: ScalarEngine> Num<E> {
     pub fn zero() -> Self {
         Num {
             value: Some(E::Fr::zero()),
@@ -522,7 +523,7 @@ mod test {
         let mut cs = TestConstraintSystem::<Bls12>::new();
 
         let n = AllocatedNum::alloc(&mut cs, || Ok(negone)).unwrap();
-        n.into_bits_le_strict(&mut cs).unwrap();
+        n.to_bits_le_strict(&mut cs).unwrap();
 
         assert!(cs.is_satisfied());
 
@@ -550,9 +551,9 @@ mod test {
             let n = AllocatedNum::alloc(&mut cs, || Ok(r)).unwrap();
 
             let bits = if i % 2 == 0 {
-                n.into_bits_le(&mut cs).unwrap()
+                n.to_bits_le(&mut cs).unwrap()
             } else {
-                n.into_bits_le_strict(&mut cs).unwrap()
+                n.to_bits_le_strict(&mut cs).unwrap()
             };
 
             assert!(cs.is_satisfied());

bellman/src/gadgets/sha256.rs

@@ -1,9 +1,15 @@
+//! Circuits for the [SHA-256] hash function and its internal compression
+//! function.
+//!
+//! [SHA-256]: https://tools.ietf.org/html/rfc6234
+
 use super::boolean::Boolean;
 use super::multieq::MultiEq;
 use super::uint32::UInt32;
 use crate::{ConstraintSystem, SynthesisError};
-use pairing::Engine;
+use ff::ScalarEngine;
 
+#[allow(clippy::unreadable_literal)]
 const ROUND_CONSTANTS: [u32; 64] = [
     0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
     0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
@@ -15,6 +21,7 @@ const ROUND_CONSTANTS: [u32; 64] = [
     0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
 ];
 
+#[allow(clippy::unreadable_literal)]
 const IV: [u32; 8] = [
     0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19,
 ];
@@ -24,7 +31,7 @@ pub fn sha256_block_no_padding<E, CS>(
     input: &[Boolean],
 ) -> Result<Vec<Boolean>, SynthesisError>
 where
-    E: Engine,
+    E: ScalarEngine,
     CS: ConstraintSystem<E>,
 {
     assert_eq!(input.len(), 512);
@@ -39,7 +46,7 @@ where
 
 pub fn sha256<E, CS>(mut cs: CS, input: &[Boolean]) -> Result<Vec<Boolean>, SynthesisError>
 where
-    E: Engine,
+    E: ScalarEngine,
     CS: ConstraintSystem<E>,
 {
     assert!(input.len() % 8 == 0);
@@ -76,7 +83,7 @@ fn sha256_compression_function<E, CS>(
     current_hash_value: &[UInt32],
 ) -> Result<Vec<UInt32>, SynthesisError>
 where
-    E: Engine,
+    E: ScalarEngine,
     CS: ConstraintSystem<E>,
 {
     assert_eq!(input.len(), 512);
@@ -123,14 +130,14 @@ where
     impl Maybe {
         fn compute<E, CS, M>(self, cs: M, others: &[UInt32]) -> Result<UInt32, SynthesisError>
         where
-            E: Engine,
+            E: ScalarEngine,
             CS: ConstraintSystem<E>,
             M: ConstraintSystem<E, Root = MultiEq<E, CS>>,
         {
             Ok(match self {
                 Maybe::Concrete(ref v) => return Ok(v.clone()),
                 Maybe::Deferred(mut v) => {
-                    v.extend(others.into_iter().cloned());
+                    v.extend(others.iter().cloned());
                     UInt32::addmany(cs, &v)?
                 }
             })
@@ -266,6 +273,7 @@ mod test {
     use super::*;
     use crate::gadgets::boolean::AllocatedBit;
     use crate::gadgets::test::TestConstraintSystem;
+    use hex_literal::hex;
     use pairing::bls12_381::Bls12;
     use rand_core::{RngCore, SeedableRng};
     use rand_xorshift::XorShiftRng;
@@ -286,7 +294,7 @@ mod test {
         let expected = hex!("e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855");
 
         let mut out = out_bits.into_iter();
-        for b in expected.into_iter() {
+        for b in expected.iter() {
             for i in (0..8).rev() {
                 let c = out.next().unwrap().get_value().unwrap();
 

bellman/src/gadgets/test/mod.rs

@@ -1,5 +1,6 @@
-use ff::{Field, PrimeField, PrimeFieldRepr};
-use pairing::Engine;
+//! Helpers for testing circuit implementations.
+
+use ff::{Field, PrimeField, PrimeFieldRepr, ScalarEngine};
 
 use crate::{ConstraintSystem, Index, LinearCombination, SynthesisError, Variable};
 
@@ -20,7 +21,7 @@ enum NamedObject {
 }
 
 /// Constraint system for testing purposes.
-pub struct TestConstraintSystem<E: Engine> {
+pub struct TestConstraintSystem<E: ScalarEngine> {
     named_objects: HashMap<String, NamedObject>,
     current_namespace: Vec<String>,
     constraints: Vec<(
@@ -62,11 +63,11 @@ impl Ord for OrderedVariable {
     }
 }
 
-fn proc_lc<E: Engine>(terms: &[(Variable, E::Fr)]) -> BTreeMap<OrderedVariable, E::Fr> {
+fn proc_lc<E: ScalarEngine>(terms: &[(Variable, E::Fr)]) -> BTreeMap<OrderedVariable, E::Fr> {
     let mut map = BTreeMap::new();
     for &(var, coeff) in terms {
         map.entry(OrderedVariable(var))
-            .or_insert(E::Fr::zero())
+            .or_insert_with(E::Fr::zero)
             .add_assign(&coeff);
     }
 
@@ -85,7 +86,7 @@ fn proc_lc<E: Engine>(terms: &[(Variable, E::Fr)]) -> BTreeMap<OrderedVariable,
     map
 }
 
-fn hash_lc<E: Engine>(terms: &[(Variable, E::Fr)], h: &mut Blake2sState) {
+fn hash_lc<E: ScalarEngine>(terms: &[(Variable, E::Fr)], h: &mut Blake2sState) {
     let map = proc_lc::<E>(terms);
 
     let mut buf = [0u8; 9 + 32];
@@ -110,7 +111,7 @@ fn hash_lc<E: Engine>(terms: &[(Variable, E::Fr)], h: &mut Blake2sState) {
     }
 }
 
-fn eval_lc<E: Engine>(
+fn eval_lc<E: ScalarEngine>(
     terms: &[(Variable, E::Fr)],
     inputs: &[(E::Fr, String)],
     aux: &[(E::Fr, String)],
@@ -130,7 +131,7 @@ fn eval_lc<E: Engine>(
     acc
 }
 
-impl<E: Engine> TestConstraintSystem<E> {
+impl<E: ScalarEngine> TestConstraintSystem<E> {
     pub fn new() -> TestConstraintSystem<E> {
         let mut map = HashMap::new();
         map.insert(
@@ -157,7 +158,7 @@ impl<E: Engine> TestConstraintSystem<E> {
         };
 
         let powers_of_two = (0..E::Fr::NUM_BITS)
-            .map(|i| E::Fr::from_str("2").unwrap().pow(&[i as u64]))
+            .map(|i| E::Fr::from_str("2").unwrap().pow(&[u64::from(i)]))
             .collect::<Vec<_>>();
 
         let pp = |s: &mut String, lc: &LinearCombination<E>| {
@@ -286,7 +287,7 @@ impl<E: Engine> TestConstraintSystem<E> {
             }
         }
 
-        return true;
+        true
     }
 
     pub fn num_inputs(&self) -> usize {
@@ -344,7 +345,7 @@ fn compute_path(ns: &[String], this: String) -> String {
     name
 }
 
-impl<E: Engine> ConstraintSystem<E> for TestConstraintSystem<E> {
+impl<E: ScalarEngine> ConstraintSystem<E> for TestConstraintSystem<E> {
     type Root = Self;
 
     fn alloc<F, A, AR>(&mut self, annotation: A, f: F) -> Result<Variable, SynthesisError>

bellman/src/gadgets/uint32.rs

@@ -1,5 +1,9 @@
-use ff::{Field, PrimeField};
-use pairing::Engine;
+//! Circuit representation of a [`u32`], with helpers for the [`sha256`]
+//! gadgets.
+//!
+//! [`sha256`]: crate::gadgets::sha256
+
+use ff::{Field, PrimeField, ScalarEngine};
 
 use crate::{ConstraintSystem, LinearCombination, SynthesisError};
 
@@ -33,7 +37,7 @@ impl UInt32 {
         }
 
         UInt32 {
-            bits: bits,
+            bits,
             value: Some(value),
         }
     }
@@ -41,7 +45,7 @@ impl UInt32 {
     /// Allocate a `UInt32` in the constraint system
     pub fn alloc<E, CS>(mut cs: CS, value: Option<u32>) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         let values = match value {
@@ -69,14 +73,13 @@ impl UInt32 {
             })
             .collect::<Result<Vec<_>, SynthesisError>>()?;
 
-        Ok(UInt32 {
-            bits: bits,
-            value: value,
-        })
+        Ok(UInt32 { bits, value })
     }
 
-    pub fn into_bits_be(&self) -> Vec<Boolean> {
-        self.bits.iter().rev().cloned().collect()
+    pub fn into_bits_be(self) -> Vec<Boolean> {
+        let mut ret = self.bits;
+        ret.reverse();
+        ret
     }
 
     pub fn from_bits_be(bits: &[Boolean]) -> Self {
@@ -98,14 +101,14 @@ impl UInt32 {
         }
 
         UInt32 {
-            value: value,
+            value,
             bits: bits.iter().rev().cloned().collect(),
         }
     }
 
     /// Turns this `UInt32` into its little-endian byte order representation.
-    pub fn into_bits(&self) -> Vec<Boolean> {
-        self.bits.clone()
+    pub fn into_bits(self) -> Vec<Boolean> {
+        self.bits
     }
 
     /// Converts a little-endian byte order representation of bits into a
@@ -119,20 +122,20 @@ impl UInt32 {
         for b in new_bits.iter().rev() {
             value.as_mut().map(|v| *v <<= 1);
 
-            match b {
-                &Boolean::Constant(b) => {
+            match *b {
+                Boolean::Constant(b) => {
                     if b {
                         value.as_mut().map(|v| *v |= 1);
                     }
                 }
-                &Boolean::Is(ref b) => match b.get_value() {
+                Boolean::Is(ref b) => match b.get_value() {
                     Some(true) => {
                         value.as_mut().map(|v| *v |= 1);
                     }
                     Some(false) => {}
                     None => value = None,
                 },
-                &Boolean::Not(ref b) => match b.get_value() {
+                Boolean::Not(ref b) => match b.get_value() {
                     Some(false) => {
                         value.as_mut().map(|v| *v |= 1);
                     }
@@ -143,7 +146,7 @@ impl UInt32 {
         }
 
         UInt32 {
-            value: value,
+            value,
             bits: new_bits,
         }
     }
@@ -195,7 +198,7 @@ impl UInt32 {
         circuit_fn: U,
     ) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
         F: Fn(u32, u32, u32) -> u32,
         U: Fn(&mut CS, usize, &Boolean, &Boolean, &Boolean) -> Result<Boolean, SynthesisError>,
@@ -215,7 +218,7 @@ impl UInt32 {
             .collect::<Result<_, _>>()?;
 
         Ok(UInt32 {
-            bits: bits,
+            bits,
             value: new_value,
         })
     }
@@ -224,7 +227,7 @@ impl UInt32 {
     /// during SHA256.
     pub fn sha256_maj<E, CS>(cs: CS, a: &Self, b: &Self, c: &Self) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         Self::triop(
@@ -241,7 +244,7 @@ impl UInt32 {
     /// during SHA256.
     pub fn sha256_ch<E, CS>(cs: CS, a: &Self, b: &Self, c: &Self) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         Self::triop(
@@ -257,7 +260,7 @@ impl UInt32 {
     /// XOR this `UInt32` with another `UInt32`
     pub fn xor<E, CS>(&self, mut cs: CS, other: &Self) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
     {
         let new_value = match (self.value, other.value) {
@@ -274,7 +277,7 @@ impl UInt32 {
             .collect::<Result<_, _>>()?;
 
         Ok(UInt32 {
-            bits: bits,
+            bits,
             value: new_value,
         })
     }
@@ -282,7 +285,7 @@ impl UInt32 {
     /// Perform modular addition of several `UInt32` objects.
     pub fn addmany<E, CS, M>(mut cs: M, operands: &[Self]) -> Result<Self, SynthesisError>
     where
-        E: Engine,
+        E: ScalarEngine,
         CS: ConstraintSystem<E>,
         M: ConstraintSystem<E, Root = MultiEq<E, CS>>,
     {
@@ -294,7 +297,7 @@ impl UInt32 {
 
         // Compute the maximum value of the sum so we allocate enough bits for
         // the result
-        let mut max_value = (operands.len() as u64) * (u32::max_value() as u64);
+        let mut max_value = (operands.len() as u64) * (u64::from(u32::max_value()));
 
         // Keep track of the resulting value
         let mut result_value = Some(0u64);
@@ -310,7 +313,7 @@ impl UInt32 {
             // Accumulate the value
             match op.value {
                 Some(val) => {
-                    result_value.as_mut().map(|v| *v += val as u64);
+                    result_value.as_mut().map(|v| *v += u64::from(val));
                 }
                 None => {
                     // If any of our operands have unknown value, we won't
@@ -401,15 +404,15 @@ mod test {
         ]);
 
         for _ in 0..1000 {
-            let mut v = (0..32)
+            let v = (0..32)
                 .map(|_| Boolean::constant(rng.next_u32() % 2 != 0))
                 .collect::<Vec<_>>();
 
             let b = UInt32::from_bits_be(&v);
 
             for (i, bit) in b.bits.iter().enumerate() {
-                match bit {
-                    &Boolean::Constant(bit) => {
+                match *bit {
+                    Boolean::Constant(bit) => {
                         assert!(bit == ((b.value.unwrap() >> i) & 1 == 1));
                     }
                     _ => unreachable!(),
@@ -436,15 +439,15 @@ mod test {
         ]);
 
         for _ in 0..1000 {
-            let mut v = (0..32)
+            let v = (0..32)
                 .map(|_| Boolean::constant(rng.next_u32() % 2 != 0))
                 .collect::<Vec<_>>();
 
             let b = UInt32::from_bits(&v);
 
             for (i, bit) in b.bits.iter().enumerate() {
-                match bit {
-                    &Boolean::Constant(bit) => {
+                match *bit {
+                    Boolean::Constant(bit) => {
                         assert!(bit == ((b.value.unwrap() >> i) & 1 == 1));
                     }
                     _ => unreachable!(),
@@ -491,14 +494,14 @@ mod test {
             assert!(r.value == Some(expected));
 
             for b in r.bits.iter() {
-                match b {
-                    &Boolean::Is(ref b) => {
+                match *b {
+                    Boolean::Is(ref b) => {
                         assert!(b.get_value().unwrap() == (expected & 1 == 1));
                     }
-                    &Boolean::Not(ref b) => {
+                    Boolean::Not(ref b) => {
                         assert!(!b.get_value().unwrap() == (expected & 1 == 1));
                     }
-                    &Boolean::Constant(b) => {
+                    Boolean::Constant(b) => {
                         assert!(b == (expected & 1 == 1));
                     }
                 }
@@ -538,10 +541,10 @@ mod test {
             assert!(r.value == Some(expected));
 
             for b in r.bits.iter() {
-                match b {
-                    &Boolean::Is(_) => panic!(),
-                    &Boolean::Not(_) => panic!(),
-                    &Boolean::Constant(b) => {
+                match *b {
+                    Boolean::Is(_) => panic!(),
+                    Boolean::Not(_) => panic!(),
+                    Boolean::Constant(b) => {
                         assert!(b == (expected & 1 == 1));
                     }
                 }
@@ -576,8 +579,7 @@ mod test {
             let r = a_bit.xor(cs.namespace(|| "xor"), &b_bit).unwrap();
             let r = {
                 let mut cs = MultiEq::new(&mut cs);
-                let r = UInt32::addmany(cs.namespace(|| "addition"), &[r, c_bit, d_bit]).unwrap();
-                r
+                UInt32::addmany(cs.namespace(|| "addition"), &[r, c_bit, d_bit]).unwrap()
             };
 
             assert!(cs.is_satisfied());
@@ -585,14 +587,14 @@ mod test {
             assert!(r.value == Some(expected));
 
             for b in r.bits.iter() {
-                match b {
-                    &Boolean::Is(ref b) => {
+                match *b {
+                    Boolean::Is(ref b) => {
                         assert!(b.get_value().unwrap() == (expected & 1 == 1));
                     }
-                    &Boolean::Not(ref b) => {
+                    Boolean::Not(ref b) => {
                         assert!(!b.get_value().unwrap() == (expected & 1 == 1));
                     }
-                    &Boolean::Constant(_) => unreachable!(),
+                    Boolean::Constant(_) => unreachable!(),
                 }
 
                 expected >>= 1;
@@ -628,8 +630,8 @@ mod test {
 
             let mut tmp = num;
             for b in &b.bits {
-                match b {
-                    &Boolean::Constant(b) => {
+                match *b {
+                    Boolean::Constant(b) => {
                         assert_eq!(b, tmp & 1 == 1);
                     }
                     _ => unreachable!(),

bellman/src/groth16/generator.rs

@@ -8,11 +8,11 @@ use pairing::Engine;
 
 use super::{Parameters, VerifyingKey};
 
-use {Circuit, ConstraintSystem, Index, LinearCombination, SynthesisError, Variable};
+use crate::{Circuit, ConstraintSystem, Index, LinearCombination, SynthesisError, Variable};
 
-use domain::{EvaluationDomain, Scalar};
+use crate::domain::{EvaluationDomain, Scalar};
 
-use multicore::Worker;
+use crate::multicore::Worker;
 
 /// Generates a random common reference string for
 /// a circuit.
@@ -227,7 +227,7 @@ where
             let powers_of_tau = powers_of_tau.as_mut();
             worker.scope(powers_of_tau.len(), |scope, chunk| {
                 for (i, powers_of_tau) in powers_of_tau.chunks_mut(chunk).enumerate() {
-                    scope.spawn(move || {
+                    scope.spawn(move |_scope| {
                         let mut current_tau_power = tau.pow(&[(i * chunk) as u64]);
 
                         for p in powers_of_tau {
@@ -251,7 +251,7 @@ where
             {
                 let mut g1_wnaf = g1_wnaf.shared();
 
-                scope.spawn(move || {
+                scope.spawn(move |_scope| {
                     // Set values of the H query to g1^{(tau^i * t(tau)) / delta}
                     for (h, p) in h.iter_mut().zip(p.iter()) {
                         // Compute final exponent
@@ -330,7 +330,7 @@ where
                 let mut g1_wnaf = g1_wnaf.shared();
                 let mut g2_wnaf = g2_wnaf.shared();
 
-                scope.spawn(move || {
+                scope.spawn(move |_scope| {
                     for ((((((a, b_g1), b_g2), ext), at), bt), ct) in a
                         .iter_mut()
                         .zip(b_g1.iter_mut())
@@ -451,7 +451,7 @@ where
     };
 
     Ok(Parameters {
-        vk: vk,
+        vk,
         h: Arc::new(h.into_iter().map(|e| e.into_affine()).collect()),
         l: Arc::new(l.into_iter().map(|e| e.into_affine()).collect()),
 

bellman/src/groth16/mod.rs

@@ -1,10 +1,14 @@
+//! The [Groth16] proving system.
+//!
+//! [Groth16]: https://eprint.iacr.org/2016/260
+
 use group::{CurveAffine, EncodedPoint};
 use pairing::{Engine, PairingCurveAffine};
 
-use SynthesisError;
+use crate::SynthesisError;
 
+use crate::multiexp::SourceBuilder;
 use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
-use multiexp::SourceBuilder;
 use std::io::{self, Read, Write};
 use std::sync::Arc;
 
@@ -90,7 +94,7 @@ impl<E: Engine> Proof<E> {
                 }
             })?;
 
-        Ok(Proof { a: a, b: b, c: c })
+        Ok(Proof { a, b, c })
     }
 }
 
@@ -208,13 +212,13 @@ impl<E: Engine> VerifyingKey<E> {
         }
 
         Ok(VerifyingKey {
-            alpha_g1: alpha_g1,
-            beta_g1: beta_g1,
-            beta_g2: beta_g2,
-            gamma_g2: gamma_g2,
-            delta_g1: delta_g1,
-            delta_g2: delta_g2,
-            ic: ic,
+            alpha_g1,
+            beta_g1,
+            beta_g2,
+            gamma_g2,
+            delta_g1,
+            delta_g2,
+            ic,
         })
     }
 }
@@ -376,7 +380,7 @@ impl<E: Engine> Parameters<E> {
         }
 
         Ok(Parameters {
-            vk: vk,
+            vk,
             h: Arc::new(h),
             l: Arc::new(l),
             a: Arc::new(a),
@@ -465,7 +469,7 @@ impl<'a, E: Engine> ParameterSource<E> for &'a Parameters<E> {
 #[cfg(test)]
 mod test_with_bls12_381 {
     use super::*;
-    use {Circuit, ConstraintSystem, SynthesisError};
+    use crate::{Circuit, ConstraintSystem, SynthesisError};
 
     use ff::Field;
     use pairing::bls12_381::{Bls12, Fr};

bellman/src/groth16/prover.rs

@@ -10,13 +10,13 @@ use pairing::Engine;
 
 use super::{ParameterSource, Proof};
 
-use {Circuit, ConstraintSystem, Index, LinearCombination, SynthesisError, Variable};
+use crate::{Circuit, ConstraintSystem, Index, LinearCombination, SynthesisError, Variable};
 
-use domain::{EvaluationDomain, Scalar};
+use crate::domain::{EvaluationDomain, Scalar};
 
-use multiexp::{multiexp, DensityTracker, FullDensity};
+use crate::multiexp::{multiexp, DensityTracker, FullDensity};
 
-use multicore::Worker;
+use crate::multicore::Worker;
 
 fn eval<E: Engine>(
     lc: &LinearCombination<E>,

bellman/src/groth16/tests/dummy_engine.rs

@@ -16,13 +16,13 @@ const MODULUS_R: Wrapping<u32> = Wrapping(64513);
 pub struct Fr(Wrapping<u32>);
 
 impl fmt::Display for Fr {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
         write!(f, "{}", (self.0).0)
     }
 }
 
 impl Field for Fr {
-    fn random<R: RngCore>(rng: &mut R) -> Self {
+    fn random<R: RngCore + ?std::marker::Sized>(rng: &mut R) -> Self {
         Fr(Wrapping(rng.next_u32()) % MODULUS_R)
     }
 
@@ -149,7 +149,7 @@ impl PartialOrd for FrRepr {
 }
 
 impl fmt::Display for FrRepr {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
         write!(f, "{}", (self.0)[0])
     }
 }

bellman/src/groth16/tests/mod.rs

@@ -6,7 +6,7 @@ use self::dummy_engine::*;
 
 use std::marker::PhantomData;
 
-use {Circuit, ConstraintSystem, SynthesisError};
+use crate::{Circuit, ConstraintSystem, SynthesisError};
 
 use super::{create_proof, generate_parameters, prepare_verifying_key, verify_proof};
 

bellman/src/groth16/verifier.rs

@@ -4,7 +4,7 @@ use pairing::{Engine, PairingCurveAffine};
 
 use super::{PreparedVerifyingKey, Proof, VerifyingKey};
 
-use SynthesisError;
+use crate::SynthesisError;
 
 pub fn prepare_verifying_key<E: Engine>(vk: &VerifyingKey<E>) -> PreparedVerifyingKey<E> {
     let mut gamma = vk.gamma_g2;
@@ -49,7 +49,7 @@ pub fn verify_proof<'a, E: Engine>(
             (&acc.into_affine().prepare(), &pvk.neg_gamma_g2),
             (&proof.c.prepare(), &pvk.neg_delta_g2),
         ]
-        .into_iter(),
+        .iter(),
     ))
     .unwrap()
         == pvk.alpha_g1_beta_g2)

bellman/src/lib.rs

@@ -1,33 +1,139 @@
-extern crate ff;
-extern crate group;
-#[cfg(feature = "pairing")]
-extern crate pairing;
-extern crate rand_core;
+//! `bellman` is a crate for building zk-SNARK circuits. It provides circuit
+//! traits and and primitive structures, as well as basic gadget implementations
+//! such as booleans and number abstractions.
+//!
+//! # Example circuit
+//!
+//! Say we want to write a circuit that proves we know the preimage to some hash
+//! computed using SHA-256d (calling SHA-256 twice). The preimage must have a
+//! fixed length known in advance (because the circuit parameters will depend on
+//! it), but can otherwise have any value. We take the following strategy:
+//!
+//! - Witness each bit of the preimage.
+//! - Compute `hash = SHA-256d(preimage)` inside the circuit.
+//! - Expose `hash` as a public input using multiscalar packing.
+//!
+//! ```
+//! use bellman::{
+//!     gadgets::{
+//!         boolean::{AllocatedBit, Boolean},
+//!         multipack,
+//!         sha256::sha256,
+//!     },
+//!     groth16, Circuit, ConstraintSystem, SynthesisError,
+//! };
+//! use pairing::{bls12_381::Bls12, Engine};
+//! use rand::rngs::OsRng;
+//! use sha2::{Digest, Sha256};
+//!
+//! /// Our own SHA-256d gadget. Input and output are in little-endian bit order.
+//! fn sha256d<E: Engine, CS: ConstraintSystem<E>>(
+//!     mut cs: CS,
+//!     data: &[Boolean],
+//! ) -> Result<Vec<Boolean>, SynthesisError> {
+//!     // Flip endianness of each input byte
+//!     let input: Vec<_> = data
+//!         .chunks(8)
+//!         .map(|c| c.iter().rev())
+//!         .flatten()
+//!         .cloned()
+//!         .collect();
+//!
+//!     let mid = sha256(cs.namespace(|| "SHA-256(input)"), &input)?;
+//!     let res = sha256(cs.namespace(|| "SHA-256(mid)"), &mid)?;
+//!
+//!     // Flip endianness of each output byte
+//!     Ok(res
+//!         .chunks(8)
+//!         .map(|c| c.iter().rev())
+//!         .flatten()
+//!         .cloned()
+//!         .collect())
+//! }
+//!
+//! struct MyCircuit {
+//!     /// The input to SHA-256d we are proving that we know. Set to `None` when we
+//!     /// are verifying a proof (and do not have the witness data).
+//!     preimage: Option<[u8; 80]>,
+//! }
+//!
+//! impl<E: Engine> Circuit<E> for MyCircuit {
+//!     fn synthesize<CS: ConstraintSystem<E>>(self, cs: &mut CS) -> Result<(), SynthesisError> {
+//!         // Compute the values for the bits of the preimage. If we are verifying a proof,
+//!         // we still need to create the same constraints, so we return an equivalent-size
+//!         // Vec of None (indicating that the value of each bit is unknown).
+//!         let bit_values = if let Some(preimage) = self.preimage {
+//!             preimage
+//!                 .into_iter()
+//!                 .map(|byte| (0..8).map(move |i| (byte >> i) & 1u8 == 1u8))
+//!                 .flatten()
+//!                 .map(|b| Some(b))
+//!                 .collect()
+//!         } else {
+//!             vec![None; 80 * 8]
+//!         };
+//!         assert_eq!(bit_values.len(), 80 * 8);
+//!
+//!         // Witness the bits of the preimage.
+//!         let preimage_bits = bit_values
+//!             .into_iter()
+//!             .enumerate()
+//!             // Allocate each bit.
+//!             .map(|(i, b)| {
+//!                 AllocatedBit::alloc(cs.namespace(|| format!("preimage bit {}", i)), b)
+//!             })
+//!             // Convert the AllocatedBits into Booleans (required for the sha256 gadget).
+//!             .map(|b| b.map(Boolean::from))
+//!             .collect::<Result<Vec<_>, _>>()?;
+//!
+//!         // Compute hash = SHA-256d(preimage).
+//!         let hash = sha256d(cs.namespace(|| "SHA-256d(preimage)"), &preimage_bits)?;
+//!
+//!         // Expose the vector of 32 boolean variables as compact public inputs.
+//!         multipack::pack_into_inputs(cs.namespace(|| "pack hash"), &hash)
+//!     }
+//! }
+//!
+//! // Create parameters for our circuit. In a production deployment these would
+//! // be generated securely using a multiparty computation.
+//! let params = {
+//!     let c = MyCircuit { preimage: None };
+//!     groth16::generate_random_parameters::<Bls12, _, _>(c, &mut OsRng).unwrap()
+//! };
+//!
+//! // Prepare the verification key (for proof verification).
+//! let pvk = groth16::prepare_verifying_key(&params.vk);
+//!
+//! // Pick a preimage and compute its hash.
+//! let preimage = [42; 80];
+//! let hash = Sha256::digest(&Sha256::digest(&preimage));
+//!
+//! // Create an instance of our circuit (with the preimage as a witness).
+//! let c = MyCircuit {
+//!     preimage: Some(preimage),
+//! };
+//!
+//! // Create a Groth16 proof with our parameters.
+//! let proof = groth16::create_random_proof(c, &params, &mut OsRng).unwrap();
+//!
+//! // Pack the hash as inputs for proof verification.
+//! let hash_bits = multipack::bytes_to_bits_le(&hash);
+//! let inputs = multipack::compute_multipacking::<Bls12>(&hash_bits);
+//!
+//! // Check the proof!
+//! assert!(groth16::verify_proof(&pvk, &proof, &inputs).unwrap());
+//! ```
+//!
+//! # Roadmap
+//!
+//! `bellman` is being refactored into a generic proving library. Currently it
+//! is pairing-specific, and different types of proving systems need to be
+//! implemented as sub-modules. After the refactor, `bellman` will be generic
+//! using the [`ff`] and [`group`] crates, while specific proving systems will
+//! be separate crates that pull in the dependencies they require.
 
-extern crate bit_vec;
-extern crate blake2s_simd;
-extern crate byteorder;
-extern crate futures;
-
-#[cfg(feature = "multicore")]
-extern crate crossbeam;
-#[cfg(feature = "multicore")]
-extern crate futures_cpupool;
-#[cfg(feature = "multicore")]
-extern crate num_cpus;
-
-#[cfg(test)]
-#[macro_use]
-extern crate hex_literal;
-
-#[cfg(test)]
-extern crate rand;
-
-#[cfg(test)]
-extern crate rand_xorshift;
-
-#[cfg(test)]
-extern crate sha2;
+// Catch documentation errors caused by code changes.
+#![deny(intra_doc_link_resolution_failure)]
 
 pub mod domain;
 pub mod gadgets;
@@ -109,6 +215,7 @@ impl<E: ScalarEngine> Add<(E::Fr, Variable)> for LinearCombination<E> {
 impl<E: ScalarEngine> Sub<(E::Fr, Variable)> for LinearCombination<E> {
     type Output = LinearCombination<E>;
 
+    #[allow(clippy::suspicious_arithmetic_impl)]
     fn sub(self, (mut coeff, var): (E::Fr, Variable)) -> LinearCombination<E> {
         coeff.negate();
 
@@ -230,8 +337,8 @@ impl Error for SynthesisError {
 }
 
 impl fmt::Display for SynthesisError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        if let &SynthesisError::IoError(ref e) = self {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        if let SynthesisError::IoError(ref e) = *self {
             write!(f, "I/O error: ")?;
             e.fmt(f)
         } else {
@@ -296,7 +403,7 @@ pub trait ConstraintSystem<E: ScalarEngine>: Sized {
     fn get_root(&mut self) -> &mut Self::Root;
 
     /// Begin a namespace for this constraint system.
-    fn namespace<'a, NR, N>(&'a mut self, name_fn: N) -> Namespace<'a, E, Self::Root>
+    fn namespace<NR, N>(&mut self, name_fn: N) -> Namespace<'_, E, Self::Root>
     where
         NR: Into<String>,
         N: FnOnce() -> NR,
@@ -309,7 +416,7 @@ pub trait ConstraintSystem<E: ScalarEngine>: Sized {
 
 /// This is a "namespaced" constraint system which borrows a constraint system (pushing
 /// a namespace context) and, when dropped, pops out of the namespace context.
-pub struct Namespace<'a, E: ScalarEngine, CS: ConstraintSystem<E> + 'a>(&'a mut CS, PhantomData<E>);
+pub struct Namespace<'a, E: ScalarEngine, CS: ConstraintSystem<E>>(&'a mut CS, PhantomData<E>);
 
 impl<'cs, E: ScalarEngine, CS: ConstraintSystem<E>> ConstraintSystem<E> for Namespace<'cs, E, CS> {
     type Root = CS::Root;

bellman/src/multicore.rs

@@ -1,12 +1,13 @@
-//! This is an interface for dealing with the kinds of
-//! parallel computations involved in bellman. It's
-//! currently just a thin wrapper around CpuPool and
-//! crossbeam but may be extended in the future to
-//! allow for various parallelism strategies.
+//! An interface for dealing with the kinds of parallel computations involved in
+//! `bellman`. It's currently just a thin wrapper around [`CpuPool`] and
+//! [`crossbeam`] but may be extended in the future to allow for various
+//! parallelism strategies.
+//!
+//! [`CpuPool`]: futures_cpupool::CpuPool
 
 #[cfg(feature = "multicore")]
 mod implementation {
-    use crossbeam::{self, Scope};
+    use crossbeam::{self, thread::Scope};
     use futures::{Future, IntoFuture, Poll};
     use futures_cpupool::{CpuFuture, CpuPool};
     use num_cpus;
@@ -23,7 +24,7 @@ mod implementation {
         // CPUs configured.
         pub(crate) fn new_with_cpus(cpus: usize) -> Worker {
             Worker {
-                cpus: cpus,
+                cpus,
                 pool: CpuPool::new(cpus),
             }
         }
@@ -59,7 +60,9 @@ mod implementation {
                 elements / self.cpus
             };
 
+            // TODO: Handle case where threads fail
             crossbeam::scope(|scope| f(scope, chunk_size))
+                .expect("Threads aren't allowed to fail yet")
         }
     }
 
@@ -152,8 +155,8 @@ mod implementation {
     pub struct DummyScope;
 
     impl DummyScope {
-        pub fn spawn<F: FnOnce()>(&self, f: F) {
-            f();
+        pub fn spawn<F: FnOnce(&DummyScope)>(&self, f: F) {
+            f(self);
         }
     }
 }

bellman/src/multiexp.rs

@@ -153,7 +153,7 @@ fn multiexp_inner<Q, D, G, S>(
     mut skip: u32,
     c: u32,
     handle_trivial: bool,
-) -> Box<Future<Item = <G as CurveAffine>::Projective, Error = SynthesisError>>
+) -> Box<dyn Future<Item = <G as CurveAffine>::Projective, Error = SynthesisError>>
 where
     for<'a> &'a Q: QueryDensity,
     D: Send + Sync + 'static + Clone + AsRef<Q>,
@@ -256,7 +256,7 @@ pub fn multiexp<Q, D, G, S>(
     bases: S,
     density_map: D,
     exponents: Arc<Vec<<<G::Engine as ScalarEngine>::Fr as PrimeField>::Repr>>,
-) -> Box<Future<Item = <G as CurveAffine>::Projective, Error = SynthesisError>>
+) -> Box<dyn Future<Item = <G as CurveAffine>::Projective, Error = SynthesisError>>
 where
     for<'a> &'a Q: QueryDensity,
     D: Send + Sync + 'static + Clone + AsRef<Q>,

bellman/tests/mimc.rs

@@ -1,8 +1,3 @@
-extern crate bellman;
-extern crate ff;
-extern crate pairing;
-extern crate rand;
-
 // For randomness (during paramgen and proof generation)
 use rand::thread_rng;
 
@@ -90,12 +85,12 @@ impl<'a, E: Engine> Circuit<E> for MiMCDemo<'a, E> {
             let cs = &mut cs.namespace(|| format!("round {}", i));
 
             // tmp = (xL + Ci)^2
-            let mut tmp_value = xl_value.map(|mut e| {
+            let tmp_value = xl_value.map(|mut e| {
                 e.add_assign(&self.constants[i]);
                 e.square();
                 e
             });
-            let mut tmp = cs.alloc(
+            let tmp = cs.alloc(
                 || "tmp",
                 || tmp_value.ok_or(SynthesisError::AssignmentMissing),
             )?;
@@ -110,14 +105,14 @@ impl<'a, E: Engine> Circuit<E> for MiMCDemo<'a, E> {
             // new_xL = xR + (xL + Ci)^3
             // new_xL = xR + tmp * (xL + Ci)
             // new_xL - xR = tmp * (xL + Ci)
-            let mut new_xl_value = xl_value.map(|mut e| {
+            let new_xl_value = xl_value.map(|mut e| {
                 e.add_assign(&self.constants[i]);
                 e.mul_assign(&tmp_value.unwrap());
                 e.add_assign(&xr_value.unwrap());
                 e
             });
 
-            let mut new_xl = if i == (MIMC_ROUNDS - 1) {
+            let new_xl = if i == (MIMC_ROUNDS - 1) {
                 // This is the last round, xL is our image and so
                 // we allocate a public input.
                 cs.alloc_input(

ff/Cargo.toml

@@ -1,18 +1,23 @@
 [package]
 name = "ff"
-version = "0.4.0"
+version = "0.5.2"
 authors = ["Sean Bowe <ewillbefull@gmail.com>"]
 description = "Library for building and interfacing with finite fields"
+readme = "README.md"
 documentation = "https://docs.rs/ff/"
 homepage = "https://github.com/ebfull/ff"
 license = "MIT/Apache-2.0"
 repository = "https://github.com/ebfull/ff"
+edition = "2018"
 
 [dependencies]
 byteorder = "1"
-ff_derive = { version = "0.3.0", path = "ff_derive", optional = true }
+ff_derive = { version = "^0.4.1", path = "ff_derive", optional = true }
 rand_core = "0.5"
 
 [features]
 default = []
 derive = ["ff_derive"]
+
+[badges]
+maintenance = { status = "actively-developed" }

ff/README.md

@@ -12,14 +12,18 @@ Add the `ff` crate to your `Cargo.toml`:
 
 ```toml
 [dependencies]
-ff = "0.4"
+ff = "0.5"
 ```
 
-The `ff` crate contains `Field`, `PrimeField`, `PrimeFieldRepr` and `SqrtField` traits. See the **[documentation](https://docs.rs/ff/0.4.0/ff/)** for more.
+The `ff` crate contains `Field`, `PrimeField`, `PrimeFieldRepr` and `SqrtField` traits.
+See the **[documentation](https://docs.rs/ff/)** for more.
 
 ### #![derive(PrimeField)]
 
-If you need an implementation of a prime field, this library also provides a procedural macro that will expand into an efficient implementation of a prime field when supplied with the modulus. `PrimeFieldGenerator` must be an element of Fp of p-1 order, that is also quadratic nonresidue.
+If you need an implementation of a prime field, this library also provides a procedural
+macro that will expand into an efficient implementation of a prime field when supplied
+with the modulus. `PrimeFieldGenerator` must be an element of Fp of p-1 order, that is
+also quadratic nonresidue.
 
 First, enable the `derive` crate feature:
 
@@ -41,13 +45,16 @@ extern crate ff;
 struct Fp(FpRepr);
 ```
 
-And that's it! `Fp` now implements `Field` and `PrimeField`. `Fp` will also implement `SqrtField` if supported. The library implements `FpRepr` itself and derives `PrimeFieldRepr` for it.
+And that's it! `Fp` now implements `Field` and `PrimeField`. `Fp` will also implement
+`SqrtField` if supported. The library implements `FpRepr` itself and derives
+`PrimeFieldRepr` for it.
 
 ## License
 
 Licensed under either of
 
- * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+   http://www.apache.org/licenses/LICENSE-2.0)
  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
 
 at your option.

ff/ff_derive/Cargo.toml

@@ -1,12 +1,13 @@
 [package]
 name = "ff_derive"
-version = "0.3.0"
+version = "0.4.1"
 authors = ["Sean Bowe <ewillbefull@gmail.com>"]
 description = "Procedural macro library used to build custom prime field implementations"
 documentation = "https://docs.rs/ff/"
 homepage = "https://github.com/ebfull/ff"
 license = "MIT/Apache-2.0"
 repository = "https://github.com/ebfull/ff"
+edition = "2018"
 
 [lib]
 proc-macro = true
@@ -15,6 +16,9 @@ proc-macro = true
 num-bigint = "0.2"
 num-traits = "0.2"
 num-integer = "0.1"
-proc-macro2 = "0.4"
-quote = "0.6"
-syn = "0.14"
+proc-macro2 = "1"
+quote = "1"
+syn = "1"
+
+[badges]
+maintenance = { status = "passively-maintained" }

ff/ff_derive/src/lib.rs

@@ -2,17 +2,11 @@
 
 extern crate proc_macro;
 extern crate proc_macro2;
-extern crate syn;
-#[macro_use]
-extern crate quote;
-
-extern crate num_bigint;
-extern crate num_integer;
-extern crate num_traits;
 
 use num_bigint::BigUint;
 use num_integer::Integer;
 use num_traits::{One, ToPrimitive, Zero};
+use quote::quote;
 use quote::TokenStreamExt;
 use std::str::FromStr;
 
@@ -91,10 +85,10 @@ fn fetch_wrapped_ident(body: &syn::Data) -> Option<syn::Ident> {
 /// Fetch an attribute string from the derived struct.
 fn fetch_attr(name: &str, attrs: &[syn::Attribute]) -> Option<String> {
     for attr in attrs {
-        if let Some(meta) = attr.interpret_meta() {
+        if let Ok(meta) = attr.parse_meta() {
             match meta {
                 syn::Meta::NameValue(nv) => {
-                    if nv.ident.to_string() == name {
+                    if nv.path.get_ident().map(|i| i.to_string()) == Some(name.to_string()) {
                         match nv.lit {
                             syn::Lit::Str(ref s) => return Some(s.value()),
                             _ => {
@@ -122,9 +116,9 @@ fn prime_field_repr_impl(repr: &syn::Ident, limbs: usize) -> proc_macro2::TokenS
         impl ::std::fmt::Debug for #repr
         {
             fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
-                try!(write!(f, "0x"));
+                write!(f, "0x")?;
                 for i in self.0.iter().rev() {
-                    try!(write!(f, "{:016x}", *i));
+                    write!(f, "{:016x}", *i)?;
                 }
 
                 Ok(())
@@ -133,9 +127,9 @@ fn prime_field_repr_impl(repr: &syn::Ident, limbs: usize) -> proc_macro2::TokenS
 
         impl ::std::fmt::Display for #repr {
             fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
-                try!(write!(f, "0x"));
+                write!(f, "0x")?;
                 for i in self.0.iter().rev() {
-                    try!(write!(f, "{:016x}", *i));
+                    write!(f, "{:016x}", *i)?;
                 }
 
                 Ok(())
@@ -883,7 +877,7 @@ fn prime_field_impl(
 
         impl ::ff::Field for #name {
             /// Computes a uniformly random element using rejection sampling.
-            fn random<R: ::rand_core::RngCore>(rng: &mut R) -> Self {
+            fn random<R: ::rand_core::RngCore + ?std::marker::Sized>(rng: &mut R) -> Self {
                 loop {
                     let mut tmp = {
                         let mut repr = [0u64; #limbs];

ff/src/lib.rs

@@ -1,12 +1,9 @@
+//! This crate provides traits for working with finite fields.
+
+// Catch documentation errors caused by code changes.
+#![deny(intra_doc_link_resolution_failure)]
 #![allow(unused_imports)]
 
-extern crate byteorder;
-extern crate rand_core;
-
-#[cfg(feature = "derive")]
-#[macro_use]
-extern crate ff_derive;
-
 #[cfg(feature = "derive")]
 pub use ff_derive::*;
 
@@ -20,7 +17,7 @@ pub trait Field:
     Sized + Eq + Copy + Clone + Send + Sync + fmt::Debug + fmt::Display + 'static
 {
     /// Returns an element chosen uniformly at random using a user-provided RNG.
-    fn random<R: RngCore>(rng: &mut R) -> Self;
+    fn random<R: RngCore + ?std::marker::Sized>(rng: &mut R) -> Self;
 
     /// Returns the zero element of the field, the additive identity.
     fn zero() -> Self;
@@ -210,7 +207,7 @@ impl Error for PrimeFieldDecodingError {
 }
 
 impl fmt::Display for PrimeFieldDecodingError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
         match *self {
             PrimeFieldDecodingError::NotInField(ref repr) => {
                 write!(f, "{} is not an element of the field", repr)
@@ -266,7 +263,7 @@ pub trait PrimeField: Field {
     }
 
     /// Convert this prime field element into a biginteger representation.
-    fn from_repr(Self::Repr) -> Result<Self, PrimeFieldDecodingError>;
+    fn from_repr(_: Self::Repr) -> Result<Self, PrimeFieldDecodingError>;
 
     /// Convert a biginteger representation into a prime field element, if
     /// the number is an element of the field.

group/Cargo.toml

@@ -1,18 +1,23 @@
 [package]
 name = "group"
-version = "0.1.0"
+version = "0.2.0"
 authors = [
     "Sean Bowe <ewillbefull@gmail.com>",
     "Jack Grigg <jack@z.cash>",
 ]
+readme = "README.md"
 license = "MIT/Apache-2.0"
 
 description = "Elliptic curve group traits and utilities"
 documentation = "https://docs.rs/group/"
 homepage = "https://github.com/ebfull/group"
 repository = "https://github.com/ebfull/group"
+edition = "2018"
 
 [dependencies]
-ff = { path = "../ff" }
+ff = { version = "0.5.0", path = "../ff" }
 rand = "0.7"
 rand_xorshift = "0.2"
+
+[badges]
+maintenance = { status = "actively-developed" }

group/README.md

@@ -1,10 +1,13 @@
 # group [![Crates.io](https://img.shields.io/crates/v/group.svg)](https://crates.io/crates/group) #
 
+`group` is a crate for working with groups over elliptic curves.
+
 ## License
 
 Licensed under either of
 
- * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+   http://www.apache.org/licenses/LICENSE-2.0)
  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
 
 at your option.

group/src/lib.rs

@@ -1,6 +1,5 @@
-extern crate ff;
-extern crate rand;
-extern crate rand_xorshift;
+// Catch documentation errors caused by code changes.
+#![deny(intra_doc_link_resolution_failure)]
 
 use ff::{PrimeField, PrimeFieldDecodingError, ScalarEngine, SqrtField};
 use rand::RngCore;
@@ -180,7 +179,7 @@ impl Error for GroupDecodingError {
 }
 
 impl fmt::Display for GroupDecodingError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
         match *self {
             GroupDecodingError::CoordinateDecodingError(description, ref err) => {
                 write!(f, "{} decoding error: {}", description, err)

group/src/tests/mod.rs

@@ -2,7 +2,7 @@ use ff::{Field, PrimeField};
 use rand::SeedableRng;
 use rand_xorshift::XorShiftRng;
 
-use {CurveAffine, CurveProjective, EncodedPoint};
+use crate::{CurveAffine, CurveProjective, EncodedPoint};
 
 pub fn curve_tests<G: CurveProjective>() {
     let mut rng = XorShiftRng::from_seed([
@@ -71,7 +71,7 @@ pub fn curve_tests<G: CurveProjective>() {
 }
 
 fn random_wnaf_tests<G: CurveProjective>() {
-    use wnaf::*;
+    use crate::wnaf::*;
 
     let mut rng = XorShiftRng::from_seed([
         0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,

librustzcash/Cargo.toml

@@ -1,12 +1,18 @@
 [package]
 name = "librustzcash"
-version = "0.1.0"
+description = "Rust FFI used by the zcashd binary. Not an official API."
+version = "0.2.0"
 authors = [
     "Sean Bowe <ewillbefull@gmail.com>",
     "Jack Grigg <jack@z.cash>",
     "Jay Graber <jay@z.cash>",
     "Simon Liu <simon@z.cash>"
-    ]
+]
+homepage = "https://github.com/zcash/librustzcash"
+repository = "https://github.com/zcash/librustzcash"
+readme = "README.md"
+license = "MIT OR Apache-2.0"
+edition = "2018"
 
 [lib]
 name = "rustzcash"
@@ -14,15 +20,17 @@ path = "src/rustzcash.rs"
 crate-type = ["staticlib"]
 
 [dependencies]
-bellman = { path = "../bellman" }
+bellman = { version = "0.2.0", path = "../bellman" }
 blake2b_simd = "0.5"
 blake2s_simd = "0.5"
-ff = { path = "../ff" }
+ff = { version = "0.5.0", path = "../ff" }
 libc = "0.2"
-pairing = { path = "../pairing" }
+pairing = { version = "0.15.0", path = "../pairing" }
 lazy_static = "1"
-byteorder = "1"
-rand_core = "0.5"
-rand_os = "0.2"
-zcash_primitives = { path = "../zcash_primitives" }
-zcash_proofs = { path = "../zcash_proofs" }
+rand_core = "0.5.1"
+zcash_history = { version = "0.0.1", path = "../zcash_history" }
+zcash_primitives = { version = "0.1.0", path = "../zcash_primitives" }
+zcash_proofs = { version = "0.1.0", path = "../zcash_proofs" }
+
+[badges]
+maintenance = { status = "deprecated" }

librustzcash/README.md

@@ -1,12 +1,17 @@
 # librustzcash
 
-This repository contains librustzcash, a static library for Zcash code assets written in Rust.
+`librustzcash` is an FFI library crate that exposes the Zcash Rust components to
+the `zcashd` full node.
+
+The FFI API does not have any stability guarantees, and will change as required
+by `zcashd`.
 
 ## License
 
 Licensed under either of
 
- * Apache License, Version 2.0, ([LICENSE-APACHE](../LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+ * Apache License, Version 2.0, ([LICENSE-APACHE](../LICENSE-APACHE) or
+   http://www.apache.org/licenses/LICENSE-2.0)
  * MIT license ([LICENSE-MIT](../LICENSE-MIT) or http://opensource.org/licenses/MIT)
 
 at your option.

librustzcash/include/librustzcash.h

@@ -112,8 +112,7 @@ extern "C" {
     bool librustzcash_sapling_output_proof(
         void *ctx,
         const unsigned char *esk,
-        const unsigned char *diversifier,
-        const unsigned char *pk_d,
+        const unsigned char *payment_address,
         const unsigned char *rcm,
         const uint64_t value,
         unsigned char *cv,
@@ -308,6 +307,33 @@ extern "C" {
         unsigned char *j_ret,
         unsigned char *addr_ret
     );
+
+    uint32_t librustzcash_mmr_append(
+        uint32_t cbranch,
+        uint32_t t_len,
+        const uint32_t *ni_ptr,
+        const unsigned char *n_ptr,
+        size_t p_len,
+        const unsigned char *nn_ptr,
+        unsigned char *rt_ret,
+        unsigned char *buf_ret
+    );
+
+    uint32_t librustzcash_mmr_delete(
+        uint32_t cbranch,
+        uint32_t t_len,
+        const uint32_t *ni_ptr,
+        const unsigned char *n_ptr,
+        size_t p_len,
+        size_t e_len,
+        unsigned char *rt_ret
+    );
+
+    uint32_t librustzcash_mmr_hash_node(
+        uint32_t cbranch,
+        const unsigned char *n_ptr,
+        unsigned char *h_ret
+    );
 }
 
 #endif // LIBRUSTZCASH_INCLUDE_H_

librustzcash/src/tests/key_agreement.rs

@@ -1,11 +1,10 @@
 use ff::{PrimeField, PrimeFieldRepr};
 use pairing::bls12_381::Bls12;
-use rand_core::RngCore;
-use rand_os::OsRng;
+use rand_core::{OsRng, RngCore};
 use zcash_primitives::jubjub::{edwards, JubjubBls12};
 use zcash_primitives::primitives::{Diversifier, ViewingKey};
 
-use {
+use crate::{
     librustzcash_sapling_generate_r, librustzcash_sapling_ka_agree,
     librustzcash_sapling_ka_derivepublic,
 };
@@ -25,7 +24,7 @@ fn test_key_agreement() {
     let addr = loop {
         let mut d = [0; 11];
         rng.fill_bytes(&mut d);
-        match vk.into_payment_address(Diversifier(d), &params) {
+        match vk.to_payment_address(Diversifier(d), &params) {
             Some(a) => break a,
             None => {}
         }
@@ -47,7 +46,7 @@ fn test_key_agreement() {
 
     // Serialize pk_d for the call to librustzcash_sapling_ka_agree
     let mut addr_pk_d = [0u8; 32];
-    addr.pk_d.write(&mut addr_pk_d[..]).unwrap();
+    addr.pk_d().write(&mut addr_pk_d[..]).unwrap();
 
     assert!(librustzcash_sapling_ka_agree(
         &addr_pk_d,
@@ -59,7 +58,7 @@ fn test_key_agreement() {
     // using the diversifier and esk.
     let mut epk = [0u8; 32];
     assert!(librustzcash_sapling_ka_derivepublic(
-        &addr.diversifier.0,
+        &addr.diversifier().0,
         &esk,
         &mut epk
     ));

librustzcash/src/tests/key_components.rs

@@ -7,7 +7,7 @@ use zcash_primitives::{
 
 use super::JUBJUB;
 
-use {
+use crate::{
     librustzcash_ask_to_ak, librustzcash_check_diversifier, librustzcash_crh_ivk,
     librustzcash_ivk_to_pkd, librustzcash_nsk_to_nk,
 };
@@ -678,7 +678,7 @@ fn key_components() {
         }
 
         let pgk = ProofGenerationKey { ak, nsk };
-        let fvk = pgk.into_viewing_key(&JUBJUB);
+        let fvk = pgk.to_viewing_key(&JUBJUB);
         {
             let mut vec = Vec::new();
             fvk.nk.write(&mut vec).unwrap();
@@ -704,10 +704,10 @@ fn key_components() {
         let diversifier = Diversifier(tv.default_d);
         assert!(librustzcash_check_diversifier(&tv.default_d));
 
-        let addr = fvk.into_payment_address(diversifier, &JUBJUB).unwrap();
+        let addr = fvk.to_payment_address(diversifier, &JUBJUB).unwrap();
         {
             let mut vec = Vec::new();
-            addr.pk_d.write(&mut vec).unwrap();
+            addr.pk_d().write(&mut vec).unwrap();
             assert_eq!(&vec, &tv.default_pk_d);
         }
         {

librustzcash/src/tests/mmr.rs

@@ -0,0 +1,225 @@
+use zcash_history::{Entry, EntryLink, NodeData};
+
+use crate::{librustzcash_mmr_append, librustzcash_mmr_delete};
+
+const NODE_DATA_16L: &[u8] = include_bytes!("./res/tree16.dat");
+const NODE_DATA_1023L: &[u8] = include_bytes!("./res/tree1023.dat");
+
+struct TreeView {
+    peaks: Vec<(u32, Entry)>,
+    extra: Vec<(u32, Entry)>,
+}
+
+fn draft(into: &mut Vec<(u32, Entry)>, nodes: &[NodeData], peak_pos: usize, h: u32) {
+    let node_data = nodes[peak_pos - 1].clone();
+    let peak: Entry = match h {
+        0 => node_data.into(),
+        _ => Entry::new(
+            node_data,
+            EntryLink::Stored((peak_pos - (1 << h) - 1) as u32),
+            EntryLink::Stored((peak_pos - 2) as u32),
+        ),
+    };
+
+    into.push(((peak_pos - 1) as u32, peak));
+}
+
+fn prepare_tree(nodes: &[NodeData]) -> TreeView {
+    assert!(!nodes.is_empty());
+
+    // integer log2 of (nodes.len()+1), -1
+    let mut h = (32 - ((nodes.len() + 1) as u32).leading_zeros() - 1) - 1;
+    let mut peak_pos = (1 << (h + 1)) - 1;
+    let mut peaks = Vec::new();
+
+    // used later
+    let mut last_peak_pos = 0;
+    let mut last_peak_h = 0;
+
+    loop {
+        if peak_pos > nodes.len() {
+            // left child, -2^h
+            peak_pos -= 1 << h;
+            h -= 1;
+        }
+
+        if peak_pos <= nodes.len() {
+            draft(&mut peaks, nodes, peak_pos, h);
+
+            // save to be used in next loop
+            last_peak_pos = peak_pos;
+            last_peak_h = h;
+
+            // right sibling
+            peak_pos += (1 << (h + 1)) - 1;
+        }
+
+        if h == 0 {
+            break;
+        }
+    }
+
+    // for deletion, everything on the right slope of the last peak should be pre-loaded
+    let mut extra = Vec::new();
+    let mut h = last_peak_h;
+    let mut peak_pos = last_peak_pos;
+
+    while h > 0 {
+        let left_pos = peak_pos - (1 << h);
+        let right_pos = peak_pos - 1;
+        h -= 1;
+
+        // drafting left child
+        draft(&mut extra, nodes, left_pos, h);
+
+        // drafting right child
+        draft(&mut extra, nodes, right_pos, h);
+
+        // continuing on right slope
+        peak_pos = right_pos;
+    }
+
+    TreeView { peaks, extra }
+}
+
+fn preload_tree_append(nodes: &[NodeData]) -> (Vec<u32>, Vec<[u8; zcash_history::MAX_ENTRY_SIZE]>) {
+    assert!(!nodes.is_empty());
+
+    let tree_view = prepare_tree(nodes);
+
+    let mut indices = Vec::new();
+    let mut bytes = Vec::new();
+
+    for (idx, entry) in tree_view.peaks.into_iter() {
+        let mut buf = [0u8; zcash_history::MAX_ENTRY_SIZE];
+        entry
+            .write(&mut &mut buf[..])
+            .expect("Cannot fail if enough buffer length");
+        indices.push(idx);
+        bytes.push(buf);
+    }
+
+    (indices, bytes)
+}
+
+// also returns number of peaks
+fn preload_tree_delete(
+    nodes: &[NodeData],
+) -> (Vec<u32>, Vec<[u8; zcash_history::MAX_ENTRY_SIZE]>, usize) {
+    assert!(!nodes.is_empty());
+
+    let tree_view = prepare_tree(nodes);
+
+    let mut indices = Vec::new();
+    let mut bytes = Vec::new();
+
+    let peak_count = tree_view.peaks.len();
+
+    for (idx, entry) in tree_view
+        .peaks
+        .into_iter()
+        .chain(tree_view.extra.into_iter())
+    {
+        let mut buf = [0u8; zcash_history::MAX_ENTRY_SIZE];
+        entry
+            .write(&mut &mut buf[..])
+            .expect("Cannot fail if enough buffer length");
+        indices.push(idx);
+        bytes.push(buf);
+    }
+
+    (indices, bytes, peak_count)
+}
+
+fn load_nodes(bytes: &'static [u8]) -> Vec<NodeData> {
+    let mut res = Vec::new();
+    let mut cursor = std::io::Cursor::new(bytes);
+    while (cursor.position() as usize) < bytes.len() {
+        let node_data = zcash_history::NodeData::read(0, &mut cursor)
+            .expect("Statically checked to be correct");
+        res.push(node_data);
+    }
+
+    res
+}
+
+#[test]
+fn append() {
+    let nodes = load_nodes(NODE_DATA_16L);
+    let (indices, peaks) = preload_tree_append(&nodes);
+
+    let mut rt_ret = [0u8; 32];
+
+    let mut buf_ret = Vec::<[u8; zcash_history::MAX_NODE_DATA_SIZE]>::with_capacity(32);
+
+    let mut new_node_data = [0u8; zcash_history::MAX_NODE_DATA_SIZE];
+    let new_node = NodeData {
+        consensus_branch_id: 0,
+        subtree_commitment: [0u8; 32],
+        start_time: 101,
+        end_time: 110,
+        start_target: 190,
+        end_target: 200,
+        start_sapling_root: [0u8; 32],
+        end_sapling_root: [0u8; 32],
+        subtree_total_work: Default::default(),
+        start_height: 10,
+        end_height: 10,
+        sapling_tx: 13,
+    };
+    new_node
+        .write(&mut &mut new_node_data[..])
+        .expect("Failed to write node data");
+
+    let result = librustzcash_mmr_append(
+        0,
+        nodes.len() as u32,
+        indices.as_ptr(),
+        peaks.as_ptr(),
+        peaks.len(),
+        &new_node_data,
+        &mut rt_ret,
+        buf_ret.as_mut_ptr(),
+    );
+
+    unsafe {
+        buf_ret.set_len(result as usize);
+    }
+
+    assert_eq!(result, 2);
+
+    let new_node_1 =
+        NodeData::from_bytes(0, &buf_ret[0][..]).expect("Failed to reconstruct return node #1");
+
+    let new_node_2 =
+        NodeData::from_bytes(0, &buf_ret[1][..]).expect("Failed to reconstruct return node #2");
+
+    assert_eq!(new_node_1.start_height, 10);
+    assert_eq!(new_node_1.end_height, 10);
+
+    // this is combined new node (which is `new_node_1`) + the one which was there before (for block #9)
+    assert_eq!(new_node_2.start_height, 9);
+    assert_eq!(new_node_2.end_height, 10);
+    assert_eq!(new_node_2.sapling_tx, 27);
+}
+
+#[test]
+fn delete() {
+    let nodes = load_nodes(NODE_DATA_1023L);
+    let (indices, nodes, peak_count) = preload_tree_delete(&nodes);
+
+    let mut rt_ret = [0u8; 32];
+
+    let result = librustzcash_mmr_delete(
+        0,
+        nodes.len() as u32,
+        indices.as_ptr(),
+        nodes.as_ptr(),
+        peak_count,
+        indices.len() - peak_count,
+        &mut rt_ret,
+    );
+
+    // Deleting from full tree of 9 height would result in cascade deleting of 10 nodes
+    assert_eq!(result, 10);
+}

librustzcash/src/tests/mod.rs

@@ -4,6 +4,7 @@ use super::JUBJUB;
 
 mod key_agreement;
 mod key_components;
+mod mmr;
 mod notes;
 mod signatures;
 

librustzcash/src/tests/notes.rs

@@ -1,5 +1,5 @@
-use librustzcash_sapling_compute_cm;
-use librustzcash_sapling_compute_nf;
+use crate::librustzcash_sapling_compute_cm;
+use crate::librustzcash_sapling_compute_nf;
 
 #[test]
 fn notes() {

pairing/Cargo.toml

@@ -2,22 +2,24 @@
 name = "pairing"
 
 # Remember to change version string in README.md.
-version = "0.14.2"
+version = "0.15.1"
 authors = [
     "Sean Bowe <ewillbefull@gmail.com>",
     "Jack Grigg <jack@z.cash>",
 ]
+readme = "README.md"
 license = "MIT/Apache-2.0"
 
 description = "Pairing-friendly elliptic curve library"
 documentation = "https://docs.rs/pairing/"
 homepage = "https://github.com/ebfull/pairing"
 repository = "https://github.com/ebfull/pairing"
+edition ="2018"
 
 [dependencies]
 byteorder = "1"
-ff = { path = "../ff", features = ["derive"] }
-group = { path = "../group" }
+ff = { version = "^0.5.2", path = "../ff", features = ["derive"] }
+group = { version = "0.2.0", path = "../group" }
 rand_core = "0.5"
 
 [dev-dependencies]
@@ -27,3 +29,6 @@ rand_xorshift = "0.2"
 unstable-features = ["expose-arith"]
 expose-arith = []
 default = []
+
+[badges]
+maintenance = { status = "actively-developed" }

pairing/README.md

@@ -1,6 +1,16 @@
 # pairing [![Crates.io](https://img.shields.io/crates/v/pairing.svg)](https://crates.io/crates/pairing) #
 
-This is a Rust crate for using pairing-friendly elliptic curves. Currently, only the [BLS12-381](https://z.cash/blog/new-snark-curve.html) construction is implemented.
+`pairing` is a crate for using pairing-friendly elliptic curves.
+
+Currently, only the [BLS12-381](https://z.cash/blog/new-snark-curve.html)
+construction is implemented.
+
+## Roadmap
+
+`pairing` is being refactored into a generic library for working with
+pairing-friendly curves. After the refactor, `pairing` will provide basic traits
+for pairing-friendly elliptic curve constructions, while specific curves will be
+in separate crates.
 
 ## [Documentation](https://docs.rs/pairing/)
 
@@ -8,13 +18,15 @@ Bring the `pairing` crate into your project just as you normally would.
 
 ## Security Warnings
 
-This library does not make any guarantees about constant-time operations, memory access patterns, or resistance to side-channel attacks.
+This library does not make any guarantees about constant-time operations, memory
+access patterns, or resistance to side-channel attacks.
 
 ## License
 
 Licensed under either of
 
- * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+   http://www.apache.org/licenses/LICENSE-2.0)
  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
 
 at your option.

pairing/benches/bls12_381/ec.rs

@@ -1,6 +1,8 @@
 mod g1 {
-    use rand::{Rand, SeedableRng, XorShiftRng};
+    use rand_core::SeedableRng;
+    use rand_xorshift::XorShiftRng;
 
+    use ff::Field;
     use group::CurveProjective;
     use pairing::bls12_381::*;
 
@@ -8,10 +10,13 @@ mod g1 {
     fn bench_g1_mul_assign(b: &mut ::test::Bencher) {
         const SAMPLES: usize = 1000;
 
-        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let mut rng = XorShiftRng::from_seed([
+            0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06,
+            0xbc, 0xe5,
+        ]);
 
         let v: Vec<(G1, Fr)> = (0..SAMPLES)
-            .map(|_| (G1::rand(&mut rng), Fr::rand(&mut rng)))
+            .map(|_| (G1::random(&mut rng), Fr::random(&mut rng)))
             .collect();
 
         let mut count = 0;
@@ -27,10 +32,13 @@ mod g1 {
     fn bench_g1_add_assign(b: &mut ::test::Bencher) {
         const SAMPLES: usize = 1000;
 
-        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let mut rng = XorShiftRng::from_seed([
+            0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06,
+            0xbc, 0xe5,
+        ]);
 
         let v: Vec<(G1, G1)> = (0..SAMPLES)
-            .map(|_| (G1::rand(&mut rng), G1::rand(&mut rng)))
+            .map(|_| (G1::random(&mut rng), G1::random(&mut rng)))
             .collect();
 
         let mut count = 0;
@@ -46,10 +54,13 @@ mod g1 {
     fn bench_g1_add_assign_mixed(b: &mut ::test::Bencher) {
         const SAMPLES: usize = 1000;
 
-        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let mut rng = XorShiftRng::from_seed([
+            0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06,
+            0xbc, 0xe5,
+        ]);
 
         let v: Vec<(G1, G1Affine)> = (0..SAMPLES)
-            .map(|_| (G1::rand(&mut rng), G1::rand(&mut rng).into()))
+            .map(|_| (G1::random(&mut rng), G1::random(&mut rng).into()))
             .collect();
 
         let mut count = 0;
@@ -63,8 +74,10 @@ mod g1 {
 }
 
 mod g2 {
-    use rand::{Rand, SeedableRng, XorShiftRng};
+    use rand_core::SeedableRng;
+    use rand_xorshift::XorShiftRng;
 
+    use ff::Field;
     use group::CurveProjective;
     use pairing::bls12_381::*;
 
@@ -72,10 +85,13 @@ mod g2 {
     fn bench_g2_mul_assign(b: &mut ::test::Bencher) {
         const SAMPLES: usize = 1000;
 
-        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let mut rng = XorShiftRng::from_seed([
+            0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06,
+            0xbc, 0xe5,
+        ]);
 
         let v: Vec<(G2, Fr)> = (0..SAMPLES)
-            .map(|_| (G2::rand(&mut rng), Fr::rand(&mut rng)))
+            .map(|_| (G2::random(&mut rng), Fr::random(&mut rng)))
             .collect();
 
         let mut count = 0;
@@ -91,10 +107,13 @@ mod g2 {
     fn bench_g2_add_assign(b: &mut ::test::Bencher) {
         const SAMPLES: usize = 1000;
 
-        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let mut rng = XorShiftRng::from_seed([
+            0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06,
+            0xbc, 0xe5,
+        ]);
 
         let v: Vec<(G2, G2)> = (0..SAMPLES)
-            .map(|_| (G2::rand(&mut rng), G2::rand(&mut rng)))
+            .map(|_| (G2::random(&mut rng), G2::random(&mut rng)))
             .collect();
 
         let mut count = 0;
@@ -110,10 +129,13 @@ mod g2 {
     fn bench_g2_add_assign_mixed(b: &mut ::test::Bencher) {
         const SAMPLES: usize = 1000;
 
-        let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+        let mut rng = XorShiftRng::from_seed([
+            0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06,
+            0xbc, 0xe5,
+        ]);
 
         let v: Vec<(G2, G2Affine)> = (0..SAMPLES)
-            .map(|_| (G2::rand(&mut rng), G2::rand(&mut rng).into()))
+            .map(|_| (G2::random(&mut rng), G2::random(&mut rng).into()))
             .collect();
 
         let mut count = 0;

pairing/benches/bls12_381/fq.rs

@@ -1,4 +1,5 @@
-use rand::{Rand, SeedableRng, XorShiftRng};
+use rand_core::SeedableRng;
+use rand_xorshift::XorShiftRng;
 
 use ff::{Field, PrimeField, PrimeFieldRepr, SqrtField};
 use pairing::bls12_381::*;
@@ -7,12 +8,15 @@ use pairing::bls12_381::*;
 fn bench_fq_repr_add_nocarry(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(FqRepr, FqRepr)> = (0..SAMPLES)
         .map(|_| {
-            let mut tmp1 = FqRepr::rand(&mut rng);
-            let mut tmp2 = FqRepr::rand(&mut rng);
+            let mut tmp1 = Fq::random(&mut rng).into_repr();
+            let mut tmp2 = Fq::random(&mut rng).into_repr();
             // Shave a few bits off to avoid overflow.
             for _ in 0..3 {
                 tmp1.div2();
@@ -35,11 +39,14 @@ fn bench_fq_repr_add_nocarry(b: &mut ::test::Bencher) {
 fn bench_fq_repr_sub_noborrow(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(FqRepr, FqRepr)> = (0..SAMPLES)
         .map(|_| {
-            let tmp1 = FqRepr::rand(&mut rng);
+            let tmp1 = Fq::random(&mut rng).into_repr();
             let mut tmp2 = tmp1;
             // Ensure tmp2 is smaller than tmp1.
             for _ in 0..10 {
@@ -62,9 +69,14 @@ fn bench_fq_repr_sub_noborrow(b: &mut ::test::Bencher) {
 fn bench_fq_repr_num_bits(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<FqRepr> = (0..SAMPLES).map(|_| FqRepr::rand(&mut rng)).collect();
+    let v: Vec<FqRepr> = (0..SAMPLES)
+        .map(|_| Fq::random(&mut rng).into_repr())
+        .collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -78,9 +90,14 @@ fn bench_fq_repr_num_bits(b: &mut ::test::Bencher) {
 fn bench_fq_repr_mul2(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<FqRepr> = (0..SAMPLES).map(|_| FqRepr::rand(&mut rng)).collect();
+    let v: Vec<FqRepr> = (0..SAMPLES)
+        .map(|_| Fq::random(&mut rng).into_repr())
+        .collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -95,9 +112,14 @@ fn bench_fq_repr_mul2(b: &mut ::test::Bencher) {
 fn bench_fq_repr_div2(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<FqRepr> = (0..SAMPLES).map(|_| FqRepr::rand(&mut rng)).collect();
+    let v: Vec<FqRepr> = (0..SAMPLES)
+        .map(|_| Fq::random(&mut rng).into_repr())
+        .collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -112,10 +134,13 @@ fn bench_fq_repr_div2(b: &mut ::test::Bencher) {
 fn bench_fq_add_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fq, Fq)> = (0..SAMPLES)
-        .map(|_| (Fq::rand(&mut rng), Fq::rand(&mut rng)))
+        .map(|_| (Fq::random(&mut rng), Fq::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -131,10 +156,13 @@ fn bench_fq_add_assign(b: &mut ::test::Bencher) {
 fn bench_fq_sub_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fq, Fq)> = (0..SAMPLES)
-        .map(|_| (Fq::rand(&mut rng), Fq::rand(&mut rng)))
+        .map(|_| (Fq::random(&mut rng), Fq::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -150,10 +178,13 @@ fn bench_fq_sub_assign(b: &mut ::test::Bencher) {
 fn bench_fq_mul_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fq, Fq)> = (0..SAMPLES)
-        .map(|_| (Fq::rand(&mut rng), Fq::rand(&mut rng)))
+        .map(|_| (Fq::random(&mut rng), Fq::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -169,9 +200,12 @@ fn bench_fq_mul_assign(b: &mut ::test::Bencher) {
 fn bench_fq_square(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fq> = (0..SAMPLES).map(|_| Fq::rand(&mut rng)).collect();
+    let v: Vec<Fq> = (0..SAMPLES).map(|_| Fq::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -186,9 +220,12 @@ fn bench_fq_square(b: &mut ::test::Bencher) {
 fn bench_fq_inverse(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fq> = (0..SAMPLES).map(|_| Fq::rand(&mut rng)).collect();
+    let v: Vec<Fq> = (0..SAMPLES).map(|_| Fq::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -201,9 +238,12 @@ fn bench_fq_inverse(b: &mut ::test::Bencher) {
 fn bench_fq_negate(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fq> = (0..SAMPLES).map(|_| Fq::rand(&mut rng)).collect();
+    let v: Vec<Fq> = (0..SAMPLES).map(|_| Fq::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -218,11 +258,14 @@ fn bench_fq_negate(b: &mut ::test::Bencher) {
 fn bench_fq_sqrt(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<Fq> = (0..SAMPLES)
         .map(|_| {
-            let mut tmp = Fq::rand(&mut rng);
+            let mut tmp = Fq::random(&mut rng);
             tmp.square();
             tmp
         })
@@ -239,9 +282,12 @@ fn bench_fq_sqrt(b: &mut ::test::Bencher) {
 fn bench_fq_into_repr(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fq> = (0..SAMPLES).map(|_| Fq::rand(&mut rng)).collect();
+    let v: Vec<Fq> = (0..SAMPLES).map(|_| Fq::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -254,10 +300,13 @@ fn bench_fq_into_repr(b: &mut ::test::Bencher) {
 fn bench_fq_from_repr(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<FqRepr> = (0..SAMPLES)
-        .map(|_| Fq::rand(&mut rng).into_repr())
+        .map(|_| Fq::random(&mut rng).into_repr())
         .collect();
 
     let mut count = 0;

pairing/benches/bls12_381/fq12.rs

@@ -1,4 +1,5 @@
-use rand::{Rand, SeedableRng, XorShiftRng};
+use rand_core::SeedableRng;
+use rand_xorshift::XorShiftRng;
 
 use ff::Field;
 use pairing::bls12_381::*;
@@ -7,10 +8,13 @@ use pairing::bls12_381::*;
 fn bench_fq12_add_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fq12, Fq12)> = (0..SAMPLES)
-        .map(|_| (Fq12::rand(&mut rng), Fq12::rand(&mut rng)))
+        .map(|_| (Fq12::random(&mut rng), Fq12::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -26,10 +30,13 @@ fn bench_fq12_add_assign(b: &mut ::test::Bencher) {
 fn bench_fq12_sub_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fq12, Fq12)> = (0..SAMPLES)
-        .map(|_| (Fq12::rand(&mut rng), Fq12::rand(&mut rng)))
+        .map(|_| (Fq12::random(&mut rng), Fq12::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -45,10 +52,13 @@ fn bench_fq12_sub_assign(b: &mut ::test::Bencher) {
 fn bench_fq12_mul_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fq12, Fq12)> = (0..SAMPLES)
-        .map(|_| (Fq12::rand(&mut rng), Fq12::rand(&mut rng)))
+        .map(|_| (Fq12::random(&mut rng), Fq12::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -64,9 +74,12 @@ fn bench_fq12_mul_assign(b: &mut ::test::Bencher) {
 fn bench_fq12_squaring(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fq12> = (0..SAMPLES).map(|_| Fq12::rand(&mut rng)).collect();
+    let v: Vec<Fq12> = (0..SAMPLES).map(|_| Fq12::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -81,9 +94,12 @@ fn bench_fq12_squaring(b: &mut ::test::Bencher) {
 fn bench_fq12_inverse(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fq12> = (0..SAMPLES).map(|_| Fq12::rand(&mut rng)).collect();
+    let v: Vec<Fq12> = (0..SAMPLES).map(|_| Fq12::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {

pairing/benches/bls12_381/fq2.rs

@@ -1,4 +1,5 @@
-use rand::{Rand, SeedableRng, XorShiftRng};
+use rand_core::SeedableRng;
+use rand_xorshift::XorShiftRng;
 
 use ff::{Field, SqrtField};
 use pairing::bls12_381::*;
@@ -7,10 +8,13 @@ use pairing::bls12_381::*;
 fn bench_fq2_add_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fq2, Fq2)> = (0..SAMPLES)
-        .map(|_| (Fq2::rand(&mut rng), Fq2::rand(&mut rng)))
+        .map(|_| (Fq2::random(&mut rng), Fq2::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -26,10 +30,13 @@ fn bench_fq2_add_assign(b: &mut ::test::Bencher) {
 fn bench_fq2_sub_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fq2, Fq2)> = (0..SAMPLES)
-        .map(|_| (Fq2::rand(&mut rng), Fq2::rand(&mut rng)))
+        .map(|_| (Fq2::random(&mut rng), Fq2::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -45,10 +52,13 @@ fn bench_fq2_sub_assign(b: &mut ::test::Bencher) {
 fn bench_fq2_mul_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fq2, Fq2)> = (0..SAMPLES)
-        .map(|_| (Fq2::rand(&mut rng), Fq2::rand(&mut rng)))
+        .map(|_| (Fq2::random(&mut rng), Fq2::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -64,9 +74,12 @@ fn bench_fq2_mul_assign(b: &mut ::test::Bencher) {
 fn bench_fq2_squaring(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fq2> = (0..SAMPLES).map(|_| Fq2::rand(&mut rng)).collect();
+    let v: Vec<Fq2> = (0..SAMPLES).map(|_| Fq2::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -81,9 +94,12 @@ fn bench_fq2_squaring(b: &mut ::test::Bencher) {
 fn bench_fq2_inverse(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fq2> = (0..SAMPLES).map(|_| Fq2::rand(&mut rng)).collect();
+    let v: Vec<Fq2> = (0..SAMPLES).map(|_| Fq2::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -97,9 +113,12 @@ fn bench_fq2_inverse(b: &mut ::test::Bencher) {
 fn bench_fq2_sqrt(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fq2> = (0..SAMPLES).map(|_| Fq2::rand(&mut rng)).collect();
+    let v: Vec<Fq2> = (0..SAMPLES).map(|_| Fq2::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {

pairing/benches/bls12_381/fr.rs

@@ -1,4 +1,5 @@
-use rand::{Rand, SeedableRng, XorShiftRng};
+use rand_core::SeedableRng;
+use rand_xorshift::XorShiftRng;
 
 use ff::{Field, PrimeField, PrimeFieldRepr, SqrtField};
 use pairing::bls12_381::*;
@@ -7,12 +8,15 @@ use pairing::bls12_381::*;
 fn bench_fr_repr_add_nocarry(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(FrRepr, FrRepr)> = (0..SAMPLES)
         .map(|_| {
-            let mut tmp1 = FrRepr::rand(&mut rng);
-            let mut tmp2 = FrRepr::rand(&mut rng);
+            let mut tmp1 = Fr::random(&mut rng).into_repr();
+            let mut tmp2 = Fr::random(&mut rng).into_repr();
             // Shave a few bits off to avoid overflow.
             for _ in 0..3 {
                 tmp1.div2();
@@ -35,11 +39,14 @@ fn bench_fr_repr_add_nocarry(b: &mut ::test::Bencher) {
 fn bench_fr_repr_sub_noborrow(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(FrRepr, FrRepr)> = (0..SAMPLES)
         .map(|_| {
-            let tmp1 = FrRepr::rand(&mut rng);
+            let tmp1 = Fr::random(&mut rng).into_repr();
             let mut tmp2 = tmp1;
             // Ensure tmp2 is smaller than tmp1.
             for _ in 0..10 {
@@ -62,9 +69,14 @@ fn bench_fr_repr_sub_noborrow(b: &mut ::test::Bencher) {
 fn bench_fr_repr_num_bits(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<FrRepr> = (0..SAMPLES).map(|_| FrRepr::rand(&mut rng)).collect();
+    let v: Vec<FrRepr> = (0..SAMPLES)
+        .map(|_| Fr::random(&mut rng).into_repr())
+        .collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -78,9 +90,14 @@ fn bench_fr_repr_num_bits(b: &mut ::test::Bencher) {
 fn bench_fr_repr_mul2(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<FrRepr> = (0..SAMPLES).map(|_| FrRepr::rand(&mut rng)).collect();
+    let v: Vec<FrRepr> = (0..SAMPLES)
+        .map(|_| Fr::random(&mut rng).into_repr())
+        .collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -95,9 +112,14 @@ fn bench_fr_repr_mul2(b: &mut ::test::Bencher) {
 fn bench_fr_repr_div2(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<FrRepr> = (0..SAMPLES).map(|_| FrRepr::rand(&mut rng)).collect();
+    let v: Vec<FrRepr> = (0..SAMPLES)
+        .map(|_| Fr::random(&mut rng).into_repr())
+        .collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -112,10 +134,13 @@ fn bench_fr_repr_div2(b: &mut ::test::Bencher) {
 fn bench_fr_add_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fr, Fr)> = (0..SAMPLES)
-        .map(|_| (Fr::rand(&mut rng), Fr::rand(&mut rng)))
+        .map(|_| (Fr::random(&mut rng), Fr::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -131,10 +156,13 @@ fn bench_fr_add_assign(b: &mut ::test::Bencher) {
 fn bench_fr_sub_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fr, Fr)> = (0..SAMPLES)
-        .map(|_| (Fr::rand(&mut rng), Fr::rand(&mut rng)))
+        .map(|_| (Fr::random(&mut rng), Fr::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -150,10 +178,13 @@ fn bench_fr_sub_assign(b: &mut ::test::Bencher) {
 fn bench_fr_mul_assign(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(Fr, Fr)> = (0..SAMPLES)
-        .map(|_| (Fr::rand(&mut rng), Fr::rand(&mut rng)))
+        .map(|_| (Fr::random(&mut rng), Fr::random(&mut rng)))
         .collect();
 
     let mut count = 0;
@@ -169,9 +200,12 @@ fn bench_fr_mul_assign(b: &mut ::test::Bencher) {
 fn bench_fr_square(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fr> = (0..SAMPLES).map(|_| Fr::rand(&mut rng)).collect();
+    let v: Vec<Fr> = (0..SAMPLES).map(|_| Fr::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -186,9 +220,12 @@ fn bench_fr_square(b: &mut ::test::Bencher) {
 fn bench_fr_inverse(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fr> = (0..SAMPLES).map(|_| Fr::rand(&mut rng)).collect();
+    let v: Vec<Fr> = (0..SAMPLES).map(|_| Fr::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -201,9 +238,12 @@ fn bench_fr_inverse(b: &mut ::test::Bencher) {
 fn bench_fr_negate(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fr> = (0..SAMPLES).map(|_| Fr::rand(&mut rng)).collect();
+    let v: Vec<Fr> = (0..SAMPLES).map(|_| Fr::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -218,11 +258,14 @@ fn bench_fr_negate(b: &mut ::test::Bencher) {
 fn bench_fr_sqrt(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<Fr> = (0..SAMPLES)
         .map(|_| {
-            let mut tmp = Fr::rand(&mut rng);
+            let mut tmp = Fr::random(&mut rng);
             tmp.square();
             tmp
         })
@@ -239,9 +282,12 @@ fn bench_fr_sqrt(b: &mut ::test::Bencher) {
 fn bench_fr_into_repr(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<Fr> = (0..SAMPLES).map(|_| Fr::rand(&mut rng)).collect();
+    let v: Vec<Fr> = (0..SAMPLES).map(|_| Fr::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -254,10 +300,13 @@ fn bench_fr_into_repr(b: &mut ::test::Bencher) {
 fn bench_fr_from_repr(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<FrRepr> = (0..SAMPLES)
-        .map(|_| Fr::rand(&mut rng).into_repr())
+        .map(|_| Fr::random(&mut rng).into_repr())
         .collect();
 
     let mut count = 0;

pairing/benches/bls12_381/mod.rs

@@ -4,8 +4,10 @@ mod fq12;
 mod fq2;
 mod fr;
 
-use rand::{Rand, SeedableRng, XorShiftRng};
+use rand_core::SeedableRng;
+use rand_xorshift::XorShiftRng;
 
+use group::CurveProjective;
 use pairing::bls12_381::*;
 use pairing::{Engine, PairingCurveAffine};
 
@@ -13,9 +15,12 @@ use pairing::{Engine, PairingCurveAffine};
 fn bench_pairing_g1_preparation(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<G1> = (0..SAMPLES).map(|_| G1::rand(&mut rng)).collect();
+    let v: Vec<G1> = (0..SAMPLES).map(|_| G1::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -29,9 +34,12 @@ fn bench_pairing_g1_preparation(b: &mut ::test::Bencher) {
 fn bench_pairing_g2_preparation(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
-    let v: Vec<G2> = (0..SAMPLES).map(|_| G2::rand(&mut rng)).collect();
+    let v: Vec<G2> = (0..SAMPLES).map(|_| G2::random(&mut rng)).collect();
 
     let mut count = 0;
     b.iter(|| {
@@ -45,13 +53,16 @@ fn bench_pairing_g2_preparation(b: &mut ::test::Bencher) {
 fn bench_pairing_miller_loop(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(G1Prepared, G2Prepared)> = (0..SAMPLES)
         .map(|_| {
             (
-                G1Affine::from(G1::rand(&mut rng)).prepare(),
-                G2Affine::from(G2::rand(&mut rng)).prepare(),
+                G1Affine::from(G1::random(&mut rng)).prepare(),
+                G2Affine::from(G2::random(&mut rng)).prepare(),
             )
         })
         .collect();
@@ -68,13 +79,16 @@ fn bench_pairing_miller_loop(b: &mut ::test::Bencher) {
 fn bench_pairing_final_exponentiation(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<Fq12> = (0..SAMPLES)
         .map(|_| {
             (
-                G1Affine::from(G1::rand(&mut rng)).prepare(),
-                G2Affine::from(G2::rand(&mut rng)).prepare(),
+                G1Affine::from(G1::random(&mut rng)).prepare(),
+                G2Affine::from(G2::random(&mut rng)).prepare(),
             )
         })
         .map(|(ref p, ref q)| Bls12::miller_loop(&[(p, q)]))
@@ -92,10 +106,13 @@ fn bench_pairing_final_exponentiation(b: &mut ::test::Bencher) {
 fn bench_pairing_full(b: &mut ::test::Bencher) {
     const SAMPLES: usize = 1000;
 
-    let mut rng = XorShiftRng::from_seed([0x5dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
+    let mut rng = XorShiftRng::from_seed([
+        0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,
+        0xe5,
+    ]);
 
     let v: Vec<(G1, G2)> = (0..SAMPLES)
-        .map(|_| (G1::rand(&mut rng), G2::rand(&mut rng)))
+        .map(|_| (G1::random(&mut rng), G2::random(&mut rng)))
         .collect();
 
     let mut count = 0;

pairing/benches/pairing_benches.rs

@@ -3,7 +3,8 @@
 extern crate ff;
 extern crate group;
 extern crate pairing;
-extern crate rand;
+extern crate rand_core;
+extern crate rand_xorshift;
 extern crate test;
 
 mod bls12_381;

pairing/src/bls12_381/ec.rs

@@ -18,7 +18,7 @@ macro_rules! curve_impl {
         }
 
         impl ::std::fmt::Display for $affine {
-            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+            fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
                 if self.infinity {
                     write!(f, "{}(Infinity)", $name)
                 } else {
@@ -35,7 +35,7 @@ macro_rules! curve_impl {
         }
 
         impl ::std::fmt::Display for $projective {
-            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+            fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
                 write!(f, "{}", self.into_affine())
             }
         }
@@ -200,7 +200,7 @@ macro_rules! curve_impl {
             type Base = $basefield;
             type Affine = $affine;
 
-            fn random<R: RngCore>(rng: &mut R) -> Self {
+            fn random<R: RngCore + ?std::marker::Sized>(rng: &mut R) -> Self {
                 loop {
                     let x = $basefield::random(rng);
                     let greatest = rng.next_u32() % 2 != 0;
@@ -622,11 +622,11 @@ macro_rules! curve_impl {
 pub mod g1 {
     use super::super::{Bls12, Fq, Fq12, FqRepr, Fr, FrRepr};
     use super::g2::G2Affine;
+    use crate::{Engine, PairingCurveAffine};
     use ff::{BitIterator, Field, PrimeField, PrimeFieldRepr, SqrtField};
     use group::{CurveAffine, CurveProjective, EncodedPoint, GroupDecodingError};
     use rand_core::RngCore;
     use std::fmt;
-    use {Engine, PairingCurveAffine};
 
     curve_impl!(
         "G1",
@@ -656,7 +656,7 @@ pub mod g1 {
     }
 
     impl fmt::Debug for G1Uncompressed {
-        fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
             self.0[..].fmt(formatter)
         }
     }
@@ -766,7 +766,7 @@ pub mod g1 {
     }
 
     impl fmt::Debug for G1Compressed {
-        fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
             self.0[..].fmt(formatter)
         }
     }
@@ -934,7 +934,7 @@ pub mod g1 {
 
     #[test]
     fn g1_generator() {
-        use SqrtField;
+        use crate::SqrtField;
 
         let mut x = Fq::zero();
         let mut i = 0;
@@ -1291,11 +1291,11 @@ pub mod g1 {
 pub mod g2 {
     use super::super::{Bls12, Fq, Fq12, Fq2, FqRepr, Fr, FrRepr};
     use super::g1::G1Affine;
+    use crate::{Engine, PairingCurveAffine};
     use ff::{BitIterator, Field, PrimeField, PrimeFieldRepr, SqrtField};
     use group::{CurveAffine, CurveProjective, EncodedPoint, GroupDecodingError};
     use rand_core::RngCore;
     use std::fmt;
-    use {Engine, PairingCurveAffine};
 
     curve_impl!(
         "G2",
@@ -1325,7 +1325,7 @@ pub mod g2 {
     }
 
     impl fmt::Debug for G2Uncompressed {
-        fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
             self.0[..].fmt(formatter)
         }
     }
@@ -1451,7 +1451,7 @@ pub mod g2 {
     }
 
     impl fmt::Debug for G2Compressed {
-        fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
             self.0[..].fmt(formatter)
         }
     }
@@ -1640,7 +1640,7 @@ pub mod g2 {
 
     #[test]
     fn g2_generator() {
-        use SqrtField;
+        use crate::SqrtField;
 
         let mut x = Fq2::zero();
         let mut i = 0;

pairing/src/bls12_381/fq.rs

@@ -2225,10 +2225,10 @@ fn test_fq_root_of_unity() {
 
 #[test]
 fn fq_field_tests() {
-    ::tests::field::random_field_tests::<Fq>();
-    ::tests::field::random_sqrt_tests::<Fq>();
-    ::tests::field::random_frobenius_tests::<Fq, _>(Fq::char(), 13);
-    ::tests::field::from_str_tests::<Fq>();
+    crate::tests::field::random_field_tests::<Fq>();
+    crate::tests::field::random_sqrt_tests::<Fq>();
+    crate::tests::field::random_frobenius_tests::<Fq, _>(Fq::char(), 13);
+    crate::tests::field::from_str_tests::<Fq>();
 }
 
 #[test]
@@ -2244,7 +2244,7 @@ fn test_fq_ordering() {
 
 #[test]
 fn fq_repr_tests() {
-    ::tests::repr::random_repr_tests::<Fq>();
+    crate::tests::repr::random_repr_tests::<Fq>();
 }
 
 #[test]

pairing/src/bls12_381/fq12.rs

@@ -12,7 +12,7 @@ pub struct Fq12 {
 }
 
 impl ::std::fmt::Display for Fq12 {
-    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
         write!(f, "Fq12({} + {} * w)", self.c0, self.c1)
     }
 }
@@ -40,7 +40,7 @@ impl Fq12 {
 }
 
 impl Field for Fq12 {
-    fn random<R: RngCore>(rng: &mut R) -> Self {
+    fn random<R: RngCore + ?std::marker::Sized>(rng: &mut R) -> Self {
         Fq12 {
             c0: Fq6::random(rng),
             c1: Fq6::random(rng),
@@ -187,6 +187,6 @@ fn test_fq12_mul_by_014() {
 fn fq12_field_tests() {
     use ff::PrimeField;
 
-    ::tests::field::random_field_tests::<Fq12>();
-    ::tests::field::random_frobenius_tests::<Fq12, _>(super::fq::Fq::char(), 13);
+    crate::tests::field::random_field_tests::<Fq12>();
+    crate::tests::field::random_frobenius_tests::<Fq12, _>(super::fq::Fq::char(), 13);
 }

pairing/src/bls12_381/fq2.rs

@@ -12,7 +12,7 @@ pub struct Fq2 {
 }
 
 impl ::std::fmt::Display for Fq2 {
-    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
         write!(f, "Fq2({} + {} * u)", self.c0, self.c1)
     }
 }
@@ -57,7 +57,7 @@ impl Fq2 {
 }
 
 impl Field for Fq2 {
-    fn random<R: RngCore>(rng: &mut R) -> Self {
+    fn random<R: RngCore + ?std::marker::Sized>(rng: &mut R) -> Self {
         Fq2 {
             c0: Fq::random(rng),
             c1: Fq::random(rng),
@@ -958,7 +958,7 @@ fn test_fq2_mul_nonresidue() {
 fn fq2_field_tests() {
     use ff::PrimeField;
 
-    ::tests::field::random_field_tests::<Fq2>();
-    ::tests::field::random_sqrt_tests::<Fq2>();
-    ::tests::field::random_frobenius_tests::<Fq2, _>(super::fq::Fq::char(), 13);
+    crate::tests::field::random_field_tests::<Fq2>();
+    crate::tests::field::random_sqrt_tests::<Fq2>();
+    crate::tests::field::random_frobenius_tests::<Fq2, _>(super::fq::Fq::char(), 13);
 }

pairing/src/bls12_381/fq6.rs

@@ -12,7 +12,7 @@ pub struct Fq6 {
 }
 
 impl ::std::fmt::Display for Fq6 {
-    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
         write!(f, "Fq6({} + {} * v, {} * v^2)", self.c0, self.c1, self.c2)
     }
 }
@@ -100,7 +100,7 @@ impl Fq6 {
 }
 
 impl Field for Fq6 {
-    fn random<R: RngCore>(rng: &mut R) -> Self {
+    fn random<R: RngCore + ?std::marker::Sized>(rng: &mut R) -> Self {
         Fq6 {
             c0: Fq2::random(rng),
             c1: Fq2::random(rng),
@@ -378,6 +378,6 @@ fn test_fq6_mul_by_01() {
 fn fq6_field_tests() {
     use ff::PrimeField;
 
-    ::tests::field::random_field_tests::<Fq6>();
-    ::tests::field::random_frobenius_tests::<Fq6, _>(super::fq::Fq::char(), 13);
+    crate::tests::field::random_field_tests::<Fq6>();
+    crate::tests::field::random_frobenius_tests::<Fq6, _>(super::fq::Fq::char(), 13);
 }

pairing/src/bls12_381/fr.rs

@@ -1015,13 +1015,13 @@ fn test_fr_root_of_unity() {
 
 #[test]
 fn fr_field_tests() {
-    ::tests::field::random_field_tests::<Fr>();
-    ::tests::field::random_sqrt_tests::<Fr>();
-    ::tests::field::random_frobenius_tests::<Fr, _>(Fr::char(), 13);
-    ::tests::field::from_str_tests::<Fr>();
+    crate::tests::field::random_field_tests::<Fr>();
+    crate::tests::field::random_sqrt_tests::<Fr>();
+    crate::tests::field::random_frobenius_tests::<Fr, _>(Fr::char(), 13);
+    crate::tests::field::from_str_tests::<Fr>();
 }
 
 #[test]
 fn fr_repr_tests() {
-    ::tests::repr::random_repr_tests::<Fr>();
+    crate::tests::repr::random_repr_tests::<Fr>();
 }

pairing/src/bls12_381/mod.rs

@@ -1,3 +1,6 @@
+//! An implementation of the BLS12-381 pairing-friendly elliptic curve
+//! construction.
+
 mod ec;
 mod fq;
 mod fq12;
@@ -366,5 +369,5 @@ impl G2Prepared {
 
 #[test]
 fn bls12_engine_tests() {
-    ::tests::engine::engine_tests::<Bls12>();
+    crate::tests::engine::engine_tests::<Bls12>();
 }

pairing/src/bls12_381/tests/mod.rs

@@ -2,7 +2,7 @@ use ff::PrimeFieldRepr;
 use group::{CurveAffine, CurveProjective, EncodedPoint, GroupDecodingError};
 
 use super::*;
-use *;
+use crate::*;
 
 #[test]
 fn test_pairing_result_against_relic() {

pairing/src/lib.rs

@@ -1,3 +1,5 @@
+//! A library for working with pairing-friendly curves.
+
 // `clippy` is a code linting tool for improving code quality by catching
 // common mistakes or strange code patterns. If the `cargo-clippy` feature
 // is provided, all compiler warnings are prohibited.
@@ -8,17 +10,11 @@
 #![cfg_attr(feature = "cargo-clippy", allow(clippy::many_single_char_names))]
 #![cfg_attr(feature = "cargo-clippy", allow(clippy::new_without_default))]
 #![cfg_attr(feature = "cargo-clippy", allow(clippy::write_literal))]
+// Catch documentation errors caused by code changes.
+#![deny(intra_doc_link_resolution_failure)]
 // Force public structures to implement Debug
 #![deny(missing_debug_implementations)]
 
-extern crate byteorder;
-extern crate ff;
-extern crate group;
-extern crate rand_core;
-
-#[cfg(test)]
-extern crate rand_xorshift;
-
 #[cfg(test)]
 pub mod tests;
 
@@ -87,7 +83,7 @@ pub trait Engine: ScalarEngine {
         >;
 
     /// Perform final exponentiation of the result of a miller loop.
-    fn final_exponentiation(&Self::Fqk) -> Option<Self::Fqk>;
+    fn final_exponentiation(_: &Self::Fqk) -> Option<Self::Fqk>;
 
     /// Performs a complete pairing operation `(p, q)`.
     fn pairing<G1, G2>(p: G1, q: G2) -> Self::Fqk

pairing/src/tests/engine.rs

@@ -2,7 +2,7 @@ use group::{CurveAffine, CurveProjective};
 use rand_core::SeedableRng;
 use rand_xorshift::XorShiftRng;
 
-use {Engine, Field, PairingCurveAffine, PrimeField};
+use crate::{Engine, Field, PairingCurveAffine, PrimeField};
 
 pub fn engine_tests<E: Engine>() {
     let mut rng = XorShiftRng::from_seed([

zcash_client_backend/.gitignore

@@ -0,0 +1,2 @@
+# Protobufs
+src/proto/

zcash_client_backend/Cargo.toml

@@ -1,16 +1,31 @@
 [package]
 name = "zcash_client_backend"
-version = "0.0.0"
+description = "APIs for creating shielded Zcash light clients"
+version = "0.1.0"
 authors = [
     "Jack Grigg <jack@z.cash>",
 ]
+homepage = "https://github.com/zcash/librustzcash"
+repository = "https://github.com/zcash/librustzcash"
+readme = "README.md"
+license = "MIT OR Apache-2.0"
 edition = "2018"
 
 [dependencies]
 bech32 = "0.7"
-pairing = { path = "../pairing" }
-zcash_primitives = { path = "../zcash_primitives" }
+ff = { version = "0.5.0", path = "../ff" }
+hex = "0.3"
+pairing = { version = "0.15.0", path = "../pairing" }
+protobuf = "2"
+subtle = "2"
+zcash_primitives = { version = "0.1.0", path = "../zcash_primitives" }
+
+[build-dependencies]
+protobuf-codegen-pure = "2"
 
 [dev-dependencies]
 rand_core = "0.5"
 rand_xorshift = "0.2"
+
+[badges]
+maintenance = { status = "actively-developed" }

zcash_client_backend/README.md

@@ -1,12 +1,14 @@
 # zcash_client_backend
 
-This library contains Rust structs and traits for creating shielded Zcash light clients.
+This library contains Rust structs and traits for creating shielded Zcash light
+clients.
 
 ## License
 
 Licensed under either of
 
- * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+   http://www.apache.org/licenses/LICENSE-2.0)
  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
 
 at your option.

zcash_client_backend/build.rs

@@ -0,0 +1,11 @@
+use protobuf_codegen_pure;
+
+fn main() {
+    protobuf_codegen_pure::run(protobuf_codegen_pure::Args {
+        out_dir: "src/proto",
+        input: &["proto/compact_formats.proto"],
+        includes: &["proto"],
+        customize: Default::default(),
+    })
+    .expect("protoc");
+}

zcash_client_backend/proto/compact_formats.proto

@@ -0,0 +1,48 @@
+syntax = "proto3";
+package cash.z.wallet.sdk.rpc;
+option go_package = "walletrpc";
+
+// Remember that proto3 fields are all optional. A field that is not present will be set to its zero value.
+// bytes fields of hashes are in canonical little-endian format.
+
+// CompactBlock is a packaging of ONLY the data from a block that's needed to:
+//   1. Detect a payment to your shielded Sapling address
+//   2. Detect a spend of your shielded Sapling notes
+//   3. Update your witnesses to generate new Sapling spend proofs.
+message CompactBlock {
+    uint32 protoVersion = 1; // the version of this wire format, for storage
+    uint64 height = 2; // the height of this block
+    bytes hash = 3;
+    bytes prevHash = 4;
+    uint32 time = 5;
+    bytes header = 6; // (hash, prevHash, and time) OR (full header)
+    repeated CompactTx vtx = 7; // compact transactions from this block
+}
+
+message CompactTx {
+    // Index and hash will allow the receiver to call out to chain
+    // explorers or other data structures to retrieve more information
+    // about this transaction.
+    uint64 index = 1;
+    bytes hash = 2;
+
+    // The transaction fee: present if server can provide. In the case of a
+    // stateless server and a transaction with transparent inputs, this will be
+    // unset because the calculation requires reference to prior transactions.
+    // in a pure-Sapling context, the fee will be calculable as:
+    //    valueBalance + (sum(vPubNew) - sum(vPubOld) - sum(tOut))
+    uint32 fee = 3;
+
+    repeated CompactSpend spends = 4;
+    repeated CompactOutput outputs = 5;
+}
+
+message CompactSpend {
+    bytes nf = 1;
+}
+
+message CompactOutput {
+    bytes cmu = 1;
+    bytes epk = 2;
+    bytes ciphertext = 3;
+}

zcash_client_backend/src/constants.rs

@@ -1,4 +1,5 @@
 //! Zcash global and per-network constants.
 
 pub mod mainnet;
+pub mod regtest;
 pub mod testnet;

zcash_client_backend/src/constants/mainnet.rs

@@ -1,3 +1,5 @@
+//! Constants for the Zcash main network.
+
 /// The mainnet coin type for ZEC, as defined by [SLIP 44].
 ///
 /// [SLIP 44]: https://github.com/satoshilabs/slips/blob/master/slip-0044.md
@@ -23,6 +25,6 @@ pub const HRP_SAPLING_EXTENDED_FULL_VIEWING_KEY: &str = "zxviews";
 ///
 /// Defined in section 5.6.4 of the [Zcash Protocol Specification].
 ///
-/// [`PaymentAddress`]: sapling_crypto::primitives::PaymentAddress
+/// [`PaymentAddress`]: zcash_primitives::primitives::PaymentAddress
 /// [Zcash Protocol Specification]: https://github.com/zcash/zips/blob/master/protocol/protocol.pdf
 pub const HRP_SAPLING_PAYMENT_ADDRESS: &str = "zs";

zcash_client_backend/src/constants/regtest.rs

@@ -0,0 +1,45 @@
+//! # Regtest constants
+//!
+//! `regtest` is a `zcashd`-specific environment used for local testing. They mostly reuse
+//! the testnet constants.
+//! These constants are defined in [the `zcashd` codebase].
+//! [the `zcashd` codebase]: https://github.com/zcash/zcash/blob/128d863fb8be39ee294fda397c1ce3ba3b889cb2/src/chainparams.cpp#L482-L496
+
+/// The regtest cointype reuses the testnet cointype
+pub const COIN_TYPE: u32 = 1;
+
+/// The HRP for a Bech32-encoded regtest [`ExtendedSpendingKey`].
+///
+/// It is defined in [the `zcashd` codebase].
+///
+/// [`ExtendedSpendingKey`]: zcash_primitives::zip32::ExtendedSpendingKey
+/// [the `zcashd` codebase]: https://github.com/zcash/zcash/blob/128d863fb8be39ee294fda397c1ce3ba3b889cb2/src/chainparams.cpp#L496
+pub const HRP_SAPLING_EXTENDED_SPENDING_KEY: &str = "secret-extended-key-regtest";
+
+/// The HRP for a Bech32-encoded regtest [`ExtendedFullViewingKey`].
+///
+/// It is defined in [the `zcashd` codebase].
+///
+/// [`ExtendedFullViewingKey`]: zcash_primitives::zip32::ExtendedFullViewingKey
+/// [the `zcashd` codebase]: https://github.com/zcash/zcash/blob/128d863fb8be39ee294fda397c1ce3ba3b889cb2/src/chainparams.cpp#L494
+pub const HRP_SAPLING_EXTENDED_FULL_VIEWING_KEY: &str = "zxviewregtestsapling";
+
+/// The HRP for a Bech32-encoded regtest [`PaymentAddress`].
+///
+/// It is defined in [the `zcashd` codebase].
+///
+/// [`PaymentAddress`]: zcash_primitives::primitives::PaymentAddress
+/// [the `zcashd` codebase]: https://github.com/zcash/zcash/blob/128d863fb8be39ee294fda397c1ce3ba3b889cb2/src/chainparams.cpp#L493
+pub const HRP_SAPLING_PAYMENT_ADDRESS: &str = "zregtestsapling";
+
+/// The prefix for a Base58Check-encoded regtest [`TransparentAddress::PublicKey`].
+/// Same as the testnet prefix.
+///
+/// [`TransparentAddress::PublicKey`]: zcash_primitives::legacy::TransparentAddress::PublicKey
+pub const B58_PUBKEY_ADDRESS_PREFIX: [u8; 2] = [0x1d, 0x25];
+
+/// The prefix for a Base58Check-encoded regtest [`TransparentAddress::Script`].
+/// Same as the testnet prefix.
+///
+/// [`TransparentAddress::Script`]: zcash_primitives::legacy::TransparentAddress::Script
+pub const B58_SCRIPT_ADDRESS_PREFIX: [u8; 2] = [0x1c, 0xba];

zcash_client_backend/src/constants/testnet.rs

@@ -1,3 +1,5 @@
+//! Constants for the Zcash test network.
+
 /// The testnet coin type for ZEC, as defined by [SLIP 44].
 ///
 /// [SLIP 44]: https://github.com/satoshilabs/slips/blob/master/slip-0044.md
@@ -23,6 +25,6 @@ pub const HRP_SAPLING_EXTENDED_FULL_VIEWING_KEY: &str = "zxviewtestsapling";
 ///
 /// Defined in section 5.6.4 of the [Zcash Protocol Specification].
 ///
-/// [`PaymentAddress`]: sapling_crypto::primitives::PaymentAddress
+/// [`PaymentAddress`]: zcash_primitives::primitives::PaymentAddress
 /// [Zcash Protocol Specification]: https://github.com/zcash/zips/blob/master/protocol/protocol.pdf
 pub const HRP_SAPLING_PAYMENT_ADDRESS: &str = "ztestsapling";

zcash_client_backend/src/decrypt.rs

@@ -0,0 +1,76 @@
+use pairing::bls12_381::Bls12;
+use zcash_primitives::{
+    note_encryption::{try_sapling_note_decryption, try_sapling_output_recovery, Memo},
+    primitives::{Note, PaymentAddress},
+    transaction::Transaction,
+    zip32::ExtendedFullViewingKey,
+    JUBJUB,
+};
+
+/// A decrypted shielded output.
+pub struct DecryptedOutput {
+    /// The index of the output within [`shielded_outputs`].
+    ///
+    /// [`shielded_outputs`]: zcash_primitives::transaction::TransactionData
+    pub index: usize,
+    /// The note within the output.
+    pub note: Note<Bls12>,
+    /// The address the note was sent to.
+    pub to: PaymentAddress<Bls12>,
+    /// The memo included with the note.
+    pub memo: Memo,
+    /// True if this output was recovered using an [`OutgoingViewingKey`], meaning that
+    /// this is a logical output of the transaction.
+    ///
+    /// [`OutgoingViewingKey`]: zcash_primitives::keys::OutgoingViewingKey
+    pub outgoing: bool,
+}
+
+/// Scans a [`Transaction`] for any information that can be decrypted by the set of
+/// [`ExtendedFullViewingKey`]s.
+pub fn decrypt_transaction(
+    tx: &Transaction,
+    extfvks: &[ExtendedFullViewingKey],
+) -> Vec<DecryptedOutput> {
+    let mut decrypted = vec![];
+
+    // Cache IncomingViewingKey calculation
+    let vks: Vec<_> = extfvks
+        .iter()
+        .map(|extfvk| (extfvk.fvk.vk.ivk(), extfvk.fvk.ovk))
+        .collect();
+
+    for (index, output) in tx.shielded_outputs.iter().enumerate() {
+        let epk = match output.ephemeral_key.as_prime_order(&JUBJUB) {
+            Some(p) => p,
+            None => continue,
+        };
+
+        for (ivk, ovk) in &vks {
+            let ((note, to, memo), outgoing) =
+                match try_sapling_note_decryption(ivk, &epk, &output.cmu, &output.enc_ciphertext) {
+                    Some(ret) => (ret, false),
+                    None => match try_sapling_output_recovery(
+                        ovk,
+                        &output.cv,
+                        &output.cmu,
+                        &epk,
+                        &output.enc_ciphertext,
+                        &output.out_ciphertext,
+                    ) {
+                        Some(ret) => (ret, true),
+                        None => continue,
+                    },
+                };
+            decrypted.push(DecryptedOutput {
+                index,
+                note,
+                to,
+                memo,
+                outgoing,
+            })
+        }
+    }
+
+    decrypted
+}

zcash_client_backend/src/encoding.rs

@@ -2,15 +2,14 @@
 //!
 //! Human-Readable Prefixes (HRPs) for Bech32 encodings are located in the [`constants`]
 //! module.
+//!
+//! [`constants`]: crate::constants
 
 use bech32::{self, Error, FromBase32, ToBase32};
 use pairing::bls12_381::Bls12;
 use std::io::{self, Write};
 use zcash_primitives::{
-    jubjub::edwards,
-    primitives::{Diversifier, PaymentAddress},
-};
-use zcash_primitives::{
+    primitives::PaymentAddress,
     zip32::{ExtendedFullViewingKey, ExtendedSpendingKey},
     JUBJUB,
 };
@@ -113,10 +112,11 @@ pub fn decode_extended_full_viewing_key(
 ///     0xbc, 0xe5,
 /// ]);
 ///
-/// let pa = PaymentAddress {
-///     diversifier: Diversifier([0u8; 11]),
-///     pk_d: edwards::Point::<Bls12, _>::rand(rng, &JUBJUB).mul_by_cofactor(&JUBJUB),
-/// };
+/// let pa = PaymentAddress::from_parts(
+///     Diversifier([0u8; 11]),
+///     edwards::Point::<Bls12, _>::rand(rng, &JUBJUB).mul_by_cofactor(&JUBJUB),
+/// )
+/// .unwrap();
 ///
 /// assert_eq!(
 ///     encode_payment_address(HRP_SAPLING_PAYMENT_ADDRESS, &pa),
@@ -124,10 +124,7 @@ pub fn decode_extended_full_viewing_key(
 /// );
 /// ```
 pub fn encode_payment_address(hrp: &str, addr: &PaymentAddress<Bls12>) -> String {
-    bech32_encode(hrp, |w| {
-        w.write_all(&addr.diversifier.0)?;
-        addr.pk_d.write(w)
-    })
+    bech32_encode(hrp, |w| w.write_all(&addr.to_bytes()))
 }
 
 /// Decodes a [`PaymentAddress`] from a Bech32-encoded string.
@@ -153,10 +150,11 @@ pub fn encode_payment_address(hrp: &str, addr: &PaymentAddress<Bls12>) -> String
 ///     0xbc, 0xe5,
 /// ]);
 ///
-/// let pa = PaymentAddress {
-///     diversifier: Diversifier([0u8; 11]),
-///     pk_d: edwards::Point::<Bls12, _>::rand(rng, &JUBJUB).mul_by_cofactor(&JUBJUB),
-/// };
+/// let pa = PaymentAddress::from_parts(
+///     Diversifier([0u8; 11]),
+///     edwards::Point::<Bls12, _>::rand(rng, &JUBJUB).mul_by_cofactor(&JUBJUB),
+/// )
+/// .unwrap();
 ///
 /// assert_eq!(
 ///     decode_payment_address(
@@ -168,17 +166,13 @@ pub fn encode_payment_address(hrp: &str, addr: &PaymentAddress<Bls12>) -> String
 /// ```
 pub fn decode_payment_address(hrp: &str, s: &str) -> Result<Option<PaymentAddress<Bls12>>, Error> {
     bech32_decode(hrp, s, |data| {
-        let mut diversifier = Diversifier([0; 11]);
-        diversifier.0.copy_from_slice(&data[0..11]);
-        // Check that the diversifier is valid
-        if diversifier.g_d::<Bls12>(&JUBJUB).is_none() {
+        if data.len() != 43 {
             return None;
         }
 
-        edwards::Point::<Bls12, _>::read(&data[11..], &JUBJUB)
-            .ok()?
-            .as_prime_order(&JUBJUB)
-            .map(|pk_d| PaymentAddress { pk_d, diversifier })
+        let mut bytes = [0; 43];
+        bytes.copy_from_slice(&data);
+        PaymentAddress::<Bls12>::from_bytes(&bytes, &JUBJUB)
     })
 }
 
@@ -191,11 +185,95 @@ mod tests {
     use zcash_primitives::{
         jubjub::edwards,
         primitives::{Diversifier, PaymentAddress},
+        zip32::ExtendedSpendingKey,
     };
 
-    use super::{decode_payment_address, encode_payment_address};
+    use super::{
+        decode_extended_full_viewing_key, decode_extended_spending_key, decode_payment_address,
+        encode_extended_full_viewing_key, encode_extended_spending_key, encode_payment_address,
+    };
     use crate::constants;
 
+    #[test]
+    fn extended_spending_key() {
+        let extsk = ExtendedSpendingKey::master(&[0; 32][..]);
+
+        let encoded_main = "secret-extended-key-main1qqqqqqqqqqqqqq8n3zjjmvhhr854uy3qhpda3ml34haf0x388z5r7h4st4kpsf6qysqws3xh6qmha7gna72fs2n4clnc9zgyd22s658f65pex4exe56qjk5pqj9vfdq7dfdhjc2rs9jdwq0zl99uwycyrxzp86705rk687spn44e2uhm7h0hsagfvkk4n7n6nfer6u57v9cac84t7nl2zth0xpyfeg0w2p2wv2yn6jn923aaz0vdaml07l60ahapk6efchyxwysrvjs87qvlj";
+        let encoded_test = "secret-extended-key-test1qqqqqqqqqqqqqq8n3zjjmvhhr854uy3qhpda3ml34haf0x388z5r7h4st4kpsf6qysqws3xh6qmha7gna72fs2n4clnc9zgyd22s658f65pex4exe56qjk5pqj9vfdq7dfdhjc2rs9jdwq0zl99uwycyrxzp86705rk687spn44e2uhm7h0hsagfvkk4n7n6nfer6u57v9cac84t7nl2zth0xpyfeg0w2p2wv2yn6jn923aaz0vdaml07l60ahapk6efchyxwysrvjsvzyw8j";
+
+        assert_eq!(
+            encode_extended_spending_key(
+                constants::mainnet::HRP_SAPLING_EXTENDED_SPENDING_KEY,
+                &extsk
+            ),
+            encoded_main
+        );
+        assert_eq!(
+            decode_extended_spending_key(
+                constants::mainnet::HRP_SAPLING_EXTENDED_SPENDING_KEY,
+                encoded_main
+            )
+            .unwrap(),
+            Some(extsk.clone())
+        );
+
+        assert_eq!(
+            encode_extended_spending_key(
+                constants::testnet::HRP_SAPLING_EXTENDED_SPENDING_KEY,
+                &extsk
+            ),
+            encoded_test
+        );
+        assert_eq!(
+            decode_extended_spending_key(
+                constants::testnet::HRP_SAPLING_EXTENDED_SPENDING_KEY,
+                encoded_test
+            )
+            .unwrap(),
+            Some(extsk)
+        );
+    }
+
+    #[test]
+    fn extended_full_viewing_key() {
+        let extfvk = (&ExtendedSpendingKey::master(&[0; 32][..])).into();
+
+        let encoded_main = "zxviews1qqqqqqqqqqqqqq8n3zjjmvhhr854uy3qhpda3ml34haf0x388z5r7h4st4kpsf6qy3zw4wc246aw9rlfyg5ndlwvne7mwdq0qe6vxl42pqmcf8pvmmd5slmjxduqa9evgej6wa3th2505xq4nggrxdm93rxk4rpdjt5nmq2vn44e2uhm7h0hsagfvkk4n7n6nfer6u57v9cac84t7nl2zth0xpyfeg0w2p2wv2yn6jn923aaz0vdaml07l60ahapk6efchyxwysrvjsxmansf";
+        let encoded_test = "zxviewtestsapling1qqqqqqqqqqqqqq8n3zjjmvhhr854uy3qhpda3ml34haf0x388z5r7h4st4kpsf6qy3zw4wc246aw9rlfyg5ndlwvne7mwdq0qe6vxl42pqmcf8pvmmd5slmjxduqa9evgej6wa3th2505xq4nggrxdm93rxk4rpdjt5nmq2vn44e2uhm7h0hsagfvkk4n7n6nfer6u57v9cac84t7nl2zth0xpyfeg0w2p2wv2yn6jn923aaz0vdaml07l60ahapk6efchyxwysrvjs8evfkz";
+
+        assert_eq!(
+            encode_extended_full_viewing_key(
+                constants::mainnet::HRP_SAPLING_EXTENDED_FULL_VIEWING_KEY,
+                &extfvk
+            ),
+            encoded_main
+        );
+        assert_eq!(
+            decode_extended_full_viewing_key(
+                constants::mainnet::HRP_SAPLING_EXTENDED_FULL_VIEWING_KEY,
+                encoded_main
+            )
+            .unwrap(),
+            Some(extfvk.clone())
+        );
+
+        assert_eq!(
+            encode_extended_full_viewing_key(
+                constants::testnet::HRP_SAPLING_EXTENDED_FULL_VIEWING_KEY,
+                &extfvk
+            ),
+            encoded_test
+        );
+        assert_eq!(
+            decode_extended_full_viewing_key(
+                constants::testnet::HRP_SAPLING_EXTENDED_FULL_VIEWING_KEY,
+                encoded_test
+            )
+            .unwrap(),
+            Some(extfvk)
+        );
+    }
+
     #[test]
     fn payment_address() {
         let rng = &mut XorShiftRng::from_seed([
@@ -203,10 +281,11 @@ mod tests {
             0xbc, 0xe5,
         ]);
 
-        let addr = PaymentAddress {
-            diversifier: Diversifier([0u8; 11]),
-            pk_d: edwards::Point::<Bls12, _>::rand(rng, &JUBJUB).mul_by_cofactor(&JUBJUB),
-        };
+        let addr = PaymentAddress::from_parts(
+            Diversifier([0u8; 11]),
+            edwards::Point::<Bls12, _>::rand(rng, &JUBJUB).mul_by_cofactor(&JUBJUB),
+        )
+        .unwrap();
 
         let encoded_main =
             "zs1qqqqqqqqqqqqqqqqqrjq05nyfku05msvu49mawhg6kr0wwljahypwyk2h88z6975u563j8nfaxd";
@@ -247,10 +326,11 @@ mod tests {
             0xbc, 0xe5,
         ]);
 
-        let addr = PaymentAddress {
-            diversifier: Diversifier([1u8; 11]),
-            pk_d: edwards::Point::<Bls12, _>::rand(rng, &JUBJUB).mul_by_cofactor(&JUBJUB),
-        };
+        let addr = PaymentAddress::from_parts(
+            Diversifier([1u8; 11]),
+            edwards::Point::<Bls12, _>::rand(rng, &JUBJUB).mul_by_cofactor(&JUBJUB),
+        )
+        .unwrap();
 
         let encoded_main =
             encode_payment_address(constants::mainnet::HRP_SAPLING_PAYMENT_ADDRESS, &addr);

zcash_client_backend/src/keys.rs

@@ -5,6 +5,10 @@ use zcash_primitives::zip32::{ChildIndex, ExtendedSpendingKey};
 /// Derives the ZIP 32 [`ExtendedSpendingKey`] for a given coin type and account from the
 /// given seed.
 ///
+/// # Panics
+///
+/// Panics if `seed` is shorter than 32 bytes.
+///
 /// # Examples
 ///
 /// ```
@@ -13,6 +17,10 @@ use zcash_primitives::zip32::{ChildIndex, ExtendedSpendingKey};
 /// let extsk = spending_key(&[0; 32][..], COIN_TYPE, 0);
 /// ```
 pub fn spending_key(seed: &[u8], coin_type: u32, account: u32) -> ExtendedSpendingKey {
+    if seed.len() < 32 {
+        panic!("ZIP 32 seeds MUST be at least 32 bytes");
+    }
+
     ExtendedSpendingKey::from_path(
         &ExtendedSpendingKey::master(&seed),
         &[
@@ -22,3 +30,14 @@ pub fn spending_key(seed: &[u8], coin_type: u32, account: u32) -> ExtendedSpendi
         ],
     )
 }
+
+#[cfg(test)]
+mod tests {
+    use super::spending_key;
+
+    #[test]
+    #[should_panic]
+    fn spending_key_panics_on_short_seed() {
+        let _ = spending_key(&[0; 31][..], 0, 0);
+    }
+}

zcash_client_backend/src/lib.rs

@@ -3,6 +3,15 @@
 //! `zcash_client_backend` contains Rust structs and traits for creating shielded Zcash
 //! light clients.
 
+// Catch documentation errors caused by code changes.
+#![deny(intra_doc_link_resolution_failure)]
+
 pub mod constants;
+mod decrypt;
 pub mod encoding;
 pub mod keys;
+pub mod proto;
+pub mod wallet;
+pub mod welding_rig;
+
+pub use decrypt::{decrypt_transaction, DecryptedOutput};

zcash_client_backend/src/proto/mod.rs

@@ -0,0 +1,83 @@
+//! Generated code for handling light client protobuf structs.
+
+use ff::{PrimeField, PrimeFieldRepr};
+use pairing::bls12_381::{Bls12, Fr, FrRepr};
+use zcash_primitives::{
+    block::{BlockHash, BlockHeader},
+    jubjub::{edwards, PrimeOrder},
+    JUBJUB,
+};
+
+pub mod compact_formats;
+
+impl compact_formats::CompactBlock {
+    /// Returns the [`BlockHash`] for this block.
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if [`CompactBlock.header`] is not set and
+    /// [`CompactBlock.hash`] is not exactly 32 bytes.
+    ///
+    /// [`CompactBlock.header`]: #structfield.header
+    /// [`CompactBlock.hash`]: #structfield.hash
+    pub fn hash(&self) -> BlockHash {
+        if let Some(header) = self.header() {
+            header.hash()
+        } else {
+            BlockHash::from_slice(&self.hash)
+        }
+    }
+
+    /// Returns the [`BlockHash`] for this block's parent.
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if [`CompactBlock.header`] is not set and
+    /// [`CompactBlock.prevHash`] is not exactly 32 bytes.
+    ///
+    /// [`CompactBlock.header`]: #structfield.header
+    /// [`CompactBlock.prevHash`]: #structfield.prevHash
+    pub fn prev_hash(&self) -> BlockHash {
+        if let Some(header) = self.header() {
+            header.prev_block
+        } else {
+            BlockHash::from_slice(&self.prevHash)
+        }
+    }
+
+    /// Returns the [`BlockHeader`] for this block if present.
+    ///
+    /// A convenience method that parses [`CompactBlock.header`] if present.
+    ///
+    /// [`CompactBlock.header`]: #structfield.header
+    pub fn header(&self) -> Option<BlockHeader> {
+        if self.header.is_empty() {
+            None
+        } else {
+            BlockHeader::read(&self.header[..]).ok()
+        }
+    }
+}
+
+impl compact_formats::CompactOutput {
+    /// Returns the note commitment for this output.
+    ///
+    /// A convenience method that parses [`CompactOutput.cmu`].
+    ///
+    /// [`CompactOutput.cmu`]: #structfield.cmu
+    pub fn cmu(&self) -> Result<Fr, ()> {
+        let mut repr = FrRepr::default();
+        repr.read_le(&self.cmu[..]).map_err(|_| ())?;
+        Fr::from_repr(repr).map_err(|_| ())
+    }
+
+    /// Returns the ephemeral public key for this output.
+    ///
+    /// A convenience method that parses [`CompactOutput.epk`].
+    ///
+    /// [`CompactOutput.epk`]: #structfield.epk
+    pub fn epk(&self) -> Result<edwards::Point<Bls12, PrimeOrder>, ()> {
+        let p = edwards::Point::<Bls12, _>::read(&self.epk[..], &JUBJUB).map_err(|_| ())?;
+        p.as_prime_order(&JUBJUB).ok_or(())
+    }
+}

zcash_client_backend/src/wallet.rs

@@ -0,0 +1,46 @@
+//! Structs representing transaction data scanned from the block chain by a wallet or
+//! light client.
+
+use pairing::bls12_381::{Bls12, Fr};
+use zcash_primitives::{
+    jubjub::{edwards, PrimeOrder},
+    merkle_tree::IncrementalWitness,
+    primitives::{Note, PaymentAddress},
+    sapling::Node,
+    transaction::TxId,
+};
+
+/// A subset of a [`Transaction`] relevant to wallets and light clients.
+///
+/// [`Transaction`]: zcash_primitives::transaction::Transaction
+pub struct WalletTx {
+    pub txid: TxId,
+    pub index: usize,
+    pub num_spends: usize,
+    pub num_outputs: usize,
+    pub shielded_spends: Vec<WalletShieldedSpend>,
+    pub shielded_outputs: Vec<WalletShieldedOutput>,
+}
+
+/// A subset of a [`SpendDescription`] relevant to wallets and light clients.
+///
+/// [`SpendDescription`]: zcash_primitives::transaction::components::SpendDescription
+pub struct WalletShieldedSpend {
+    pub index: usize,
+    pub nf: Vec<u8>,
+    pub account: usize,
+}
+
+/// A subset of an [`OutputDescription`] relevant to wallets and light clients.
+///
+/// [`OutputDescription`]: zcash_primitives::transaction::components::OutputDescription
+pub struct WalletShieldedOutput {
+    pub index: usize,
+    pub cmu: Fr,
+    pub epk: edwards::Point<Bls12, PrimeOrder>,
+    pub account: usize,
+    pub note: Note<Bls12>,
+    pub to: PaymentAddress<Bls12>,
+    pub is_change: bool,
+    pub witness: IncrementalWitness<Node>,
+}

zcash_client_backend/src/welding_rig.rs

@@ -0,0 +1,397 @@
+//! Tools for scanning a compact representation of the Zcash block chain.
+
+use ff::PrimeField;
+use std::collections::HashSet;
+use subtle::{ConditionallySelectable, ConstantTimeEq, CtOption};
+use zcash_primitives::{
+    jubjub::fs::Fs,
+    merkle_tree::{CommitmentTree, IncrementalWitness},
+    note_encryption::try_sapling_compact_note_decryption,
+    sapling::Node,
+    transaction::TxId,
+    zip32::ExtendedFullViewingKey,
+};
+
+use crate::proto::compact_formats::{CompactBlock, CompactOutput};
+use crate::wallet::{WalletShieldedOutput, WalletShieldedSpend, WalletTx};
+
+/// Scans a [`CompactOutput`] with a set of [`ExtendedFullViewingKey`]s.
+///
+/// Returns a [`WalletShieldedOutput`] and corresponding [`IncrementalWitness`] if this
+/// output belongs to any of the given [`ExtendedFullViewingKey`]s.
+///
+/// The given [`CommitmentTree`] and existing [`IncrementalWitness`]es are incremented
+/// with this output's commitment.
+fn scan_output(
+    (index, output): (usize, CompactOutput),
+    ivks: &[Fs],
+    spent_from_accounts: &HashSet<usize>,
+    tree: &mut CommitmentTree<Node>,
+    existing_witnesses: &mut [&mut IncrementalWitness<Node>],
+    block_witnesses: &mut [&mut IncrementalWitness<Node>],
+    new_witnesses: &mut [&mut IncrementalWitness<Node>],
+) -> Option<WalletShieldedOutput> {
+    let cmu = output.cmu().ok()?;
+    let epk = output.epk().ok()?;
+    let ct = output.ciphertext;
+
+    // Increment tree and witnesses
+    let node = Node::new(cmu.into_repr());
+    for witness in existing_witnesses {
+        witness.append(node).unwrap();
+    }
+    for witness in block_witnesses {
+        witness.append(node).unwrap();
+    }
+    for witness in new_witnesses {
+        witness.append(node).unwrap();
+    }
+    tree.append(node).unwrap();
+
+    for (account, ivk) in ivks.iter().enumerate() {
+        let (note, to) = match try_sapling_compact_note_decryption(ivk, &epk, &cmu, &ct) {
+            Some(ret) => ret,
+            None => continue,
+        };
+
+        // A note is marked as "change" if the account that received it
+        // also spent notes in the same transaction. This will catch,
+        // for instance:
+        // - Change created by spending fractions of notes.
+        // - Notes created by consolidation transactions.
+        // - Notes sent from one account to itself.
+        let is_change = spent_from_accounts.contains(&account);
+
+        return Some(WalletShieldedOutput {
+            index,
+            cmu,
+            epk,
+            account,
+            note,
+            to,
+            is_change,
+            witness: IncrementalWitness::from_tree(tree),
+        });
+    }
+    None
+}
+
+/// Scans a [`CompactBlock`] with a set of [`ExtendedFullViewingKey`]s.
+///
+/// Returns a vector of [`WalletTx`]s belonging to any of the given
+/// [`ExtendedFullViewingKey`]s, and the corresponding new [`IncrementalWitness`]es.
+///
+/// The given [`CommitmentTree`] and existing [`IncrementalWitness`]es are
+/// incremented appropriately.
+pub fn scan_block(
+    block: CompactBlock,
+    extfvks: &[ExtendedFullViewingKey],
+    nullifiers: &[(&[u8], usize)],
+    tree: &mut CommitmentTree<Node>,
+    existing_witnesses: &mut [&mut IncrementalWitness<Node>],
+) -> Vec<WalletTx> {
+    let mut wtxs: Vec<WalletTx> = vec![];
+    let ivks: Vec<_> = extfvks.iter().map(|extfvk| extfvk.fvk.vk.ivk()).collect();
+
+    for tx in block.vtx.into_iter() {
+        let num_spends = tx.spends.len();
+        let num_outputs = tx.outputs.len();
+
+        // Check for spent notes
+        // The only step that is not constant-time is the filter() at the end.
+        let shielded_spends: Vec<_> = tx
+            .spends
+            .into_iter()
+            .enumerate()
+            .map(|(index, spend)| {
+                // Find the first tracked nullifier that matches this spend, and produce
+                // a WalletShieldedSpend if there is a match, in constant time.
+                nullifiers
+                    .iter()
+                    .map(|&(nf, account)| CtOption::new(account as u64, nf.ct_eq(&spend.nf[..])))
+                    .fold(CtOption::new(0, 0.into()), |first, next| {
+                        CtOption::conditional_select(&next, &first, first.is_some())
+                    })
+                    .map(|account| WalletShieldedSpend {
+                        index,
+                        nf: spend.nf,
+                        account: account as usize,
+                    })
+            })
+            .filter(|spend| spend.is_some().into())
+            .map(|spend| spend.unwrap())
+            .collect();
+
+        // Collect the set of accounts that were spent from in this transaction
+        let spent_from_accounts: HashSet<_> =
+            shielded_spends.iter().map(|spend| spend.account).collect();
+
+        // Check for incoming notes while incrementing tree and witnesses
+        let mut shielded_outputs: Vec<WalletShieldedOutput> = vec![];
+        {
+            // Grab mutable references to new witnesses from previous transactions
+            // in this block so that we can update them. Scoped so we don't hold
+            // mutable references to wtxs for too long.
+            let mut block_witnesses: Vec<_> = wtxs
+                .iter_mut()
+                .flat_map(|tx| {
+                    tx.shielded_outputs
+                        .iter_mut()
+                        .map(|output| &mut output.witness)
+                })
+                .collect();
+
+            for to_scan in tx.outputs.into_iter().enumerate() {
+                // Grab mutable references to new witnesses from previous outputs
+                // in this transaction so that we can update them. Scoped so we
+                // don't hold mutable references to shielded_outputs for too long.
+                let mut new_witnesses: Vec<_> = shielded_outputs
+                    .iter_mut()
+                    .map(|output| &mut output.witness)
+                    .collect();
+
+                if let Some(output) = scan_output(
+                    to_scan,
+                    &ivks,
+                    &spent_from_accounts,
+                    tree,
+                    existing_witnesses,
+                    &mut block_witnesses,
+                    &mut new_witnesses,
+                ) {
+                    shielded_outputs.push(output);
+                }
+            }
+        }
+
+        if !(shielded_spends.is_empty() && shielded_outputs.is_empty()) {
+            let mut txid = TxId([0u8; 32]);
+            txid.0.copy_from_slice(&tx.hash);
+            wtxs.push(WalletTx {
+                txid,
+                index: tx.index as usize,
+                num_spends,
+                num_outputs,
+                shielded_spends,
+                shielded_outputs,
+            });
+        }
+    }
+
+    wtxs
+}
+
+#[cfg(test)]
+mod tests {
+    use ff::{Field, PrimeField, PrimeFieldRepr};
+    use pairing::bls12_381::{Bls12, Fr};
+    use rand_core::{OsRng, RngCore};
+    use zcash_primitives::{
+        jubjub::{fs::Fs, FixedGenerators, JubjubParams, ToUniform},
+        merkle_tree::CommitmentTree,
+        note_encryption::{Memo, SaplingNoteEncryption},
+        primitives::Note,
+        transaction::components::Amount,
+        zip32::{ExtendedFullViewingKey, ExtendedSpendingKey},
+        JUBJUB,
+    };
+
+    use super::scan_block;
+    use crate::proto::compact_formats::{CompactBlock, CompactOutput, CompactSpend, CompactTx};
+
+    fn random_compact_tx<R: RngCore>(rng: &mut R) -> CompactTx {
+        let fake_nf = {
+            let mut nf = vec![0; 32];
+            rng.fill_bytes(&mut nf);
+            nf
+        };
+        let fake_cmu = {
+            let fake_cmu = Fr::random(rng);
+            let mut bytes = vec![];
+            fake_cmu.into_repr().write_le(&mut bytes).unwrap();
+            bytes
+        };
+        let fake_epk = {
+            let mut buffer = vec![0; 64];
+            rng.fill_bytes(&mut buffer);
+            let fake_esk = Fs::to_uniform(&buffer[..]);
+            let fake_epk = JUBJUB
+                .generator(FixedGenerators::SpendingKeyGenerator)
+                .mul(fake_esk, &JUBJUB);
+            let mut bytes = vec![];
+            fake_epk.write(&mut bytes).unwrap();
+            bytes
+        };
+        let mut cspend = CompactSpend::new();
+        cspend.set_nf(fake_nf);
+        let mut cout = CompactOutput::new();
+        cout.set_cmu(fake_cmu);
+        cout.set_epk(fake_epk);
+        cout.set_ciphertext(vec![0; 52]);
+        let mut ctx = CompactTx::new();
+        let mut txid = vec![0; 32];
+        rng.fill_bytes(&mut txid);
+        ctx.set_hash(txid);
+        ctx.spends.push(cspend);
+        ctx.outputs.push(cout);
+        ctx
+    }
+
+    /// Create a fake CompactBlock at the given height, with a transaction containing a
+    /// single spend of the given nullifier and a single output paying the given address.
+    /// Returns the CompactBlock.
+    fn fake_compact_block(
+        height: i32,
+        nf: [u8; 32],
+        extfvk: ExtendedFullViewingKey,
+        value: Amount,
+        tx_after: bool,
+    ) -> CompactBlock {
+        let to = extfvk.default_address().unwrap().1;
+
+        // Create a fake Note for the account
+        let mut rng = OsRng;
+        let note = Note {
+            g_d: to.diversifier().g_d::<Bls12>(&JUBJUB).unwrap(),
+            pk_d: to.pk_d().clone(),
+            value: value.into(),
+            r: Fs::random(&mut rng),
+        };
+        let encryptor = SaplingNoteEncryption::new(
+            extfvk.fvk.ovk,
+            note.clone(),
+            to.clone(),
+            Memo::default(),
+            &mut rng,
+        );
+        let mut cmu = vec![];
+        note.cm(&JUBJUB).into_repr().write_le(&mut cmu).unwrap();
+        let mut epk = vec![];
+        encryptor.epk().write(&mut epk).unwrap();
+        let enc_ciphertext = encryptor.encrypt_note_plaintext();
+
+        // Create a fake CompactBlock containing the note
+        let mut cb = CompactBlock::new();
+        cb.set_height(height as u64);
+
+        // Add a random Sapling tx before ours
+        {
+            let mut tx = random_compact_tx(&mut rng);
+            tx.index = cb.vtx.len() as u64;
+            cb.vtx.push(tx);
+        }
+
+        let mut cspend = CompactSpend::new();
+        cspend.set_nf(nf.to_vec());
+        let mut cout = CompactOutput::new();
+        cout.set_cmu(cmu);
+        cout.set_epk(epk);
+        cout.set_ciphertext(enc_ciphertext[..52].to_vec());
+        let mut ctx = CompactTx::new();
+        let mut txid = vec![0; 32];
+        rng.fill_bytes(&mut txid);
+        ctx.set_hash(txid);
+        ctx.spends.push(cspend);
+        ctx.outputs.push(cout);
+        ctx.index = cb.vtx.len() as u64;
+        cb.vtx.push(ctx);
+
+        // Optionally add another random Sapling tx after ours
+        if tx_after {
+            let mut tx = random_compact_tx(&mut rng);
+            tx.index = cb.vtx.len() as u64;
+            cb.vtx.push(tx);
+        }
+
+        cb
+    }
+
+    #[test]
+    fn scan_block_with_my_tx() {
+        let extsk = ExtendedSpendingKey::master(&[]);
+        let extfvk = ExtendedFullViewingKey::from(&extsk);
+
+        let cb = fake_compact_block(
+            1,
+            [0; 32],
+            extfvk.clone(),
+            Amount::from_u64(5).unwrap(),
+            false,
+        );
+        assert_eq!(cb.vtx.len(), 2);
+
+        let mut tree = CommitmentTree::new();
+        let txs = scan_block(cb, &[extfvk], &[], &mut tree, &mut []);
+        assert_eq!(txs.len(), 1);
+
+        let tx = &txs[0];
+        assert_eq!(tx.index, 1);
+        assert_eq!(tx.num_spends, 1);
+        assert_eq!(tx.num_outputs, 1);
+        assert_eq!(tx.shielded_spends.len(), 0);
+        assert_eq!(tx.shielded_outputs.len(), 1);
+        assert_eq!(tx.shielded_outputs[0].index, 0);
+        assert_eq!(tx.shielded_outputs[0].account, 0);
+        assert_eq!(tx.shielded_outputs[0].note.value, 5);
+
+        // Check that the witness root matches
+        assert_eq!(tx.shielded_outputs[0].witness.root(), tree.root());
+    }
+
+    #[test]
+    fn scan_block_with_txs_after_my_tx() {
+        let extsk = ExtendedSpendingKey::master(&[]);
+        let extfvk = ExtendedFullViewingKey::from(&extsk);
+
+        let cb = fake_compact_block(
+            1,
+            [0; 32],
+            extfvk.clone(),
+            Amount::from_u64(5).unwrap(),
+            true,
+        );
+        assert_eq!(cb.vtx.len(), 3);
+
+        let mut tree = CommitmentTree::new();
+        let txs = scan_block(cb, &[extfvk], &[], &mut tree, &mut []);
+        assert_eq!(txs.len(), 1);
+
+        let tx = &txs[0];
+        assert_eq!(tx.index, 1);
+        assert_eq!(tx.num_spends, 1);
+        assert_eq!(tx.num_outputs, 1);
+        assert_eq!(tx.shielded_spends.len(), 0);
+        assert_eq!(tx.shielded_outputs.len(), 1);
+        assert_eq!(tx.shielded_outputs[0].index, 0);
+        assert_eq!(tx.shielded_outputs[0].account, 0);
+        assert_eq!(tx.shielded_outputs[0].note.value, 5);
+
+        // Check that the witness root matches
+        assert_eq!(tx.shielded_outputs[0].witness.root(), tree.root());
+    }
+
+    #[test]
+    fn scan_block_with_my_spend() {
+        let extsk = ExtendedSpendingKey::master(&[]);
+        let extfvk = ExtendedFullViewingKey::from(&extsk);
+        let nf = [7; 32];
+        let account = 12;
+
+        let cb = fake_compact_block(1, nf, extfvk, Amount::from_u64(5).unwrap(), false);
+        assert_eq!(cb.vtx.len(), 2);
+
+        let mut tree = CommitmentTree::new();
+        let txs = scan_block(cb, &[], &[(&nf, account)], &mut tree, &mut []);
+        assert_eq!(txs.len(), 1);
+
+        let tx = &txs[0];
+        assert_eq!(tx.index, 1);
+        assert_eq!(tx.num_spends, 1);
+        assert_eq!(tx.num_outputs, 1);
+        assert_eq!(tx.shielded_spends.len(), 1);
+        assert_eq!(tx.shielded_outputs.len(), 0);
+        assert_eq!(tx.shielded_spends[0].index, 0);
+        assert_eq!(tx.shielded_spends[0].nf, nf);
+        assert_eq!(tx.shielded_spends[0].account, account);
+    }
+}

zcash_history/.gitignore

@@ -0,0 +1,4 @@
+/target
+**/*.rs.bk
+Cargo.lock
+.idea

zcash_history/COPYRIGHT

@@ -0,0 +1,14 @@
+Copyrights in the "zcash_history" library are retained by their contributors. No
+copyright assignment is required to contribute to the "zcash_history" library.
+
+The "zcash_history" library is licensed under either of
+
+ * Apache License, Version 2.0, (see ./LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
+ * MIT license (see ./LICENSE-MIT or http://opensource.org/licenses/MIT)
+
+at your option.
+
+Unless you explicitly state otherwise, any contribution intentionally
+submitted for inclusion in the work by you, as defined in the Apache-2.0
+license, shall be dual licensed as above, without any additional terms or
+conditions.

zcash_history/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "zcash_history"
+version = "0.0.1"
+authors = ["NikVolf <nikvolf@gmail.com>"]
+edition = "2018"
+license = "MIT/Apache-2.0"
+documentation = "https://docs.rs/zcash_history/"
+description = "Library for Zcash blockchain history tools"
+
+[dev-dependencies]
+assert_matches = "1.3.0"
+quickcheck = "0.8"
+
+[dependencies]
+bigint = "4"
+byteorder = "1"
+blake2 = { package = "blake2b_simd", version = "0.5" }

zcash_history/LICENSE-APACHE

@@ -0,0 +1,201 @@
+                              Apache License
+                        Version 2.0, January 2004
+                     http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+1. Definitions.
+
+   "License" shall mean the terms and conditions for use, reproduction,
+   and distribution as defined by Sections 1 through 9 of this document.
+
+   "Licensor" shall mean the copyright owner or entity authorized by
+   the copyright owner that is granting the License.
+
+   "Legal Entity" shall mean the union of the acting entity and all
+   other entities that control, are controlled by, or are under common
+   control with that entity. For the purposes of this definition,
+   "control" means (i) the power, direct or indirect, to cause the
+   direction or management of such entity, whether by contract or
+   otherwise, or (ii) ownership of fifty percent (50%) or more of the
+   outstanding shares, or (iii) beneficial ownership of such entity.
+
+   "You" (or "Your") shall mean an individual or Legal Entity
+   exercising permissions granted by this License.
+
+   "Source" form shall mean the preferred form for making modifications,
+   including but not limited to software source code, documentation
+   source, and configuration files.
+
+   "Object" form shall mean any form resulting from mechanical
+   transformation or translation of a Source form, including but
+   not limited to compiled object code, generated documentation,
+   and conversions to other media types.
+
+   "Work" shall mean the work of authorship, whether in Source or
+   Object form, made available under the License, as indicated by a
+   copyright notice that is included in or attached to the work
+   (an example is provided in the Appendix below).
+
+   "Derivative Works" shall mean any work, whether in Source or Object
+   form, that is based on (or derived from) the Work and for which the
+   editorial revisions, annotations, elaborations, or other modifications
+   represent, as a whole, an original work of authorship. For the purposes
+   of this License, Derivative Works shall not include works that remain
+   separable from, or merely link (or bind by name) to the interfaces of,
+   the Work and Derivative Works thereof.
+
+   "Contribution" shall mean any work of authorship, including
+   the original version of the Work and any modifications or additions
+   to that Work or Derivative Works thereof, that is intentionally
+   submitted to Licensor for inclusion in the Work by the copyright owner
+   or by an individual or Legal Entity authorized to submit on behalf of
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+See the License for the specific language governing permissions and
+limitations under the License.

zcash_history/LICENSE-MIT

@@ -0,0 +1,25 @@
+Copyright (c) 2019 Nikolay Volf
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

zcash_history/README.md

@@ -0,0 +1,26 @@
+# zcash_history
+
+Special implementation of Merkle mountain ranges (MMR) for Zcash!
+
+[![Build Status](https://travis-ci.org/NikVolf/zcash-mmr.svg?branch=master)](https://travis-ci.org/NikVolf/zcash-mmr)
+
+The main design goals of this MMR implementation are
+
+- Allow zero-cache and avoid db callbacks. As it is implemented, calling side must just smartly pre-load MMR nodes from the database (about log2(tree length) for append, twice as much for deletion).
+
+- Reuse as much logic between rust and c++ clients and place it here and librustzcash.
+
+- Close to zero memory consumption.
+
+# License
+
+`zcash_history` is distributed under the terms of both the MIT
+license and the Apache License (Version 2.0), at your choice.
+
+See LICENSE-APACHE, and LICENSE-MIT for details.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in `zcash_history` by you, as defined in the Apache-2.0 license, shall be
+dual licensed as above, without any additional terms or conditions.

zcash_history/examples/lib/main.rs

@@ -0,0 +1,2 @@
+// dummy example
+pub fn main() {}

zcash_history/examples/lib/shared.rs

@@ -0,0 +1,86 @@
+use zcash_history::{Entry, EntryLink, NodeData, Tree};
+
+pub struct NodeDataIterator {
+    return_stack: Vec<NodeData>,
+    tree: Tree,
+    cursor: usize,
+    leaf_cursor: usize,
+}
+
+impl Iterator for NodeDataIterator {
+    type Item = NodeData;
+
+    fn next(&mut self) -> Option<NodeData> {
+        let result = if self.cursor == 1 {
+            self.leaf_cursor = 2;
+            Some(leaf(1))
+        } else if self.cursor == 2 {
+            self.leaf_cursor = 3;
+            Some(leaf(2))
+        } else if self.cursor == 3 {
+            Some(self.tree.root_node().expect("always exists").data().clone())
+        } else if self.return_stack.len() > 0 {
+            self.return_stack.pop()
+        } else {
+            for n_append in self
+                .tree
+                .append_leaf(leaf(self.leaf_cursor as u32))
+                .expect("full tree cannot fail")
+                .into_iter()
+                .rev()
+            {
+                self.return_stack.push(
+                    self.tree
+                        .resolve_link(n_append)
+                        .expect("just pushed")
+                        .data()
+                        .clone(),
+                )
+            }
+            self.leaf_cursor += 1;
+            self.return_stack.pop()
+        };
+
+        self.cursor += 1;
+        result
+    }
+}
+
+impl NodeDataIterator {
+    pub fn new() -> Self {
+        let root = Entry::new(
+            NodeData::combine(&leaf(1), &leaf(2)),
+            EntryLink::Stored(0),
+            EntryLink::Stored(1),
+        );
+        let tree = Tree::new(
+            3,
+            vec![(2, root)],
+            vec![(0, leaf(1).into()), (1, leaf(2).into())],
+        );
+
+        NodeDataIterator {
+            return_stack: Vec::new(),
+            tree,
+            cursor: 1,
+            leaf_cursor: 1,
+        }
+    }
+}
+
+fn leaf(height: u32) -> NodeData {
+    NodeData {
+        consensus_branch_id: 0,
+        subtree_commitment: [0u8; 32],
+        start_time: height * 10 + 1,
+        end_time: (height + 1) * 10,
+        start_target: 100 + height * 10,
+        end_target: 100 + (height + 1) * 10,
+        start_sapling_root: [0u8; 32],
+        end_sapling_root: [0u8; 32],
+        subtree_total_work: 0.into(),
+        start_height: height as u64,
+        end_height: height as u64,
+        sapling_tx: 5 + height as u64,
+    }
+}

zcash_history/examples/long.rs

@@ -0,0 +1,113 @@
+use zcash_history::{Entry, EntryLink, NodeData, Tree};
+
+#[path = "lib/shared.rs"]
+mod share;
+
+fn draft(into: &mut Vec<(u32, Entry)>, vec: &Vec<NodeData>, peak_pos: usize, h: u32) {
+    let node_data = vec[peak_pos - 1].clone();
+    let peak: Entry = match h {
+        0 => node_data.into(),
+        _ => Entry::new(
+            node_data,
+            EntryLink::Stored((peak_pos - (1 << h) - 1) as u32),
+            EntryLink::Stored((peak_pos - 2) as u32),
+        ),
+    };
+
+    println!("Entry #{}: {}", into.len(), peak);
+
+    into.push(((peak_pos - 1) as u32, peak));
+}
+
+fn prepare_tree(vec: &Vec<NodeData>) -> Tree {
+    assert!(vec.len() > 0);
+
+    // integer log2 of (vec.len()+1), -1
+    let mut h = (32 - ((vec.len() + 1) as u32).leading_zeros() - 1) - 1;
+    let mut peak_pos = (1 << (h + 1)) - 1;
+    let mut nodes = Vec::new();
+
+    // used later
+    let mut last_peak_pos = 0;
+    let mut last_peak_h = 0;
+
+    loop {
+        if peak_pos > vec.len() {
+            // left child, -2^h
+            peak_pos = peak_pos - (1 << h);
+            h = h - 1;
+        }
+
+        if peak_pos <= vec.len() {
+            draft(&mut nodes, vec, peak_pos, h);
+
+            // save to be used in next loop
+            last_peak_pos = peak_pos;
+            last_peak_h = h;
+
+            // right sibling
+            peak_pos = peak_pos + (1 << (h + 1)) - 1;
+        }
+
+        if h == 0 {
+            break;
+        }
+    }
+
+    // for deletion, everything on the right slope of the last peak should be pre-loaded
+    let mut extra = Vec::new();
+    let mut h = last_peak_h;
+    let mut peak_pos = last_peak_pos;
+
+    while h > 0 {
+        let left_pos = peak_pos - (1 << h);
+        let right_pos = peak_pos - 1;
+        h = h - 1;
+
+        // drafting left child
+        draft(&mut extra, vec, left_pos, h);
+
+        // drafting right child
+        draft(&mut extra, vec, right_pos, h);
+
+        // continuing on right slope
+        peak_pos = right_pos;
+    }
+
+    println!("Total extra of {} required for deletion!", extra.len());
+
+    Tree::new(vec.len() as u32, nodes, extra)
+}
+
+fn main() {
+    let number = match std::env::args().skip(1).next() {
+        None => {
+            eprintln!("writer <number of nodes> [<out_file>]");
+            std::process::exit(1);
+        }
+        Some(number) => number.parse::<usize>().expect("invalid number"),
+    };
+
+    let long_vec = share::NodeDataIterator::new()
+        .take(number)
+        .collect::<Vec<NodeData>>();
+
+    let now = std::time::Instant::now();
+
+    let tree = prepare_tree(&long_vec);
+    let elapsed = now.elapsed();
+
+    println!(
+        "Tree final root: {}-{}",
+        tree.root_node().expect("root").data().start_height,
+        tree.root_node().expect("root").data().end_height,
+    );
+
+    println!(
+        "Prepare tree of {} length: {} ns / {} mcs / {} ms",
+        number,
+        elapsed.as_nanos(),
+        elapsed.as_micros(),
+        elapsed.as_millis()
+    );
+}

zcash_history/examples/write.rs

@@ -0,0 +1,44 @@
+#[path = "lib/shared.rs"]
+mod share;
+
+// Test data generator
+// $ cargo run --example writer -- 16 nodes.dat
+// or
+// $ cargo run --example writer -- 16
+// to preview
+
+fn main() {
+    let mut args = std::env::args().skip(1);
+
+    let (number, out_file) = match args.next() {
+        None => {
+            eprintln!("writer <number of nodes> [<out_file>]");
+            std::process::exit(1);
+        }
+        Some(number) => (
+            number.parse::<usize>().expect("invalid number"),
+            args.next(),
+        ),
+    };
+
+    let iterator = share::NodeDataIterator::new().take(number);
+
+    if let Some(out_file_path) = out_file {
+        use std::io::Write;
+
+        let mut buf = Vec::new();
+
+        for node in iterator {
+            node.write(&mut buf).expect("Failed to write data");
+        }
+
+        let mut file = std::fs::File::create(&out_file_path).expect("Failed to create output file");
+
+        file.write_all(&buf[..])
+            .expect("Failed to write data to file");
+    } else {
+        for n in iterator {
+            println!("{:?}", n);
+        }
+    }
+}

zcash_history/src/entry.rs

@@ -0,0 +1,123 @@
+use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
+
+use crate::{EntryKind, EntryLink, Error, NodeData, MAX_NODE_DATA_SIZE};
+
+/// Max serialized length of entry data.
+pub const MAX_ENTRY_SIZE: usize = MAX_NODE_DATA_SIZE + 9;
+
+/// MMR Entry.
+#[derive(Debug)]
+pub struct Entry {
+    pub(crate) kind: EntryKind,
+    pub(crate) data: NodeData,
+}
+
+impl Entry {
+    /// New entry of type node.
+    pub fn new(data: NodeData, left: EntryLink, right: EntryLink) -> Self {
+        Entry {
+            kind: EntryKind::Node(left, right),
+            data,
+        }
+    }
+
+    /// Returns if is this node complete (has total of 2^N leaves)
+    pub fn complete(&self) -> bool {
+        let leaves = self.leaf_count();
+        leaves & (leaves - 1) == 0
+    }
+
+    /// Number of leaves under this node.
+    pub fn leaf_count(&self) -> u64 {
+        self.data.end_height - (self.data.start_height - 1)
+    }
+
+    /// Is this node a leaf.
+    pub fn leaf(&self) -> bool {
+        if let EntryKind::Leaf = self.kind {
+            true
+        } else {
+            false
+        }
+    }
+
+    /// Left child
+    pub fn left(&self) -> Result<EntryLink, Error> {
+        match self.kind {
+            EntryKind::Leaf => Err(Error::node_expected()),
+            EntryKind::Node(left, _) => Ok(left),
+        }
+    }
+
+    /// Right child.
+    pub fn right(&self) -> Result<EntryLink, Error> {
+        match self.kind {
+            EntryKind::Leaf => Err(Error::node_expected()),
+            EntryKind::Node(_, right) => Ok(right),
+        }
+    }
+
+    /// Read from byte representation.
+    pub fn read<R: std::io::Read>(consensus_branch_id: u32, r: &mut R) -> std::io::Result<Self> {
+        let kind = {
+            match r.read_u8()? {
+                0 => {
+                    let left = r.read_u32::<LittleEndian>()?;
+                    let right = r.read_u32::<LittleEndian>()?;
+                    EntryKind::Node(EntryLink::Stored(left), EntryLink::Stored(right))
+                }
+                1 => EntryKind::Leaf,
+                _ => return Err(std::io::Error::from(std::io::ErrorKind::InvalidData)),
+            }
+        };
+
+        let data = NodeData::read(consensus_branch_id, r)?;
+
+        Ok(Entry { kind, data })
+    }
+
+    /// Write to byte representation.
+    pub fn write<W: std::io::Write>(&self, w: &mut W) -> std::io::Result<()> {
+        match self.kind {
+            EntryKind::Node(EntryLink::Stored(left), EntryLink::Stored(right)) => {
+                w.write_u8(0)?;
+                w.write_u32::<LittleEndian>(left)?;
+                w.write_u32::<LittleEndian>(right)?;
+            }
+            EntryKind::Leaf => {
+                w.write_u8(1)?;
+            }
+            _ => {
+                return Err(std::io::Error::from(std::io::ErrorKind::InvalidData));
+            }
+        }
+
+        self.data.write(w)?;
+
+        Ok(())
+    }
+
+    /// Convert from byte representation.
+    pub fn from_bytes<T: AsRef<[u8]>>(consensus_branch_id: u32, buf: T) -> std::io::Result<Self> {
+        let mut cursor = std::io::Cursor::new(buf);
+        Self::read(consensus_branch_id, &mut cursor)
+    }
+}
+
+impl From<NodeData> for Entry {
+    fn from(s: NodeData) -> Self {
+        Entry {
+            kind: EntryKind::Leaf,
+            data: s,
+        }
+    }
+}
+
+impl std::fmt::Display for Entry {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self.kind {
+            EntryKind::Node(l, r) => write!(f, "node({}, {}, ..)", l, r),
+            EntryKind::Leaf => write!(f, "leaf(..)"),
+        }
+    }
+}

zcash_history/src/lib.rs

@@ -0,0 +1,79 @@
+//! Chain history library for Zcash
+//!
+//! To be used in zebra and via FFI bindings in zcashd
+#![warn(missing_docs)]
+
+mod entry;
+mod node_data;
+mod tree;
+
+pub use entry::{Entry, MAX_ENTRY_SIZE};
+pub use node_data::{NodeData, MAX_NODE_DATA_SIZE};
+pub use tree::Tree;
+
+/// Crate-level error type
+#[derive(Debug)]
+pub enum Error {
+    /// Entry expected to be presented in the tree view while it was not.
+    ExpectedInMemory(EntryLink),
+    /// Entry expected to be a node (specifying for which link this is not true).
+    ExpectedNode(Option<EntryLink>),
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match *self {
+            Self::ExpectedInMemory(l) => write!(f, "Node/leaf expected to be in memory: {}", l),
+            Self::ExpectedNode(None) => write!(f, "Node expected"),
+            Self::ExpectedNode(Some(l)) => write!(f, "Node expected, not leaf: {}", l),
+        }
+    }
+}
+
+/// Reference to to the tree node.
+#[repr(C)]
+#[derive(Clone, Copy, Debug)]
+pub enum EntryLink {
+    /// Reference to the stored (in the array representation) leaf/node.
+    Stored(u32),
+    /// Reference to the generated leaf/node.
+    Generated(u32),
+}
+
+impl std::fmt::Display for EntryLink {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match *self {
+            Self::Stored(v) => write!(f, "stored({})", v),
+            Self::Generated(v) => write!(f, "generated({})", v),
+        }
+    }
+}
+
+/// MMR Node. It is leaf when `left`, `right` are `None` and node when they are not.
+#[repr(C)]
+#[derive(Debug)]
+pub enum EntryKind {
+    /// Leaf entry.
+    Leaf,
+    /// Node entry with children links.
+    Node(EntryLink, EntryLink),
+}
+
+impl Error {
+    /// Entry expected to be a node (specifying for which link this is not true).
+    pub fn link_node_expected(link: EntryLink) -> Self {
+        Self::ExpectedNode(Some(link))
+    }
+
+    /// Some entry is expected to be node
+    pub fn node_expected() -> Self {
+        Self::ExpectedNode(None)
+    }
+
+    pub(crate) fn augment(self, link: EntryLink) -> Self {
+        match self {
+            Error::ExpectedNode(_) => Error::ExpectedNode(Some(link)),
+            val => val,
+        }
+    }
+}

zcash_history/src/node_data.rs

@@ -0,0 +1,238 @@
+use bigint::U256;
+use blake2::Params as Blake2Params;
+use byteorder::{ByteOrder, LittleEndian, ReadBytesExt, WriteBytesExt};
+
+/// Maximum serialized size of the node metadata.
+pub const MAX_NODE_DATA_SIZE: usize = 32 + // subtree commitment
+    4 +  // start time
+    4 +  // end time
+    4 +  // start target
+    4 +  // end target
+    32 + // start sapling tree root
+    32 + // end sapling tree root
+    32 + // subtree total work
+    9 +  // start height (compact uint)
+    9 +  // end height (compact uint)
+    9; // Sapling tx count (compact uint)
+       // = total of 171
+
+/// Node metadata.
+#[repr(C)]
+#[derive(Debug, Clone, Default)]
+#[cfg_attr(test, derive(PartialEq))]
+pub struct NodeData {
+    /// Consensus branch id, should be provided by deserializing node.
+    pub consensus_branch_id: u32,
+    /// Subtree commitment - either block hash for leaves or hashsum of children for nodes.
+    pub subtree_commitment: [u8; 32],
+    /// Start time.
+    pub start_time: u32,
+    /// End time.
+    pub end_time: u32,
+    /// Start target.
+    pub start_target: u32,
+    /// End target.
+    pub end_target: u32,
+    /// Start sapling tree root.
+    pub start_sapling_root: [u8; 32],
+    /// End sapling tree root.
+    pub end_sapling_root: [u8; 32],
+    /// Part of tree total work.
+    pub subtree_total_work: U256,
+    /// Start height.
+    pub start_height: u64,
+    /// End height
+    pub end_height: u64,
+    /// Number of Sapling transactions.
+    pub sapling_tx: u64,
+}
+
+fn blake2b_personal(personalization: &[u8], input: &[u8]) -> [u8; 32] {
+    let hash_result = Blake2Params::new()
+        .hash_length(32)
+        .personal(personalization)
+        .to_state()
+        .update(input)
+        .finalize();
+    let mut result = [0u8; 32];
+    result.copy_from_slice(hash_result.as_bytes());
+    result
+}
+
+fn personalization(branch_id: u32) -> [u8; 16] {
+    let mut result = [0u8; 16];
+    result[..12].copy_from_slice(b"ZcashHistory");
+    LittleEndian::write_u32(&mut result[12..], branch_id);
+    result
+}
+
+impl NodeData {
+    /// Combine two nodes metadata.
+    pub fn combine(left: &NodeData, right: &NodeData) -> NodeData {
+        assert_eq!(left.consensus_branch_id, right.consensus_branch_id);
+
+        let mut hash_buf = [0u8; MAX_NODE_DATA_SIZE * 2];
+        let size = {
+            let mut cursor = ::std::io::Cursor::new(&mut hash_buf[..]);
+            left.write(&mut cursor)
+                .expect("Writing to memory buf with enough length cannot fail; qed");
+            right
+                .write(&mut cursor)
+                .expect("Writing to memory buf with enough length cannot fail; qed");
+            cursor.position() as usize
+        };
+
+        let hash = blake2b_personal(
+            &personalization(left.consensus_branch_id),
+            &hash_buf[..size],
+        );
+
+        NodeData {
+            consensus_branch_id: left.consensus_branch_id,
+            subtree_commitment: hash,
+            start_time: left.start_time,
+            end_time: right.end_time,
+            start_target: left.start_target,
+            end_target: right.end_target,
+            start_sapling_root: left.start_sapling_root,
+            end_sapling_root: right.end_sapling_root,
+            subtree_total_work: left.subtree_total_work + right.subtree_total_work,
+            start_height: left.start_height,
+            end_height: right.end_height,
+            sapling_tx: left.sapling_tx + right.sapling_tx,
+        }
+    }
+
+    fn write_compact<W: std::io::Write>(w: &mut W, compact: u64) -> std::io::Result<()> {
+        match compact {
+            0..=0xfc => w.write_all(&[compact as u8])?,
+            0xfd..=0xffff => {
+                w.write_all(&[0xfd])?;
+                w.write_u16::<LittleEndian>(compact as u16)?;
+            }
+            0x10000..=0xffff_ffff => {
+                w.write_all(&[0xfe])?;
+                w.write_u32::<LittleEndian>(compact as u32)?;
+            }
+            _ => {
+                w.write_all(&[0xff])?;
+                w.write_u64::<LittleEndian>(compact)?;
+            }
+        }
+        Ok(())
+    }
+
+    fn read_compact<R: std::io::Read>(reader: &mut R) -> std::io::Result<u64> {
+        let result = match reader.read_u8()? {
+            i @ 0..=0xfc => i.into(),
+            0xfd => reader.read_u16::<LittleEndian>()?.into(),
+            0xfe => reader.read_u32::<LittleEndian>()?.into(),
+            _ => reader.read_u64::<LittleEndian>()?,
+        };
+
+        Ok(result)
+    }
+
+    /// Write to the byte representation.
+    pub fn write<W: std::io::Write>(&self, w: &mut W) -> std::io::Result<()> {
+        w.write_all(&self.subtree_commitment)?;
+        w.write_u32::<LittleEndian>(self.start_time)?;
+        w.write_u32::<LittleEndian>(self.end_time)?;
+        w.write_u32::<LittleEndian>(self.start_target)?;
+        w.write_u32::<LittleEndian>(self.end_target)?;
+        w.write_all(&self.start_sapling_root)?;
+        w.write_all(&self.end_sapling_root)?;
+
+        let mut work_buf = [0u8; 32];
+        self.subtree_total_work.to_little_endian(&mut work_buf[..]);
+        w.write_all(&work_buf)?;
+
+        Self::write_compact(w, self.start_height)?;
+        Self::write_compact(w, self.end_height)?;
+        Self::write_compact(w, self.sapling_tx)?;
+        Ok(())
+    }
+
+    /// Read from the byte representation.
+    pub fn read<R: std::io::Read>(consensus_branch_id: u32, r: &mut R) -> std::io::Result<Self> {
+        let mut data = Self::default();
+        data.consensus_branch_id = consensus_branch_id;
+        r.read_exact(&mut data.subtree_commitment)?;
+        data.start_time = r.read_u32::<LittleEndian>()?;
+        data.end_time = r.read_u32::<LittleEndian>()?;
+        data.start_target = r.read_u32::<LittleEndian>()?;
+        data.end_target = r.read_u32::<LittleEndian>()?;
+        r.read_exact(&mut data.start_sapling_root)?;
+        r.read_exact(&mut data.end_sapling_root)?;
+
+        let mut work_buf = [0u8; 32];
+        r.read_exact(&mut work_buf)?;
+        data.subtree_total_work = U256::from_little_endian(&work_buf);
+
+        data.start_height = Self::read_compact(r)?;
+        data.end_height = Self::read_compact(r)?;
+        data.sapling_tx = Self::read_compact(r)?;
+
+        Ok(data)
+    }
+
+    /// Convert to byte representation.
+    pub fn to_bytes(&self) -> Vec<u8> {
+        let mut buf = [0u8; MAX_NODE_DATA_SIZE];
+        let pos = {
+            let mut cursor = std::io::Cursor::new(&mut buf[..]);
+            self.write(&mut cursor).expect("Cursor cannot fail");
+            cursor.position() as usize
+        };
+
+        buf[0..pos].to_vec()
+    }
+
+    /// Convert from byte representation.
+    pub fn from_bytes<T: AsRef<[u8]>>(consensus_branch_id: u32, buf: T) -> std::io::Result<Self> {
+        let mut cursor = std::io::Cursor::new(buf);
+        Self::read(consensus_branch_id, &mut cursor)
+    }
+
+    /// Hash node metadata
+    pub fn hash(&self) -> [u8; 32] {
+        let bytes = self.to_bytes();
+
+        blake2b_personal(&personalization(self.consensus_branch_id), &bytes)
+    }
+}
+
+#[cfg(test)]
+impl quickcheck::Arbitrary for NodeData {
+    fn arbitrary<G: quickcheck::Gen>(gen: &mut G) -> Self {
+        let mut node_data = NodeData::default();
+        node_data.consensus_branch_id = 0;
+        gen.fill_bytes(&mut node_data.subtree_commitment[..]);
+        node_data.start_time = gen.next_u32();
+        node_data.end_time = gen.next_u32();
+        node_data.start_target = gen.next_u32();
+        node_data.end_target = gen.next_u32();
+        gen.fill_bytes(&mut node_data.start_sapling_root[..]);
+        gen.fill_bytes(&mut node_data.end_sapling_root[..]);
+        let mut number = [0u8; 32];
+        gen.fill_bytes(&mut number[..]);
+        node_data.subtree_total_work = U256::from_little_endian(&number[..]);
+        node_data.start_height = gen.next_u64();
+        node_data.end_height = gen.next_u64();
+        node_data.sapling_tx = gen.next_u64();
+
+        node_data
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::NodeData;
+    use quickcheck::{quickcheck, TestResult};
+
+    quickcheck! {
+        fn serialization_round_trip(node_data: NodeData) -> TestResult {
+            TestResult::from_bool(NodeData::from_bytes(0, &node_data.to_bytes()).unwrap() == node_data)
+        }
+    }
+}

zcash_history/src/tree.rs

@@ -0,0 +1,741 @@
+use std::collections::HashMap;
+
+use crate::{Entry, EntryKind, EntryLink, Error, NodeData};
+
+/// Represents partially loaded tree.
+///
+/// Some kind of "view" into the array representation of the MMR tree.
+/// With only some of the leaves/nodes pre-loaded / pre-generated.
+/// Exact amount of the loaded data can be calculated by the constructing party,
+/// depending on the length of the tree and maximum amount of operations that are going
+/// to happen after construction. `Tree` should not be used as self-contained data structure,
+/// since it's internal state can grow indefinitely after serial operations.
+/// Intended use of this `Tree` is to instantiate it based on partially loaded data (see example
+/// how to pick right nodes from the array representation of MMR Tree), perform several operations
+/// (append-s/delete-s) and then drop it.
+pub struct Tree {
+    stored: HashMap<u32, Entry>,
+
+    // This can grow indefinitely if `Tree` is misused as a self-contained data structure
+    generated: Vec<Entry>,
+
+    // number of persistent(!) tree entries
+    stored_count: u32,
+
+    root: EntryLink,
+}
+
+impl Tree {
+    /// Resolve link originated from this tree
+    pub fn resolve_link(&self, link: EntryLink) -> Result<IndexedNode, Error> {
+        match link {
+            EntryLink::Generated(index) => self.generated.get(index as usize),
+            EntryLink::Stored(index) => self.stored.get(&index),
+        }
+        .map(|node| IndexedNode { node, link })
+        .ok_or(Error::ExpectedInMemory(link))
+    }
+
+    fn push(&mut self, data: Entry) -> EntryLink {
+        let idx = self.stored_count;
+        self.stored_count += 1;
+        self.stored.insert(idx, data);
+        EntryLink::Stored(idx)
+    }
+
+    fn push_generated(&mut self, data: Entry) -> EntryLink {
+        self.generated.push(data);
+        EntryLink::Generated(self.generated.len() as u32 - 1)
+    }
+
+    /// Populate tree with plain list of the leaves/nodes. For now, only for tests,
+    /// since this `Tree` structure is for partially loaded tree (but it might change)
+    #[cfg(test)]
+    pub fn populate(loaded: Vec<Entry>, root: EntryLink) -> Self {
+        let mut result = Tree::invalid();
+        result.stored_count = loaded.len() as u32;
+        for (idx, item) in loaded.into_iter().enumerate() {
+            result.stored.insert(idx as u32, item);
+        }
+        result.root = root;
+
+        result
+    }
+
+    // Empty tree with invalid root
+    fn invalid() -> Self {
+        Tree {
+            root: EntryLink::Generated(0),
+            generated: Default::default(),
+            stored: Default::default(),
+            stored_count: 0,
+        }
+    }
+
+    /// New view into the the tree array representation
+    ///
+    /// `length` is total length of the array representation (is generally not a sum of
+    ///     peaks.len + extra.len)
+    /// `peaks` is peaks of the mmr tree
+    /// `extra` is some extra nodes that calculated to be required during next one or more
+    /// operations on the tree.
+    ///
+    /// # Panics
+    ///
+    /// Will panic if `peaks` is empty.
+    pub fn new(length: u32, peaks: Vec<(u32, Entry)>, extra: Vec<(u32, Entry)>) -> Self {
+        assert!(peaks.len() > 0);
+
+        let mut result = Tree::invalid();
+
+        result.stored_count = length;
+
+        let mut gen = 0;
+        let mut root = EntryLink::Stored(peaks[0].0);
+        for (idx, node) in peaks.into_iter() {
+            result.stored.insert(idx, node);
+            if gen != 0 {
+                let next_generated = combine_nodes(
+                    result
+                        .resolve_link(root)
+                        .expect("Inserted before, cannot fail; qed"),
+                    result
+                        .resolve_link(EntryLink::Stored(idx))
+                        .expect("Inserted before, cannot fail; qed"),
+                );
+                root = result.push_generated(next_generated);
+            }
+            gen += 1;
+        }
+
+        for (idx, node) in extra {
+            result.stored.insert(idx, node);
+        }
+
+        result.root = root;
+
+        result
+    }
+
+    fn get_peaks(&self, root: EntryLink, target: &mut Vec<EntryLink>) -> Result<(), Error> {
+        let (left_child_link, right_child_link) = {
+            let root = self.resolve_link(root)?;
+            if root.node.complete() {
+                target.push(root.link);
+                return Ok(());
+            }
+            (root.left()?, root.right()?)
+        };
+
+        self.get_peaks(left_child_link, target)?;
+        self.get_peaks(right_child_link, target)?;
+        Ok(())
+    }
+
+    /// Append one leaf to the tree.
+    ///
+    /// Returns links to actual nodes that has to be persisted as the result of the append.
+    /// If completed without error, at least one link to the appended
+    /// node (with metadata provided in `new_leaf`) will be returned.
+    pub fn append_leaf(&mut self, new_leaf: NodeData) -> Result<Vec<EntryLink>, Error> {
+        let root = self.root;
+        let new_leaf_link = self.push(new_leaf.into());
+        let mut appended = Vec::new();
+        appended.push(new_leaf_link);
+
+        let mut peaks = Vec::new();
+        self.get_peaks(root, &mut peaks)?;
+
+        let mut merge_stack = Vec::new();
+        merge_stack.push(new_leaf_link);
+
+        // Scan the peaks right-to-left, merging together equal-sized adjacent
+        // complete subtrees. After this, merge_stack only contains peaks of
+        // unequal-sized subtrees.
+        while let Some(next_peak) = peaks.pop() {
+            let next_merge = merge_stack
+                .pop()
+                .expect("there should be at least one, initial or re-pushed");
+
+            if let Some(stored) = {
+                let peak = self.resolve_link(next_peak)?;
+                let m = self.resolve_link(next_merge)?;
+                if peak.node.leaf_count() == m.node.leaf_count() {
+                    Some(combine_nodes(peak, m))
+                } else {
+                    None
+                }
+            } {
+                let link = self.push(stored);
+                merge_stack.push(link);
+                appended.push(link);
+                continue;
+            } else {
+                merge_stack.push(next_merge);
+                merge_stack.push(next_peak);
+            }
+        }
+
+        let mut new_root = merge_stack
+            .pop()
+            .expect("Loop above cannot reduce the merge_stack");
+        // Scan the peaks left-to-right, producing new generated nodes that
+        // connect the subtrees
+        while let Some(next_child) = merge_stack.pop() {
+            new_root = self.push_generated(combine_nodes(
+                self.resolve_link(new_root)?,
+                self.resolve_link(next_child)?,
+            ))
+        }
+
+        self.root = new_root;
+
+        Ok(appended)
+    }
+
+    #[cfg(test)]
+    fn for_children<F: Fn(EntryLink, EntryLink)>(&self, node: EntryLink, f: F) {
+        let (left, right) = {
+            let link = self
+                .resolve_link(node)
+                .expect("Failed to resolve link in test");
+            (
+                link.left().expect("Failed to find node in test"),
+                link.right().expect("Failed to find node in test"),
+            )
+        };
+        f(left, right);
+    }
+
+    fn pop(&mut self) {
+        self.stored.remove(&(self.stored_count - 1));
+        self.stored_count = self.stored_count - 1;
+    }
+
+    /// Truncate one leaf from the end of the tree.
+    ///
+    /// Returns actual number of nodes that should be removed by the caller
+    /// from the end of the array representation.
+    pub fn truncate_leaf(&mut self) -> Result<u32, Error> {
+        let root = {
+            let (leaves, root_left_child) = {
+                let n = self.resolve_link(self.root)?;
+                (n.node.leaf_count(), n.node.left()?)
+            };
+            if leaves & 1 != 0 {
+                self.pop();
+                self.root = root_left_child;
+                return Ok(1);
+            } else {
+                self.resolve_link(self.root)?
+            }
+        };
+
+        let mut peaks = vec![root.left()?];
+        let mut subtree_root_link = root.right()?;
+        let mut truncated = 1;
+
+        loop {
+            let left_link = self.resolve_link(subtree_root_link)?.node;
+            if let EntryKind::Node(left, right) = left_link.kind {
+                peaks.push(left);
+                subtree_root_link = right;
+                truncated += 1;
+            } else {
+                if root.node.complete() {
+                    truncated += 1;
+                }
+                break;
+            }
+        }
+
+        let mut new_root = *peaks.get(0).expect("At lest 1 elements in peaks");
+
+        for next_peak in peaks.into_iter().skip(1) {
+            new_root = self.push_generated(combine_nodes(
+                self.resolve_link(new_root)?,
+                self.resolve_link(next_peak)?,
+            ));
+        }
+
+        for _ in 0..truncated {
+            self.pop();
+        }
+
+        self.root = new_root;
+
+        Ok(truncated)
+    }
+
+    /// Length of array representation of the tree.
+    pub fn len(&self) -> u32 {
+        self.stored_count
+    }
+
+    /// Link to the root node
+    pub fn root(&self) -> EntryLink {
+        self.root
+    }
+
+    /// Reference to the root node.
+    pub fn root_node(&self) -> Result<IndexedNode, Error> {
+        self.resolve_link(self.root)
+    }
+
+    /// If this tree is empty.
+    pub fn is_empty(&self) -> bool {
+        self.stored_count == 0
+    }
+}
+
+/// Reference to the node with link attached.
+#[derive(Debug)]
+pub struct IndexedNode<'a> {
+    node: &'a Entry,
+    link: EntryLink,
+}
+
+impl<'a> IndexedNode<'a> {
+    fn left(&self) -> Result<EntryLink, Error> {
+        self.node.left().map_err(|e| e.augment(self.link))
+    }
+
+    fn right(&self) -> Result<EntryLink, Error> {
+        self.node.right().map_err(|e| e.augment(self.link))
+    }
+
+    /// Reference to the entry struct.
+    pub fn node(&self) -> &Entry {
+        self.node
+    }
+
+    /// Reference to the entry metadata.
+    pub fn data(&self) -> &NodeData {
+        &self.node.data
+    }
+
+    /// Actual link by what this node was resolved.
+    pub fn link(&self) -> EntryLink {
+        self.link
+    }
+}
+
+fn combine_nodes<'a>(left: IndexedNode<'a>, right: IndexedNode<'a>) -> Entry {
+    Entry {
+        kind: EntryKind::Node(left.link, right.link),
+        data: NodeData::combine(&left.node.data, &right.node.data),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+
+    use super::{Entry, EntryKind, EntryLink, NodeData, Tree};
+    use assert_matches::assert_matches;
+    use quickcheck::{quickcheck, TestResult};
+
+    fn leaf(height: u32) -> NodeData {
+        NodeData {
+            consensus_branch_id: 1,
+            subtree_commitment: [0u8; 32],
+            start_time: 0,
+            end_time: 0,
+            start_target: 0,
+            end_target: 0,
+            start_sapling_root: [0u8; 32],
+            end_sapling_root: [0u8; 32],
+            subtree_total_work: 0.into(),
+            start_height: height as u64,
+            end_height: height as u64,
+            sapling_tx: 7,
+        }
+    }
+
+    fn initial() -> Tree {
+        let node1: Entry = leaf(1).into();
+        let node2: Entry = leaf(2).into();
+
+        let node3 = Entry {
+            data: NodeData::combine(&node1.data, &node2.data),
+            kind: EntryKind::Leaf,
+        };
+
+        Tree::populate(vec![node1, node2, node3], EntryLink::Stored(2))
+    }
+
+    // returns tree with specified number of leafs and it's root
+    fn generated(length: u32) -> Tree {
+        assert!(length >= 3);
+        let mut tree = initial();
+        for i in 2..length {
+            tree.append_leaf(leaf(i + 1).into())
+                .expect("Failed to append");
+        }
+
+        tree
+    }
+
+    #[test]
+    fn discrete_append() {
+        let mut tree = initial();
+
+        // ** APPEND 3 **
+        let appended = tree.append_leaf(leaf(3)).expect("Failed to append");
+        let new_root = tree.root_node().expect("Failed to resolve root").node;
+
+        // initial tree:  (2)
+        //               /   \
+        //             (0)   (1)
+        //
+        // new tree:
+        //                (4g)
+        //               /   \
+        //             (2)    \
+        //             /  \    \
+        //           (0)  (1)  (3)
+        //
+        // so only (3) is added as real leaf
+        // while new root, (4g) is generated one
+        assert_eq!(new_root.data.end_height, 3);
+        assert_eq!(appended.len(), 1);
+
+        // ** APPEND 4 **
+        let appended = tree.append_leaf(leaf(4)).expect("Failed to append");
+
+        let new_root = tree.root_node().expect("Failed to resolve root").node;
+
+        // intermediate tree:
+        //                (4g)
+        //               /   \
+        //             (2)    \
+        //             /  \    \
+        //           (0)  (1)  (3)
+        //
+        // new tree:
+        //                 ( 6 )
+        //                /     \
+        //             (2)       (5)
+        //             /  \     /   \
+        //           (0)  (1) (3)   (4)
+        //
+        // so (4), (5), (6) are added as real leaves
+        // and new root, (6) is stored one
+        assert_eq!(new_root.data.end_height, 4);
+        assert_eq!(appended.len(), 3);
+        assert_matches!(tree.root(), EntryLink::Stored(6));
+
+        // ** APPEND 5 **
+
+        let appended = tree.append_leaf(leaf(5)).expect("Failed to append");
+        let new_root = tree.root_node().expect("Failed to resolve root").node;
+
+        // intermediate tree:
+        //                 ( 6 )
+        //                /     \
+        //             (2)       (5)
+        //             /  \     /   \
+        //           (0)  (1) (3)   (4)
+        //
+        // new tree:
+        //                     ( 8g )
+        //                    /      \
+        //                 ( 6 )      \
+        //                /     \      \
+        //             (2)       (5)    \
+        //             /  \     /   \    \
+        //           (0)  (1) (3)   (4)  (7)
+        //
+        // so (7) is added as real leaf
+        // and new root, (8g) is generated one
+        assert_eq!(new_root.data.end_height, 5);
+        assert_eq!(appended.len(), 1);
+        assert_matches!(tree.root(), EntryLink::Generated(_));
+        tree.for_children(tree.root(), |l, r| {
+            assert_matches!(l, EntryLink::Stored(6));
+            assert_matches!(r, EntryLink::Stored(7));
+        });
+
+        // *** APPEND #6 ***
+        let appended = tree.append_leaf(leaf(6)).expect("Failed to append");
+        let new_root = tree.root_node().expect("Failed to resolve root").node;
+
+        // intermediate tree:
+        //                     ( 8g )
+        //                    /      \
+        //                 ( 6 )      \
+        //                /     \      \
+        //             (2)       (5)    \
+        //             /  \     /   \    \
+        //           (0)  (1) (3)   (4)  (7)
+        //
+        // new tree:
+        //                     (---10g--)
+        //                    /          \
+        //                 ( 6 )          \
+        //                /     \          \
+        //             (2)       (5)       (9)
+        //             /  \     /   \     /   \
+        //           (0)  (1) (3)   (4)  (7)  (8)
+        //
+        // so (7) is added as real leaf
+        // and new root, (10g) is generated one
+        assert_eq!(new_root.data.end_height, 6);
+        assert_eq!(appended.len(), 2);
+        assert_matches!(tree.root(), EntryLink::Generated(_));
+        tree.for_children(tree.root(), |l, r| {
+            assert_matches!(l, EntryLink::Stored(6));
+            assert_matches!(r, EntryLink::Stored(9));
+        });
+
+        // *** APPEND #7 ***
+
+        let appended = tree.append_leaf(leaf(7)).expect("Failed to append");
+        let new_root = tree.root_node().expect("Failed to resolve root").node;
+
+        // intermediate tree:
+        //                     (---8g---)
+        //                    /          \
+        //                 ( 6 )          \
+        //                /     \          \
+        //             (2)       (5)       (9)
+        //             /  \     /   \     /   \
+        //           (0)  (1) (3)   (4)  (7)  (8)
+        //
+        // new tree:
+        //                          (---12g--)
+        //                         /          \
+        //                    (---11g---)      \
+        //                   /           \      \
+        //                 ( 6 )          \      \
+        //                /     \          \      \
+        //             (2)       (5)       (9)     \
+        //             /  \     /   \     /   \     \
+        //           (0)  (1) (3)   (4) (7)   (8)  (10)
+        //
+        // so (10) is added as real leaf
+        // and new root, (12g) is generated one
+        assert_eq!(new_root.data.end_height, 7);
+        assert_eq!(appended.len(), 1);
+        assert_matches!(tree.root(), EntryLink::Generated(_));
+        tree.for_children(tree.root(), |l, r| {
+            assert_matches!(l, EntryLink::Generated(_));
+            tree.for_children(l, |l, r| {
+                assert_matches!((l, r), (EntryLink::Stored(6), EntryLink::Stored(9)))
+            });
+            assert_matches!(r, EntryLink::Stored(10));
+        });
+    }
+
+    #[test]
+    fn truncate_simple() {
+        let mut tree = generated(9);
+        let total_truncated = tree.truncate_leaf().expect("Failed to truncate");
+
+        // initial tree:
+        //
+        //                               (-------16g------)
+        //                              /                  \
+        //                    (--------14-------)           \
+        //                   /                   \           \
+        //                 ( 6 )              (  13  )        \
+        //                /     \            /        \        \
+        //             (2)       (5)       (9)        (12)      \
+        //             /  \     /   \     /   \      /    \      \
+        //           (0)  (1) (3)   (4) (7)   (8)  (10)  (11)    (15)
+        //
+        // new tree:
+        //                    (--------14-------)
+        //                   /                   \
+        //                 ( 6 )              (  13  )
+        //                /     \            /        \
+        //             (2)       (5)       (9)        (12)
+        //             /  \     /   \     /   \      /    \
+        //           (0)  (1) (3)   (4) (7)   (8)  (10)  (11)
+        //
+        // so (15) is truncated
+        // and new root, (14) is a stored one now
+
+        assert_matches!(tree.root(), EntryLink::Stored(14));
+        assert_eq!(total_truncated, 1);
+        assert_eq!(tree.len(), 15);
+    }
+
+    #[test]
+    fn truncate_generated() {
+        let mut tree = generated(10);
+        let deleted = tree.truncate_leaf().expect("Failed to truncate");
+
+        // initial tree:
+        //
+        //                               (--------18g--------)
+        //                              /                     \
+        //                    (--------14-------)              \
+        //                   /                   \              \
+        //                 ( 6 )              (  13  )           \
+        //                /     \            /        \           \
+        //             (2)       (5)       (9)        (12)        (17)
+        //             /  \     /   \     /   \      /    \      /    \
+        //           (0)  (1) (3)   (4) (7)   (8)  (10)  (11)  (15)  (16)
+        //
+        // new tree:
+        //                               (-------16g------)
+        //                              /                  \
+        //                    (--------14-------)           \
+        //                   /                   \           \
+        //                 ( 6 )              (  13  )        \
+        //                /     \            /        \        \
+        //             (2)       (5)       (9)        (12)      \
+        //             /  \     /   \     /   \      /    \      \
+        //           (0)  (1) (3)   (4) (7)   (8)  (10)  (11)    (15)
+
+        // new root is generated
+
+        assert_matches!(tree.root(), EntryLink::Generated(_));
+
+        tree.for_children(tree.root(), |left, right| {
+            assert_matches!(
+                (left, right),
+                (EntryLink::Stored(14), EntryLink::Stored(15))
+            )
+        });
+
+        // two stored nodes should leave us (leaf 16 and no longer needed node 17)
+        assert_eq!(deleted, 2);
+        assert_eq!(tree.len(), 16);
+    }
+
+    #[test]
+    fn tree_len() {
+        let mut tree = initial();
+
+        assert_eq!(tree.len(), 3);
+
+        for i in 0..2 {
+            tree.append_leaf(leaf(i + 3)).expect("Failed to append");
+        }
+        assert_eq!(tree.len(), 7);
+
+        tree.truncate_leaf().expect("Failed to truncate");
+
+        assert_eq!(tree.len(), 4);
+    }
+
+    #[test]
+    fn tree_len_long() {
+        let mut tree = initial();
+
+        assert_eq!(tree.len(), 3);
+
+        for i in 0..4094 {
+            tree.append_leaf(leaf(i + 3)).expect("Failed to append");
+        }
+        assert_eq!(tree.len(), 8191); // 4096*2-1 (full tree)
+
+        for _ in 0..2049 {
+            tree.truncate_leaf().expect("Failed to truncate");
+        }
+
+        assert_eq!(tree.len(), 4083); // 4095 - log2(4096)
+    }
+
+    quickcheck! {
+        fn there_and_back(number: u32) -> TestResult {
+            if number > 1024*1024 {
+                TestResult::discard()
+            } else {
+                let mut tree = initial();
+                for i in 0..number {
+                    tree.append_leaf(leaf(i+3)).expect("Failed to append");
+                }
+                for _ in 0..number {
+                    tree.truncate_leaf().expect("Failed to truncate");
+                }
+
+                TestResult::from_bool(if let EntryLink::Stored(2) = tree.root() { true } else { false })
+            }
+        }
+
+        fn leaf_count(number: u32) -> TestResult {
+            if number > 1024 * 1024 || number < 3 {
+                TestResult::discard()
+            } else {
+                let mut tree = initial();
+                for i in 1..(number-1) {
+                    tree.append_leaf(leaf(i+2)).expect("Failed to append");
+                }
+
+                TestResult::from_bool(
+                    tree.root_node().expect("no root").node.leaf_count() == number as u64
+                )
+            }
+        }
+
+        fn parity(number: u32) -> TestResult {
+            if number > 2048 * 2048 || number < 3 {
+                TestResult::discard()
+            } else {
+                let mut tree = initial();
+                for i in 1..(number-1) {
+                    tree.append_leaf(leaf(i+2)).expect("Failed to append");
+                }
+
+                TestResult::from_bool(
+                    if number & (number - 1) == 0 {
+                        if let EntryLink::Stored(_) = tree.root() { true }
+                        else { false }
+                    } else {
+                        if let EntryLink::Generated(_) = tree.root() { true }
+                        else { false }
+                    }
+                )
+            }
+        }
+
+        fn parity_with_truncate(add: u32, delete: u32) -> TestResult {
+            // First we add `add` number of leaves, then delete `delete` number of leaves
+            // What is left should be consistent with generated-stored structure
+            if add > 2048 * 2048 || add < delete {
+                TestResult::discard()
+            } else {
+                let mut tree = initial();
+                for i in 0..add {
+                    tree.append_leaf(leaf(i+3)).expect("Failed to append");
+                }
+                for _ in 0..delete {
+                    tree.truncate_leaf().expect("Failed to truncate");
+                }
+
+                let total = add - delete + 2;
+
+                TestResult::from_bool(
+                    if total & total - 1 == 0 {
+                        if let EntryLink::Stored(_) = tree.root() { true }
+                        else { false }
+                    } else {
+                        if let EntryLink::Generated(_) = tree.root() { true }
+                        else { false }
+                    }
+                )
+            }
+        }
+
+        // Length of tree is always less than number of leaves squared
+        fn stored_length(add: u32, delete: u32) -> TestResult {
+            if add > 2048 * 2048 || add < delete {
+                TestResult::discard()
+            } else {
+                let mut tree = initial();
+                for i in 0..add {
+                    tree.append_leaf(leaf(i+3)).expect("Failed to append");
+                }
+                for _ in 0..delete {
+                    tree.truncate_leaf().expect("Failed to truncate");
+                }
+
+                let total = add - delete + 2;
+
+                TestResult::from_bool(total * total > tree.len())
+            }
+        }
+    }
+}

zcash_primitives/Cargo.toml

@@ -1,9 +1,15 @@
 [package]
 name = "zcash_primitives"
-version = "0.0.0"
+description = "Rust implementations of the Zcash primitives"
+version = "0.1.0"
 authors = [
     "Jack Grigg <jack@z.cash>",
 ]
+homepage = "https://github.com/zcash/librustzcash"
+repository = "https://github.com/zcash/librustzcash"
+readme = "README.md"
+license = "MIT OR Apache-2.0"
+edition = "2018"
 
 [dependencies]
 aes = "0.3"
@@ -11,16 +17,24 @@ blake2b_simd = "0.5"
 blake2s_simd = "0.5"
 byteorder = "1"
 crypto_api_chachapoly = "0.2.1"
-ff = { path = "../ff" }
+ff = { version = "0.5.0", path = "../ff" }
 fpe = "0.2"
 hex = "0.3"
 lazy_static = "1"
-pairing = { path = "../pairing" }
+log = "0.4"
+pairing = { version = "0.15.0", path = "../pairing" }
 rand = "0.7"
-rand_core = "0.5"
-rand_os = "0.2"
+rand_core = "0.5.1"
+ripemd160 = { version = "0.8", optional = true }
+secp256k1 = { version = "=0.15.0", optional = true }
 sha2 = "0.8"
 
 [dev-dependencies]
-hex-literal = "0.1"
+hex-literal = "0.2"
 rand_xorshift = "0.2"
+
+[features]
+transparent-inputs = ["ripemd160", "secp256k1"]
+
+[badges]
+maintenance = { status = "actively-developed" }

zcash_primitives/README.md

@@ -6,7 +6,8 @@ This library contains Rust implementations of the Zcash primitives.
 
 Licensed under either of
 
- * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+   http://www.apache.org/licenses/LICENSE-2.0)
  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
 
 at your option.

zcash_primitives/benches/pedersen_hash.rs

@@ -2,13 +2,11 @@
 
 extern crate pairing;
 extern crate rand_core;
-extern crate rand_os;
 extern crate test;
 extern crate zcash_primitives;
 
 use pairing::bls12_381::Bls12;
-use rand_core::RngCore;
-use rand_os::OsRng;
+use rand_core::{OsRng, RngCore};
 use zcash_primitives::jubjub::JubjubBls12;
 use zcash_primitives::pedersen_hash::{pedersen_hash, Personalization};
 

zcash_primitives/src/block.rs

@@ -1,30 +1,52 @@
+//! Structs and methods for handling Zcash block headers.
+
 use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
 use hex;
+use sha2::{Digest, Sha256};
 use std::fmt;
 use std::io::{self, Read, Write};
 use std::ops::Deref;
 
-use serialize::Vector;
+use crate::serialize::Vector;
+
+pub mod equihash;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub struct BlockHash(pub [u8; 32]);
 
 impl fmt::Display for BlockHash {
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-        let mut data = self.0.clone();
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut data = self.0;
         data.reverse();
         formatter.write_str(&hex::encode(data))
     }
 }
 
+impl BlockHash {
+    /// Constructs a [`BlockHash`] from the given slice.
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if the slice is not exactly 32 bytes.
+    pub fn from_slice(bytes: &[u8]) -> Self {
+        assert_eq!(bytes.len(), 32);
+        let mut hash = [0; 32];
+        hash.copy_from_slice(&bytes);
+        BlockHash(hash)
+    }
+}
+
 /// A Zcash block header.
-pub struct BlockHeader(BlockHeaderData);
+pub struct BlockHeader {
+    hash: BlockHash,
+    data: BlockHeaderData,
+}
 
 impl Deref for BlockHeader {
     type Target = BlockHeaderData;
 
     fn deref(&self) -> &BlockHeaderData {
-        &self.0
+        &self.data
     }
 }
 
@@ -40,12 +62,31 @@ pub struct BlockHeaderData {
 }
 
 impl BlockHeaderData {
-    pub fn freeze(self) -> BlockHeader {
-        BlockHeader(self)
+    pub fn freeze(self) -> io::Result<BlockHeader> {
+        BlockHeader::from_data(self)
     }
 }
 
 impl BlockHeader {
+    fn from_data(data: BlockHeaderData) -> io::Result<Self> {
+        let mut header = BlockHeader {
+            hash: BlockHash([0; 32]),
+            data,
+        };
+        let mut raw = vec![];
+        header.write(&mut raw)?;
+        header
+            .hash
+            .0
+            .copy_from_slice(&Sha256::digest(&Sha256::digest(&raw)));
+        Ok(header)
+    }
+
+    /// Returns the hash of this header.
+    pub fn hash(&self) -> BlockHash {
+        self.hash
+    }
+
     pub fn read<R: Read>(mut reader: R) -> io::Result<Self> {
         let version = reader.read_i32::<LittleEndian>()?;
 
@@ -66,7 +107,7 @@ impl BlockHeader {
 
         let solution = Vector::read(&mut reader, |r| r.read_u8())?;
 
-        Ok(BlockHeader(BlockHeaderData {
+        BlockHeader::from_data(BlockHeaderData {
             version,
             prev_block,
             merkle_root,
@@ -75,7 +116,7 @@ impl BlockHeader {
             bits,
             nonce,
             solution,
-        }))
+        })
     }
 
     pub fn write<W: Write>(&self, mut writer: W) -> io::Result<()> {
@@ -202,6 +243,10 @@ mod tests {
     #[test]
     fn header_read_write() {
         let header = BlockHeader::read(&HEADER_MAINNET_415000[..]).unwrap();
+        assert_eq!(
+            format!("{}", header.hash()),
+            "0000000001ab37793ce771262b2ffa082519aa3fe891250a1adb43baaf856168"
+        );
         let mut encoded = Vec::with_capacity(HEADER_MAINNET_415000.len());
         header.write(&mut encoded).unwrap();
         assert_eq!(&HEADER_MAINNET_415000[..], &encoded[..]);