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General code quality improvements.

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This commit is contained in:
Sean Bowe
2018-03-08 00:41:47 -07:00
parent 896b144a7d
commit b6ef12b077
4 changed files with 133 additions and 40 deletions
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src/jubjub/mod.rs
+43 -18
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@@ -33,8 +33,14 @@ use pairing::bls12_381::{
Fr
};
/// This is an implementation of the twisted Edwards Jubjub curve.
pub mod edwards;
/// This is an implementation of the birationally equivalent
/// Montgomery curve.
pub mod montgomery;
/// This is an implementation of the scalar field for Jubjub.
pub mod fs;
#[cfg(test)]
@@ -83,7 +89,9 @@ pub enum FixedGenerators {
/// offers a scalar field for the embedded curve (Jubjub)
/// and some pre-computed parameters.
pub trait JubjubEngine: Engine {
/// The scalar field of the Jubjub curve
type Fs: PrimeField + SqrtField;
/// The parameters of Jubjub and the Sapling protocol
type Params: JubjubParams<Self>;
}
@@ -167,7 +175,7 @@ impl JubjubBls12 {
let mut montgomery_2a = montgomery_a;
montgomery_2a.double();
let mut tmp = JubjubBls12 {
let mut tmp_params = JubjubBls12 {
// d = -(10240/10241)
edwards_d: Fr::from_str("19257038036680949359750312669786877991949435402254120286184196891950884077233").unwrap(),
// A = 40962
@@ -177,20 +185,24 @@ impl JubjubBls12 {
// scaling factor = sqrt(4 / (a - d))
scale: Fr::from_str("17814886934372412843466061268024708274627479829237077604635722030778476050649").unwrap(),
// We'll initialize these below
pedersen_hash_generators: vec![],
pedersen_circuit_generators: vec![],
fixed_base_generators: vec![],
fixed_base_circuit_generators: vec![],
};
// Create the bases for the Pedersen hashes
{
// TODO: This currently does not match the specification
let mut cur = 0;
let mut pedersen_hash_generators = vec![];
// TODO: This generates more bases for the Pedersen hashes
// than necessary, which is just a performance issue in
// practice.
while pedersen_hash_generators.len() < 5 {
let gh = group_hash(&[cur], constants::PEDERSEN_HASH_GENERATORS_PERSONALIZATION, &tmp);
let gh = group_hash(&[cur], constants::PEDERSEN_HASH_GENERATORS_PERSONALIZATION, &tmp_params);
// We don't want to overflow and start reusing generators
assert!(cur != u8::max_value());
cur += 1;
@@ -200,7 +212,20 @@ impl JubjubBls12 {
}
}
tmp.pedersen_hash_generators = pedersen_hash_generators;
// Check for duplicates, far worse than spec inconsistencies!
for (i, p1) in pedersen_hash_generators.iter().enumerate() {
if p1 == &edwards::Point::zero() {
panic!("Neutral element!");
}
for p2 in pedersen_hash_generators.iter().skip(i+1) {
if p1 == p2 {
panic!("Duplicate generator!");
}
}
}
tmp_params.pedersen_hash_generators = pedersen_hash_generators;
}
// Create the bases for other parts of the protocol
@@ -211,10 +236,10 @@ impl JubjubBls12 {
// Each generator is found by invoking the group hash
// on tag 0x00, 0x01, ... until we find a valid result.
let find_first_gh = |personalization| {
let mut cur = 0;
let mut cur = 0u8;
loop {
let gh = group_hash::<Bls12>(&[cur], personalization, &tmp);
let gh = group_hash::<Bls12>(&[cur], personalization, &tmp_params);
// We don't want to overflow.
assert!(cur != u8::max_value());
cur += 1;
@@ -267,7 +292,7 @@ impl JubjubBls12 {
}
}
tmp.fixed_base_generators = fixed_base_generators;
tmp_params.fixed_base_generators = fixed_base_generators;
}
// Create the 2-bit window table lookups for each 4-bit
@@ -276,10 +301,10 @@ impl JubjubBls12 {
let mut pedersen_circuit_generators = vec![];
// Process each segment
for mut gen in tmp.pedersen_hash_generators.iter().cloned() {
let mut gen = montgomery::Point::from_edwards(&gen, &tmp);
for mut gen in tmp_params.pedersen_hash_generators.iter().cloned() {
let mut gen = montgomery::Point::from_edwards(&gen, &tmp_params);
let mut windows = vec![];
for _ in 0..tmp.pedersen_hash_chunks_per_generator() {
for _ in 0..tmp_params.pedersen_hash_chunks_per_generator() {
// Create (x, y) coeffs for this chunk
let mut coeffs = vec![];
let mut g = gen.clone();
@@ -287,19 +312,19 @@ impl JubjubBls12 {
// coeffs = g, g*2, g*3, g*4
for _ in 0..4 {
coeffs.push(g.into_xy().expect("cannot produce O"));
g = g.add(&gen, &tmp);
g = g.add(&gen, &tmp_params);
}
windows.push(coeffs);
// Our chunks are separated by 2 bits to prevent overlap.
for _ in 0..4 {
gen = gen.double(&tmp);
gen = gen.double(&tmp_params);
}
}
pedersen_circuit_generators.push(windows);
}
tmp.pedersen_circuit_generators = pedersen_circuit_generators;
tmp_params.pedersen_circuit_generators = pedersen_circuit_generators;
}
// Create the 3-bit window table lookups for fixed-base
@@ -307,14 +332,14 @@ impl JubjubBls12 {
{
let mut fixed_base_circuit_generators = vec![];
for mut gen in tmp.fixed_base_generators.iter().cloned() {
for mut gen in tmp_params.fixed_base_generators.iter().cloned() {
let mut windows = vec![];
for _ in 0..tmp.fixed_base_chunks_per_generator() {
for _ in 0..tmp_params.fixed_base_chunks_per_generator() {
let mut coeffs = vec![(Fr::zero(), Fr::one())];
let mut g = gen.clone();
for _ in 0..7 {
coeffs.push(g.into_xy());
g = g.add(&gen, &tmp);
g = g.add(&gen, &tmp_params);
}
windows.push(coeffs);
@@ -324,10 +349,10 @@ impl JubjubBls12 {
fixed_base_circuit_generators.push(windows);
}
tmp.fixed_base_circuit_generators = fixed_base_circuit_generators;
tmp_params.fixed_base_circuit_generators = fixed_base_circuit_generators;
}
tmp
tmp_params
}
}