Change pedersen hash outside the circuit to use window table lookups.

benches/pedersen_hash.rs

@@ -0,0 +1,23 @@
+#![feature(test)]
+
+extern crate rand;
+extern crate test;
+extern crate pairing;
+extern crate sapling_crypto;
+
+use rand::{Rand, thread_rng};
+use pairing::bls12_381::Bls12;
+use sapling_crypto::jubjub::JubjubBls12;
+use sapling_crypto::pedersen_hash::{pedersen_hash, Personalization};
+
+#[bench]
+fn bench_pedersen_hash(b: &mut test::Bencher) {
+    let params = JubjubBls12::new();
+    let rng = &mut thread_rng();
+    let bits = (0..510).map(|_| bool::rand(rng)).collect::<Vec<_>>();
+    let personalization = Personalization::MerkleTree(31);
+
+    b.iter(|| {
+        pedersen_hash::<Bls12, _>(personalization, bits.clone(), &params)
+    });
+}