Fix a corner case for ate pairing in BLS12 and BW6 models (#460)

arkworks-rs · Aug 28, 2022 · 77fb6ab · 77fb6ab
1 parent 6263006
commit 77fb6ab
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -94,6 +94,7 @@
 - [\#366](https://github.com/arkworks-rs/algebra/pull/366) (`ark-ff`) Fix `norm()` for cubic extension field towers.
 - [\#394](https://github.com/arkworks-rs/algebra/pull/394) (`ark-ff`, `ark-serialize`) Remove `EmptyFlags` construction checks.
 - [\#442](https://github.com/arkworks-rs/algebra/pull/442) (`ark-ff`) Fix deserialization for modulo with 64 shaving bits.
+- [\#460](https://github.com/arkworks-rs/algebra/pull/460) (`ark-ec`) Fix a corner case for ate pairing in BLS12 and BW6 models.
 
 ## v0.3.0
 

diff --git a/ec/src/models/bls12/mod.rs b/ec/src/models/bls12/mod.rs
@@ -114,7 +114,7 @@ impl<P: Bls12Parameters> PairingEngine for Bls12<P> {
             }
         }
         let mut f = Self::Fqk::one();
-        for i in BitIteratorBE::new(P::X).skip(1) {
+        for i in BitIteratorBE::without_leading_zeros(P::X).skip(1) {
             f.square_in_place();
             for (p, ref mut coeffs) in &mut pairs {
                 Self::ell(&mut f, coeffs.next().unwrap(), &p.0);
@@ -161,7 +161,7 @@ impl<P: Bls12Parameters> PairingEngine for Bls12<P> {
          -> Fp12<<P as Bls12Parameters>::Fp12Config> {
             let coeffs = coeffs.as_slice();
             let mut j = 0;
-            for i in BitIteratorBE::new(P::X).skip(1) {
+            for i in BitIteratorBE::without_leading_zeros(P::X).skip(1) {
                 f.square_in_place();
                 Self::ell(&mut f, &coeffs[j], &p.0);
                 j += 1;

diff --git a/ec/src/models/bw6/mod.rs b/ec/src/models/bw6/mod.rs
@@ -242,7 +242,7 @@ impl<P: BW6Parameters> PairingEngine for BW6<P> {
         // f_{u+1,Q}(P)
         let mut f_1 = Self::Fqk::one();
 
-        for i in BitIteratorBE::new(P::ATE_LOOP_COUNT_1).skip(1) {
+        for i in BitIteratorBE::without_leading_zeros(P::ATE_LOOP_COUNT_1).skip(1) {
             f_1.square_in_place();
 
             for (p, ref mut coeffs) in &mut pairs_1 {