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Conditionally squeeze scalar hasher before interacting with base hasher

This commit is contained in:
therealyingtong 2020-10-21 22:33:22 +08:00 committed by Jack Grigg
parent 15682bf16f
commit bffab9953e
1 changed files with 12 additions and 7 deletions
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19
src/transcript.rs
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@ -91,9 +91,19 @@ impl<C: CurveAffine, HBase: Hasher<C::Base>, HScalar: Hasher<C::Scalar>>
}
}
fn conditional_scalar_squeeze(&mut self) {
if self.scalar_needs_squeezing {
let transcript_scalar_point =
C::Base::from_bytes(&(self.scalar_hasher.squeeze()).to_bytes()).unwrap();
self.base_hasher.absorb(transcript_scalar_point);
self.scalar_needs_squeezing = false;
}
}
/// Absorb a curve point into the transcript by absorbing
/// its x and y coordinates
pub fn absorb_point(&mut self, point: &C) -> Result<(), ()> {
self.conditional_scalar_squeeze();
let tmp = point.get_xy();
if bool::from(tmp.is_none()) {
return Err(());
@ -106,6 +116,7 @@ impl<C: CurveAffine, HBase: Hasher<C::Base>, HScalar: Hasher<C::Scalar>>
/// Absorb a base into the base_hasher
pub fn absorb_base(&mut self, base: C::Base) {
self.conditional_scalar_squeeze();
self.base_hasher.absorb(base);
}
@ -117,13 +128,7 @@ impl<C: CurveAffine, HBase: Hasher<C::Base>, HScalar: Hasher<C::Scalar>>
/// Squeeze the transcript to obtain a C::Base value.
pub fn squeeze(&mut self) -> C::Base {
if self.scalar_needs_squeezing {
let transcript_scalar_point =
C::Base::from_bytes(&(self.scalar_hasher.squeeze()).to_bytes()).unwrap();
self.base_hasher.absorb(transcript_scalar_point);
self.scalar_needs_squeezing = false;
}
self.conditional_scalar_squeeze();
self.base_hasher.squeeze()
}
}