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Co-authored-by: ying tong <yingtong@z.cash>
This commit is contained in:
Daira Hopwood 2021-01-30 22:08:17 +00:00
parent fa3afc29bb
commit db11c47045
1 changed files with 5 additions and 21 deletions
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26
src/arithmetic/hashtocurve.rs
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@ -105,7 +105,7 @@ pub trait MessageHasher<F: FieldExt> {
/// It does not support domain separation tags longer than 128 bytes. /// It does not support domain separation tags longer than 128 bytes.
#[derive(Debug, Default)] #[derive(Debug, Default)]
pub struct Shake128<F: FieldExt> { pub struct Shake128<F: FieldExt> {
marker: PhantomData<F>, _marker: PhantomData<F>,
} }
impl<F: FieldExt> MessageHasher<F> for Shake128<F> { impl<F: FieldExt> MessageHasher<F> for Shake128<F> {
@ -143,23 +143,6 @@ impl<F: FieldExt> MessageHasher<F> for Shake128<F> {
} }
} }
/// A MessageHasher for BLAKE2b.
#[derive(Debug, Default)]
pub struct Blake2bXof<F: FieldExt> {
marker: PhantomData<F>,
}
impl<F: FieldExt> MessageHasher<F> for Blake2bXof<F> {
fn hash_name(&self) -> &str {
"XOF:BLAKE2b"
}
#[allow(unused_variables)]
fn hash_to_field(&self, message: &[u8], domain_separation_tag: &[u8], count: usize) -> Vec<F> {
todo!()
}
}
/// The simplified SWU hash-to-curve method, using an isogenous curve /// The simplified SWU hash-to-curve method, using an isogenous curve
/// y^2 = x^3 + a*x + b. This currently only supports prime-order curves. /// y^2 = x^3 + a*x + b. This currently only supports prime-order curves.
#[derive(Debug)] #[derive(Debug)]
@ -168,7 +151,7 @@ pub struct SimplifiedSWUWithDegree3Isogeny<
I: CurveAffine<Base = F>, I: CurveAffine<Base = F>,
C: CurveAffine<Base = F>, C: CurveAffine<Base = F>,
> { > {
/// `Z` parameter (ξ in [WB2019]). /// `Z` parameter (ξ in [WB2019](https://eprint.iacr.org/2019/403)).
pub z: F, pub z: F,
/// Precomputed -b/a for the isogenous curve. /// Precomputed -b/a for the isogenous curve.
@ -268,8 +251,9 @@ impl<F: FieldExt, I: CurveAffine<Base = F>, C: CurveAffine<Base = F>> HashToCurv
// This magic also comes from a generalization of [WB2019, section 4.2]. // This magic also comes from a generalization of [WB2019, section 4.2].
// //
// The Sarkar square root algorithm with input s gives us a square root of // The Sarkar square root algorithm with input s gives us a square root of
// ROOT_OF_UNITY * s for free when s is not square, where h is a fixed nonsquare. // h * s for free when s is not square, where h is a fixed nonsquare.
// We know that Z / ROOT_OF_UNITY is a square since both Z and ROOT_OF_UNITY are // In our implementation, h = ROOT_OF_UNITY.
// We know that Z / h is a square since both Z and h are
// nonsquares. Precompute theta as a square root of Z / ROOT_OF_UNITY. // nonsquares. Precompute theta as a square root of Z / ROOT_OF_UNITY.
// //
// We have gx2 = g(Z * u^2 * x1) = Z^3 * u^6 * gx1 // We have gx2 = g(Z * u^2 * x1) = Z^3 * u^6 * gx1