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allow the provider to provide byte representation of a scalar (#140)

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This commit is contained in:
Srinath Setty
2023-02-10 12:36:51 -08:00
committed by GitHub
parent 8faffd38ea
commit c4b07f0925
2 changed files with 25 additions and 21 deletions
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15
src/provider/pasta.rs
View File

@@ -1,13 +1,15 @@
//! This module implements the Nova traits for pallas::Point, pallas::Scalar, vesta::Point, vesta::Scalar.
use crate::{
errors::NovaError,
provider::{
keccak::Keccak256Transcript,
pedersen::CommitmentEngine,
poseidon::{PoseidonRO, PoseidonROCircuit},
},
traits::{CompressedGroup, Group, PrimeFieldExt},
traits::{ChallengeTrait, CompressedGroup, Group, PrimeFieldExt, TranscriptEngineTrait},
};
use digest::{ExtendableOutput, Input};
use ff::PrimeField;
use num_bigint::BigInt;
use num_traits::Num;
use pasta_curves::{
@@ -175,6 +177,10 @@ macro_rules! impl_traits {
let bytes_arr: [u8; 64] = bytes.try_into().unwrap();
$name::Scalar::from_bytes_wide(&bytes_arr)
}
fn to_bytes(s: &Self) -> Vec<u8> {
s.to_repr().as_ref().to_vec()
}
}
impl CompressedGroup for $name_compressed {
@@ -191,6 +197,12 @@ macro_rules! impl_traits {
};
}
impl<G: Group<Scalar = F>, F: PrimeField> ChallengeTrait<G> for F {
fn challenge(label: &'static [u8], transcript: &mut G::TE) -> Result<F, NovaError> {
transcript.squeeze_scalar(label)
}
}
impl_traits!(
pallas,
PallasCompressedElementWrapper,
@@ -210,7 +222,6 @@ impl_traits!(
/// Native implementation of fast multiexp for platforms that do not support pasta_msm/semolina
/// Adapted from zcash/halo2
fn cpu_multiexp_serial<C: CurveAffine>(coeffs: &[C::Scalar], bases: &[C], acc: &mut C::Curve) {
use ff::PrimeField;
let coeffs: Vec<_> = coeffs.iter().map(|a| a.to_repr()).collect();
let c = if bases.len() < 4 {

31
src/traits/mod.rs
View File

@@ -224,35 +224,28 @@ pub trait ChallengeTrait<G: Group> {
/// Defines additional methods on PrimeField objects
pub trait PrimeFieldExt: PrimeField {
/// Returns a Scalar representing the bytes
/// Returns a scalar representing the bytes
fn from_uniform(bytes: &[u8]) -> Self;
/// Returns a byte representation
fn to_bytes(v: &[Self]) -> Vec<u8> {
(0..v.len())
.map(|i| v[i].to_repr().as_ref().to_vec())
.collect::<Vec<Vec<u8>>>()
.into_iter()
.flatten()
.collect::<Vec<u8>>()
}
/// Returns a vector of bytes representing the scalar
fn to_bytes(s: &Self) -> Vec<u8>;
}
impl<G: Group<Scalar = F>, F: PrimeField> ChallengeTrait<G> for F {
fn challenge(label: &'static [u8], transcript: &mut G::TE) -> Result<F, NovaError> {
transcript.squeeze_scalar(label)
}
}
impl<G: Group<Scalar = F>, F: PrimeField> AppendToTranscriptTrait<G> for F {
impl<G: Group<Scalar = F>, F: PrimeField + PrimeFieldExt> AppendToTranscriptTrait<G> for F {
fn append_to_transcript(&self, label: &'static [u8], transcript: &mut G::TE) {
transcript.absorb_bytes(label, self.to_repr().as_ref());
transcript.absorb_bytes(label, &<Self as PrimeFieldExt>::to_bytes(self));
}
}
impl<G: Group<Scalar = F>, F: PrimeField + PrimeFieldExt> AppendToTranscriptTrait<G> for [F] {
fn append_to_transcript(&self, label: &'static [u8], transcript: &mut G::TE) {
transcript.absorb_bytes(label, &<F as PrimeFieldExt>::to_bytes(self));
let bytes = (0..self.len())
.map(|i| <F as PrimeFieldExt>::to_bytes(&self[i]))
.collect::<Vec<_>>()
.into_iter()
.flatten()
.collect::<Vec<u8>>();
transcript.absorb_bytes(label, &bytes);
}
}