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multiopen: Rename [x_4, x_5] challenges to [x_1, x_2] 

Also added types for these challenges, even though it's not technically
necessary yet because we don't pass these around anywhere.
This commit is contained in:
Jack Grigg 2020-12-01 21:42:32 +00:00
parent eb7ce442f9
commit f0723dbbcc
3 changed files with 28 additions and 18 deletions
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10
src/poly/multiopen.rs
View File

@ -12,6 +12,16 @@ use crate::arithmetic::{CurveAffine, FieldExt};
mod prover;
mod verifier;
#[derive(Clone, Copy, Debug)]
struct X1 {}
/// Challenge for compressing openings at the same point sets together.
type ChallengeX1<F> = commitment::ChallengeScalar<F, X1>;
#[derive(Clone, Copy, Debug)]
struct X2 {}
/// Challenge for keeping the multi-point quotient polynomial terms linearly independent.
type ChallengeX2<F> = commitment::ChallengeScalar<F, X2>;
/// This is a multi-point opening proof used in the polynomial commitment scheme opening.
#[derive(Debug, Clone)]
pub struct Proof<C: CurveAffine> {

16
src/poly/multiopen/prover.rs
View File

@ -2,7 +2,7 @@ use super::super::{
commitment::{self, Blind, ChallengeScalar, ChallengeZ, Params},
Coeff, Error, Polynomial,
};
use super::{construct_intermediate_sets, Proof, ProverQuery, Query};
use super::{construct_intermediate_sets, ChallengeX1, ChallengeX2, Proof, ProverQuery, Query};
use crate::arithmetic::{
eval_polynomial, kate_division, lagrange_interpolate, Curve, CurveAffine, FieldExt,
@ -30,13 +30,13 @@ impl<C: CurveAffine> Proof<C> {
where
I: IntoIterator<Item = ProverQuery<'a, C>> + Clone,
{
let x_4 = ChallengeScalar::<_, ()>::get(transcript);
let x_5 = ChallengeScalar::<_, ()>::get(transcript);
let x_1 = ChallengeX1::get(transcript);
let x_2 = ChallengeX2::get(transcript);
let (poly_map, point_sets) = construct_intermediate_sets(queries);
// Collapse openings at same point sets together into single openings using
// x_4 challenge.
// x_1 challenge.
let mut q_polys: Vec<Option<Polynomial<C::Scalar, Coeff>>> = vec![None; point_sets.len()];
let mut q_blinds = vec![Blind(C::Scalar::zero()); point_sets.len()];
@ -53,16 +53,16 @@ impl<C: CurveAffine> Proof<C> {
blind: Blind<C::Scalar>,
evals: Vec<C::Scalar>| {
if let Some(poly) = &q_polys[set_idx] {
q_polys[set_idx] = Some(poly.clone() * *x_4 + new_poly);
q_polys[set_idx] = Some(poly.clone() * *x_1 + new_poly);
} else {
q_polys[set_idx] = Some(new_poly.clone());
}
q_blinds[set_idx] *= *x_4;
q_blinds[set_idx] *= *x_1;
q_blinds[set_idx] += blind;
// Each polynomial is evaluated at a set of points. For each set,
// we collapse each polynomial's evals pointwise.
for (eval, set_eval) in evals.iter().zip(q_eval_sets[set_idx].iter_mut()) {
*set_eval *= &x_4;
*set_eval *= &x_1;
*set_eval += eval;
}
};
@ -99,7 +99,7 @@ impl<C: CurveAffine> Proof<C> {
if f_poly.is_none() {
Some(poly)
} else {
f_poly.map(|f_poly| f_poly * *x_5 + &poly)
f_poly.map(|f_poly| f_poly * *x_2 + &poly)
}
})
.unwrap();

20
src/poly/multiopen/verifier.rs
View File

@ -4,7 +4,7 @@ use super::super::{
commitment::{ChallengeScalar, ChallengeZ, Guard, Params, MSM},
Error,
};
use super::{construct_intermediate_sets, Proof, Query, VerifierQuery};
use super::{construct_intermediate_sets, ChallengeX1, ChallengeX2, Proof, Query, VerifierQuery};
use crate::arithmetic::{eval_polynomial, lagrange_interpolate, CurveAffine, FieldExt};
use crate::transcript::{Hasher, Transcript};
@ -32,17 +32,17 @@ impl<C: CurveAffine> Proof<C> {
// with it to make it true, with high probability.
msm.scale(C::Scalar::rand());
// Sample x_4 for compressing openings at the same point sets together
let x_4 = ChallengeScalar::<_, ()>::get(transcript);
// Sample x_1 for compressing openings at the same point sets together
let x_1 = ChallengeX1::get(transcript);
// Sample a challenge x_5 for keeping the multi-point quotient
// Sample a challenge x_2 for keeping the multi-point quotient
// polynomial terms linearly independent.
let x_5 = ChallengeScalar::<_, ()>::get(transcript);
let x_2 = ChallengeX2::get(transcript);
let (commitment_map, point_sets) = construct_intermediate_sets(queries);
// Compress the commitments and expected evaluations at x together.
// using the challenge x_4
// using the challenge x_1
let mut q_commitments: Vec<_> = vec![params.empty_msm(); point_sets.len()];
// A vec of vecs of evals. The outer vec corresponds to the point set,
@ -53,10 +53,10 @@ impl<C: CurveAffine> Proof<C> {
}
{
let mut accumulate = |set_idx: usize, new_commitment, evals: Vec<C::Scalar>| {
q_commitments[set_idx].scale(*x_4);
q_commitments[set_idx].scale(*x_1);
q_commitments[set_idx].append_term(C::Scalar::one(), new_commitment);
for (eval, set_eval) in evals.iter().zip(q_eval_sets[set_idx].iter_mut()) {
*set_eval *= &x_4;
*set_eval *= &x_1;
*set_eval += eval;
}
};
@ -86,7 +86,7 @@ impl<C: CurveAffine> Proof<C> {
}
// We can compute the expected msm_eval at z using the q_evals provided
// by the prover and from x_5
// by the prover and from x_2
let msm_eval = point_sets
.iter()
.zip(q_eval_sets.iter())
@ -99,7 +99,7 @@ impl<C: CurveAffine> Proof<C> {
let eval = points.iter().fold(*proof_eval - &r_eval, |eval, point| {
eval * &(*z - point).invert().unwrap()
});
msm_eval * &x_5 + &eval
msm_eval * &x_2 + &eval
},
);