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@ -6,13 +6,18 @@ use ark_std::{ |
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use std::marker::PhantomData;
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use crate::transcript::Transcript;
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use crate::utils::naive_msm;
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use crate::utils::{naive_msm, vec_add, vector_elem_product};
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pub struct Proof<C: AffineRepr> {
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pub struct Proof_elem<C: AffineRepr> {
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R: C,
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t1: C::ScalarField,
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t2: C::ScalarField,
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}
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pub struct Proof<C: AffineRepr> {
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R: C,
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u_: Vec<C::ScalarField>,
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ru_: C::ScalarField,
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}
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pub struct Params<C: AffineRepr> {
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g: C,
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@ -46,9 +51,14 @@ impl Pedersen { |
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let cm: C = (params.g.mul(v) + params.h.mul(r)).into();
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CommitmentElem::<C> { cm, r }
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}
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pub fn commit(rs: &Vec<C>, v: &Vec<C::ScalarField>) -> Commitment<C> {
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let cm = naive_msm(v, &rs);
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Commitment::<C>(cm)
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pub fn commit<R: RngCore>(
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rng: &mut R,
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params: &Params<C>,
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v: &Vec<C::ScalarField>,
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) -> Commitment<C> {
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let r = C::ScalarField::rand(rng);
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let cm = params.h.mul(r) + naive_msm(v, ¶ms.r_vec);
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Commitment::<C> { cm: cm.into(), r }
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}
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pub fn prove_elem(
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@ -57,36 +67,77 @@ impl Pedersen { |
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cm: C,
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v: C::ScalarField,
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r: C::ScalarField,
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) -> Proof_elem<C> {
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let r1 = transcript.get_challenge(b"r_1");
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let r2 = transcript.get_challenge(b"r_2");
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let R: C = (params.g.mul(r1) + params.h.mul(r2)).into();
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transcript.add(b"cm", &cm);
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transcript.add(b"R", &R);
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let e = transcript.get_challenge(b"e");
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let t1 = r1 + v * e;
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let t2 = r2 + r * e;
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Proof_elem::<C> { R, t1, t2 }
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}
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pub fn prove(
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params: &Params<C>,
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transcript: &mut Transcript<C::ScalarField>,
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cm: C,
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v: Vec<C::ScalarField>,
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r: C::ScalarField,
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) -> Proof<C> {
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let s1 = transcript.get_challenge(b"s_1");
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let s2 = transcript.get_challenge(b"s_2");
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let r1 = transcript.get_challenge(b"r_1");
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let d = transcript.get_challenge_vec(b"d", v.len());
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let R: C = (params.g.mul(s1) + params.h.mul(s2)).into();
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let R: C = (params.h.mul(r1) + naive_msm(&d, ¶ms.r_vec)).into();
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transcript.add(b"cm", &cm);
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transcript.add(b"R", &R);
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let c = transcript.get_challenge(b"c");
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let e = transcript.get_challenge(b"e");
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let t1 = s1 + v * c;
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let t2 = s2 + r * c;
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let u_ = vec_add(&vector_elem_product(&v, &e), &d);
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let ru_ = e * r + r1;
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Proof::<C> { R, t1, t2 }
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Proof::<C> { R, u_, ru_ }
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}
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pub fn verify(
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params: &Params<C>,
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transcript: &mut Transcript<C::ScalarField>,
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cm: C,
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proof: Proof<C>,
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) -> bool {
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// r1, d just to match Prover's transcript
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transcript.get_challenge(b"r_1");
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transcript.get_challenge_vec(b"d", proof.u_.len());
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transcript.add(b"cm", &cm);
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transcript.add(b"R", &proof.R);
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let e = transcript.get_challenge(b"e");
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let lhs = proof.R + cm.mul(e);
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let rhs = params.h.mul(proof.ru_) + naive_msm(&proof.u_, ¶ms.r_vec);
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if lhs != rhs {
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return false;
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}
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true
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}
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pub fn verify_elem(
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params: &Params<C>,
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transcript: &mut Transcript<C::ScalarField>,
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cm: C,
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proof: Proof<C>,
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proof: Proof_elem<C>,
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) -> bool {
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// s1, s2 just to match Prover's transcript
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transcript.get_challenge(b"s_1");
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transcript.get_challenge(b"s_2");
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transcript.get_challenge(b"r_1");
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transcript.get_challenge(b"r_2");
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transcript.add(b"cm", &cm);
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transcript.add(b"R", &proof.R);
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let c = transcript.get_challenge(b"c");
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let lhs = proof.R + cm.mul(c);
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let e = transcript.get_challenge(b"e");
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let lhs = proof.R + cm.mul(e);
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let rhs = params.g.mul(proof.t1) + params.h.mul(proof.t2);
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if lhs != rhs {
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return false;
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@ -95,7 +146,20 @@ impl Pedersen { |
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}
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}
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pub struct Commitment<C: AffineRepr>(pub C);
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pub struct Commitment<C: AffineRepr> {
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pub cm: C,
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pub r: C::ScalarField,
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}
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impl<C: AffineRepr> Commitment<C> {
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pub fn prove(
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&self,
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params: &Params<C>,
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transcript: &mut Transcript<C::ScalarField>,
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v: Vec<C::ScalarField>,
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) -> Proof<C> {
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Pedersen::<C>::prove(params, transcript, self.cm, v, self.r)
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}
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}
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pub struct CommitmentElem<C: AffineRepr> {
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pub cm: C,
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@ -107,7 +171,7 @@ impl CommitmentElem { |
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params: &Params<C>,
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transcript: &mut Transcript<C::ScalarField>,
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v: C::ScalarField,
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) -> Proof<C> {
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) -> Proof_elem<C> {
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Pedersen::<C>::prove_elem(params, transcript, self.cm, v, self.r)
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}
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}
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@ -120,7 +184,7 @@ mod tests { |
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use std::ops::Mul;
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#[test]
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fn test_pedersen() {
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fn test_pedersen_single_element() {
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let mut rng = ark_std::test_rng();
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// setup params
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@ -142,4 +206,26 @@ mod tests { |
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let v = Pedersen::verify_elem(¶ms, &mut transcript_v, cm.cm, proof);
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assert!(v);
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}
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#[test]
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fn test_pedersen_vector() {
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let mut rng = ark_std::test_rng();
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const n: usize = 10;
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// setup params
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let params = Pedersen::<G1Affine>::new_params(&mut rng, n);
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// init Prover's transcript
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let mut transcript_p: Transcript<Fr> = Transcript::<Fr>::new();
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// init Verifier's transcript
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let mut transcript_v: Transcript<Fr> = Transcript::<Fr>::new();
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let mut v: Vec<Fr> = vec![Fr::rand(&mut rng); n];
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let cm = Pedersen::commit(&mut rng, ¶ms, &v);
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let proof = cm.prove(¶ms, &mut transcript_p, v);
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// also can use:
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// let proof = Pedersen::prove(¶ms, &mut transcript_p, cm.cm, v, cm.r);
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let v = Pedersen::verify(¶ms, &mut transcript_v, cm.cm, proof);
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assert!(v);
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}
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}
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