mirror of https://github.com/zcash/halo2.git
Fix bug in compute_g()
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1eb2a36086
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19ee27e51a
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@ -51,8 +51,11 @@ impl<'a, C: CurveAffine> MSM<'a, C> {
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&self.other_bases.push(point);
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}
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/// Add a vector of scalars to `g_scalars`
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/// Add a vector of scalars to `g_scalars`. This function will panic if the
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/// caller provides a slice of scalars that is not of length `params.n`.
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// TODO: parallelize
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pub fn add_to_g(&mut self, scalars: &[C::Scalar]) {
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assert_eq!(scalars.len(), self.params.n as usize);
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if let Some(g_scalars) = &mut self.g_scalars {
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for (g_scalar, scalar) in g_scalars.iter_mut().zip(scalars.iter()) {
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*g_scalar += &scalar;
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@ -68,6 +71,7 @@ impl<'a, C: CurveAffine> MSM<'a, C> {
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}
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/// Scale all scalars in the MSM by a random blinding factor
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// TODO: parallelize
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pub fn scale(&mut self, factor: C::Scalar) {
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if let Some(g_scalars) = &mut self.g_scalars {
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for g_scalar in g_scalars.iter_mut() {
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@ -75,6 +79,7 @@ impl<'a, C: CurveAffine> MSM<'a, C> {
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}
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}
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// TODO: parallelize
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for other_scalar in self.other_scalars.iter_mut() {
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*other_scalar *= &factor;
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}
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@ -292,25 +297,7 @@ impl<'a, C: CurveAffine> Guard<'a, C> {
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/// Computes the g value when given a potential scalar as input.
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pub fn compute_g(&self, scalar: C::Scalar) -> C {
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let s = compute_s(&self.challenges_sq, self.allinv * &scalar);
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let mut g = C::Projective::zero();
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if let Some(g_scalars) = &self.msm.g_scalars {
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for ((g_scalar, g_base), s) in
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g_scalars.iter().zip(self.msm.params.g.iter()).zip(s.iter())
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{
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// g_base * (g_scalar + s)
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let tmp = g_base.mul(*g_scalar + &s);
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g = g.add(&tmp);
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}
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} else {
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for (g_base, s) in self.msm.params.g.iter().zip(s.iter()) {
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// g_base * (g_scalar + s)
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let tmp = g_base.mul(*s);
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g = g.add(&tmp);
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}
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}
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g.to_affine()
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best_multiexp(&s, &self.msm.params.g).to_affine()
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}
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}
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@ -425,7 +412,7 @@ fn test_opening_proof() {
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transcript.absorb(Fp::from_bytes(&v.to_bytes()).unwrap()); // unlikely to fail since p ~ q
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loop {
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let mut transcript_dup = transcript.clone();
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let transcript_dup = transcript.clone();
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let opening_proof = OpeningProof::create(¶ms, &mut transcript, &px, blind, x);
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if opening_proof.is_err() {
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@ -434,18 +421,30 @@ fn test_opening_proof() {
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} else {
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let opening_proof = opening_proof.unwrap();
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// Verify the opening proof
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let msm = params.empty_msm();
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let guard = opening_proof
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.verify(¶ms, msm, &mut transcript_dup, x, &p, v)
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.verify(
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¶ms,
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params.empty_msm(),
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&mut transcript_dup.clone(),
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x,
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&p,
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v,
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)
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.unwrap();
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// Generate a `new_guard` to populate `msm.g_scalars`
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let msm = guard.use_challenges();
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let new_guard = opening_proof
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.verify(¶ms, msm, &mut transcript_dup.clone(), x, &p, v)
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.unwrap();
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// Test use_challenges()
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let msm_challenges = guard.clone().use_challenges();
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let msm_challenges = new_guard.clone().use_challenges();
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assert!(msm_challenges.is_zero());
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// Test use_g()
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let g = guard.compute_g(Field::one());
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let (msm_g, _accumulator) = guard.clone().use_g(g);
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let g = new_guard.compute_g(Field::one());
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let (msm_g, _accumulator) = new_guard.clone().use_g(g);
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assert!(msm_g.is_zero());
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