grand product argument is complete

This commit is contained in:
Alex Vlasov 2019-02-26 16:58:47 +03:00
parent f8d99df957
commit b70af73621

@ -296,7 +296,7 @@ impl<E: Engine> GrandProductArgument<E> {
let n = self.n;
let mut c_polynomials = self.c_polynomials;
let c_polynomials = self.c_polynomials;
let mut e_polynomial: Option<Vec<E::Fr>> = None;
let mut f_polynomial: Option<Vec<E::Fr>> = None;
@ -335,6 +335,7 @@ impl<E: Engine> GrandProductArgument<E> {
let mut rc = c_zy;
rc.mul_assign(challenge);
let mut ry = y;
ry.mul_assign(challenge);
@ -386,17 +387,19 @@ impl<E: Engine> GrandProductArgument<E> {
f_val.negate();
let mut t_poly = self.t_polynomial.unwrap();
assert_eq!(t_poly.len(), 4*n + 3);
// largest negative power of t is -2n-1
let t_zy = {
let tmp = z_inv.pow([(2*n+2) as u64]);
let tmp = z_inv.pow([(2*n+1) as u64]);
evaluate_at_consequitive_powers(&t_poly, tmp, z)
};
t_poly[2*n + 2].sub_assign(&t_zy);
t_poly[2*n + 1].sub_assign(&t_zy);
let t_opening = polynomial_commitment_opening(
2*n + 2,
2*n + 2,
2*n + 1,
2*n + 1,
t_poly.iter(),
z,
srs);
@ -410,7 +413,6 @@ impl<E: Engine> GrandProductArgument<E> {
}
}
pub fn verify_ab_commitment(n: usize,
randomness: & Vec<E::Fr>,
a_commitments: &Vec<E::G1Affine>,
@ -492,44 +494,149 @@ impl<E: Engine> GrandProductArgument<E> {
])).unwrap() == E::Fqk::one()
}
pub fn verify(
n: usize,
randomness: & Vec<E::Fr>,
a_zy: & Vec<E::Fr>,
challenges: &Vec<E::Fr>,
t_commitment: E::G1Affine,
commitments: &Vec<(E::G1Affine, E::Fr)>,
proof: &GrandProductProof<E>,
y: E::Fr,
z: E::Fr,
srs: &SRS<E>
) -> bool {
assert_eq!(randomness.len(), 3);
assert_eq!(a_zy.len(), challenges.len());
assert_eq!(commitments.len(), challenges.len());
let d = srs.d;
let g = srs.g_positive_x[0];
let h_alpha_x_precomp = srs.h_positive_x_alpha[1].prepare();
let h_alpha_precomp = srs.h_positive_x_alpha[0].prepare();
let mut h_prep = srs.h_positive_x[0];
h_prep.negate();
let h_prep = h_prep.prepare();
// first re-calculate cj and t(z,y)
let mut yz = y;
yz.mul_assign(&z);
let z_inv = z.inverse().unwrap();
let mut t_zy = E::Fr::zero();
t_zy.add_assign(&proof.e_zinv);
t_zy.sub_assign(&proof.f_y);
let mut commitments_points = vec![];
let mut rc_vec = vec![];
let mut ry_vec = vec![];
for ((r, commitment), a) in challenges.iter()
.zip(commitments.iter())
.zip(a_zy.iter()) {
let (c, v) = commitment;
commitments_points.push(c.clone());
// cj = ((aj + vj(yz)n+1)y + zn+2 + zn+1y z2n+2y)z1
let mut c_zy = yz.pow([(n + 1) as u64]);
c_zy.mul_assign(v);
c_zy.add_assign(a);
c_zy.mul_assign(&y);
let mut z_n_plus_1 = z.pow([(n + 1) as u64]);
let mut z_n_plus_2 = z_n_plus_1;
z_n_plus_2.mul_assign(&z);
let mut z_2n_plus_2 = z_n_plus_1;
z_2n_plus_2.square();
z_2n_plus_2.mul_assign(&y);
z_n_plus_1.mul_assign(&y);
c_zy.add_assign(&z_n_plus_1);
c_zy.add_assign(&z_n_plus_2);
c_zy.sub_assign(&z_2n_plus_2);
c_zy.mul_assign(&z_inv);
let mut rc = c_zy;
rc.mul_assign(&r);
rc_vec.push(rc);
let mut ry = y;
ry.mul_assign(&r);
ry_vec.push(ry);
let mut val = rc;
val.sub_assign(r);
t_zy.add_assign(&val);
}
let c_rc = multiexp(
commitments_points.iter(),
rc_vec.iter(),
).into_affine();
let c_ry = multiexp(
commitments_points.iter(),
ry_vec.iter(),
).into_affine();
let mut minus_y = y;
minus_y.negate();
let mut f_y = proof.f_opening.mul(minus_y.into_repr());
let g_f = g.mul(proof.f_y.into_repr());
f_y.add_assign(&g_f);
let mut minus_z = z;
minus_z.negate();
let mut t_z = proof.t_opening.mul(minus_z.into_repr());
let g_tzy = g.mul(t_zy.into_repr());
t_z.add_assign(&g_tzy);
let mut minus_z_inv = z_inv;
minus_z_inv.negate();
let mut e_z_inv = proof.e_opening.mul(minus_z_inv.into_repr());
let g_e = g.mul(proof.e_zinv.into_repr());
e_z_inv.add_assign(&g_e);
let h_alpha_term = multiexp(
vec![e_z_inv.into_affine(), f_y.into_affine(), t_z.into_affine()].iter(),
randomness.iter(),
).into_affine();
let h_alpha_x_term = multiexp(
Some(proof.e_opening).iter()
.chain_ext(Some(proof.f_opening).iter())
.chain_ext(Some(proof.t_opening).iter()),
randomness.iter(),
).into_affine();
// pub fn verify(n: usize, challenges: &Vec<E::Fr>, commitments: &Vec<E::G1Affine>, proof: &WellformednessProof<E>, srs: &SRS<E>) -> bool {
// let d = srs.d;
let h_term = multiexp(
Some(c_rc).iter()
.chain_ext(Some(c_ry).iter())
.chain_ext(Some(t_commitment).iter()),
randomness.iter(),
).into_affine();
// let alpha_x_d_precomp = srs.h_positive_x_alpha[d].prepare();
// let alpha_x_n_minus_d_precomp = srs.h_negative_x_alpha[d - n].prepare();
// let mut h_prep = srs.h_positive_x[0];
// h_prep.negate();
// let h_prep = h_prep.prepare();
E::final_exponentiation(&E::miller_loop(&[
(&h_alpha_x_term.prepare(), &h_alpha_x_precomp),
(&h_alpha_term.prepare(), &h_alpha_precomp),
(&h_term.prepare(), &h_prep),
])).unwrap() == E::Fqk::one()
// let a = multiexp(
// commitments.iter(),
// challenges.iter(),
// ).into_affine();
// let a = a.prepare();
// let valid = E::final_exponentiation(&E::miller_loop(&[
// (&a, &h_prep),
// (&proof.l.prepare(), &alpha_x_d_precomp)
// ])).unwrap() == E::Fqk::one();
// if !valid {
// return false;
// }
// let valid = E::final_exponentiation(&E::miller_loop(&[
// (&a, &h_prep),
// (&proof.r.prepare(), &alpha_x_n_minus_d_precomp)
// ])).unwrap() == E::Fqk::one();
// if !valid {
// return false;
// }
// true
// }
}
}
#[test]
@ -542,10 +649,9 @@ fn test_grand_product_argument() {
let srs_alpha = Fr::from_str("23728792").unwrap();
let srs = SRS::<Bls12>::dummy(830564, srs_x, srs_alpha);
let n: usize = 1 << 1;
let n: usize = 1 << 8;
let rng = &mut XorShiftRng::from_seed([0x3dbe6259, 0x8d313d76, 0x3237db17, 0xe5bc0654]);
// let coeffs = (0..n).map(|_| Fr::rand(rng)).collect::<Vec<_>>();
let coeffs = vec![Fr::from_str("1").unwrap(), Fr::from_str("2").unwrap()];
let coeffs = (0..n).map(|_| Fr::rand(rng)).collect::<Vec<_>>();
let mut permutation = coeffs.clone();
rng.shuffle(&mut permutation);
@ -558,9 +664,7 @@ fn test_grand_product_argument() {
assert_eq!(commitments_and_v_values.len(), 1);
// let y : Fr = rng.gen();
let y = Fr::one();
let y : Fr = rng.gen();
let challenges = (0..1).map(|_| Fr::rand(rng)).collect::<Vec<_>>();
@ -581,6 +685,26 @@ fn test_grand_product_argument() {
z,
&srs);
assert!(valid);
assert!(valid, "grand product commitments should be valid");
let a_zy: Vec<Fr> = grand_product_openings.iter().map(|el| el.0.clone()).collect();
let proof = argument.make_argument(&a_zy, &challenges, y, z, &srs);
let randomness = (0..3).map(|_| Fr::rand(rng)).collect::<Vec<_>>();
let valid = GrandProductArgument::verify(
n,
&randomness,
&a_zy,
&challenges,
t_commitment,
&commitments_and_v_values,
&proof,
y,
z,
&srs);
assert!(valid, "t commitment should be valid");
}