Merge pull request #90 from paritytech/domain-ref

ZK_ROWS can differ

Author: swasilyev

pasta-tree/src/lib.rs

@@ -86,7 +86,7 @@ fn piop_params<G: AffineRepr<BaseField: PrimeField>, R: Rng>(
     h: G,
     rng: &mut R,
 ) -> PiopParams<G> {
-    let domain = Domain::<G::BaseField>::new(domain_size, true);
+    let domain = Domain::<G::BaseField>::with_zk_rows(domain_size, 3);
     let seed = G::rand(rng);
     let padding = G::rand(rng);
     PiopParams::setup(domain, h, seed, padding)

w3f-plonk-common/benches/plonk_common.rs

@@ -16,10 +16,10 @@ fn bench_domain_creation(c: &mut Criterion) {
     for log_n in [9, 10, 12, 14] {
         let n = 1usize << log_n;
         group.bench_with_input(BenchmarkId::new("hiding", n), &n, |b, &n| {
-            b.iter(|| Domain::<Fq>::new(n, true));
+            b.iter(|| Domain::<Fq>::with_zk_rows(n, 3));
         });
         group.bench_with_input(BenchmarkId::new("non_hiding", n), &n, |b, &n| {
-            b.iter(|| Domain::<Fq>::new(n, false));
+            b.iter(|| Domain::<Fq>::no_zk(n));
         });
     }
     group.finish();
@@ -30,14 +30,14 @@ fn bench_field_column(c: &mut Criterion) {
     let mut group = c.benchmark_group("field_column");
     for log_n in [9, 10, 12] {
         let n = 1usize << log_n;
-        let domain = Domain::<Fq>::new(n, true);
+        let domain = Domain::<Fq>::with_zk_rows(n, 3);
         let vals: Vec<Fq> = random_vec(domain.capacity - 1, rng);
 
         group.bench_with_input(
             BenchmarkId::new("private_column", n),
             &(vals.clone(), &domain),
             |b, (vals, domain)| {
-                b.iter(|| domain.private_column(vals.clone()));
+                b.iter(|| domain.column(vals.clone()));
             },
         );
 
@@ -62,7 +62,7 @@ fn bench_booleanity_gadget(c: &mut Criterion) {
     let mut group = c.benchmark_group("booleanity");
     for log_n in [9, 10, 12] {
         let n = 1usize << log_n;
-        let domain = Domain::<Fq>::new(n, true);
+        let domain = Domain::<Fq>::with_zk_rows(n, 3);
         let bits = random_bitvec(domain.capacity - 1, 0.5, rng);
         let bit_col = BitColumn::init(bits, &domain);
 
@@ -83,7 +83,7 @@ fn bench_inner_prod_gadget(c: &mut Criterion) {
     let mut group = c.benchmark_group("inner_prod");
     for log_n in [9, 10, 12] {
         let n = 1usize << log_n;
-        let domain = Domain::<Fq>::new(n, true);
+        let domain = Domain::<Fq>::with_zk_rows(n, 3);
         let a: Vec<Fq> = random_vec(domain.capacity - 1, rng);
         let b_vals: Vec<Fq> = random_vec(domain.capacity - 1, rng);
 
@@ -92,8 +92,8 @@ fn bench_inner_prod_gadget(c: &mut Criterion) {
             &(a.clone(), b_vals.clone(), &domain),
             |bench, (a, b_vals, domain)| {
                 bench.iter(|| {
-                    let a_col = domain.private_column(a.clone());
-                    let b_col = domain.private_column(b_vals.clone());
+                    let a_col = domain.column(a.clone());
+                    let b_col = domain.column(b_vals.clone());
                     InnerProd::<Fq>::init(a_col, b_col, domain);
                 });
             },
@@ -128,7 +128,7 @@ fn bench_te_cond_add_gadget(c: &mut Criterion) {
     let mut group = c.benchmark_group("te_cond_add");
     for log_n in [9, 10, 12] {
         let n = 1usize << log_n;
-        let domain = Domain::<Fq>::new(n, true);
+        let domain = Domain::<Fq>::with_zk_rows(n, 3);
         let seed = EdwardsAffine::generator();
 
         let bitmask = random_bitvec(domain.capacity - 1, 0.5, rng);

w3f-plonk-common/src/domain.rs

@@ -7,8 +7,6 @@ use ark_poly::{
 use ark_std::{vec, vec::Vec};
 use getrandom_or_panic::getrandom_or_panic;
 
-pub const ZK_ROWS: usize = 3;
-
 // Domains for performing calculations with constraint polynomials of degree up to 4.
 #[derive(Clone)]
 pub struct Domains<F: FftField> {
@@ -69,14 +67,14 @@ pub struct Domain<F: FftField> {
 }
 
 impl<F: FftField> Domain<F> {
-    pub fn new(n: usize, hiding: bool) -> Self {
-        if hiding {
-            Self::with_zk_rows(n, ZK_ROWS)
-        } else {
-            Self::with_zk_rows(n, 0)
-        }
+    /// Returns a "non-blinding" domain of full `capacity = N`.
+    pub fn no_zk(n: usize) -> Self {
+        Self::with_zk_rows(n, 0)
     }
 
+    /// Returns a domain that blinds (column) polynomials.
+    /// The highest `zk_rows` evaluations (aka Lagrange coefficients) are set random.
+    /// After interpolation that is equivallent to adding `r(X).Z'(X)`, for a random `deg(r) = zk_rows - 1`.
     pub fn with_zk_rows(n: usize, zk_rows: usize) -> Self {
         let domains = Domains::new(n);
         let domain_size = domains.x1.size();
@@ -88,7 +86,7 @@ impl<F: FftField> Domain<F> {
         let l_last = l_i(last_row_index, domain_size);
         let l_last = domains.column_from_evals(l_last, 0);
 
-        let (zk_rows_prod, last_row) = compute_row_polys(domains.x1, zk_rows).unwrap();
+        let (zk_rows_prod, last_row) = compute_row_polys(domains.x1, zk_rows);
         let not_last_row = domains.column_from_poly(last_row);
 
         Self {
@@ -102,6 +100,18 @@ impl<F: FftField> Domain<F> {
         }
     }
 
+    #[cfg(test)]
+    pub const ZK_ROWS_TEST: usize = 3;
+
+    #[cfg(test)]
+    pub fn test_domain(n: usize, hiding: bool) -> Self {
+        if hiding {
+            Self::with_zk_rows(n, Self::ZK_ROWS_TEST)
+        } else {
+            Self::with_zk_rows(n, 0)
+        }
+    }
+
     pub fn is_hiding(&self) -> bool {
         self.zk_rows != 0
     }
@@ -176,27 +186,27 @@ fn elements_rev<F: FftField, D: EvaluationDomain<F>>(domain: D) -> impl Iterator
 }
 
 /// `Z(c) = X - c`
-fn z<F: Field>(c: F) -> DensePolynomial<F> {
+fn z_poly<F: Field>(c: F) -> DensePolynomial<F> {
     DensePolynomial::from_coefficients_vec(vec![-c, F::one()])
 }
 
 fn one<F: Field>() -> DensePolynomial<F> {
     DensePolynomial::from_coefficients_vec(vec![F::one()])
 }
 
-/// For a domain of size `N`, returns `(Z(X), (X - w^{N - zk_rows - 1}))`,
-/// where `Z(X) = (X - w^{N-1}) * (X - w^{N-2}) * ... * (X - w^{N - zk_rows})`.
+/// For a domain of size `N` returns the vanishing polynomial `Z` of its suffix, `deg(Z) = zk_rows`,
+/// `Z(X) = (X - w^{N-1}) * (X - w^{N-2}) * ... * (X - w^{N-zk_rows})`,
+/// and the following not included term `X - w^{N-zk_rows-1}`.
 fn compute_row_polys<F: FftField, D: EvaluationDomain<F>>(
     domain: D,
     zk_rows: usize,
-) -> Option<(DensePolynomial<F>, DensePolynomial<F>)> {
-    if domain.size() < zk_rows + 1 {
-        return None;
-    }
-    let mut wis = elements_rev(domain).map(|wi| z(wi));
-    let zk_rows_prod = wis.by_ref().take(zk_rows).fold(one(), |acc, x| acc * x);
-    let last_row = wis.by_ref().next().unwrap();
-    Some((zk_rows_prod, last_row))
+) -> (DensePolynomial<F>, DensePolynomial<F>) {
+    assert!(domain.size() >= 1 + zk_rows, "0 domain");
+    let ws_rev_iter = elements_rev(domain); // `w^{N-1},...,0 = w^N`
+    let mut z_polys = ws_rev_iter.map(|wi| z_poly(wi));
+    let zk_rows_prod = z_polys.by_ref().take(zk_rows).fold(one(), |acc, x| acc * x);
+    let last_row = z_polys.next().unwrap();
+    (zk_rows_prod, last_row)
 }
 
 pub struct EvaluatedDomain<F: FftField> {
@@ -268,7 +278,7 @@ mod tests {
 
         // let domain = GeneralEvaluationDomain::new(1024);
         let n = 1024;
-        let domain = Domain::new(n, hiding);
+        let domain = Domain::test_domain(n, hiding);
         let z = Fq::rand(rng);
         let domain_eval = domain.evaluate(z);
         assert_eq!(domain.l_first.poly.evaluate(&z), domain_eval.l_first);
@@ -280,31 +290,32 @@ mod tests {
     }
 
     #[test]
+    #[should_panic(expected = "0 domain")]
     fn test_domain_zk_rows() {
         let log_n = 4;
         let n = 1 << log_n;
         let domain = Radix2EvaluationDomain::<Fq>::new(n).unwrap();
         let w = domain.group_gen();
-        let (zk_rows_prod, last_row) = compute_row_polys(domain, 0).unwrap();
+        let (zk_rows_prod, last_row) = compute_row_polys(domain, 0);
         assert_eq!(zk_rows_prod, one());
-        assert_eq!(last_row, z(domain.group_gen_inv()));
+        assert_eq!(last_row, z_poly(domain.group_gen_inv()));
 
         let zk_rows = 3;
-        let (zk_rows_prod, last_row) = compute_row_polys(domain, zk_rows).unwrap();
+        let (zk_rows_prod, last_row) = compute_row_polys(domain, zk_rows);
         assert_eq!(zk_rows_prod.degree(), zk_rows);
         let last_row_index = n - (zk_rows + 1);
-        assert_eq!(last_row, z(w.pow([last_row_index as u64])));
+        assert_eq!(last_row, z_poly(w.pow([last_row_index as u64])));
 
         let zk_rows = n - 1;
-        let (zk_rows_prod, last_row) = compute_row_polys(domain, zk_rows).unwrap();
-        assert_eq!(last_row, z(Fq::one()));
+        let (zk_rows_prod, last_row) = compute_row_polys(domain, zk_rows);
+        assert_eq!(last_row, z_poly(Fq::one()));
         assert_eq!(
             zk_rows_prod * last_row,
             domain.vanishing_polynomial().into()
         );
 
         let zk_rows = n;
-        assert!(compute_row_polys(domain, zk_rows).is_none());
+        compute_row_polys(domain, zk_rows);
     }
 
     #[test]

w3f-plonk-common/src/gadgets/column_sum.rs

@@ -110,7 +110,7 @@ mod tests {
 
         let log_n = 10;
         let n = 2usize.pow(log_n);
-        let domain = Domain::new(n, hiding);
+        let domain = Domain::test_domain(n, hiding);
 
         let col = random_vec(domain.capacity - 1, rng);
         let sum = col.iter().sum();

w3f-plonk-common/src/gadgets/ec/sw_cond_add.rs

@@ -168,7 +168,7 @@ mod tests {
 
         let log_n = 10;
         let n = 2usize.pow(log_n);
-        let domain = Domain::new(n, hiding);
+        let domain = Domain::test_domain(n, hiding);
         let seed = SWAffine::generator();
 
         let bitmask = random_bitvec(domain.capacity - 1, 0.5, rng);

w3f-plonk-common/src/gadgets/ec/te_cond_add.rs

@@ -170,7 +170,7 @@ mod tests {
 
         let log_n = 10;
         let n = 2usize.pow(log_n);
-        let domain = Domain::new(n, hiding);
+        let domain = Domain::test_domain(n, hiding);
         let seed = EdwardsAffine::generator();
 
         let bitmask = random_bitvec(domain.capacity - 1, 0.5, rng);

w3f-plonk-common/src/gadgets/ec/te_doubling.rs

@@ -169,7 +169,7 @@ mod tests {
 
         let log_n = 4;
         let n = 2usize.pow(log_n);
-        let domain = Domain::new(n, false);
+        let domain = Domain::test_domain(n, false);
         let p = EdwardsAffine::rand(rng);
 
         let gadget = Doubling::init(p, &domain);

w3f-plonk-common/src/gadgets/inner_prod.rs

@@ -106,7 +106,7 @@ mod tests {
 
         let log_n = 10;
         let n = 2usize.pow(log_n);
-        let domain = Domain::new(n, hiding);
+        let domain = Domain::test_domain(n, hiding);
 
         let a = random_vec(domain.capacity - 1, rng);
         let b = random_vec(domain.capacity - 1, rng);

w3f-ring-proof/benches/ring_proof.rs

@@ -2,15 +2,14 @@ use criterion::{criterion_group, criterion_main, BatchSize, BenchmarkId, Criteri
 
 use ark_bls12_381::Bls12_381;
 use ark_ec::CurveGroup;
-use ark_ed_on_bls12_381_bandersnatch::{BandersnatchConfig, EdwardsAffine, Fq, Fr};
+use ark_ed_on_bls12_381_bandersnatch::{EdwardsAffine, Fq, Fr};
 use ark_serialize::CanonicalSerialize;
 use ark_std::ops::Mul;
 use ark_std::rand::Rng;
 use ark_std::{test_rng, UniformRand};
 use w3f_pcs::pcs::kzg::KZG;
 use w3f_pcs::pcs::PCS;
 
-use w3f_plonk_common::domain::Domain;
 use w3f_plonk_common::test_helpers::random_vec;
 use w3f_ring_proof::ring_prover::RingProver;
 use w3f_ring_proof::ring_verifier::RingVerifier;
@@ -21,14 +20,10 @@ type CS = KZG<Bls12_381>;
 fn setup(
     rng: &mut impl Rng,
     domain_size: usize,
-) -> (<CS as PCS<Fq>>::Params, PiopParams<Fq, BandersnatchConfig>) {
+) -> (<CS as PCS<Fq>>::Params, PiopParams<EdwardsAffine>) {
     let setup_degree = 3 * domain_size;
     let pcs_params = CS::setup(setup_degree, rng);
-    let domain = Domain::new(domain_size, true);
-    let h = EdwardsAffine::rand(rng);
-    let seed = EdwardsAffine::rand(rng);
-    let padding = EdwardsAffine::rand(rng);
-    let piop_params = PiopParams::setup(domain, h, seed, padding);
+    let piop_params = PiopParams::rand(domain_size, rng);
     (pcs_params, piop_params)
 }
 
@@ -37,13 +32,13 @@ fn make_transcript() -> ArkTranscript {
 }
 
 /// Get the Pedersen blinding base H from the PIOP params (first element of the power-of-2 multiples).
-fn get_h(piop_params: &PiopParams<Fq, BandersnatchConfig>) -> EdwardsAffine {
+fn get_h(piop_params: &PiopParams<EdwardsAffine>) -> EdwardsAffine {
     piop_params.power_of_2_multiples_of_h()[0]
 }
 
 /// Generate a proof and its corresponding blinded public key.
 fn generate_proof(
-    piop_params: &PiopParams<Fq, BandersnatchConfig>,
+    piop_params: &PiopParams<EdwardsAffine>,
     pcs_params: &<CS as PCS<Fq>>::Params,
     pks: &[EdwardsAffine],
     rng: &mut impl Rng,

w3f-ring-proof/src/lib.rs

@@ -155,13 +155,7 @@ mod tests {
     ) -> (CS::Params, PiopParams<EdwardsAffine>) {
         let setup_degree = 3 * domain_size;
         let pcs_params = CS::setup(setup_degree, rng);
-
-        let domain = Domain::new(domain_size, true);
-        let h = EdwardsAffine::rand(rng);
-        let seed = EdwardsAffine::rand(rng);
-        let padding = EdwardsAffine::rand(rng);
-        let piop_params = PiopParams::setup(domain, h, seed, padding);
-
+        let piop_params = PiopParams::rand(domain_size, rng);
         (pcs_params, piop_params)
     }