refactor

halo2_proofs/examples/folding.rs

@@ -1,23 +1,15 @@
 use ff::{BatchInvert, FromUniformBytes};
 use halo2_proofs::{
-    arithmetic::{CurveAffine, Field},
+    arithmetic::Field,
     circuit::{floor_planner::V1, Layouter, Value},
-    dev::{metadata, FailureLocation, MockProver, VerifyFailure},
     plonk::*,
-    poly::{
+    poly::{self, commitment::ParamsProver, VerificationStrategy},
+    protostar::{
         self,
-        commitment::ParamsProver,
-        ipa::{
-            commitment::{IPACommitmentScheme, ParamsIPA},
-            multiopen::{ProverIPA, VerifierIPA},
-            strategy::AccumulatorStrategy,
-        },
-        VerificationStrategy,
-    },
-    protostar::{self, decider::create_proof},
-    transcript::{
-        Blake2bRead, Blake2bWrite, Challenge255, TranscriptReadBuffer, TranscriptWriterBuffer,
+        accumulator::Accumulator,
+        // decider::create_proof,
     },
+    transcript::{Blake2bWrite, Challenge255, TranscriptReadBuffer, TranscriptWriterBuffer},
 };
 use halo2curves::pasta::pallas;
 use rand_core::{OsRng, RngCore};
@@ -264,7 +256,8 @@ fn main() {
 
     let mut transcript = Blake2bWrite::<_, _, Challenge255<_>>::init(vec![]);
     let pk = protostar::ProvingKey::new(&params, &circuit1).unwrap();
-    let mut acc = protostar::prover::create_accumulator(
+
+    let acc1 = protostar::prover::create_accumulator(
         &params,
         &pk,
         &circuit1,
@@ -273,15 +266,17 @@ fn main() {
         &mut transcript,
     )
     .unwrap();
-    assert!(acc.decide(&params, &pk));
+
+    // An accumulator is always valid
+    assert!(Accumulator::decide(&params, &pk, &acc1));
 
     // Folding an accumulator with itself should yield the same one,
     // since (1-X)*acc + X*acc = acc
-    let acc1 = acc.clone();
-    acc.fold(&pk, acc1.clone(), &mut transcript);
-    assert!(acc.decide(&params, &pk));
+    let acc = Accumulator::fold(&pk, acc1.clone(), acc1.clone(), &mut transcript);
     assert_eq!(acc, acc1);
 
+    assert!(Accumulator::decide(&params, &pk, &acc));
+
     let acc2 = protostar::prover::create_accumulator(
         &params,
         &pk,
@@ -291,31 +286,9 @@ fn main() {
         &mut transcript,
     )
     .unwrap();
-    acc.fold(&pk, acc2, &mut transcript);
-    assert!(acc.decide(&params, &pk));
 
-    let acc3 = protostar::prover::create_accumulator(
-        &params,
-        &pk,
-        &circuit3,
-        &[],
-        &mut rng,
-        &mut transcript,
-    )
-    .unwrap();
-    acc.fold(&pk, acc3, &mut transcript);
-
-    let acc4 = protostar::prover::create_accumulator(
-        &params,
-        &pk,
-        &circuit3,
-        &[],
-        &mut rng,
-        &mut transcript,
-    )
-    .unwrap();
-    acc.fold(&pk, acc4, &mut transcript);
-    assert!(acc.decide(&params, &pk));
+    let acc = Accumulator::fold(&pk, acc, acc2, &mut transcript);
+    assert!(Accumulator::decide(&params, &pk, &acc));
 
-    let _ = create_proof::<_, ProverIPA<_>, _, _, _>(&params, &pk, acc, &mut rng, &mut transcript);
+    // let _ = create_proof::<_, ProverIPA<_>, _, _, _>(&params, &pk, acc, &mut rng, &mut transcript);
 }

halo2_proofs/src/plonk/circuit.rs

@@ -2234,7 +2234,6 @@ impl<F: Field> ConstraintSystem<F> {
 
     /// Compute the degree of the constraint system (the maximum degree of all
     /// constraints).
-    /// TODO(@adr1anh): Folding degree?
     pub fn degree(&self) -> usize {
         // The permutation argument will serve alongside the gates, so must be
         // accounted for.

halo2_proofs/src/protostar.rs

@@ -1,11 +1,8 @@
 //! Contains logic for handling halo2 circuits with Protostar
 
-pub mod decider;
-mod error_check;
+pub mod accumulator;
+mod constraints;
 mod keygen;
 pub mod prover;
-mod row_evaluator;
-mod transcript;
 
-pub use error_check::Accumulator;
 pub use keygen::ProvingKey;

halo2_proofs/src/protostar/accumulator.rs

@@ -0,0 +1,156 @@
+use std::iter::{self, zip};
+
+use ff::Field;
+use group::Curve;
+use halo2curves::CurveAffine;
+use rand_core::RngCore;
+
+use crate::{
+    arithmetic::{eval_polynomial, parallelize},
+    dev::metadata::Gate,
+    poly::{
+        commitment::{Blind, Params},
+        LagrangeCoeff, Polynomial,
+    },
+    transcript::{EncodedChallenge, TranscriptWrite},
+};
+
+use self::committed::Committed;
+
+use super::{
+    constraints::{paired::Paired, polynomial::PolynomialRef, Data},
+    ProvingKey,
+};
+
+pub(super) mod advice;
+pub(super) mod committed;
+pub(super) mod compressed_verifier;
+pub(super) mod instance;
+pub(super) mod lookup;
+
+/// An `Accumulator` contains the entirety of the IOP transcript,
+/// including commitments and verifier challenges.
+#[derive(Debug, Clone, PartialEq)]
+pub struct Accumulator<C: CurveAffine> {
+    pub instance: instance::Transcript<C>,
+    pub advice: advice::Transcript<C>,
+    pub lookups: Vec<lookup::Transcript<C>>,
+    pub beta: compressed_verifier::Transcript<C>,
+
+    pub ys: Vec<C::Scalar>,
+
+    // Error value for all constraints
+    pub error: C::Scalar,
+}
+
+impl<C: CurveAffine> Accumulator<C> {
+    pub fn fold<E: EncodedChallenge<C>, T: TranscriptWrite<C, E>>(
+        pk: &ProvingKey<C>,
+        acc0: Self,
+        acc1: Self,
+        transcript: &mut T,
+    ) -> Self {
+        let paired_data = Paired::<'_, C::Scalar>::new_data(pk, &acc0, &acc1);
+
+        let full_constraint = paired_data.full_constraint(pk.cs.gates(), pk.cs.lookups());
+
+        let error_poly = Paired::<'_, C::Scalar>::evaluate_compressed_polynomial(
+            full_constraint,
+            pk.usable_rows.clone(),
+            pk.num_rows,
+        );
+
+        for coef in &error_poly {
+            let _ = transcript.write_scalar(*coef);
+        }
+        let alpha = *transcript.squeeze_challenge_scalar::<C::Scalar>();
+        Self::merge(acc0, acc1, error_poly, alpha)
+    }
+
+    fn merge(acc0: Self, acc1: Self, error_poly: Vec<C::Scalar>, alpha: C::Scalar) -> Self {
+        let instance = instance::Transcript::merge(alpha, acc0.instance, acc1.instance);
+        let advice = advice::Transcript::merge(alpha, acc0.advice, acc1.advice);
+        let lookups = zip(acc0.lookups.into_iter(), acc1.lookups.into_iter())
+            .map(|(lookup0, lookup1)| lookup::Transcript::merge(alpha, lookup0, lookup1))
+            .collect();
+        let beta = compressed_verifier::Transcript::merge(alpha, acc0.beta, acc1.beta);
+
+        let ys = zip(acc0.ys.into_iter(), acc1.ys.into_iter())
+            .map(|(y0, y1)| y0 + alpha * (y1 - y0))
+            .collect();
+
+        let error = eval_polynomial(&error_poly, alpha);
+
+        let error0 = eval_polynomial(&error_poly, C::Scalar::ZERO);
+        let error1 = eval_polynomial(&error_poly, C::Scalar::ONE);
+
+        assert_eq!(error0, acc0.error);
+        assert_eq!(error1, acc1.error);
+
+        Self {
+            instance,
+            advice,
+            lookups,
+            beta,
+            ys,
+            error,
+        }
+    }
+
+    pub fn decide<'params, P: Params<'params, C>>(
+        params: &P,
+        pk: &ProvingKey<C>,
+        acc: &Self,
+    ) -> bool {
+        let committed_iter: Vec<&Committed<C>> = acc
+            .instance
+            .committed
+            .iter()
+            .chain(&acc.advice.committed)
+            .chain([&acc.beta.beta, &acc.beta.beta_shift].into_iter())
+            .chain(
+                acc.lookups
+                    .iter()
+                    .flat_map(|lookup| [&lookup.m, &lookup.g, &lookup.h].into_iter()),
+            )
+            .collect();
+
+        let committed_ok = committed_iter.iter().all(|c| c.decide(params));
+
+        let error_vec = Self::error_vector(pk, acc);
+
+        let error = error_vec
+            .iter()
+            .zip(acc.beta.beta.values.iter())
+            .fold(C::Scalar::ZERO, |acc, (e, b)| acc + (*e * b));
+
+        let error: C::Scalar = error_vec.iter().sum();
+
+        let error_ok = error == acc.error;
+
+        committed_ok && error_ok
+    }
+
+    pub fn error_vector(pk: &ProvingKey<C>, acc: &Self) -> Polynomial<C::Scalar, LagrangeCoeff> {
+        let lagrange_data = Data::<PolynomialRef<'_, C::Scalar, LagrangeCoeff>>::new(&pk, &acc);
+
+        let full_constraint = lagrange_data.full_constraint_no_beta(pk.cs.gates(), pk.cs.lookups());
+
+        let mut error = pk.domain.empty_lagrange();
+        parallelize(&mut error, |value, start| {
+            for (i, v) in value.iter_mut().enumerate() {
+                let row_idx = i + start;
+                *v = full_constraint.evaluate(
+                    &|c| c,
+                    &|challenge| *challenge.value,
+                    &|fixed| fixed.column[fixed.row_idx(row_idx, pk.num_rows)],
+                    &|witness| witness.column[witness.row_idx(row_idx, pk.num_rows)],
+                    &|e| -e,
+                    &|a, b| a + b,
+                    &|a, b| a * b,
+                );
+            }
+        });
+        error
+    }
+}