Disable ZK in large_config (#180)

* Disable ZK in large_config

Speeds up the tests from ~6m to ~1m (debug mode). `large_config` is crate-private so I don't think we need to worry about real users forgetting ZK, and I don't think ZK seems important in these tests, though we should probably have ZK enabled for a couple tests.

A couple tests need ZK or they fail; I added a TODO to look later.

This led to a few other changes:
- Fixed a bug where `trim` could truncate the final poly to a non-power-of-two length. This was improbable when ZK is on due to randomization.
- Gave a few methods access to the whole `CircuitConfig` vs `FriConfig` -- sort of necessary for the above fix, and I don't think there's much downside.
- Remove `cap_height` from `FriConfig` -- didn't really need it any more after giving more methods access to `CircuitConfig`, and having a single copy of the param feels cleaner/safer to me.

* PR feedback

src/bin/bench_recursion.rs

@@ -32,7 +32,6 @@ fn bench_prove<F: Field + Extendable<D>, const D: usize>() -> Result<()> {
             proof_of_work_bits: 20,
             reduction_arity_bits: vec![2, 2, 2, 2, 2, 2],
             num_query_rounds: 35,
-            cap_height: 1,
         },
     };
 

src/fri/commitment.rs

@@ -205,7 +205,7 @@ impl<F: Field> PolynomialBatchCommitment<F> {
             lde_final_poly,
             lde_final_values,
             challenger,
-            &config.fri_config,
+            &config,
             timing,
         );
 
@@ -281,8 +281,8 @@ mod tests {
             proof_of_work_bits: 2,
             reduction_arity_bits: vec![2, 3, 1, 2],
             num_query_rounds: 3,
-            cap_height: 1,
         };
+
         // We only care about `fri_config, num_constants`, and `num_routed_wires` here.
         let common_data = CommonCircuitData {
             config: CircuitConfig {
@@ -300,12 +300,12 @@ mod tests {
             circuit_digest: HashOut::from_partial(vec![]),
         };
 
-        let lpcs = (0..4)
+        let commitments = (0..4)
             .map(|i| {
                 PolynomialBatchCommitment::<F>::from_values(
                     gen_random_test_case(ks[i], degree_bits),
                     common_data.config.rate_bits,
-                    PlonkPolynomials::polynomials(i).blinding,
+                    common_data.config.zero_knowledge && PlonkPolynomials::polynomials(i).blinding,
                     common_data.config.cap_height,
                     &mut TimingTree::default(),
                 )
@@ -314,7 +314,12 @@ mod tests {
 
         let zeta = gen_random_point::<F, D>(degree_bits);
         let (proof, os) = PolynomialBatchCommitment::open_plonk::<D>(
-            &[&lpcs[0], &lpcs[1], &lpcs[2], &lpcs[3]],
+            &[
+                &commitments[0],
+                &commitments[1],
+                &commitments[2],
+                &commitments[3],
+            ],
             zeta,
             &mut Challenger::new(),
             &common_data,
@@ -322,10 +327,10 @@ mod tests {
         );
 
         let merkle_caps = &[
-            lpcs[0].merkle_tree.cap.clone(),
-            lpcs[1].merkle_tree.cap.clone(),
-            lpcs[2].merkle_tree.cap.clone(),
-            lpcs[3].merkle_tree.cap.clone(),
+            commitments[0].merkle_tree.cap.clone(),
+            commitments[1].merkle_tree.cap.clone(),
+            commitments[2].merkle_tree.cap.clone(),
+            commitments[3].merkle_tree.cap.clone(),
         ];
 
         verify_fri_proof(

src/fri/mod.rs

@@ -16,6 +16,4 @@ pub struct FriConfig {
 
     /// Number of query rounds to perform.
     pub num_query_rounds: usize,
-
-    pub cap_height: usize,
 }

src/fri/prover.rs

@@ -8,6 +8,7 @@ use crate::hash::hash_types::HashOut;
 use crate::hash::hashing::hash_n_to_1;
 use crate::hash::merkle_tree::MerkleTree;
 use crate::iop::challenger::Challenger;
+use crate::plonk::circuit_data::CircuitConfig;
 use crate::plonk::plonk_common::reduce_with_powers;
 use crate::polynomial::polynomial::{PolynomialCoeffs, PolynomialValues};
 use crate::timed;
@@ -22,7 +23,7 @@ pub fn fri_proof<F: Field + Extendable<D>, const D: usize>(
     // Evaluation of the polynomial on the large domain.
     lde_polynomial_values: PolynomialValues<F::Extension>,
     challenger: &mut Challenger<F>,
-    config: &FriConfig,
+    config: &CircuitConfig,
     timing: &mut TimingTree,
 ) -> FriProof<F, D> {
     let n = lde_polynomial_values.values.len();
@@ -45,12 +46,17 @@ pub fn fri_proof<F: Field + Extendable<D>, const D: usize>(
     let pow_witness = timed!(
         timing,
         "find for proof-of-work witness",
-        fri_proof_of_work(current_hash, config)
+        fri_proof_of_work(current_hash, &config.fri_config)
     );
 
     // Query phase
-    let query_round_proofs =
-        fri_prover_query_rounds(initial_merkle_trees, &trees, challenger, n, config);
+    let query_round_proofs = fri_prover_query_rounds(
+        initial_merkle_trees,
+        &trees,
+        challenger,
+        n,
+        &config.fri_config,
+    );
 
     FriProof {
         commit_phase_merkle_caps: trees.iter().map(|t| t.cap.clone()).collect(),
@@ -64,14 +70,14 @@ fn fri_committed_trees<F: Field + Extendable<D>, const D: usize>(
     mut coeffs: PolynomialCoeffs<F::Extension>,
     mut values: PolynomialValues<F::Extension>,
     challenger: &mut Challenger<F>,
-    config: &FriConfig,
+    config: &CircuitConfig,
 ) -> (Vec<MerkleTree<F>>, PolynomialCoeffs<F::Extension>) {
     let mut trees = Vec::new();
 
     let mut shift = F::MULTIPLICATIVE_GROUP_GENERATOR;
-    let num_reductions = config.reduction_arity_bits.len();
+    let num_reductions = config.fri_config.reduction_arity_bits.len();
     for i in 0..num_reductions {
-        let arity = 1 << config.reduction_arity_bits[i];
+        let arity = 1 << config.fri_config.reduction_arity_bits[i];
 
         reverse_index_bits_in_place(&mut values.values);
         let chunked_values = values
@@ -97,7 +103,9 @@ fn fri_committed_trees<F: Field + Extendable<D>, const D: usize>(
         values = coeffs.coset_fft(shift.into())
     }
 
-    coeffs.trim();
+    /// The coefficients being removed here should always be zero.
+    coeffs.coeffs.truncate(coeffs.len() >> config.rate_bits);
+
     challenger.observe_extension_elements(&coeffs.coeffs);
     (trees, coeffs)
 }

src/fri/recursive_verifier.rs

@@ -291,15 +291,13 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
         round_proof: &FriQueryRoundTarget<D>,
         common_data: &CommonCircuitData<F, D>,
     ) {
-        let config = &common_data.config.fri_config;
+        let config = &common_data.config;
         let n_log = log2_strict(n);
         // TODO: Do we need to range check `x_index` to a target smaller than `p`?
         let x_index = challenger.get_challenge(self);
         let mut x_index_bits = self.low_bits(x_index, n_log, 64);
-        let cap_index = self.le_sum(
-            x_index_bits[x_index_bits.len() - common_data.config.fri_config.cap_height..]
-                .into_iter(),
-        );
+        let cap_index = self
+            .le_sum(x_index_bits[x_index_bits.len() - common_data.config.cap_height..].into_iter());
         with_context!(
             self,
             "check FRI initial proof",
@@ -349,7 +347,7 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
             )
         );
 
-        for (i, &arity_bits) in config.reduction_arity_bits.iter().enumerate() {
+        for (i, &arity_bits) in config.fri_config.reduction_arity_bits.iter().enumerate() {
             let evals = &round_proof.steps[i].evals;
 
             // Split x_index into the index of the coset x is in, and the index of x within that coset.

src/gadgets/arithmetic_extension.rs

@@ -712,7 +712,7 @@ mod tests {
         type FF = QuarticCrandallField;
         const D: usize = 4;
 
-        let config = CircuitConfig::large_config();
+        let config = CircuitConfig::large_zk_config();
 
         let pw = PartialWitness::new(config.num_wires);
         let mut builder = CircuitBuilder::<F, D>::new(config);

src/gadgets/interpolation.rs

@@ -113,7 +113,7 @@ mod tests {
     fn test_interpolate2() -> Result<()> {
         type F = CrandallField;
         type FF = QuarticCrandallField;
-        let config = CircuitConfig::large_config();
+        let config = CircuitConfig::large_zk_config();
         let pw = PartialWitness::new(config.num_wires);
         let mut builder = CircuitBuilder::<F, 4>::new(config);
 

src/plonk/circuit_data.rs

@@ -48,7 +48,6 @@ impl Default for CircuitConfig {
                 proof_of_work_bits: 1,
                 reduction_arity_bits: vec![1, 1, 1, 1],
                 num_query_rounds: 1,
-                cap_height: 1,
             },
         }
     }
@@ -66,14 +65,25 @@ impl CircuitConfig {
             security_bits: 128,
             rate_bits: 3,
             num_challenges: 3,
-            zero_knowledge: true,
+            zero_knowledge: false,
             cap_height: 1,
+            fri_config: FriConfig {
+                proof_of_work_bits: 1,
+                reduction_arity_bits: vec![1],
+                num_query_rounds: 1,
+            },
+        }
+    }
+
+    pub(crate) fn large_zk_config() -> Self {
+        CircuitConfig {
+            zero_knowledge: true,
             fri_config: FriConfig {
                 proof_of_work_bits: 1,
                 reduction_arity_bits: vec![1, 1, 1, 1],
                 num_query_rounds: 1,
-                cap_height: 1,
             },
+            ..Self::large_config()
         }
     }
 }

src/plonk/recursive_verifier.rs

@@ -375,7 +375,6 @@ mod tests {
                 proof_of_work_bits: 1,
                 reduction_arity_bits: vec![2, 2, 2, 2, 2, 2],
                 num_query_rounds: 40,
-                cap_height: 1,
             },
         };
         let (proof_with_pis, vd, cd) = {
@@ -431,7 +430,6 @@ mod tests {
                 proof_of_work_bits: 1,
                 reduction_arity_bits: vec![2, 2, 2, 2, 2, 2],
                 num_query_rounds: 40,
-                cap_height: 3,
             },
         };
         let (proof_with_pis, vd, cd) = {

src/util/mod.rs

@@ -26,7 +26,7 @@ pub(crate) fn log2_ceil(n: usize) -> usize {
 
 /// Computes `log_2(n)`, panicking if `n` is not a power of two.
 pub(crate) fn log2_strict(n: usize) -> usize {
-    assert!(n.is_power_of_two(), "Not a power of two");
+    assert!(n.is_power_of_two(), "Not a power of two: {}", n);
     log2_ceil(n)
 }