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Author: LindaGuiga

recursion/src/recursive_challenger.rs

@@ -35,7 +35,9 @@ pub trait RecursiveChallenger<F: Field> {
         (0..count).map(|_| self.sample(circuit)).collect()
     }
 
-    fn sample_bits(
+    /// Samples a challenge from the current challenger state and decomposes it into `total_num_bits` (public input) bits.
+    /// Returns the first `num_bits` bits.
+    fn sample_public_bits(
         &mut self,
         circuit: &mut CircuitBuilder<F>,
         total_num_bits: usize,
@@ -49,16 +51,16 @@ pub trait RecursiveChallenger<F: Field> {
         bits[..num_bits].to_vec()
     }
 
+    /// Checks a PoW witness.
     fn check_witness(
         &mut self,
         circuit: &mut CircuitBuilder<F>,
         witness_bits: usize,
         witness: Target,
         total_num_bits: usize,
     ) {
-        // TODO: Replace `sample_bits` with a specific method that only gets returns the final bits: the first ones are all 0.
         self.observe(circuit, witness);
-        let bits = self.sample_bits(circuit, total_num_bits, witness_bits);
+        let bits = self.sample_public_bits(circuit, total_num_bits, witness_bits);
         for bit in bits {
             circuit.assert_zero(bit);
         }

recursion/src/recursive_generation.rs

@@ -250,7 +250,7 @@ where
         // Check PoW witness.
         challenger.observe(opening_proof.pow_witness);
 
-        // Sample bits, and add the nonzero bits to the challenges.
+        // Sample a challenge and decompose it into bits. Add the nonzero bits to the challenges.
         let rand_f: Val<SC> = challenger.sample();
         let rand_usize = rand_f.as_canonical_biguint().to_u64_digits()[0] as usize;
         // Get the bits. The total number of bits is the number of bits in a base field element.

recursion/src/recursive_pcs.rs

@@ -638,7 +638,7 @@ where
         // Observe final polynomial coefficients
         challenger.observe_slice(circuit, &fri_proof.final_poly);
 
-        // TODO: Use sample_bits and check that the output is 0.
+        // Check PoW witness.
         challenger.check_witness(
             circuit,
             params.pow_bits,

recursion/tests/fri.rs

@@ -464,22 +464,16 @@ fn run_fri_test(setup: FriSetup, build_only: bool) {
     builder.pop_scope();
 
     // 4) Wire the arithmetic-only FRI verifier
-    let verif_res =
-        verify_fri_circuit::<F, Challenge, RecExt, RecVal, RecWitness<F>, p3_recursion::Target>(
-            &mut builder,
-            &fri_targets,
-            alpha_t,
-            &betas_t,
-            &index_bits_t_per_query,
-            &commitments_with_opening_points_targets,
-            log_blowup,
-        );
-
-    assert!(
-        verif_res.is_ok(),
-        "FRI verification failed: {:?}",
-        verif_res
-    );
+    verify_fri_circuit::<F, Challenge, RecExt, RecVal, RecWitness<F>, p3_recursion::Target>(
+        &mut builder,
+        &fri_targets,
+        alpha_t,
+        &betas_t,
+        &index_bits_t_per_query,
+        &commitments_with_opening_points_targets,
+        log_blowup,
+    )
+    .unwrap();
 
     builder.dump_allocation_log();
     let circuit = builder.build().unwrap();