Remove unnecessary separate msm from commitment::verify_proof.

src/poly/commitment.rs

@@ -322,15 +322,7 @@ fn test_opening_proof() {
 
     let mut commitment_msm = params.empty_msm();
     commitment_msm.append_term(Field::one(), p);
-    let guard = verify_proof(
-        &params,
-        params.empty_msm(),
-        &mut transcript,
-        *x,
-        commitment_msm,
-        v,
-    )
-    .unwrap();
+    let guard = verify_proof(&params, commitment_msm, &mut transcript, *x, v).unwrap();
     let ch_verifier = transcript.squeeze_challenge();
     assert_eq!(ch_prover, ch_verifier);
 

src/poly/commitment/verifier.rs

@@ -66,25 +66,23 @@ impl<'a, C: CurveAffine> Guard<'a, C> {
 
 /// Checks to see if an [`Proof`] is valid given the current `transcript`, and a
 /// point `x` that the polynomial commitment `P` opens purportedly to the value
-/// `v`. The provided `commitment_msm` should evaluate to the commitment `P`
-/// being opened.
+/// `v`. The provided `msm` should evaluate to the commitment `P` being opened.
 pub fn verify_proof<'a, C: CurveAffine, R: Read, T: TranscriptRead<R, C>>(
     params: &'a Params<C>,
     mut msm: MSM<'a, C>,
     transcript: &mut T,
     x: C::Scalar,
-    mut commitment_msm: MSM<'a, C>,
     v: C::Scalar,
 ) -> Result<Guard<'a, C>, Error> {
     let k = params.k as usize;
 
     //     P - [v] G_0 + S * iota
     //   + \sum(L_i * u_i^2) + \sum(R_i * u_i^-2)
-    commitment_msm.add_constant_term(-v);
+    msm.add_constant_term(-v);
     let s_poly_commitment = transcript.read_point().map_err(|_| Error::OpeningError)?;
 
     let iota = *ChallengeScalar::<C, ()>::get(transcript);
-    commitment_msm.append_term(iota, s_poly_commitment);
+    msm.append_term(iota, s_poly_commitment);
 
     let z = *ChallengeScalar::<C, ()>::get(transcript);
 
@@ -121,8 +119,8 @@ pub fn verify_proof<'a, C: CurveAffine, R: Read, T: TranscriptRead<R, C>>(
 
         let challenge_sq_inv = challenge_inv.square();
 
-        commitment_msm.append_term(challenge_sq, l);
-        commitment_msm.append_term(challenge_sq_inv, r);
+        msm.append_term(challenge_sq, l);
+        msm.append_term(challenge_sq_inv, r);
 
         challenges.push(challenge);
         challenges_inv.push(challenge_inv);
@@ -131,7 +129,7 @@ pub fn verify_proof<'a, C: CurveAffine, R: Read, T: TranscriptRead<R, C>>(
     }
 
     // Our goal is to open
-    //     commitment_msm - [v] G_0 + random_poly_commitment * iota
+    //     msm - [v] G_0 + random_poly_commitment * iota
     //   + \sum(L_i * u_i^2) + \sum(R_i * u_i^-2)
     // at x to 0, by asking the prover to supply (a, h) such that it equals
     //   = [a] (G + [b * z] U) + [h] H
@@ -148,10 +146,8 @@ pub fn verify_proof<'a, C: CurveAffine, R: Read, T: TranscriptRead<R, C>>(
     let h = transcript.read_scalar().map_err(|_| Error::SamplingError)?;
     let b = compute_b(x, &challenges, &challenges_inv);
 
-    commitment_msm.add_to_u_scalar(neg_a * &b * &z);
-    commitment_msm.add_to_h_scalar(a - &h);
-
-    msm.add_msm(&commitment_msm);
+    msm.add_to_u_scalar(neg_a * &b * &z);
+    msm.add_to_h_scalar(a - &h);
 
     let guard = Guard {
         msm,

src/poly/multiopen/verifier.rs

@@ -110,19 +110,18 @@ where
     let x_4 = ChallengeX4::get(transcript);
 
     // Compute the final commitment that has to be opened
-    let mut commitment_msm = params.empty_msm();
-    commitment_msm.append_term(C::Scalar::one(), f_commitment);
-    let (commitment_msm, msm_eval) = q_commitments.into_iter().zip(q_evals.iter()).fold(
-        (commitment_msm, msm_eval),
-        |(mut commitment_msm, msm_eval), (q_commitment, q_eval)| {
-            commitment_msm.scale(*x_4);
-            commitment_msm.add_msm(&q_commitment);
-            (commitment_msm, msm_eval * &x_4 + q_eval)
+    msm.append_term(C::Scalar::one(), f_commitment);
+    let (msm, msm_eval) = q_commitments.into_iter().zip(q_evals.iter()).fold(
+        (msm, msm_eval),
+        |(mut msm, msm_eval), (q_commitment, q_eval)| {
+            msm.scale(*x_4);
+            msm.add_msm(&q_commitment);
+            (msm, msm_eval * &x_4 + q_eval)
         },
     );
 
     // Verify the opening proof
-    super::commitment::verify_proof(params, msm, transcript, *x_3, commitment_msm, msm_eval)
+    super::commitment::verify_proof(params, msm, transcript, *x_3, msm_eval)
 }
 
 #[doc(hidden)]