update zero evaluation and comments

AztecProtocol · Sep 5, 2023 · 05e872f · 05e872f
1 parent 9abfd42
commit 05e872f
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Showing 2 changed files with 3 additions and 12 deletions.
diff --git a/circuits/cpp/barretenberg/cpp/src/barretenberg/honk/pcs/kzg/kzg.hpp b/circuits/cpp/barretenberg/cpp/src/barretenberg/honk/pcs/kzg/kzg.hpp
@@ -89,13 +89,8 @@ template <typename Curve, bool goblin_flag = false> class KZG {
             std::vector<GroupElement> commitments = { claim.commitment, quotient_commitment };
             std::vector<Fr> scalars = { one, claim.opening_pair.challenge };
             P_0 = GroupElement::template batch_mul<goblin_flag>(commitments, scalars);
-            // WORKTODO(luke): The evaluation is always zero due to the nature of shplonk. What is the proper way to
-            // handle this? Contraints to show scalar (evaluation) is zero? Or simply dont add anything and ensure this
-            // function is only used in the current context? 
-            // if (!claim.opening_pair.evaluation.get_value().is_zero()) {
-            //     auto ctx = verifier_transcript.builder;
-            //     lhs -= GroupElement::one(ctx) * claim.opening_pair.evaluation;
-            // }
+            // Note: This implementation assumes the evaluation is zero (as is the case for shplonk).
+            ASSERT(claim.opening_pair.evaluation.get_value() == 0);
         } else {
             P_0 = claim.commitment;
             P_0 += quotient_commitment * claim.opening_pair.challenge;

diff --git a/circuits/cpp/barretenberg/cpp/src/barretenberg/honk/pcs/shplonk/shplonk.hpp b/circuits/cpp/barretenberg/cpp/src/barretenberg/honk/pcs/shplonk/shplonk.hpp
@@ -173,7 +173,6 @@ template <typename Curve, bool goblin_flag = false> class ShplonkVerifier_ {
         auto Q_commitment = transcript.template receive_from_prover<Commitment>("Shplonk:Q");
 
         const Fr z_challenge = transcript.get_challenge("Shplonk:z");
-        Fr evaluation_zero; // 0 \in Fr
 
         // [G] = [Q] - ∑ⱼ ρʲ / ( r − xⱼ )⋅[fⱼ] + G₀⋅[1]
         //     = [Q] - [∑ⱼ ρʲ ⋅ ( fⱼ(X) − vⱼ) / ( r − xⱼ )]
@@ -192,7 +191,6 @@ template <typename Curve, bool goblin_flag = false> class ShplonkVerifier_ {
         // using a builder Simulator.
         if constexpr (Curve::is_stdlib_type) {
             auto builder = nu.get_context();
-            evaluation_zero = Fr(builder, 0);
 
             // Containers for the inputs to the final batch mul
             std::vector<Commitment> commitments;
@@ -236,8 +234,6 @@ template <typename Curve, bool goblin_flag = false> class ShplonkVerifier_ {
             G_commitment = GroupElement::template batch_mul<goblin_flag>(commitments, scalars);
 
         } else {
-            evaluation_zero = Fr(0);
-
             // [G] = [Q] - ∑ⱼ ρʲ / ( r − xⱼ )⋅[fⱼ] + G₀⋅[1]
             //     = [Q] - [∑ⱼ ρʲ ⋅ ( fⱼ(X) − vⱼ) / ( r − xⱼ )]
             G_commitment = Q_commitment;
@@ -272,7 +268,7 @@ template <typename Curve, bool goblin_flag = false> class ShplonkVerifier_ {
         }
 
         // Return opening pair (z, 0) and commitment [G]
-        return { { z_challenge, evaluation_zero }, G_commitment };
+        return { { z_challenge, Fr(0) }, G_commitment };
     };
 };
 } // namespace proof_system::honk::pcs::shplonk