Making sumcheck work with challenges (#102)

Fixes sumcheck relations so the full relation is now correct
---------

Co-authored-by: Rumata888 <[email protected]>
Co-authored-by: ledwards2225 <[email protected]>

barretenberg/cpp/src/aztec/honk/proof_system/prover.cpp

@@ -295,7 +295,7 @@ template <typename settings> void Prover<settings>::execute_relation_check_round
     using Sumcheck = sumcheck::Sumcheck<Multivariates,
                                         Transcript,
                                         sumcheck::ArithmeticRelation,
-                                        // sumcheck::GrandProductComputationRelation,
+                                        sumcheck::GrandProductComputationRelation,
                                         sumcheck::GrandProductInitializationRelation>;
 
     // Compute alpha challenge

barretenberg/cpp/src/aztec/honk/proof_system/verifier.cpp

@@ -135,7 +135,7 @@ template <typename program_settings> bool Verifier<program_settings>::verify_pro
     auto sumcheck = Sumcheck<Multivariates,
                              Transcript,
                              ArithmeticRelation,
-                             //  GrandProductComputationRelation,
+                             GrandProductComputationRelation,
                              GrandProductInitializationRelation>(transcript);
     bool sumcheck_result = sumcheck.execute_verifier();
 

barretenberg/cpp/src/aztec/honk/sumcheck/relations/arithmetic_relation.hpp

@@ -27,8 +27,11 @@ template <typename FF> class ArithmeticRelation : public Relation<FF> {
      *
      * @param extended_edges Contain inputs for the relation
      * @param evals Contains the resulting univariate polynomial
+     *
+     * The final parameter is left to conform to the general argument structure (input,output, challenges) even though
+     * we don't need challenges in this relation.
      */
-    void add_edge_contribution(auto& extended_edges, Univariate<FF, RELATION_LENGTH>& evals)
+    template <typename T> void add_edge_contribution(auto& extended_edges, Univariate<FF, RELATION_LENGTH>& evals, T)
     {
         add_edge_contribution_internal(extended_edges, evals);
     };
@@ -70,7 +73,8 @@ template <typename FF> class ArithmeticRelation : public Relation<FF> {
         evals += q_c;
     };
 
-    void add_full_relation_value_contribution(auto& purported_evaluations, FF& full_honk_relation_value)
+    template <typename T>
+    void add_full_relation_value_contribution(auto& purported_evaluations, FF& full_honk_relation_value, T)
     {
         auto w_l = purported_evaluations[MULTIVARIATE::W_L];
         auto w_r = purported_evaluations[MULTIVARIATE::W_R];

barretenberg/cpp/src/aztec/honk/sumcheck/relations/grand_product_computation_relation.hpp

@@ -12,19 +12,20 @@ template <typename FF> class GrandProductComputationRelation : public Relation<F
     using MULTIVARIATE = StandardHonk::MULTIVARIATE;
 
   public:
-    // TODO(luke): make these real challenges once manifest is done
-    const FF beta_default = FF::one();
-    const FF gamma_default = FF::one();
-    const FF public_input_delta_default = FF::one();
-
     GrandProductComputationRelation() = default;
     explicit GrandProductComputationRelation(auto){}; // TODO(luke): should just be default?
     /**
      * @brief Add contribution of the permutation relation for a given edge (used by sumcheck round)
      */
-    void add_edge_contribution(auto& extended_edges, Univariate<FF, RELATION_LENGTH>& evals)
+    void add_edge_contribution(auto& extended_edges,
+                               Univariate<FF, RELATION_LENGTH>& evals,
+                               const RelationParameters<FF>& relation_parameters)
     {
-        add_edge_contribution_internal(extended_edges, evals, beta_default, gamma_default, public_input_delta_default);
+        add_edge_contribution_internal(extended_edges,
+                                       evals,
+                                       relation_parameters.beta,
+                                       relation_parameters.gamma,
+                                       relation_parameters.public_input_delta);
     };
 
     /**
@@ -53,8 +54,11 @@ template <typename FF> class GrandProductComputationRelation : public Relation<F
      *      delta is the public input correction term
      *
      */
-    inline void add_edge_contribution_internal(
-        auto& extended_edges, Univariate<FF, RELATION_LENGTH>& evals, FF beta, FF gamma, FF public_input_delta)
+    inline void add_edge_contribution_internal(auto& extended_edges,
+                                               Univariate<FF, RELATION_LENGTH>& evals,
+                                               const FF& beta,
+                                               const FF& gamma,
+                                               const FF& public_input_delta)
     {
         auto w_1 = UnivariateView<FF, RELATION_LENGTH>(extended_edges[MULTIVARIATE::W_L]);
         auto w_2 = UnivariateView<FF, RELATION_LENGTH>(extended_edges[MULTIVARIATE::W_R]);
@@ -77,7 +81,9 @@ template <typename FF> class GrandProductComputationRelation : public Relation<F
                   (w_2 + sigma_2 * beta + gamma) * (w_3 + sigma_3 * beta + gamma));
     };
 
-    void add_full_relation_value_contribution(auto& purported_evaluations, FF& full_honk_relation_value)
+    void add_full_relation_value_contribution(auto& purported_evaluations,
+                                              FF& full_honk_relation_value,
+                                              const RelationParameters<FF>& relation_parameters)
     {
         auto w_1 = purported_evaluations[MULTIVARIATE::W_L];
         auto w_2 = purported_evaluations[MULTIVARIATE::W_R];
@@ -86,20 +92,22 @@ template <typename FF> class GrandProductComputationRelation : public Relation<F
         auto sigma_2 = purported_evaluations[MULTIVARIATE::SIGMA_2];
         auto sigma_3 = purported_evaluations[MULTIVARIATE::SIGMA_3];
         auto id_1 = purported_evaluations[MULTIVARIATE::ID_1];
-        auto id_2 = purported_evaluations[MULTIVARIATE::ID_1];
-        auto id_3 = purported_evaluations[MULTIVARIATE::ID_1];
+        auto id_2 = purported_evaluations[MULTIVARIATE::ID_2];
+        auto id_3 = purported_evaluations[MULTIVARIATE::ID_3];
         auto z_perm = purported_evaluations[MULTIVARIATE::Z_PERM];
         auto z_perm_shift = purported_evaluations[MULTIVARIATE::Z_PERM_SHIFT];
         auto lagrange_first = purported_evaluations[MULTIVARIATE::LAGRANGE_FIRST];
         auto lagrange_last = purported_evaluations[MULTIVARIATE::LAGRANGE_LAST];
 
         // Contribution (1)
-        full_honk_relation_value +=
-            (z_perm + lagrange_first) * (w_1 + beta_default * id_1 + gamma_default) *
-                (w_2 + beta_default * id_2 + gamma_default) * (w_3 + beta_default * id_3 + gamma_default) -
-            (z_perm_shift + lagrange_last * public_input_delta_default) *
-                (w_1 + beta_default * sigma_1 + gamma_default) * (w_2 + beta_default * sigma_2 + gamma_default) *
-                (w_3 + beta_default * sigma_3 + gamma_default);
+        full_honk_relation_value += (z_perm + lagrange_first) *
+                                        (w_1 + relation_parameters.beta * id_1 + relation_parameters.gamma) *
+                                        (w_2 + relation_parameters.beta * id_2 + relation_parameters.gamma) *
+                                        (w_3 + relation_parameters.beta * id_3 + relation_parameters.gamma) -
+                                    (z_perm_shift + lagrange_last * relation_parameters.public_input_delta) *
+                                        (w_1 + relation_parameters.beta * sigma_1 + relation_parameters.gamma) *
+                                        (w_2 + relation_parameters.beta * sigma_2 + relation_parameters.gamma) *
+                                        (w_3 + relation_parameters.beta * sigma_3 + relation_parameters.gamma);
     };
 };
 } // namespace honk::sumcheck

barretenberg/cpp/src/aztec/honk/sumcheck/relations/grand_product_initialization_relation.hpp

@@ -21,8 +21,13 @@ template <typename FF> class GrandProductInitializationRelation : public Relatio
      * This file handles the relation Z_perm_shift(n_last) = 0 via the relation:
      *
      *                      C(X) = L_LAST(X) * Z_perm_shift(X)
+     *
+     *
+     * The final parameter is left to conform to the general argument structure (input,output, challenges) even though
+     * we don't need challenges in this relation.
+     *
      */
-    void add_edge_contribution(auto& extended_edges, Univariate<FF, RELATION_LENGTH>& evals)
+    template <typename T> void add_edge_contribution(auto& extended_edges, Univariate<FF, RELATION_LENGTH>& evals, T)
     {
         add_edge_contribution_internal(extended_edges, evals);
     };
@@ -55,7 +60,8 @@ template <typename FF> class GrandProductInitializationRelation : public Relatio
         add_edge_contribution_internal(extended_edges, evals);
     }
 
-    void add_full_relation_value_contribution(auto& purported_evaluations, FF& full_honk_relation_value)
+    template <typename T>
+    void add_full_relation_value_contribution(auto& purported_evaluations, FF& full_honk_relation_value, T)
     {
         auto z_perm_shift = purported_evaluations[MULTIVARIATE::Z_PERM_SHIFT];
         auto lagrange_last = purported_evaluations[MULTIVARIATE::LAGRANGE_LAST];

barretenberg/cpp/src/aztec/honk/sumcheck/relations/relation.hpp

@@ -4,4 +4,10 @@ namespace honk::sumcheck {
 
 template <typename Fr> class Relation {}; // TODO(Cody): Use or eventually remove.
 
+template <typename FF> struct RelationParameters {
+    FF alpha;
+    FF beta;
+    FF gamma;
+    FF public_input_delta;
+};
 } // namespace honk::sumcheck

barretenberg/cpp/src/aztec/honk/sumcheck/relations/relation.test.cpp

@@ -83,7 +83,7 @@ TYPED_TEST(SumcheckRelation, ArithmeticRelation)
     Univariate expected_evals = (q_m * w_r * w_l) + (q_r * w_r) + (q_l * w_l) + (q_o * w_o) + (q_c);
 
     auto evals = Univariate<FF, relation.RELATION_LENGTH>();
-    relation.add_edge_contribution(extended_edges, evals);
+    relation.add_edge_contribution(extended_edges, evals, 0);
 
     EXPECT_EQ(evals, expected_evals);
 };
@@ -120,9 +120,12 @@ TYPED_TEST(SumcheckRelation, GrandProductComputationRelation)
     auto lagrange_first = UnivariateView(extended_edges[MULTIVARIATE::LAGRANGE_FIRST]);
     auto lagrange_last = UnivariateView(extended_edges[MULTIVARIATE::LAGRANGE_LAST]);
     // TODO(luke): use real transcript/challenges once manifest is done
-    FF beta = FF::one();
-    FF gamma = FF::one();
-    FF public_input_delta = FF::one();
+    FF beta = FF::random_element();
+    FF gamma = FF::random_element();
+    FF public_input_delta = FF::random_element();
+    const RelationParameters<FF> relation_parameters = RelationParameters<FF>{
+        .alpha = FF ::zero(), .beta = beta, .gamma = gamma, .public_input_delta = public_input_delta
+    };
 
     auto expected_evals = Univariate();
     // expected_evals in the below step { { 27, 250, 1029, 2916, 6655 } }
@@ -133,7 +136,7 @@ TYPED_TEST(SumcheckRelation, GrandProductComputationRelation)
                       (w_2 + sigma_2 * beta + gamma) * (w_3 + sigma_3 * beta + gamma);
 
     auto evals = Univariate();
-    relation.add_edge_contribution(extended_edges, evals);
+    relation.add_edge_contribution(extended_edges, evals, relation_parameters);
 
     EXPECT_EQ(evals, expected_evals);
 };
@@ -157,7 +160,7 @@ TYPED_TEST(SumcheckRelation, GrandProductInitializationRelation)
 
     // Compute the edge contribution using add_edge_contribution
     auto evals = Univariate();
-    relation.add_edge_contribution(extended_edges, evals);
+    relation.add_edge_contribution(extended_edges, evals, 0);
 
     EXPECT_EQ(evals, expected_evals);
 };

barretenberg/cpp/src/aztec/honk/sumcheck/sumcheck.hpp

@@ -1,6 +1,7 @@
 #pragma once
 #include "common/serialize.hpp"
 #include "proof_system/types/polynomial_manifest.hpp"
+#include <honk/utils/public_inputs.hpp>
 #include "common/throw_or_abort.hpp"
 #include "ecc/curves/bn254/fr.hpp"
 #include "sumcheck_round.hpp"
@@ -35,6 +36,34 @@ template <class Multivariates, class Transcript, template <class> class... Relat
         , transcript(transcript)
         , round(std::tuple(Relations<FF>()...)){};
 
+    /**
+     * @brief Get all the challenges and computed parameters used in sumcheck in a convenient format
+     *
+     * @return RelationParameters<FF>
+     */
+    RelationParameters<FF> retrieve_proof_parameters()
+    {
+        const FF alpha = FF::serialize_from_buffer(transcript.get_challenge("alpha").begin());
+        const FF beta = FF::serialize_from_buffer(transcript.get_challenge("beta").begin());
+        const FF gamma = FF::serialize_from_buffer(transcript.get_challenge("beta", 1).begin());
+        const auto public_input_size_vector = transcript.get_element("public_input_size");
+        const size_t public_input_size = (static_cast<size_t>(public_input_size_vector[0]) << 24) |
+                                         (static_cast<size_t>(public_input_size_vector[1]) << 16) |
+                                         (static_cast<size_t>(public_input_size_vector[2]) << 8) |
+
+                                         static_cast<size_t>(public_input_size_vector[3]);
+        const auto circut_size_vector = transcript.get_element("circuit_size");
+        const size_t n = (static_cast<size_t>(circut_size_vector[0]) << 24) |
+                         (static_cast<size_t>(circut_size_vector[1]) << 16) |
+                         (static_cast<size_t>(circut_size_vector[2]) << 8) | static_cast<size_t>(circut_size_vector[3]);
+        std::vector<FF> public_inputs = many_from_buffer<FF>(transcript.get_element("public_inputs"));
+        ASSERT(public_inputs.size() == public_input_size);
+        FF public_input_delta = honk::compute_public_input_delta<FF>(public_inputs, beta, gamma, n);
+        const RelationParameters<FF> relation_parameters = RelationParameters<FF>{
+            .alpha = alpha, .beta = beta, .gamma = gamma, .public_input_delta = public_input_delta
+        };
+        return relation_parameters;
+    }
     /**
      * @brief Compute univariate restriction place in transcript, generate challenge, fold,... repeat until final round,
      * then compute multivariate evaluations and place in transcript.
@@ -45,8 +74,9 @@ template <class Multivariates, class Transcript, template <class> class... Relat
     {
         // First round
         // This populates multivariates.folded_polynomials.
-        FF alpha = FF::serialize_from_buffer(transcript.get_challenge("alpha").begin());
-        auto round_univariate = round.compute_univariate(multivariates.full_polynomials, alpha);
+
+        const auto relation_parameters = retrieve_proof_parameters();
+        auto round_univariate = round.compute_univariate(multivariates.full_polynomials, relation_parameters);
         transcript.add_element("univariate_" + std::to_string(multivariates.multivariate_d),
                                round_univariate.to_buffer());
         std::string challenge_label = "u_" + std::to_string(multivariates.multivariate_d);
@@ -59,7 +89,7 @@ template <class Multivariates, class Transcript, template <class> class... Relat
         // We operate on multivariates.folded_polynomials in place.
         for (size_t round_idx = 1; round_idx < multivariates.multivariate_d; round_idx++) {
             // Write the round univariate to the transcript
-            round_univariate = round.compute_univariate(multivariates.folded_polynomials, alpha);
+            round_univariate = round.compute_univariate(multivariates.folded_polynomials, relation_parameters);
             transcript.add_element("univariate_" + std::to_string(multivariates.multivariate_d - round_idx),
                                    round_univariate.to_buffer());
             challenge_label = "u_" + std::to_string(multivariates.multivariate_d - round_idx);
@@ -102,6 +132,7 @@ template <class Multivariates, class Transcript, template <class> class... Relat
     {
         bool verified(true);
 
+        const auto relation_parameters = retrieve_proof_parameters();
         // All but final round.
         // target_total_sum is initialized to zero then mutated in place.
 
@@ -127,9 +158,8 @@ template <class Multivariates, class Transcript, template <class> class... Relat
 
         // Final round
         auto purported_evaluations = transcript.get_field_element_vector("multivariate_evaluations");
-        FF alpha = FF::serialize_from_buffer(transcript.get_challenge("alpha").begin());
         FF full_honk_relation_purported_value =
-            round.compute_full_honk_relation_purported_value(purported_evaluations, alpha);
+            round.compute_full_honk_relation_purported_value(purported_evaluations, relation_parameters);
         verified = verified && (full_honk_relation_purported_value == round.target_total_sum);
         return verified;
     };