goblin_recursive_verifier.test.cpp

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#include "barretenberg/stdlib/goblin_verifier/goblin_recursive_verifier.hpp"
#include "barretenberg/circuit_checker/circuit_checker.hpp"
#include "barretenberg/common/assert.hpp"
#include "barretenberg/common/test.hpp"
#include "barretenberg/goblin/goblin.hpp"
#include "barretenberg/goblin/mock_circuits.hpp"
#include "barretenberg/srs/global_crs.hpp"
#include "barretenberg/stdlib/honk_verifier/ultra_verification_keys_comparator.hpp"
#include "barretenberg/ultra_honk/ultra_prover.hpp"
#include "barretenberg/ultra_honk/ultra_verifier.hpp"
 
namespace bb::stdlib::recursion::honk {
class GoblinRecursiveVerifierTests : public testing::Test {
  public:
    using Builder = GoblinRecursiveVerifier::Builder;
    using ECCVMVK = Goblin::ECCVMVerificationKey;
    using TranslatorVK = Goblin::TranslatorVerificationKey;
 
    using OuterFlavor = UltraFlavor;
    using OuterProver = UltraProver_<OuterFlavor>;
    using OuterVerifier = UltraVerifier_<OuterFlavor>;
    using OuterProverInstance = ProverInstance_<OuterFlavor>;
 
    using Commitment = MergeVerifier::Commitment;
    using RecursiveCommitment = GoblinRecursiveVerifier::MergeVerifier::Commitment;
    using MergeCommitments = MergeVerifier::InputCommitments;
    using RecursiveMergeCommitments = GoblinRecursiveVerifier::MergeVerifier::InputCommitments;
    using FF = TranslatorFlavor::FF;
    using BF = TranslatorFlavor::BF;
    static void SetUpTestSuite() { bb::srs::init_file_crs_factory(bb::srs::bb_crs_path()); }
 
    // Compute the size of a Translator commitment (in bb::fr's)
    static constexpr size_t comm_frs = FrCodec::calc_num_fields<Commitment>(); // 4
    static constexpr size_t eval_frs = FrCodec::calc_num_fields<FF>();         // 1
 
    // The `op` wire commitment is currently the second element of the proof, following the
    // `accumulated_result` which is a BN254 BaseField element.
    static constexpr size_t offset = FrCodec::calc_num_fields<BF>();
 
    struct ProverOutput {
        GoblinProof proof;
        Goblin::VerificationKey verifier_input;
        MergeCommitments merge_commitments;
        RecursiveMergeCommitments recursive_merge_commitments;
    };
    // TODO(https://github.com/AztecProtocol/barretenberg/issues/1298):
    // Better recursion testing - create more flexible proof tampering tests.
    // Modify the `op` commitment which a part of the Merge protocol.
    static void tamper_with_op_commitment(HonkProof& translator_proof)
    {
 
        // Extract `op` fields and convert them to a Commitment object
        auto element_frs = std::span{ translator_proof }.subspan(offset, comm_frs);
        auto op_commitment = NativeTranscript::template deserialize<Commitment>(element_frs);
        // Modify the commitment
        op_commitment = op_commitment * FF(2);
        // Serialize the tampered commitment into the proof (overwriting the valid one).
        auto op_commitment_reserialized = NativeTranscript::serialize(op_commitment);
        std::copy(op_commitment_reserialized.begin(),
                  op_commitment_reserialized.end(),
                  translator_proof.begin() + static_cast<std::ptrdiff_t>(offset));
    };
 
    // Translator proof ends with [..., Libra:quotient_eval, Shplonk:Q, KZG:W]. We invalidate the proof by multiplying
    // the eval by 2 (it leads to a Libra consistency check failure).
    static void tamper_with_libra_eval(HonkProof& translator_proof)
    {
        // Proof tail size
        static constexpr size_t tail_size = 2 * comm_frs + eval_frs; // 2*4 + 1 = 9
 
        // Index of the target field (one fr) from the beginning
        const size_t idx = translator_proof.size() - tail_size;
 
        // Tamper: multiply by 2 (or tweak however you like)
        translator_proof[idx] = translator_proof[idx] + translator_proof[idx];
    };
    static ProverOutput create_goblin_prover_output(Builder* outer_builder = nullptr, const size_t num_circuits = 5)
    {
 
        Goblin goblin;
        GoblinMockCircuits::construct_and_merge_mock_circuits(goblin, num_circuits);
 
        // Merge the ecc ops from the newly constructed circuit
        auto goblin_proof = goblin.prove(MergeSettings::APPEND);
        // Subtable values and commitments - needed for (Recursive)MergeVerifier
        MergeCommitments merge_commitments;
        auto t_current = goblin.op_queue->construct_current_ultra_ops_subtable_columns();
        auto T_prev = goblin.op_queue->construct_previous_ultra_ops_table_columns();
        CommitmentKey<curve::BN254> pcs_commitment_key(goblin.op_queue->get_ultra_ops_table_num_rows());
        for (size_t idx = 0; idx < MegaFlavor::NUM_WIRES; idx++) {
            merge_commitments.t_commitments[idx] = pcs_commitment_key.commit(t_current[idx]);
            merge_commitments.T_prev_commitments[idx] = pcs_commitment_key.commit(T_prev[idx]);
        }
 
        RecursiveMergeCommitments recursive_merge_commitments;
        if (outer_builder != nullptr) {
            for (size_t idx = 0; idx < MegaFlavor::NUM_WIRES; idx++) {
                recursive_merge_commitments.t_commitments[idx] =
                    RecursiveCommitment::from_witness(outer_builder, merge_commitments.t_commitments[idx]);
                recursive_merge_commitments.T_prev_commitments[idx] =
                    RecursiveCommitment::from_witness(outer_builder, merge_commitments.T_prev_commitments[idx]);
                // Removing the free witness tag, since the merge commitments in the full scheme are supposed to
                // be fiat-shamirred earlier
                recursive_merge_commitments.t_commitments[idx].unset_free_witness_tag();
                recursive_merge_commitments.T_prev_commitments[idx].unset_free_witness_tag();
            }
        }
 
        // Output is a goblin proof plus ECCVM/Translator verification keys
        return { goblin_proof,
                 { std::make_shared<ECCVMVK>(), std::make_shared<TranslatorVK>() },
                 merge_commitments,
                 recursive_merge_commitments };
    }
};
 
TEST_F(GoblinRecursiveVerifierTests, NativeVerification)
{
    auto [proof, verifier_input, merge_commitments, _] = create_goblin_prover_output();
 
    std::shared_ptr<Goblin::Transcript> verifier_transcript = std::make_shared<Goblin::Transcript>();
 
    EXPECT_TRUE(Goblin::verify(proof, merge_commitments, verifier_transcript, MergeSettings::APPEND));
}
 
TEST_F(GoblinRecursiveVerifierTests, Basic)
{
    Builder builder;
 
    auto [proof, verifier_input, merge_commitments, recursive_merge_commitments] =
        create_goblin_prover_output(&builder);
 
    GoblinRecursiveVerifier verifier{ &builder, verifier_input };
    GoblinRecursiveVerifierOutput output = verifier.verify(proof, recursive_merge_commitments, MergeSettings::APPEND);
    output.points_accumulator.set_public();
 
    info("Recursive Verifier: num gates = ", builder.num_gates);
 
    EXPECT_EQ(builder.failed(), false) << builder.err();
 
    EXPECT_TRUE(CircuitChecker::check(builder));
 
    // Construct and verify a proof for the Goblin Recursive Verifier circuit
    {
        auto prover_instance = std::make_shared<OuterProverInstance>(builder);
        auto verification_key =
            std::make_shared<typename OuterFlavor::VerificationKey>(prover_instance->get_precomputed());
        OuterProver prover(prover_instance, verification_key);
        OuterVerifier verifier(verification_key);
        auto proof = prover.construct_proof();
        bool verified = verifier.template verify_proof<bb::DefaultIO>(proof).result;
 
        ASSERT_TRUE(verified);
    }
}
 
// Check that the GoblinRecursiveVerifier circuit does not depend on the inputs.
TEST_F(GoblinRecursiveVerifierTests, IndependentVKHash)
{
    // Retrieves the trace blocks (each consisting of a specific gate) from the recursive verifier circuit
    auto get_blocks = [](size_t inner_size)
        -> std::tuple<typename Builder::ExecutionTrace, std::shared_ptr<OuterFlavor::VerificationKey>> {
        Builder builder;
 
        auto [proof, verifier_input, merge_commitments, recursive_merge_commitments] =
            create_goblin_prover_output(&builder, inner_size);
 
        GoblinRecursiveVerifier verifier{ &builder, verifier_input };
        GoblinRecursiveVerifierOutput output =
            verifier.verify(proof, recursive_merge_commitments, MergeSettings::APPEND);
        output.points_accumulator.set_public();
 
        info("Recursive Verifier: num gates = ", builder.num_gates);
 
        // Construct and verify a proof for the Goblin Recursive Verifier circuit
        auto prover_instance = std::make_shared<OuterProverInstance>(builder);
        auto outer_verification_key =
            std::make_shared<typename OuterFlavor::VerificationKey>(prover_instance->get_precomputed());
        OuterProver prover(prover_instance, outer_verification_key);
        OuterVerifier outer_verifier(outer_verification_key);
        return { builder.blocks, outer_verification_key };
    };
 
    auto [blocks_5, verification_key_5] = get_blocks(5);
    auto [blocks_6, verification_key_6] = get_blocks(6);
 
    compare_ultra_blocks_and_verification_keys<OuterFlavor>({ blocks_5, blocks_6 },
                                                            { verification_key_5, verification_key_6 });
}
 
TEST_F(GoblinRecursiveVerifierTests, ECCVMFailure)
{
    BB_DISABLE_ASSERTS(); // Avoid on_curve assertion failure in cycle_group etc
    Builder builder;
 
    auto [proof, verifier_input, merge_commitments, recursive_merge_commitments] =
        create_goblin_prover_output(&builder);
 
    // Tamper with the ECCVM proof
    for (auto& val : proof.eccvm_proof.pre_ipa_proof) {
        if (val > 0) { // tamper by finding the first non-zero value and incrementing it by 1
            val += 1;
            break;
        }
    }
 
    GoblinRecursiveVerifier verifier{ &builder, verifier_input };
    GoblinRecursiveVerifierOutput goblin_rec_verifier_output = verifier.verify(proof, recursive_merge_commitments);
    EXPECT_FALSE(CircuitChecker::check(builder));
 
    srs::init_file_crs_factory(bb::srs::bb_crs_path());
    auto crs_factory = srs::get_grumpkin_crs_factory();
    VerifierCommitmentKey<curve::Grumpkin> grumpkin_verifier_commitment_key(1 << CONST_ECCVM_LOG_N, crs_factory);
    OpeningClaim<curve::Grumpkin> native_claim = goblin_rec_verifier_output.opening_claim.get_native_opening_claim();
    auto native_ipa_transcript = std::make_shared<NativeTranscript>();
    auto native_ipa_proof = goblin_rec_verifier_output.ipa_proof.get_value();
    native_ipa_transcript->load_proof(native_ipa_proof);
 
    bool native_result =
        IPA<curve::Grumpkin>::reduce_verify(grumpkin_verifier_commitment_key, native_claim, native_ipa_transcript);
    EXPECT_FALSE(native_result);
}
 
TEST_F(GoblinRecursiveVerifierTests, TranslatorFailure)
{
    auto [proof, verifier_input, merge_commitments, _] = create_goblin_prover_output();
 
    // Tamper with the Translator proof preamble
    {
        GoblinProof tampered_proof = proof;
        tamper_with_op_commitment(tampered_proof.translator_proof);
        Builder builder;
 
        RecursiveMergeCommitments recursive_merge_commitments;
        for (size_t idx = 0; idx < MegaFlavor::NUM_WIRES; idx++) {
            recursive_merge_commitments.t_commitments[idx] =
                RecursiveCommitment::from_witness(&builder, merge_commitments.t_commitments[idx]);
            recursive_merge_commitments.T_prev_commitments[idx] =
                RecursiveCommitment::from_witness(&builder, merge_commitments.T_prev_commitments[idx]);
            recursive_merge_commitments.t_commitments[idx].fix_witness();
            recursive_merge_commitments.T_prev_commitments[idx].fix_witness();
        }
 
        GoblinRecursiveVerifier verifier{ &builder, verifier_input };
        [[maybe_unused]] auto goblin_rec_verifier_output =
            verifier.verify(tampered_proof, recursive_merge_commitments, MergeSettings::APPEND);
        EXPECT_FALSE(CircuitChecker::check(builder));
    }
    // Tamper with the Translator proof non - preamble values
    {
        auto tampered_proof = proof;
        tamper_with_libra_eval(tampered_proof.translator_proof);
 
        Builder builder;
 
        RecursiveMergeCommitments recursive_merge_commitments;
        for (size_t idx = 0; idx < MegaFlavor::NUM_WIRES; idx++) {
            recursive_merge_commitments.t_commitments[idx] =
                RecursiveCommitment::from_witness(&builder, merge_commitments.t_commitments[idx]);
            recursive_merge_commitments.T_prev_commitments[idx] =
                RecursiveCommitment::from_witness(&builder, merge_commitments.T_prev_commitments[idx]);
            recursive_merge_commitments.t_commitments[idx].fix_witness();
            recursive_merge_commitments.T_prev_commitments[idx].fix_witness();
        }
 
        GoblinRecursiveVerifier verifier{ &builder, verifier_input };
        [[maybe_unused]] auto goblin_rec_verifier_output =
            verifier.verify(tampered_proof, recursive_merge_commitments, MergeSettings::APPEND);
        EXPECT_FALSE(CircuitChecker::check(builder));
    }
}
 
TEST_F(GoblinRecursiveVerifierTests, TranslationEvaluationsFailure)
{
    Builder builder;
 
    auto [proof, verifier_input, merge_commitments, recursive_merge_commitments] =
        create_goblin_prover_output(&builder);
 
    // Tamper with the evaluation of `op` witness. The index is computed manually.
    // TODO(https://github.com/AztecProtocol/barretenberg/issues/1298):
    // Better recursion testing - create more flexible proof tampering tests.
    const size_t op_limb_index = 593;
    proof.eccvm_proof.pre_ipa_proof[op_limb_index] += 1;
 
    GoblinRecursiveVerifier verifier{ &builder, verifier_input };
    [[maybe_unused]] auto goblin_rec_verifier_output =
        verifier.verify(proof, recursive_merge_commitments, MergeSettings::APPEND);
 
    EXPECT_FALSE(CircuitChecker::check(builder));
}
 
TEST_F(GoblinRecursiveVerifierTests, TranslatorMergeConsistencyFailure)
{
 
    {
 
        Builder builder;
 
        auto [proof, verifier_input, merge_commitments, recursive_merge_commitments] =
            create_goblin_prover_output(&builder);
 
        std::shared_ptr<Goblin::Transcript> verifier_transcript = std::make_shared<Goblin::Transcript>();
 
        // Check natively that the proof is correct.
        EXPECT_TRUE(Goblin::verify(proof, merge_commitments, verifier_transcript, MergeSettings::APPEND));
 
        tamper_with_op_commitment(proof.translator_proof);
        // Construct and check the Goblin Recursive Verifier circuit
 
        GoblinRecursiveVerifier verifier{ &builder, verifier_input };
        [[maybe_unused]] auto goblin_rec_verifier_output =
            verifier.verify(proof, recursive_merge_commitments, MergeSettings::APPEND);
 
        EXPECT_FALSE(CircuitChecker::check(builder));
    }
 
    // TODO(https://github.com/AztecProtocol/barretenberg/issues/787)
}
} // namespace bb::stdlib::recursion::honk