permutation.test.cpp

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#include "barretenberg/circuit_checker/circuit_checker.hpp"
#include "barretenberg/honk/library/grand_product_delta.hpp"
#include "barretenberg/honk/relation_checker.hpp"
#include "ultra_honk.test.hpp"
 
using namespace bb;
 
#ifdef STARKNET_GARAGA_FLAVORS
using FlavorTypes = testing::Types<UltraFlavor,
                                   UltraZKFlavor,
                                   UltraKeccakFlavor,
                                   UltraKeccakZKFlavor,
                                   UltraRollupFlavor,
                                   UltraStarknetFlavor,
                                   UltraStarknetZKFlavor>;
#else
using FlavorTypes =
    testing::Types<UltraFlavor, UltraZKFlavor, UltraKeccakFlavor, UltraKeccakZKFlavor, UltraRollupFlavor>;
#endif
template <typename T> using PermutationTests = UltraHonkTests<T>;
TYPED_TEST_SUITE(PermutationTests, FlavorTypes);
using NonZKFlavorTypes = testing::Types<UltraFlavor, UltraKeccakFlavor, UltraRollupFlavor>;
template <typename T> using PermutationNonZKTests = UltraHonkTests<T>;
TYPED_TEST_SUITE(PermutationNonZKTests, NonZKFlavorTypes);
 
TYPED_TEST(PermutationTests, NonTrivialTagPermutation)
{
    auto builder = UltraCircuitBuilder();
 
    // Create two distinct values
    fr x = fr::random_element();
    fr y = -x;
 
    // first multiset {x, y}
    auto x1_idx = builder.add_variable(x);
    auto y1_idx = builder.add_variable(y);
 
    // second multiset {y, x}
    auto y2_idx = builder.add_variable(y);
    auto x2_idx = builder.add_variable(x);
 
    // Dummy gates to include variables in the trace
    builder.create_add_gate({ x1_idx, y1_idx, builder.zero_idx(), 1, 1, 0, 0 });
    builder.create_add_gate({ y2_idx, x2_idx, builder.zero_idx(), 1, 1, 0, 0 });
 
    // Set up tag transposition: first_tag <-> second_tag
    auto first_tag = builder.get_new_tag();
    auto second_tag = builder.get_new_tag();
    builder.set_tau_transposition(first_tag, second_tag);
 
    // Assign tags: first_tag -> {x, y}, second_tag -> {y, x}
    builder.assign_tag(x1_idx, first_tag);
    builder.assign_tag(y1_idx, first_tag);
    builder.assign_tag(y2_idx, second_tag);
    builder.assign_tag(x2_idx, second_tag);
 
    TestFixture::set_default_pairing_points_and_ipa_claim_and_proof(builder);
    TestFixture::prove_and_verify(builder, /*expected_result=*/true);
}
 
TYPED_TEST(PermutationTests, NonTrivialGeneralizedPerm)
{
    auto builder = UltraCircuitBuilder();
 
    fr x = fr::random_element();
    fr y = -x;
 
    // Helper to create a pair of equal variables (linked by copy constraint)
    auto add_equal_pair = [&](fr value) {
        auto idx1 = builder.add_variable(value);
        auto idx2 = builder.add_variable(value);
        builder.assert_equal(idx1, idx2);
        return std::make_pair(idx1, idx2);
    };
 
    // Create pairs of equal variables
    auto [x1_idx, x1_copy_idx] = add_equal_pair(x);
    auto [y1_idx, y1_copy_idx] = add_equal_pair(y);
    auto [x2_idx, x2_copy_idx] = add_equal_pair(x);
    auto [y2_idx, y2_copy_idx] = add_equal_pair(y);
 
    // Set up tag transposition for multiset-equality check
    auto first_tag = builder.get_new_tag();
    auto second_tag = builder.get_new_tag();
    builder.set_tau_transposition(first_tag, second_tag);
 
    // first_tag -> {x, y}, second_tag -> {x, y} (same multisets)
    builder.assign_tag(x1_idx, first_tag);
    builder.assign_tag(y1_idx, first_tag);
    builder.assign_tag(x2_idx, second_tag);
    builder.assign_tag(y2_idx, second_tag);
 
    // Dummy gates using copy variables (z1 - z2 = 0)
    builder.create_add_gate({ x1_copy_idx, x1_idx, builder.zero_idx(), 1, -1, 0, 0 });
    builder.create_add_gate({ y1_idx, y2_idx, builder.zero_idx(), 1, -1, 0, 0 });
    builder.create_add_gate({ x2_idx, x2_copy_idx, builder.zero_idx(), 1, -1, 0, 0 });
 
    TestFixture::set_default_pairing_points_and_ipa_claim_and_proof(builder);
    TestFixture::prove_and_verify(builder, /*expected_result=*/true);
}
 
TYPED_TEST(PermutationTests, BadTagPermutation)
{
    // With tags: multisets {x, y} vs {y, x+1} are NOT equal, so verification should FAIL
    {
        auto builder = UltraCircuitBuilder();
 
        fr x = fr::random_element();
        fr y = -x;
 
        // multiset: {x, y}
        auto x1_idx = builder.add_variable(x);
        auto y1_idx = builder.add_variable(y);
 
        // multiset: {y, x+1}
        auto y2_idx = builder.add_variable(y);
        auto x_plus_1_idx = builder.add_variable(x + 1);
 
        // Dummy gates: x + y = 0, y + (x+1) = 1
        builder.create_add_gate({ x1_idx, y1_idx, builder.zero_idx(), 1, 1, 0, 0 });
        builder.create_add_gate({ y2_idx, x_plus_1_idx, builder.zero_idx(), 1, 1, 0, -1 });
 
        auto first_tag = builder.get_new_tag();
        auto second_tag = builder.get_new_tag();
        builder.set_tau_transposition(first_tag, second_tag);
 
        builder.assign_tag(x1_idx, first_tag);
        builder.assign_tag(y1_idx, first_tag);
        builder.assign_tag(y2_idx, second_tag);
        builder.assign_tag(x_plus_1_idx, second_tag);
 
        TestFixture::set_default_pairing_points_and_ipa_claim_and_proof(builder);
        TestFixture::prove_and_verify(builder, /*expected_result=*/false);
    }
    // Without tags: same circuit passes, confirming failure above is due to tag mismatch
    {
        auto builder = UltraCircuitBuilder();
 
        fr x = fr::random_element();
        fr y = -x;
 
        auto x1_idx = builder.add_variable(x);
        auto y1_idx = builder.add_variable(y);
        auto y2_idx = builder.add_variable(y);
        auto x_plus_1_idx = builder.add_variable(x + 1);
 
        builder.create_add_gate({ x1_idx, y1_idx, builder.zero_idx(), 1, 1, 0, 0 });
        builder.create_add_gate({ y2_idx, x_plus_1_idx, builder.zero_idx(), 1, 1, 0, -1 });
 
        TestFixture::set_default_pairing_points_and_ipa_claim_and_proof(builder);
        TestFixture::prove_and_verify(builder, /*expected_result=*/true);
    }
}
 
TYPED_TEST(PermutationNonZKTests, ZPermZeroedOutFailure)
{
    using Flavor = TypeParam;
    using Builder = typename Flavor::CircuitBuilder;
 
    using ProverInstance = ProverInstance_<Flavor>;
    using VerificationKey = Flavor::VerificationKey;
 
    using Prover = TestFixture::Prover;
 
    Builder builder;
 
    auto a = fr::random_element();
    auto b = fr::random_element();
    auto c = a + b;
 
    uint32_t a_idx = builder.add_variable(a);
    uint32_t a_copy_idx = builder.add_variable(a);
    uint32_t b_idx = builder.add_variable(b);
    uint32_t c_idx = builder.add_variable(c);
 
    builder.create_add_gate({ a_idx, b_idx, c_idx, 1, 1, -1, 0 });
    builder.create_add_gate({ a_copy_idx, b_idx, c_idx, 1, 1, -1, 0 });
    builder.assert_equal(a_copy_idx, a_idx);
 
    TestFixture::set_default_pairing_points_and_ipa_claim_and_proof(builder);
 
    auto prover_instance = std::make_shared<ProverInstance>(builder);
    auto verification_key = std::make_shared<VerificationKey>(prover_instance->get_precomputed());
 
    Prover prover(prover_instance, verification_key);
    auto proof = prover.construct_proof();
    auto& z_perm = prover_instance->polynomials.z_perm;
 
    // First verify that the Permutation relation holds.
    auto permutation_relation_failures = RelationChecker<Flavor>::template check<UltraPermutationRelation<fr>>(
        prover_instance->polynomials, prover_instance->relation_parameters, "UltraPermutation - Before Tampering");
    EXPECT_TRUE(permutation_relation_failures.empty());
 
    // Tamper: zero-out z_perm
    for (size_t i = z_perm.start_index(); i < z_perm.end_index(); ++i) {
        z_perm.at(i) = fr(0);
    }
    prover_instance->polynomials.set_shifted();
    auto tampered_permutation_relation_failures = RelationChecker<Flavor>::template check<UltraPermutationRelation<fr>>(
        prover_instance->polynomials,
        prover_instance->relation_parameters,
        "UltraPermutation - After zeroing out z_perm");
    // Verify that the Permutation relation now fails
    EXPECT_FALSE(tampered_permutation_relation_failures.empty());
}
 
TYPED_TEST(PermutationNonZKTests, ZPermShiftNotZeroAtLagrangeLastFailure)
{
    using Flavor = TypeParam;
    using Builder = typename Flavor::CircuitBuilder;
 
    using ProverInstance = ProverInstance_<Flavor>;
    using VerificationKey = Flavor::VerificationKey;
 
    using Prover = TestFixture::Prover;
 
    Builder builder;
 
    auto a = fr::random_element();
    auto b = fr::random_element();
    auto c = a + b;
 
    uint32_t a_idx = builder.add_variable(a);
    uint32_t a_copy_idx = builder.add_variable(a);
    uint32_t b_idx = builder.add_variable(b);
    uint32_t c_idx = builder.add_variable(c);
 
    builder.create_add_gate({ a_idx, b_idx, c_idx, 1, 1, -1, 0 });
    builder.create_add_gate({ a_copy_idx, b_idx, c_idx, 1, 1, -1, 0 });
    builder.assert_equal(a_copy_idx, a_idx);
 
    TestFixture::set_default_pairing_points_and_ipa_claim_and_proof(builder);
 
    auto prover_instance = std::make_shared<ProverInstance>(builder);
    auto verification_key = std::make_shared<VerificationKey>(prover_instance->get_precomputed());
 
    Prover prover(prover_instance, verification_key);
    auto proof = prover.construct_proof();
 
    // first verify that the Permutation relation holds.
    auto permutation_relation_failures = RelationChecker<Flavor>::template check<UltraPermutationRelation<fr>>(
        prover_instance->polynomials, prover_instance->relation_parameters, "UltraPermutation - Before Tampering");
    EXPECT_TRUE(permutation_relation_failures.empty());
    // we make z_perm and z_perm_shift full polynomials to tamper with values that are outside the usual allocated
    // range. This allows us to failure test for the subrelation `z_perm_shift * lagrange_last == 0`.
    auto& z_perm = prover_instance->polynomials.z_perm;
    auto last_valid_index = z_perm.end_index();
    auto& z_perm_shift = prover_instance->polynomials.z_perm_shift;
    // make the polynomial full to tamper with a last value.
    prover_instance->polynomials.z_perm = z_perm.full();
    prover_instance->polynomials.z_perm_shift = z_perm_shift.full();
 
    ASSERT_EQ(prover_instance->polynomials.lagrange_last.at(last_valid_index - 1), fr(1));
    ASSERT_EQ(prover_instance->polynomials.z_perm.at(last_valid_index), fr(0));
    ASSERT_EQ(prover_instance->polynomials.z_perm_shift.at(last_valid_index - 1), fr(0));
    // Tamper: change `z_perm_shift` to something non-zero when `lagrange_last == 1`.
    prover_instance->polynomials.z_perm_shift.at(last_valid_index - 1) += fr(1);
    // Note that `z_perm_shift` and `z_perm` are no longer inextricably linked because we have replaced them by their
    // full incarnations. Therefore, we still `z_perm.at(last_valid_index) == 0`. This does not effect the test we
    // wish to check.
 
    // Verify that the Permutation relation now fails.
    auto tampered_permutation_relation_failures = RelationChecker<Flavor>::template check<UltraPermutationRelation<fr>>(
        prover_instance->polynomials,
        prover_instance->relation_parameters,
        "UltraPermutation - After incrementing z_perm_shift where lagrange_last is 1");
    EXPECT_FALSE(tampered_permutation_relation_failures.empty());
    // the first subrelation first fails at `row_idx == last_valid_index - 1`.
    ASSERT_EQ(tampered_permutation_relation_failures[1], last_valid_index - 1);
}
 
TYPED_TEST(PermutationNonZKTests, SigmaCorruptionFailure)
{
    using Flavor = TypeParam;
    using ProverInstance = ProverInstance_<Flavor>;
    using VerificationKey = typename Flavor::VerificationKey;
    using Prover = typename TestFixture::Prover;
 
    auto builder = UltraCircuitBuilder();
 
    // Create variables with a copy constraint
    auto a = fr::random_element();
    auto b = fr::random_element();
    auto c = a + b;
 
    uint32_t a_idx = builder.add_variable(a);
    uint32_t a_copy_idx = builder.add_variable(a);
    uint32_t b_idx = builder.add_variable(b);
    uint32_t c_idx = builder.add_variable(c);
 
    // Gates using a_idx and a_copy_idx (which should be equal)
    builder.create_add_gate({ a_idx, b_idx, c_idx, 1, 1, -1, 0 });
    builder.create_add_gate({ a_copy_idx, b_idx, c_idx, 1, 1, -1, 0 });
    // copy cycle we'll break
    builder.assert_equal(a_copy_idx, a_idx);
 
    TestFixture::set_default_pairing_points_and_ipa_claim_and_proof(builder);
 
    auto prover_instance = std::make_shared<ProverInstance>(builder);
    auto verification_key = std::make_shared<VerificationKey>(prover_instance->get_precomputed());
 
    // Construct proof to compute z_perm
    Prover prover(prover_instance, verification_key);
    auto proof = prover.construct_proof();
 
    // The Permutation relation holds before tampering
    auto permutation_relation_failures = RelationChecker<Flavor>::template check<UltraPermutationRelation<fr>>(
        prover_instance->polynomials, prover_instance->relation_parameters, "Permutation Relation - Before Tampering");
    ASSERT_TRUE(permutation_relation_failures.empty());
 
    // TAMPER
 
    // Corrupt sigma_1 at a row that's part of the copy cycle.
    auto& sigma_1 = prover_instance->polynomials.sigma_1;
    auto& id_1 = prover_instance->polynomials.id_1;
 
    // Find the first row that's part of a non-trivial cycle (sigma != id)
    size_t row_to_corrupt = 0;
    for (size_t row = 1; row < sigma_1.size(); ++row) {
        if (sigma_1.at(row) != id_1.at(row)) {
            row_to_corrupt = row;
            vinfo("Found copy cycle at row ", row, "; will corrupt this one");
            break;
        }
    }
    ASSERT_NE(row_to_corrupt, 0) << "No copy cycle found in sigma_1!";
 
    fr original_value = sigma_1.at(row_to_corrupt);
    sigma_1.at(row_to_corrupt) = original_value + fr(1); // Break the cycle by pointing elsewhere
    // We perform two distinct tests.
    //
    // Failure test 1: make sure that the subrelation fails when when we change sigma_1 without updating z_perm.
    {
        auto failures_of_tampered_instance = RelationChecker<Flavor>::template check<UltraPermutationRelation<fr>>(
            prover_instance->polynomials,
            prover_instance->relation_parameters,
            "Permutation Relation - After corrupting sigma_1");
 
        ASSERT_TRUE(failures_of_tampered_instance.at(0));
    }
    // Failure test 2: make sure the subrelation fails when we DO update z_perm
    {
        // Sanity check: if we are recompute z_perm, the first different value will be at `row_to_corrupt + 1`. Store
        // this to ensure that this value indeed changes.
        auto& z_perm = prover_instance->polynomials.z_perm;
        auto z_perm_before = z_perm.at(row_to_corrupt + 1);
 
        // Recompute z_perm with the corrupted sigma.
        size_t real_circuit_size = prover_instance->get_final_active_wire_idx() + 1;
        compute_grand_product<Flavor, UltraPermutationRelation<fr>>(
            prover_instance->polynomials, prover_instance->relation_parameters, real_circuit_size);
        prover_instance->polynomials.set_shifted(); // Refresh z_perm_shift
 
        // Verify z_perm actually changed after recomputation with corrupted sigma
        auto z_perm_after = z_perm.at(row_to_corrupt + 1);
        ASSERT_NE(z_perm_before, z_perm_after) << "z_perm should change after recomputing with corrupted sigma";
 
        // After recomputing z_perm, we expect a failure at the very last active wire.
        auto failures_of_tampered_instance = RelationChecker<Flavor>::template check<UltraPermutationRelation<fr>>(
            prover_instance->polynomials,
            prover_instance->relation_parameters,
            "Permutation Relation - After corrupting sigma_1 and recomputing z_perm");
 
        ASSERT_EQ(failures_of_tampered_instance.at(0), real_circuit_size - 1)
            << "Expected failure at row " << (real_circuit_size - 1) << " (the recomputation boundary)";
    }
}
 
TYPED_TEST(PermutationNonZKTests, PublicInputDeltaMismatch)
{
    using Flavor = TypeParam;
    using ProverInstance = ProverInstance_<Flavor>;
    using VerificationKey = typename Flavor::VerificationKey;
    using Prover = typename TestFixture::Prover;
 
    auto builder = UltraCircuitBuilder();
 
    // Add a public input
    fr public_value = fr(314159);
    auto pub_var = builder.add_public_variable(public_value);
 
    // Use the public input in a simple constraint so it appears in the trace
    auto private_val = fr::random_element();
    auto private_var = builder.add_variable(private_val);
    auto result_var = builder.add_variable(public_value + private_val);
    builder.create_add_gate({ pub_var, private_var, result_var, 1, 1, -1, 0 });
 
    TestFixture::set_default_pairing_points_and_ipa_claim_and_proof(builder);
 
    auto prover_instance = std::make_shared<ProverInstance>(builder);
    auto verification_key = std::make_shared<VerificationKey>(prover_instance->get_precomputed());
 
    // Construct proof to compute z_perm (with correct public_input_delta)
    Prover prover(prover_instance, verification_key);
    auto proof = prover.construct_proof();
 
    // Verify the permutation relation holds before tampering
    auto permutation_relation_failures = RelationChecker<Flavor>::template check<UltraPermutationRelation<fr>>(
        prover_instance->polynomials, prover_instance->relation_parameters, "Permutation Relation - Before Tampering");
    ASSERT_TRUE(permutation_relation_failures.empty());
 
    // Store the original public_input_delta
    fr original_delta = prover_instance->relation_parameters.public_input_delta;
 
    // TAMPER
 
    // Recompute public_input_delta with a different public input value
    // The wire polynomials still contain the original value (314159), but we compute delta as if it were 99999
    fr tampered_public_val = fr(99999);
    std::vector<fr> tampered_public_inputs = { tampered_public_val };
    fr tampered_delta = compute_public_input_delta<Flavor>(tampered_public_inputs,
                                                           prover_instance->relation_parameters.beta,
                                                           prover_instance->relation_parameters.gamma,
                                                           prover_instance->pub_inputs_offset());
 
    // Sanity check: the tampered delta should differ from the original
    ASSERT_NE(original_delta, tampered_delta) << "Tampered delta should differ from original";
 
    // Apply the tampered delta
    prover_instance->relation_parameters.public_input_delta = tampered_delta;
 
    // Verify the permutation relation now fails
    auto failures_of_tampered_instance = RelationChecker<Flavor>::template check<UltraPermutationRelation<fr>>(
        prover_instance->polynomials,
        prover_instance->relation_parameters,
        "Permutation Relation - After tampering with public_input_delta");
    // The failure should be in subrelation 0 (the recurrence relation) since z_perm was computed with
    // a different public_input_delta than what we're now using in the relation check
    ASSERT_TRUE(failures_of_tampered_instance.contains(0)) << "Expected subrelation 0 to fail";
    size_t final_active_wire_idx = prover_instance->get_final_active_wire_idx();
    ASSERT_TRUE(failures_of_tampered_instance.at(0) == final_active_wire_idx);
}