poseidon2_constraint.cpp

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// === AUDIT STATUS ===
// internal:    { status: not started, auditors: [], date: YYYY-MM-DD }
// external_1:  { status: not started, auditors: [], date: YYYY-MM-DD }
// external_2:  { status: not started, auditors: [], date: YYYY-MM-DD }
// =====================
 
#include "poseidon2_constraint.hpp"
#include "barretenberg/common/assert.hpp"
#include "barretenberg/crypto/poseidon2/poseidon2_params.hpp"
#include "barretenberg/stdlib/hash/poseidon2/poseidon2_permutation.hpp"
#include "barretenberg/stdlib/primitives/circuit_builders/circuit_builders_fwd.hpp"
#include "barretenberg/stdlib/primitives/field/field.hpp"
 
namespace acir_format {
 
using namespace bb;
 
template <typename Builder>
void create_poseidon2_permutations_constraints(Builder& builder, const Poseidon2Constraint& constraint)
{
    using field_ct = stdlib::field_t<Builder>;
    using State = stdlib::Poseidon2Permutation<Builder>::State;
 
    BB_ASSERT_EQ(constraint.state.size(), 4U);
    BB_ASSERT_EQ(constraint.result.size(), 4U);
 
    // stdlib poseidon2 does not support hashing constants
    for (const auto& input : constraint.state) {
        BB_ASSERT(!input.is_constant, "Poseidon2 constraint does not support constant inputs");
    }
 
    // Get the witness assignment for each witness index
    // Write the witness assignment to the byte array state
    State state;
    for (size_t i = 0; i < constraint.state.size(); ++i) {
        state[i] = to_field_ct(constraint.state[i], builder);
    }
    State output_state;
    output_state = stdlib::Poseidon2Permutation<Builder>::permutation(&builder, state);
    for (size_t i = 0; i < output_state.size(); ++i) {
        output_state[i].assert_equal(field_ct::from_witness_index(&builder, constraint.result[i]));
    }
}
 
template void create_poseidon2_permutations_constraints<UltraCircuitBuilder>(UltraCircuitBuilder& builder,
                                                                             const Poseidon2Constraint& constraint);
 
template void create_poseidon2_permutations_constraints<MegaCircuitBuilder>(MegaCircuitBuilder& builder,
                                                                            const Poseidon2Constraint& constraint);
} // namespace acir_format