pedersen.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 "pedersen.hpp"
#include "barretenberg/crypto/pedersen_hash/pedersen.hpp"
#include "barretenberg/ecc/curves/grumpkin/grumpkin.hpp"
namespace bb::stdlib {
 
using namespace bb;
 
template <typename Builder>
field_t<Builder> pedersen_hash<Builder>::hash(const std::vector<field_ct>& inputs, const GeneratorContext context)
{
    using cycle_scalar = typename cycle_group::cycle_scalar;
    using Curve = EmbeddedCurve;
 
    const auto base_points = context.generators->get(inputs.size(), context.offset, context.domain_separator);
 
    std::vector<cycle_scalar> scalars;
    std::vector<cycle_group> points;
    scalars.emplace_back(cycle_scalar::create_from_bn254_scalar(field_ct(inputs.size())));
    points.emplace_back(crypto::pedersen_hash_base<Curve>::length_generator);
    for (const auto [point, scalar] : zip_view(base_points, inputs)) {
        scalars.emplace_back(cycle_scalar::create_from_bn254_scalar(scalar));
        // Construct circuit-constant cycle_group objects (non-witness)
        points.emplace_back(point);
    }
 
    auto result = cycle_group::batch_mul(points, scalars);
    // pedersen hash doesn't use y coordinate of result anymore in the circuit except for hashing
    // so we can put result.y in used_witnesses
    auto builder_ptr = result.y.get_context();
    if (builder_ptr != nullptr) {
        builder_ptr->update_used_witnesses(result.y.witness_index);
    }
    return result.x;
}
 
template class pedersen_hash<bb::UltraCircuitBuilder>;
template class pedersen_hash<bb::MegaCircuitBuilder>;
 
} // namespace bb::stdlib