mpc_utils.hpp

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// Copyright (c) 2015-2022 Clearmatics Technologies Ltd
//
// SPDX-License-Identifier: LGPL-3.0+
 
#ifndef __ZETH_MPC_GROTH16_MPC_UTILS_HPP__
#define __ZETH_MPC_GROTH16_MPC_UTILS_HPP__
 
#include "libzeth/snarks/groth16/groth16_snark.hpp"
 
#include <vector>
 
// Structures and utility functions related to CRS generation via an
// MPC. Following [BoweGM17], the circuit $C$ generating the SRS is
// considered to be made up of 3 layers: $C = C_1 L_1 C_2$. The
// output from $C_1$ is exactly the powersoftau data. $L_1$
// represents the linear combination based on a specific QAP, and
// $C_2$ is the output from Phase2 of the MPC.
//
// References:
//
// \[BoweGM17]
//  "Scalable Multi-party Computation for zk-SNARK Parameters in the Random
//  Beacon Model"
//  Sean Bowe and Ariel Gabizon and Ian Miers,
//  IACR Cryptology ePrint Archive 2017,
//  <http://eprint.iacr.org/2017/1050>
 
namespace libzeth
{
 
template<typename ppT> class srs_powersoftau;
template<typename ppT> class srs_lagrange_evaluations;
 
template<typename ppT> class srs_mpc_layer_L1
{
public:
    libff::G1_vector<ppT> T_tau_powers_g1;
 
    libff::G1_vector<ppT> A_g1;
 
    libff::G1_vector<ppT> B_g1;
 
    libff::G2_vector<ppT> B_g2;
 
    libff::G1_vector<ppT> ABC_g1;
 
    srs_mpc_layer_L1(
        libff::G1_vector<ppT> &&T_tau_powers_g1,
        libff::G1_vector<ppT> &&A_g1,
        libff::G1_vector<ppT> &&B_g1,
        libff::G2_vector<ppT> &&B_g2,
        libff::G1_vector<ppT> &&ABC_g1);
 
    size_t degree() const;
 
    bool is_well_formed() const;
    void write(std::ostream &out) const;
    static srs_mpc_layer_L1 read(std::istream &in);
};
 
template<typename ppT>
srs_mpc_layer_L1<ppT> mpc_compute_linearcombination(
    const srs_powersoftau<ppT> &pot,
    const srs_lagrange_evaluations<ppT> &lagrange,
    const libsnark::qap_instance<libff::Fr<ppT>> &qap);
 
} // namespace libzeth
 
#include "libzeth/mpc/groth16/mpc_utils.tcc"
 
#endif // __ZETH_MPC_GROTH16_MPC_UTILS_HPP__