g_primitive.tcc

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// Copyright (c) 2015-2022 Clearmatics Technologies Ltd
//
// SPDX-License-Identifier: LGPL-3.0+
 
#ifndef __ZETH_CIRCUITS_G_PRIMITIVE_TCC__
#define __ZETH_CIRCUITS_G_PRIMITIVE_TCC__
 
namespace libzeth
{
 
// See: Section 3.1 of https://tools.ietf.org/html/rfc7693
template<typename FieldT>
g_primitive<FieldT>::g_primitive(
    libsnark::protoboard<FieldT> &pb,
    libsnark::pb_variable_array<FieldT> a,
    libsnark::pb_variable_array<FieldT> b,
    libsnark::pb_variable_array<FieldT> c,
    libsnark::pb_variable_array<FieldT> d,
    libsnark::pb_variable_array<FieldT> x,
    libsnark::pb_variable_array<FieldT> y,
    libsnark::pb_variable_array<FieldT> a2,
    libsnark::pb_variable_array<FieldT> b2,
    libsnark::pb_variable_array<FieldT> c2,
    libsnark::pb_variable_array<FieldT> d2,
    const std::string &annotation_prefix)
    : libsnark::gadget<FieldT>(pb, annotation_prefix)
    , a2(a2)
    , b2(b2)
    , c2(c2)
    , d2(d2)
{
    a1.allocate(pb, 32, " a1");
    b1.allocate(pb, 32, " b1");
    c1.allocate(pb, 32, " c1");
    d1.allocate(pb, 32, " d1");
    a1_temp.allocate(pb, 32, " a1_temp");
    a2_temp.allocate(pb, 32, " a2_temp");
 
    // v[a] := (v[a] + v[b] + x) mod 2^32
    a1_1_sum_gadget.reset(
        new double_bit32_sum_eq_gadget<FieldT>(pb, a, b, a1_temp));
    a1_2_sum_gadget.reset(
        new double_bit32_sum_eq_gadget<FieldT>(pb, a1_temp, x, a1));
    // v[d] := (v[d] ^ v[a]) >>> R1
    d1_xor_gadget.reset(
        new xor_rot_gadget<FieldT>(pb, d, a1, rotation_constant_r1, d1));
    // v[c] := (v[c] + v[d]) mod 2^32
    c1_sum_gadget.reset(new double_bit32_sum_eq_gadget<FieldT>(pb, c, d1, c1));
    // v[b] := (v[b] ^ v[c]) >>> R2
    b1_xor_gadget.reset(
        new xor_rot_gadget<FieldT>(pb, b, c1, rotation_constant_r2, b1));
 
    // v[a] := (v[a] + v[b] + y) mod 2^32
    a2_1_sum_gadget.reset(
        new double_bit32_sum_eq_gadget<FieldT>(pb, a1, b1, a2_temp));
    a2_2_sum_gadget.reset(
        new double_bit32_sum_eq_gadget<FieldT>(pb, a2_temp, y, a2));
    // v[d] := (v[d] ^ v[a]) >>> R3
    d2_xor_gadget.reset(
        new xor_rot_gadget<FieldT>(pb, d1, a2, rotation_constant_r3, d2));
    // v[c] := (v[c] + v[d]) mod 2^32
    c2_sum_gadget.reset(new double_bit32_sum_eq_gadget<FieldT>(pb, c1, d2, c2));
    // v[b] := (v[b] ^ v[c]) >>> R4
    b2_xor_gadget.reset(
        new xor_rot_gadget<FieldT>(pb, b1, c2, rotation_constant_r4, b2));
};
 
template<typename FieldT> void g_primitive<FieldT>::generate_r1cs_constraints()
{
    // 262 constraints (4 * 32 (xor) + 4 * 33 (add true) + 2 * 1 (add false))
    // Note: we do not check the booleaness of this temp variable
    a1_1_sum_gadget->generate_r1cs_constraints(false);
    a1_2_sum_gadget->generate_r1cs_constraints();
    d1_xor_gadget->generate_r1cs_constraints();
    c1_sum_gadget->generate_r1cs_constraints();
    b1_xor_gadget->generate_r1cs_constraints();
 
    // Note: we do not check the booleaness of this temp variable
    a2_1_sum_gadget->generate_r1cs_constraints(false);
    a2_2_sum_gadget->generate_r1cs_constraints();
    d2_xor_gadget->generate_r1cs_constraints();
    c2_sum_gadget->generate_r1cs_constraints();
    b2_xor_gadget->generate_r1cs_constraints();
};
 
template<typename FieldT> void g_primitive<FieldT>::generate_r1cs_witness()
{
    a1_1_sum_gadget->generate_r1cs_witness();
    a1_2_sum_gadget->generate_r1cs_witness();
    d1_xor_gadget->generate_r1cs_witness();
    c1_sum_gadget->generate_r1cs_witness();
    b1_xor_gadget->generate_r1cs_witness();
 
    a2_1_sum_gadget->generate_r1cs_witness();
    a2_2_sum_gadget->generate_r1cs_witness();
    d2_xor_gadget->generate_r1cs_witness();
    c2_sum_gadget->generate_r1cs_witness();
    b2_xor_gadget->generate_r1cs_witness();
};
 
} // namespace libzeth
 
#endif // __ZETH_CIRCUITS_G_PRIMITIVE_TCC__