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/*
Copyright 2018 0kims association.
This file is part of zksnark JavaScript library.
zksnark JavaScript library is a free software: you can redistribute it and/or
modify it under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at your option)
any later version.
zksnark JavaScript library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.
You should have received a copy of the GNU General Public License along with
zksnark JavaScript library. If not, see <https://www.gnu.org/licenses/>.
*/
const bigInt = require("./bigint.js");
const BN128 = require("./bn128.js");
const PolField = require("./polfield.js");
const ZqField = require("./zqfield.js");
const bn128 = new BN128();
const G1 = bn128.G1;
const G2 = bn128.G2;
const PolF = new PolField(new ZqField(bn128.r));
const F = new ZqField(bn128.r);
module.exports = function setup(circuit) {
const setup = {
vk_proof : {
nVars: circuit.nVars,
nPublic: circuit.nPubInputs + circuit.nOutputs
},
vk_verifier: {
nPublic: circuit.nPubInputs + circuit.nOutputs
},
toxic: {}
};
setup.vk_proof.domainBits = PolF.log2(circuit.nConstraints + circuit.nPubInputs + circuit.nOutputs +1 -1) +1;
setup.vk_proof.domainSize = 1 << setup.vk_proof.domainBits;
calculatePolinomials(setup, circuit);
setup.toxic.t = F.random();
calculateEncriptedValuesAtT(setup, circuit);
calculateHexps(setup, circuit);
return setup;
};
function calculatePolinomials(setup, circuit) {
setup.vk_proof.polsA = new Array(circuit.nVars);
setup.vk_proof.polsB = new Array(circuit.nVars);
setup.vk_proof.polsC = new Array(circuit.nVars);
for (let i=0; i<circuit.nVars; i++) {
setup.vk_proof.polsA[i] = {};
setup.vk_proof.polsB[i] = {};
setup.vk_proof.polsC[i] = {};
}
for (let c=0; c<circuit.nConstraints; c++) {
for (let s in circuit.constraints[c][0]) {
setup.vk_proof.polsA[s][c] = bigInt(circuit.constraints[c][0][s]);
}
for (let s in circuit.constraints[c][1]) {
setup.vk_proof.polsB[s][c] = bigInt(circuit.constraints[c][1][s]);
}
for (let s in circuit.constraints[c][2]) {
setup.vk_proof.polsC[s][c] = bigInt(circuit.constraints[c][2][s]);
}
}
/**
* add and process the constraints
* input_i * 0 = 0
* to ensure soundness of input consistency
*/
for (let i = 0; i < circuit.nPubInputs + circuit.nOutputs + 1; ++i)
{
setup.vk_proof.polsA[i][circuit.nConstraints + i] = F.one;
}
}
function calculateValuesAtT(setup, circuit) {
const z_t = PolF.computeVanishingPolinomial(setup.vk_proof.domainBits, setup.toxic.t);
const u = PolF.evaluateLagrangePolynomials(setup.vk_proof.domainBits, setup.toxic.t);
const a_t = new Array(circuit.nVars).fill(F.zero);
const b_t = new Array(circuit.nVars).fill(F.zero);
const c_t = new Array(circuit.nVars).fill(F.zero);
// TODO: substitute setup.polsA for coeficients
for (let s=0; s<circuit.nVars; s++) {
for (let c in setup.vk_proof.polsA[s]) {
a_t[s] = F.add(a_t[s], F.mul(u[c], setup.vk_proof.polsA[s][c]));
}
for (let c in setup.vk_proof.polsB[s]) {
b_t[s] = F.add(b_t[s], F.mul(u[c], setup.vk_proof.polsB[s][c]));
}
for (let c in setup.vk_proof.polsC[s]) {
c_t[s] = F.add(c_t[s], F.mul(u[c], setup.vk_proof.polsC[s][c]));
}
}
return {a_t, b_t, c_t, z_t};
}
function calculateEncriptedValuesAtT(setup, circuit) {
const v = calculateValuesAtT(setup, circuit);
setup.vk_proof.A = new Array(circuit.nVars+1);
setup.vk_proof.B = new Array(circuit.nVars+1);
setup.vk_proof.C = new Array(circuit.nVars+1);
setup.vk_proof.Ap = new Array(circuit.nVars+1);
setup.vk_proof.Bp = new Array(circuit.nVars+1);
setup.vk_proof.Cp = new Array(circuit.nVars+1);
setup.vk_proof.Kp = new Array(circuit.nVars+3);
setup.vk_verifier.A = new Array(circuit.nPublic);
setup.toxic.ka = F.random();
setup.toxic.kb = F.random();
setup.toxic.kc = F.random();
setup.toxic.ra = F.random();
setup.toxic.rb = F.random();
setup.toxic.rc = F.mul(setup.toxic.ra, setup.toxic.rb);
setup.toxic.kbeta = F.random();
setup.toxic.kgamma = F.random();
const gb = F.mul(setup.toxic.kbeta, setup.toxic.kgamma);
setup.vk_verifier.vk_a = G2.affine(G2.mulScalar( G2.g, setup.toxic.ka));
setup.vk_verifier.vk_b = G1.affine(G1.mulScalar( G1.g, setup.toxic.kb));
setup.vk_verifier.vk_c = G2.affine(G2.mulScalar( G2.g, setup.toxic.kc));
setup.vk_verifier.vk_gb_1 = G1.affine(G1.mulScalar( G1.g, gb));
setup.vk_verifier.vk_gb_2 = G2.affine(G2.mulScalar( G2.g, gb));
setup.vk_verifier.vk_g = G2.affine(G2.mulScalar( G2.g, setup.toxic.kgamma));
for (let s=0; s<circuit.nVars; s++) {
// A[i] = G1 * polA(t)
const raat = F.mul(setup.toxic.ra, v.a_t[s]);
const A = G1.affine(G1.mulScalar(G1.g, raat));
setup.vk_proof.A[s] = A;
if (s <= setup.vk_proof.nPublic) {
setup.vk_verifier.A[s]=A;
}
// B1[i] = G1 * polB(t)
const rbbt = F.mul(setup.toxic.rb, v.b_t[s]);
const B1 = G1.affine(G1.mulScalar(G1.g, rbbt));
// B2[i] = G2 * polB(t)
const B2 = G2.affine(G2.mulScalar(G2.g, rbbt));
setup.vk_proof.B[s]=B2;
// C[i] = G1 * polC(t)
const rcct = F.mul(setup.toxic.rc, v.c_t[s]);
const C = G1.affine(G1.mulScalar( G1.g, rcct));
setup.vk_proof.C[s] =C;
// K = G1 * (A+B+C)
const kt = F.affine(F.add(F.add(raat, rbbt), rcct));
const K = G1.affine(G1.mulScalar( G1.g, kt));
/*
// Comment this lines to improve the process
const Ktest = G1.affine(G1.add(G1.add(A, B1), C));
if (!G1.equals(K, Ktest)) {
console.log ("=====FAIL======");
}
*/
setup.vk_proof.Ap[s] = G1.affine(G1.mulScalar(A, setup.toxic.ka));
setup.vk_proof.Bp[s] = G1.affine(G1.mulScalar(B1, setup.toxic.kb));
setup.vk_proof.Cp[s] = G1.affine(G1.mulScalar(C, setup.toxic.kc));
setup.vk_proof.Kp[s] = G1.affine(G1.mulScalar(K, setup.toxic.kbeta));
}
// Extra coeficients
const A = G1.mulScalar( G1.g, F.mul(setup.toxic.ra, v.z_t));
setup.vk_proof.A[circuit.nVars] = G1.affine(A);
setup.vk_proof.Ap[circuit.nVars] = G1.affine(G1.mulScalar(A, setup.toxic.ka));
const B1 = G1.mulScalar( G1.g, F.mul(setup.toxic.rb, v.z_t));
const B2 = G2.mulScalar( G2.g, F.mul(setup.toxic.rb, v.z_t));
setup.vk_proof.B[circuit.nVars] = G2.affine(B2);
setup.vk_proof.Bp[circuit.nVars] = G1.affine(G1.mulScalar(B1, setup.toxic.kb));
const C = G1.mulScalar( G1.g, F.mul(setup.toxic.rc, v.z_t));
setup.vk_proof.C[circuit.nVars] = G1.affine(C);
setup.vk_proof.Cp[circuit.nVars] = G1.affine(G1.mulScalar(C, setup.toxic.kc));
setup.vk_proof.Kp[circuit.nVars ] = G1.affine(G1.mulScalar(A, setup.toxic.kbeta));
setup.vk_proof.Kp[circuit.nVars+1] = G1.affine(G1.mulScalar(B1, setup.toxic.kbeta));
setup.vk_proof.Kp[circuit.nVars+2] = G1.affine(G1.mulScalar(C, setup.toxic.kbeta));
// setup.vk_verifier.A[0] = G1.affine(G1.add(setup.vk_verifier.A[0], setup.vk_proof.A[circuit.nVars]));
// vk_z
setup.vk_verifier.vk_z = G2.affine(G2.mulScalar(
G2.g,
F.mul(setup.toxic.rc, v.z_t)));
}
function calculateHexps(setup) {
const maxH = setup.vk_proof.domainSize+1;
setup.vk_proof.hExps = new Array(maxH);
setup.vk_proof.hExps[0] = G1.g;
let eT = setup.toxic.t;
for (let i=1; i<maxH; i++) {
setup.vk_proof.hExps[i] = G1.affine(G1.mulScalar(G1.g, eT));
eT = F.mul(eT, setup.toxic.t);
}
}