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groth16_verify.js
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groth16_verify.js
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/*
Copyright 2018 0kims association.
This file is part of snarkjs.
snarkjs 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.
snarkjs 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
snarkjs. If not, see <https://www.gnu.org/licenses/>.
*/
/* Implementation of this paper: https://eprint.iacr.org/2016/260.pdf */
import { Scalar } from "ffjavascript";
import * as curves from "./curves.js";
import { utils } from "ffjavascript";
const {unstringifyBigInts} = utils;
export default async function groth16Verify(_vk_verifier, _publicSignals, _proof, logger) {
/*
let cpub = vk_verifier.IC[0];
for (let s= 0; s< vk_verifier.nPublic; s++) {
cpub = G1.add( cpub, G1.timesScalar( vk_verifier.IC[s+1], publicSignals[s]));
}
*/
const vk_verifier = unstringifyBigInts(_vk_verifier);
const proof = unstringifyBigInts(_proof);
const publicSignals = unstringifyBigInts(_publicSignals);
const curve = await curves.getCurveFromName(vk_verifier.curve);
const IC0 = curve.G1.fromObject(vk_verifier.IC[0]);
const IC = new Uint8Array(curve.G1.F.n8*2 * publicSignals.length);
const w = new Uint8Array(curve.Fr.n8 * publicSignals.length);
if (!publicInputsAreValid(curve, publicSignals)) {
if (logger) logger.error("Public inputs are not valid.");
return false;
}
for (let i=0; i<publicSignals.length; i++) {
const buffP = curve.G1.fromObject(vk_verifier.IC[i+1]);
IC.set(buffP, i*curve.G1.F.n8*2);
Scalar.toRprLE(w, curve.Fr.n8*i, publicSignals[i], curve.Fr.n8);
}
let cpub = await curve.G1.multiExpAffine(IC, w);
cpub = curve.G1.add(cpub, IC0);
const pi_a = curve.G1.fromObject(proof.pi_a);
const pi_b = curve.G2.fromObject(proof.pi_b);
const pi_c = curve.G1.fromObject(proof.pi_c);
if (!isWellConstructed(curve, {pi_a, pi_b, pi_c})) {
if(logger) logger.error("Proof commitments are not valid.");
return false;
}
const vk_gamma_2 = curve.G2.fromObject(vk_verifier.vk_gamma_2);
const vk_delta_2 = curve.G2.fromObject(vk_verifier.vk_delta_2);
const vk_alpha_1 = curve.G1.fromObject(vk_verifier.vk_alpha_1);
const vk_beta_2 = curve.G2.fromObject(vk_verifier.vk_beta_2);
const res = await curve.pairingEq(
curve.G1.neg(pi_a) , pi_b,
cpub , vk_gamma_2,
pi_c , vk_delta_2,
vk_alpha_1, vk_beta_2
);
if (! res) {
if (logger) logger.error("Invalid proof");
return false;
}
if (logger) logger.info("OK!");
return true;
}
function isWellConstructed(curve, proof) {
const G1 = curve.G1;
const G2 = curve.G2;
return G1.isValid(proof.pi_a)
&& G2.isValid(proof.pi_b)
&& G1.isValid(proof.pi_c);
}
function publicInputsAreValid(curve, publicInputs) {
for(let i = 0; i < publicInputs.length; i++) {
if(!Scalar.lt(publicInputs[i], curve.r)) {
return false;
}
}
return true;
}