87 lines
2.2 KiB
JavaScript
87 lines
2.2 KiB
JavaScript
const bn128 = require("@tornado/snarkjs").bn128;
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const bigInt = require("@tornado/snarkjs").bigInt;
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const Web3Utils = require("web3-utils");
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const F = bn128.Fr;
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const SEED = "mimcsponge";
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const NROUNDS = 220;
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exports.getIV = (seed) => {
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if (typeof seed === "undefined") seed = SEED;
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const c = Web3Utils.keccak256(seed+"_iv");
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const cn = bigInt(Web3Utils.toBN(c).toString());
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const iv = cn.mod(F.q);
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return iv;
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};
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exports.getConstants = (seed, nRounds) => {
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if (typeof seed === "undefined") seed = SEED;
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if (typeof nRounds === "undefined") nRounds = NROUNDS;
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const cts = new Array(nRounds);
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let c = Web3Utils.keccak256(SEED);
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for (let i=1; i<nRounds; i++) {
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c = Web3Utils.keccak256(c);
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const n1 = Web3Utils.toBN(c).mod(Web3Utils.toBN(F.q.toString()));
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const c2 = Web3Utils.padLeft(Web3Utils.toHex(n1), 64);
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cts[i] = bigInt(Web3Utils.toBN(c2).toString());
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}
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cts[0] = bigInt(0);
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cts[cts.length - 1] = bigInt(0);
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return cts;
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};
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const cts = exports.getConstants(SEED, NROUNDS);
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exports.hash = (_xL_in, _xR_in, _k) =>{
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let xL = bigInt(_xL_in);
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let xR = bigInt(_xR_in);
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const k = bigInt(_k);
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for (let i=0; i<NROUNDS; i++) {
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const c = cts[i];
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const t = (i==0) ? F.add(xL, k) : F.add(F.add(xL, k), c);
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const xR_tmp = bigInt(xR);
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if (i < (NROUNDS - 1)) {
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xR = xL;
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xL = F.add(xR_tmp, F.exp(t, 5));
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} else {
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xR = F.add(xR_tmp, F.exp(t, 5));
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}
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}
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return {
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xL: F.affine(xL),
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xR: F.affine(xR),
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};
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};
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exports.multiHash = (arr, key, numOutputs) => {
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if (typeof(numOutputs) === "undefined") {
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numOutputs = 1;
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}
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if (typeof(key) === "undefined") {
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key = F.zero;
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}
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let R = F.zero;
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let C = F.zero;
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for (let i=0; i<arr.length; i++) {
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R = F.add(R, bigInt(arr[i]));
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const S = exports.hash(R, C, key);
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R = S.xL;
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C = S.xR;
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}
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let outputs = [R];
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for (let i=1; i < numOutputs; i++) {
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const S = exports.hash(R, C, key);
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R = S.xL;
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C = S.xR;
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outputs.push(R);
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}
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if (numOutputs == 1) {
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return F.affine(outputs[0]);
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} else {
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return outputs.map(x => F.affine(x));
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}
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};
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