65 lines
1.6 KiB
JavaScript
65 lines
1.6 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 = "mimc";
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const NROUNDS = 91;
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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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return cts;
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};
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const cts = exports.getConstants(SEED, 91);
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exports.hash = (_x_in, _k) =>{
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const x_in = bigInt(_x_in);
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const k = bigInt(_k);
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let r;
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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(x_in, k) : F.add(F.add(r, k), c);
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r = F.exp(t, 7);
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}
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return F.affine(F.add(r, k));
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};
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exports.multiHash = (arr, key) => {
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let r;
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if (typeof(key) === "undefined") {
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r = F.zero;
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} else {
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r = key;
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}
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for (let i=0; i<arr.length; i++) {
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r = F.add(
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F.add(
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r,
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arr[i]
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),
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exports.hash(bigInt(arr[i]), r)
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);
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}
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return F.affine(r);
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};
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