merge

scripts/utils.js

@@ -0,0 +1,117 @@
+// This file is a bit of a mess because of different bigInt formats in websnark and snarkjs
+// It will be rewritten during browser integration
+
+const fs = require('fs');
+const circom = require("circom");
+const snarkjs = require("snarkjs");
+const groth = snarkjs["groth"];
+const crypto = require("crypto");
+const circomlib = require('circomlib');
+const pedersen = circomlib.pedersenHash;
+const babyjub = circomlib.babyJub;
+const mimcsponge = circomlib.mimcsponge;
+const bigInt = snarkjs.bigInt;
+const buildGroth16 = require('websnark/src/groth16');
+const stringifyBigInts = require("websnark/tools/stringifybigint").stringifyBigInts;
+const unstringifyBigInts = require("websnark/tools/stringifybigint").unstringifyBigInts;
+const stringifyBigInts2 = require("snarkjs/src/stringifybigint").stringifyBigInts;
+const unstringifyBigInts2 = require("snarkjs/src/stringifybigint").unstringifyBigInts;
+
+const rbigint = (nbytes) => snarkjs.bigInt.leBuff2int(crypto.randomBytes(nbytes));
+
+function unhexBigInts(o) {
+  if ((typeof(o) == "string") && (/^0x[0-9a-fA-F]+$/.test(o)))  {
+    return bigInt(o);
+  } else if (Array.isArray(o)) {
+    return o.map(unhexBigInts);
+  } else if (typeof o == "object") {
+    const res = {};
+    for (let k in o) {
+      res[k] = unhexBigInts(o[k]);
+    }
+    return res;
+  } else {
+    return o;
+  }
+}
+
+function pedersenHash(data) {
+  return babyjub.unpackPoint(pedersen.hash(data))[0];
+}
+
+
+function mimcHash(left, right) {
+  return mimcsponge.multiHash([bigInt(left), bigInt(right)]).toString();
+}
+
+function p256(o) {
+  if ((typeof(o) == "bigint") || (o instanceof bigInt))  {
+    let nstr = o.toString(16);
+    while (nstr.length < 64) nstr = "0"+nstr;
+    nstr = "0x"+nstr;
+    return nstr;
+  } else if (Array.isArray(o)) {
+    return o.map(p256);
+  } else if (typeof o == "object") {
+    const res = {};
+    for (let k in o) {
+      if (k === "value") {
+        return p256(o[k]);
+      }
+      res[k] = p256(o[k]);
+    }
+    return res;
+  } else {
+    return o;
+  }
+}
+
+function convertWitness(witness) {
+  witness = unstringifyBigInts(witness);
+  const buffLen = witness.length * 32;
+  const buff = new ArrayBuffer(buffLen);
+  const h = {
+    dataView: new DataView(buff),
+    offset: 0
+  };
+  for (let i=0; i<witness.length; i++) {
+    for (let j=0; j<8; j++) {
+      const v = witness[i].shiftRight(j*32).and(0xFFFFFFFF).toJSNumber();
+      h.dataView.setUint32(h.offset, v, true);
+      h.offset += 4;
+    }
+  }
+  return buff;
+}
+
+async function snarkProof(input) {
+  input = unstringifyBigInts2(input);
+  const circuit = new snarkjs.Circuit(unstringifyBigInts2(require("../build/circuits/withdraw.json")));
+  const proving_key = fs.readFileSync("../build/circuits/withdraw_proving_key.bin");
+
+  const witness = circuit.calculateWitness(input);
+  const witnessBin = convertWitness(stringifyBigInts2(witness));
+  const publicSignals = witness.slice(1, circuit.nPubInputs + circuit.nOutputs + 1);
+
+  const groth16 = await buildGroth16();
+  let proof = await groth16.proof(witnessBin, proving_key.buffer);
+  return p256(unstringifyBigInts2(stringifyBigInts({
+    pi_a: [proof.pi_a[0], proof.pi_a[1]],
+    pi_b: [[proof.pi_b[0][1], proof.pi_b[0][0]], [proof.pi_b[1][1], proof.pi_b[1][0]]],
+    pi_c: [proof.pi_c[0], proof.pi_c[1]],
+    publicSignals: publicSignals,
+  })));
+}
+
+async function snarkVerify(proof) {
+  proof = unhexBigInts(proof);
+  const verification_key = unstringifyBigInts2(require('../build/circuits/withdraw_verification_key.json'));
+  const data = {
+    pi_a: [proof.pi_a[0], proof.pi_a[1], bigInt(1)],
+    pi_b: [[proof.pi_b[0][1], proof.pi_b[0][0]], [proof.pi_b[1][1], proof.pi_b[1][0]], [bigInt(1), bigInt(0)]],
+    pi_c: [proof.pi_c[0], proof.pi_c[1], bigInt(1)]
+  };
+  return groth.isValid(verification_key, data, proof.publicSignals);
+}
+
+module.exports = {rbigint, pedersenHash, snarkProof, mimcHash, snarkVerify, unhexBigInts};