websnark/tools/buildwitness.js

const {unstringifyBigInts} = require("./stringifybigint.js");
const fs = require("fs");
const assert = require("assert");
const process = require("node:process")

var argv = require('minimist')(process.argv.slice(2), { boolean: ['h', 'help'] });
if (argv.help || argv.h) {
    console.log(`node buildpkey.js -i "witness.json" -o "witness.bin"
-i --input default: witness.json
-o --output default: witness.bin
-h --help

Copyright (C) 2018  0kims association
This program comes with ABSOLUTELY NO WARRANTY;
This is free software, and you are welcome to redistribute it under certain conditions;
see the COPYING file in the official repo directory at  https://github.com/iden3/circom`)
    process.exit()
}

const inputName = argv.input || argv.i || "witness.json";
const outputName = argv.output || argv.o || "witness.bin";


const witness = unstringifyBigInts(JSON.parse(fs.readFileSync(inputName, "utf8")));


function writeUint32(h, val) {
    h.dataView.setUint32(h.offset, val, true);
    h.offset += 4;
}


function writeBigInt(h, bi) {
    for (let i=0; i<8; i++) {
        const v = bi.shiftRight(i*32).and(0xFFFFFFFF).toJSNumber();
        writeUint32(h, v);
    }
}


function calculateBuffLen(witness) {

    let size = 0;

    // beta2, delta2
    size += witness.length * 32;

    return size;
}


const buffLen = calculateBuffLen(witness);

const buff = new ArrayBuffer(buffLen);

const h = {
    dataView: new DataView(buff),
    offset: 0
};


// writeUint32(h, witness.length);

for (let i=0; i<witness.length; i++) {
    writeBigInt(h, witness[i]);
}

assert.equal(h.offset, buffLen);

var wstream = fs.createWriteStream(outputName);
wstream.write(Buffer.from(buff));
wstream.end();