websnark/tools/buildwitness.js
tools/buildwitness.jsRaw
1const {unstringifyBigInts} = require("./stringifybigint.js");
2const fs = require("fs");
3const assert = require("assert");
4
5const version = require("../package").version;
6
7const argv = require("yargs")
8 .version(version)
9 .usage(`node buildpkey.js -i "witness.json" -o "witness.bin"
10 Default: circuit.json
11 `)
12 .alias("i", "input")
13 .alias("o", "output")
14 .help("h")
15 .alias("h", "help")
16 .epilogue(`Copyright (C) 2018 0kims association
17 This program comes with ABSOLUTELY NO WARRANTY;
18 This is free software, and you are welcome to redistribute it
19 under certain conditions; see the COPYING file in the official
20 repo directory at https://github.com/iden3/circom `)
21 .argv;
22
23const inputName = (argv.input) ? argv.input : "witness.json";
24const outputName = (argv.output) ? argv.output : "witness.bin";
25
26
27const witness = unstringifyBigInts(JSON.parse(fs.readFileSync(inputName, "utf8")));
28
29
30function writeUint32(h, val) {
31 h.dataView.setUint32(h.offset, val, true);
32 h.offset += 4;
33}
34
35
36function writeBigInt(h, bi) {
37 for (let i=0; i<8; i++) {
38 const v = bi.shiftRight(i*32).and(0xFFFFFFFF).toJSNumber();
39 writeUint32(h, v);
40 }
41}
42
43
44function calculateBuffLen(witness) {
45
46 let size = 0;
47
48 // beta2, delta2
49 size += witness.length * 32;
50
51 return size;
52}
53
54
55const buffLen = calculateBuffLen(witness);
56
57const buff = new ArrayBuffer(buffLen);
58
59const h = {
60 dataView: new DataView(buff),
61 offset: 0
62};
63
64
65// writeUint32(h, witness.length);
66
67for (let i=0; i<witness.length; i++) {
68 writeBigInt(h, witness[i]);
69}
70
71assert.equal(h.offset, buffLen);
72
73var wstream = fs.createWriteStream(outputName);
74wstream.write(Buffer.from(buff));
75wstream.end();
76