104 lines
3.1 KiB
JavaScript
104 lines
3.1 KiB
JavaScript
import sha256 from 'crypto-js/sha256.js';
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import { initialize } from 'zokrates-js';
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window.addEventListener('load', () => {
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document.getElementById('submitFlagBtn')
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.addEventListener('click', () => {
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submitFlag(document.getElementById('flagbox').value);
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});
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});
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const ZEROSTR = '0';
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/* Converts a string into a stringified hexadecimal number */
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function str2hex(string) {
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return string.split('')
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.map(c => c.charCodeAt(0).toString(16).padStart(2, '0'))
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.join('');
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}
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/* Converts a stringified hexadecimal number into a string */
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function hex2str(hex) {
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return hex.split(/(\w\w)/g)
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.filter(p => !!p)
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.map(c => String.fromCharCode(parseInt(c, 16)))
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.join('');
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}
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/* Prefix each element of a string a array with 0x */
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function map_0xprefix(arr) {
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return arr.map(s => '0x' + s);
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}
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/* Convert a string to a byte array */
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function str2asciiarr(s) {
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let charCodeArr = [];
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for (let i = 0; i < s.length; i++) {
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let code = s.charCodeAt(i);
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charCodeArr.push(code);
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}
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return charCodeArr;
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}
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/* Convert a byte array to a string */
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function asciiarr2str(arr) {
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return String.fromCharCode(...arr);
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}
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/*
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* Expand a simple number into a stringified u32[8] array for ZoKrates.
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*/
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function expand_number(number) {
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const revstr = s => Array.from(s).reverse().join('');
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const split8 = s => s.match(/.{1,8}/g);
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const parts = split8(revstr(number.toString(16)))
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.map(p => '0x' + revstr(p))
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.map(p => parseInt(p, 16).toString())
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.reverse();
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return [...Array(8 - parts.length).fill(ZEROSTR), ...parts];
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}
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const proving_key = await (await fetch('/zok_proving.key')).text();
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const program = await (await fetch('/zok_program')).arrayBuffer();
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const abi = await (await fetch('/zok_abi.json')).json();
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/* Get the proving key from the local server */
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const PROVING_KEY_URI = 'http://localhost:8080/proving.key';
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const proving_key = await (await fetch(PROVING_KEY_URI)).text();
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const artefacts = { program: new Uint8Array(program), abi: abi };
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console.log(artefacts);
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function submitFlag(flag) {
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initialize().then((defaultProvider) => {
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const zokProvider = defaultProvider.withOptions({
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backend: 'ark',
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scheme: 'gm17',
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});
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const flag_ascii = str2asciiarr(flag);
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const flag_ascii_padded = flag_ascii.concat(new Array(64 - flag_ascii.length).fill(0));
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const flag_padded = asciiarr2str(flag_ascii_padded);
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const hash = sha256(flag_padded).toString(); /* TODO get this from contract */
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const addr = 'f6e3a49fca2eb57f286d516fa60154ebfd10d5ad'; /* TODO get this from metamask */
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const flag_split = map_0xprefix(str2hex(flag).match(/.{1,2}/g));
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const flag_split_padded = flag_split.concat(new Array(64 - flag_split.length).fill('0x0'));
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const hash_split = map_0xprefix(hash.match(/.{1,8}/g));
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const addr_split = map_0xprefix(addr.match(/.{1,8}/g));
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// witness computation
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console.log('witness');
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const { witness, output } = zokProvider.computeWitness(artefacts, [hash_split, addr_split, flag_split_padded]);
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// generate proof
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console.log('proof');
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const proof = zokProvider.generateProof(artefacts.program, witness, proving_key);
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console.log(proof);
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});
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};
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