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/*
GoToSocial
Copyright (C) GoToSocial Authors admin@gotosocial.org
SPDX-License-Identifier: AGPL-3.0-or-later
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import sha256 from "./sha256";
let compute = async function(challengeStr, diffStr) {
const textEncoder = new TextEncoder();
// Get difficulty1 as number and generate
// expected zero ASCII prefix to check for.
const diff1 = parseInt(diffStr, 10);
const zeros = "0".repeat(diff1);
// Calculate hex encoded prefix required to check solution, where we
// need diff1 no. chars in hex, and hex encoding doubles input length.
const prefixLen = diff1 / 2 + (diff1 % 2 != 0 ? 2 : 0);
let nonce = 0;
while (true) { // eslint-disable-line no-constant-condition
// Create possible solution string from challenge string + nonce.
const solution = textEncoder.encode(challengeStr + nonce.toString());
// Generate SHA256 hashsum of solution string, and hex encode the
// necessary prefix length we need to check for a valid solution.
const prefixArray = Array.from(sha256(solution).slice(0, prefixLen));
const prefixHex = prefixArray.map(b => b.toString(16).padStart(2, "0")).join("");
// Check if the hex encoded hash has
// difficulty defined zeroes prefix.
if (prefixHex.startsWith(zeros)) {
return nonce;
}
// Iter.
nonce++;
}
};
onmessage = async function(e) {
console.log('worker started'); // eslint-disable-line no-console
const challenge = e.data.challenge;
const difficulty = e.data.difficulty;
// Compute the nonce that produces solution with args.
let nonce = await compute(challenge, difficulty);
// Post the solution nonce back to caller.
postMessage({ nonce: nonce, done: true });
};
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