notesnook/packages/core/utils/random.js

/* This file is part of the Notesnook project (https://notesnook.com/)
 *
 * Copyright (C) 2022 Streetwriters (Private) Limited
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/**
 *
 * @param {number} size
 * @returns {Buffer}
 */
module.exports.randomBytes = function randomBytes(size) {
  if (!global.crypto || !crypto)
    throw new Error("Crypto is not supported on this platform.");
  if (crypto.randomBytes) return crypto.randomBytes(size);

  if (!crypto.getRandomValues)
    throw new Error(
      "Crypto.getRandomValues is not available on this platform."
    );

  const buffer = Buffer.allocUnsafe(size);
  crypto.getRandomValues(buffer);
  return buffer;
};

module.exports.randomInt = function () {
  const randomBuffer = module.exports.randomBytes(1);
  let randomNumber = randomBuffer[0] / 0xff; // / (0xffffffff + 1);

  return Math.floor(randomNumber * 0xffffff);
};