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65 lines
2.4 KiB
JavaScript
65 lines
2.4 KiB
JavaScript
// GPG4Browsers - An OpenPGP implementation in javascript
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// Copyright (C) 2011 Recurity Labs GmbH
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 3.0 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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// The GPG4Browsers crypto interface
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/**
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* @fileoverview Provides tools for retrieving secure randomness from browsers or Node.js
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* @module crypto/random
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*/
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import { byteLength, mod, uint8ArrayToBigInt } from './biginteger';
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import util from '../util';
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const nodeCrypto = util.getNodeCrypto();
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/**
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* Retrieve secure random byte array of the specified length
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* @param {Integer} length - Length in bytes to generate
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* @returns {Uint8Array} Random byte array.
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*/
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export function getRandomBytes(length) {
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const webcrypto = typeof crypto !== 'undefined' ? crypto : nodeCrypto?.webcrypto;
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if (webcrypto?.getRandomValues) {
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const buf = new Uint8Array(length);
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return webcrypto.getRandomValues(buf);
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} else {
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throw new Error('No secure random number generator available.');
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}
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}
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/**
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* Create a secure random BigInt that is greater than or equal to min and less than max.
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* @param {bigint} min - Lower bound, included
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* @param {bigint} max - Upper bound, excluded
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* @returns {bigint} Random BigInt.
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* @async
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*/
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export function getRandomBigInteger(min, max) {
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if (max < min) {
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throw new Error('Illegal parameter value: max <= min');
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}
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const modulus = max - min;
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const bytes = byteLength(modulus);
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// Using a while loop is necessary to avoid bias introduced by the mod operation.
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// However, we request 64 extra random bits so that the bias is negligible.
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// Section B.1.1 here: https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf
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const r = uint8ArrayToBigInt(getRandomBytes(bytes + 8));
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return mod(r, modulus) + min;
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}
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