@keybittech/awayto/app/src/core/auth/cryptoSecureRandomInt.js

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/*!
 * Copyright 2016 Amazon.com,
 * Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Amazon Software License (the "License").
 * You may not use this file except in compliance with the
 * License. A copy of the License is located at
 *
 *     http://aws.amazon.com/asl/
 *
 * or in the "license" file accompanying this file. This file is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 * CONDITIONS OF ANY KIND, express or implied. See the License
 * for the specific language governing permissions and
 * limitations under the License.
 */

var crypto;

// Native crypto from window (Browser)
if (typeof window !== 'undefined' && window.crypto) {
	crypto = window.crypto;
}

// Native (experimental IE 11) crypto from window (Browser)
if (!crypto && typeof window !== 'undefined' && window.msCrypto) {
	crypto = window.msCrypto;
}

// Native crypto from global (NodeJS)
if (!crypto && typeof global !== 'undefined' && global.crypto) {
	crypto = global.crypto;
}

// Native crypto import via require (NodeJS)
if (!crypto && typeof require === 'function') {
	try {
		crypto = require('crypto');
	} catch (err) {}
}

/*
 * Cryptographically secure pseudorandom number generator
 * As Math.random() is cryptographically not safe to use
 */
export default function cryptoSecureRandomInt() {
	if (crypto) {
		// Use getRandomValues method (Browser)
		if (typeof crypto.getRandomValues === 'function') {
			try {
				return crypto.getRandomValues(new Uint32Array(1))[0];
			} catch (err) {}
		}

		// Use randomBytes method (NodeJS)
		if (typeof crypto.randomBytes === 'function') {
			try {
				return crypto.randomBytes(4).readInt32LE();
			} catch (err) {}
		}
	}

	throw new Error(
		'Native crypto module could not be used to get secure random number.'
	);
}