amazon-cognito-identity-js/src/utils/cryptoSecureRandomInt.web.js

Amazon Cognito Identity Provider JavaScript SDK

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;
}

/*
 * 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.'
	);
}