@keybittech/awayto/app/src/core/auth/WordArray.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.
 */

import cryptoSecureRandomInt from './cryptoSecureRandomInt';

/**
 * Hex encoding strategy.
 * Converts a word array to a hex string.
 * @param {WordArray} wordArray The word array.
 * @return {string} The hex string.
 * @static
 */
function hexStringify(wordArray) {
	// Shortcuts
	var words = wordArray.words;
	var sigBytes = wordArray.sigBytes;

	// Convert
	var hexChars = [];
	for (var i = 0; i < sigBytes; i++) {
		var bite = (words[i >>> 2] >>> (24 - (i % 4) * 8)) & 0xff;
		hexChars.push((bite >>> 4).toString(16));
		hexChars.push((bite & 0x0f).toString(16));
	}

	return hexChars.join('');
}

export default class WordArray {
	constructor(words, sigBytes) {
		words = this.words = words || [];

		if (sigBytes != undefined) {
			this.sigBytes = sigBytes;
		} else {
			this.sigBytes = words.length * 4;
		}
	}

	random(nBytes) {
		var words = [];

		for (var i = 0; i < nBytes; i += 4) {
			words.push(cryptoSecureRandomInt());
		}

		return new WordArray(words, nBytes);
	}

	toString() {
		return hexStringify(this);
	}
}