422 lines
13 KiB
JavaScript
422 lines
13 KiB
JavaScript
/*! @name aes-decrypter @version 4.0.2 @license Apache-2.0 */
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import Stream from '@videojs/vhs-utils/es/stream.js';
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import { unpad } from 'pkcs7';
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/**
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* @file aes.js
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*
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* This file contains an adaptation of the AES decryption algorithm
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* from the Standford Javascript Cryptography Library. That work is
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* covered by the following copyright and permissions notice:
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*
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* Copyright 2009-2010 Emily Stark, Mike Hamburg, Dan Boneh.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
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* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* The views and conclusions contained in the software and documentation
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* are those of the authors and should not be interpreted as representing
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* official policies, either expressed or implied, of the authors.
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*/
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/**
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* Expand the S-box tables.
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*
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* @private
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*/
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const precompute = function () {
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const tables = [[[], [], [], [], []], [[], [], [], [], []]];
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const encTable = tables[0];
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const decTable = tables[1];
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const sbox = encTable[4];
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const sboxInv = decTable[4];
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let i;
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let x;
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let xInv;
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const d = [];
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const th = [];
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let x2;
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let x4;
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let x8;
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let s;
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let tEnc;
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let tDec; // Compute double and third tables
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for (i = 0; i < 256; i++) {
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th[(d[i] = i << 1 ^ (i >> 7) * 283) ^ i] = i;
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}
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for (x = xInv = 0; !sbox[x]; x ^= x2 || 1, xInv = th[xInv] || 1) {
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// Compute sbox
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s = xInv ^ xInv << 1 ^ xInv << 2 ^ xInv << 3 ^ xInv << 4;
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s = s >> 8 ^ s & 255 ^ 99;
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sbox[x] = s;
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sboxInv[s] = x; // Compute MixColumns
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x8 = d[x4 = d[x2 = d[x]]];
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tDec = x8 * 0x1010101 ^ x4 * 0x10001 ^ x2 * 0x101 ^ x * 0x1010100;
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tEnc = d[s] * 0x101 ^ s * 0x1010100;
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for (i = 0; i < 4; i++) {
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encTable[i][x] = tEnc = tEnc << 24 ^ tEnc >>> 8;
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decTable[i][s] = tDec = tDec << 24 ^ tDec >>> 8;
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}
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} // Compactify. Considerable speedup on Firefox.
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for (i = 0; i < 5; i++) {
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encTable[i] = encTable[i].slice(0);
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decTable[i] = decTable[i].slice(0);
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}
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return tables;
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};
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let aesTables = null;
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/**
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* Schedule out an AES key for both encryption and decryption. This
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* is a low-level class. Use a cipher mode to do bulk encryption.
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*
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* @class AES
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* @param key {Array} The key as an array of 4, 6 or 8 words.
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*/
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class AES {
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constructor(key) {
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/**
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* The expanded S-box and inverse S-box tables. These will be computed
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* on the client so that we don't have to send them down the wire.
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*
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* There are two tables, _tables[0] is for encryption and
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* _tables[1] is for decryption.
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*
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* The first 4 sub-tables are the expanded S-box with MixColumns. The
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* last (_tables[01][4]) is the S-box itself.
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*
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* @private
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*/
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// if we have yet to precompute the S-box tables
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// do so now
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if (!aesTables) {
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aesTables = precompute();
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} // then make a copy of that object for use
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this._tables = [[aesTables[0][0].slice(), aesTables[0][1].slice(), aesTables[0][2].slice(), aesTables[0][3].slice(), aesTables[0][4].slice()], [aesTables[1][0].slice(), aesTables[1][1].slice(), aesTables[1][2].slice(), aesTables[1][3].slice(), aesTables[1][4].slice()]];
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let i;
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let j;
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let tmp;
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const sbox = this._tables[0][4];
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const decTable = this._tables[1];
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const keyLen = key.length;
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let rcon = 1;
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if (keyLen !== 4 && keyLen !== 6 && keyLen !== 8) {
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throw new Error('Invalid aes key size');
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}
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const encKey = key.slice(0);
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const decKey = [];
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this._key = [encKey, decKey]; // schedule encryption keys
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for (i = keyLen; i < 4 * keyLen + 28; i++) {
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tmp = encKey[i - 1]; // apply sbox
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if (i % keyLen === 0 || keyLen === 8 && i % keyLen === 4) {
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tmp = sbox[tmp >>> 24] << 24 ^ sbox[tmp >> 16 & 255] << 16 ^ sbox[tmp >> 8 & 255] << 8 ^ sbox[tmp & 255]; // shift rows and add rcon
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if (i % keyLen === 0) {
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tmp = tmp << 8 ^ tmp >>> 24 ^ rcon << 24;
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rcon = rcon << 1 ^ (rcon >> 7) * 283;
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}
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}
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encKey[i] = encKey[i - keyLen] ^ tmp;
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} // schedule decryption keys
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for (j = 0; i; j++, i--) {
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tmp = encKey[j & 3 ? i : i - 4];
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if (i <= 4 || j < 4) {
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decKey[j] = tmp;
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} else {
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decKey[j] = decTable[0][sbox[tmp >>> 24]] ^ decTable[1][sbox[tmp >> 16 & 255]] ^ decTable[2][sbox[tmp >> 8 & 255]] ^ decTable[3][sbox[tmp & 255]];
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}
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}
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}
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/**
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* Decrypt 16 bytes, specified as four 32-bit words.
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*
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* @param {number} encrypted0 the first word to decrypt
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* @param {number} encrypted1 the second word to decrypt
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* @param {number} encrypted2 the third word to decrypt
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* @param {number} encrypted3 the fourth word to decrypt
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* @param {Int32Array} out the array to write the decrypted words
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* into
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* @param {number} offset the offset into the output array to start
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* writing results
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* @return {Array} The plaintext.
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*/
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decrypt(encrypted0, encrypted1, encrypted2, encrypted3, out, offset) {
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const key = this._key[1]; // state variables a,b,c,d are loaded with pre-whitened data
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let a = encrypted0 ^ key[0];
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let b = encrypted3 ^ key[1];
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let c = encrypted2 ^ key[2];
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let d = encrypted1 ^ key[3];
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let a2;
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let b2;
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let c2; // key.length === 2 ?
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const nInnerRounds = key.length / 4 - 2;
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let i;
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let kIndex = 4;
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const table = this._tables[1]; // load up the tables
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const table0 = table[0];
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const table1 = table[1];
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const table2 = table[2];
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const table3 = table[3];
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const sbox = table[4]; // Inner rounds. Cribbed from OpenSSL.
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for (i = 0; i < nInnerRounds; i++) {
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a2 = table0[a >>> 24] ^ table1[b >> 16 & 255] ^ table2[c >> 8 & 255] ^ table3[d & 255] ^ key[kIndex];
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b2 = table0[b >>> 24] ^ table1[c >> 16 & 255] ^ table2[d >> 8 & 255] ^ table3[a & 255] ^ key[kIndex + 1];
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c2 = table0[c >>> 24] ^ table1[d >> 16 & 255] ^ table2[a >> 8 & 255] ^ table3[b & 255] ^ key[kIndex + 2];
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d = table0[d >>> 24] ^ table1[a >> 16 & 255] ^ table2[b >> 8 & 255] ^ table3[c & 255] ^ key[kIndex + 3];
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kIndex += 4;
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a = a2;
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b = b2;
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c = c2;
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} // Last round.
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for (i = 0; i < 4; i++) {
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out[(3 & -i) + offset] = sbox[a >>> 24] << 24 ^ sbox[b >> 16 & 255] << 16 ^ sbox[c >> 8 & 255] << 8 ^ sbox[d & 255] ^ key[kIndex++];
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a2 = a;
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a = b;
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b = c;
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c = d;
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d = a2;
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}
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}
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}
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/**
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* @file async-stream.js
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*/
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/**
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* A wrapper around the Stream class to use setTimeout
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* and run stream "jobs" Asynchronously
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*
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* @class AsyncStream
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* @extends Stream
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*/
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class AsyncStream extends Stream {
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constructor() {
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super(Stream);
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this.jobs = [];
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this.delay = 1;
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this.timeout_ = null;
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}
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/**
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* process an async job
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*
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* @private
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*/
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processJob_() {
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this.jobs.shift()();
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if (this.jobs.length) {
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this.timeout_ = setTimeout(this.processJob_.bind(this), this.delay);
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} else {
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this.timeout_ = null;
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}
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}
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/**
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* push a job into the stream
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*
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* @param {Function} job the job to push into the stream
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*/
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push(job) {
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this.jobs.push(job);
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if (!this.timeout_) {
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this.timeout_ = setTimeout(this.processJob_.bind(this), this.delay);
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}
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}
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}
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/**
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* @file decrypter.js
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*
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* An asynchronous implementation of AES-128 CBC decryption with
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* PKCS#7 padding.
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*/
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/**
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* Convert network-order (big-endian) bytes into their little-endian
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* representation.
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*/
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const ntoh = function (word) {
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return word << 24 | (word & 0xff00) << 8 | (word & 0xff0000) >> 8 | word >>> 24;
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};
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/**
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* Decrypt bytes using AES-128 with CBC and PKCS#7 padding.
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*
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* @param {Uint8Array} encrypted the encrypted bytes
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* @param {Uint32Array} key the bytes of the decryption key
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* @param {Uint32Array} initVector the initialization vector (IV) to
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* use for the first round of CBC.
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* @return {Uint8Array} the decrypted bytes
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*
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* @see http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
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* @see http://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Block_Chaining_.28CBC.29
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* @see https://tools.ietf.org/html/rfc2315
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*/
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const decrypt = function (encrypted, key, initVector) {
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// word-level access to the encrypted bytes
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const encrypted32 = new Int32Array(encrypted.buffer, encrypted.byteOffset, encrypted.byteLength >> 2);
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const decipher = new AES(Array.prototype.slice.call(key)); // byte and word-level access for the decrypted output
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const decrypted = new Uint8Array(encrypted.byteLength);
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const decrypted32 = new Int32Array(decrypted.buffer); // temporary variables for working with the IV, encrypted, and
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// decrypted data
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let init0;
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let init1;
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let init2;
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let init3;
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let encrypted0;
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let encrypted1;
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let encrypted2;
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let encrypted3; // iteration variable
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let wordIx; // pull out the words of the IV to ensure we don't modify the
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// passed-in reference and easier access
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init0 = initVector[0];
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init1 = initVector[1];
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init2 = initVector[2];
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init3 = initVector[3]; // decrypt four word sequences, applying cipher-block chaining (CBC)
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// to each decrypted block
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for (wordIx = 0; wordIx < encrypted32.length; wordIx += 4) {
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// convert big-endian (network order) words into little-endian
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// (javascript order)
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encrypted0 = ntoh(encrypted32[wordIx]);
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encrypted1 = ntoh(encrypted32[wordIx + 1]);
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encrypted2 = ntoh(encrypted32[wordIx + 2]);
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encrypted3 = ntoh(encrypted32[wordIx + 3]); // decrypt the block
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decipher.decrypt(encrypted0, encrypted1, encrypted2, encrypted3, decrypted32, wordIx); // XOR with the IV, and restore network byte-order to obtain the
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// plaintext
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decrypted32[wordIx] = ntoh(decrypted32[wordIx] ^ init0);
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decrypted32[wordIx + 1] = ntoh(decrypted32[wordIx + 1] ^ init1);
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decrypted32[wordIx + 2] = ntoh(decrypted32[wordIx + 2] ^ init2);
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decrypted32[wordIx + 3] = ntoh(decrypted32[wordIx + 3] ^ init3); // setup the IV for the next round
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init0 = encrypted0;
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init1 = encrypted1;
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init2 = encrypted2;
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init3 = encrypted3;
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}
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return decrypted;
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};
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/**
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* The `Decrypter` class that manages decryption of AES
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* data through `AsyncStream` objects and the `decrypt`
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* function
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*
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* @param {Uint8Array} encrypted the encrypted bytes
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* @param {Uint32Array} key the bytes of the decryption key
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* @param {Uint32Array} initVector the initialization vector (IV) to
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* @param {Function} done the function to run when done
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* @class Decrypter
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*/
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class Decrypter {
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constructor(encrypted, key, initVector, done) {
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const step = Decrypter.STEP;
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const encrypted32 = new Int32Array(encrypted.buffer);
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const decrypted = new Uint8Array(encrypted.byteLength);
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let i = 0;
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this.asyncStream_ = new AsyncStream(); // split up the encryption job and do the individual chunks asynchronously
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this.asyncStream_.push(this.decryptChunk_(encrypted32.subarray(i, i + step), key, initVector, decrypted));
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for (i = step; i < encrypted32.length; i += step) {
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initVector = new Uint32Array([ntoh(encrypted32[i - 4]), ntoh(encrypted32[i - 3]), ntoh(encrypted32[i - 2]), ntoh(encrypted32[i - 1])]);
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this.asyncStream_.push(this.decryptChunk_(encrypted32.subarray(i, i + step), key, initVector, decrypted));
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} // invoke the done() callback when everything is finished
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this.asyncStream_.push(function () {
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// remove pkcs#7 padding from the decrypted bytes
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done(null, unpad(decrypted));
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});
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}
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/**
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* a getter for step the maximum number of bytes to process at one time
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*
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* @return {number} the value of step 32000
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*/
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static get STEP() {
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// 4 * 8000;
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return 32000;
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}
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/**
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* @private
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*/
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decryptChunk_(encrypted, key, initVector, decrypted) {
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return function () {
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const bytes = decrypt(encrypted, key, initVector);
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decrypted.set(bytes, encrypted.byteOffset);
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};
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}
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}
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export { AsyncStream, Decrypter, decrypt };
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