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dca5809b by Brandon Casey Committed by GitHub
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seperate aes-decrypter from hls (#748)

1 parent 356dda76
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Showing 9 changed files with 7 additions and 687 deletions
......@@ -11,7 +11,7 @@ Play back HLS with video.js, even where it's not natively supported.
- [Installation](#installation)
- [NPM](#npm)
- [CDN](#cdn)
- [Local](#local)
- [Releases](#releases)
- [Manual Build](#manual-build)
- [Contributing](#contributing)
- [Getting Started](#getting-started)
......@@ -42,7 +42,9 @@ Play back HLS with video.js, even where it's not natively supported.
- [Testing](#testing)
- [Release History](#release-history)
- [Building](#building)
- [Development Commands](#development-commands)
- [Development](#development)
- [Tools](#tools)
- [Commands](#commands)
<!-- END doctoc generated TOC please keep comment here to allow auto update -->
......
......@@ -84,7 +84,7 @@
],
"dependencies": {
"m3u8-parser": "^1.0.2",
"pkcs7": "^0.2.2",
"aes-decrypter": "^1.0.3",
"video.js": "^5.10.1",
"videojs-contrib-media-sources": "^3.1.0",
"videojs-swf": "^5.0.2"
......
/**
* @file decrypter/aes.js
*
* This file contains an adaptation of the AES decryption algorithm
* from the Standford Javascript Cryptography Library. That work is
* covered by the following copyright and permissions notice:
*
* Copyright 2009-2010 Emily Stark, Mike Hamburg, Dan Boneh.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* The views and conclusions contained in the software and documentation
* are those of the authors and should not be interpreted as representing
* official policies, either expressed or implied, of the authors.
*/
/**
* Expand the S-box tables.
*
* @private
*/
const precompute = function() {
let tables = [[[], [], [], [], []], [[], [], [], [], []]];
let encTable = tables[0];
let decTable = tables[1];
let sbox = encTable[4];
let sboxInv = decTable[4];
let i;
let x;
let xInv;
let d = [];
let th = [];
let x2;
let x4;
let x8;
let s;
let tEnc;
let tDec;
// Compute double and third tables
for (i = 0; i < 256; i++) {
th[(d[i] = i << 1 ^ (i >> 7) * 283) ^ i] = i;
}
for (x = xInv = 0; !sbox[x]; x ^= x2 || 1, xInv = th[xInv] || 1) {
// Compute sbox
s = xInv ^ xInv << 1 ^ xInv << 2 ^ xInv << 3 ^ xInv << 4;
s = s >> 8 ^ s & 255 ^ 99;
sbox[x] = s;
sboxInv[s] = x;
// Compute MixColumns
x8 = d[x4 = d[x2 = d[x]]];
tDec = x8 * 0x1010101 ^ x4 * 0x10001 ^ x2 * 0x101 ^ x * 0x1010100;
tEnc = d[s] * 0x101 ^ s * 0x1010100;
for (i = 0; i < 4; i++) {
encTable[i][x] = tEnc = tEnc << 24 ^ tEnc >>> 8;
decTable[i][s] = tDec = tDec << 24 ^ tDec >>> 8;
}
}
// Compactify. Considerable speedup on Firefox.
for (i = 0; i < 5; i++) {
encTable[i] = encTable[i].slice(0);
decTable[i] = decTable[i].slice(0);
}
return tables;
};
let aesTables = null;
/**
* Schedule out an AES key for both encryption and decryption. This
* is a low-level class. Use a cipher mode to do bulk encryption.
*
* @class AES
* @param key {Array} The key as an array of 4, 6 or 8 words.
*/
export default class AES {
constructor(key) {
/**
* The expanded S-box and inverse S-box tables. These will be computed
* on the client so that we don't have to send them down the wire.
*
* There are two tables, _tables[0] is for encryption and
* _tables[1] is for decryption.
*
* The first 4 sub-tables are the expanded S-box with MixColumns. The
* last (_tables[01][4]) is the S-box itself.
*
* @private
*/
// if we have yet to precompute the S-box tables
// do so now
if (!aesTables) {
aesTables = precompute();
}
// then make a copy of that object for use
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()]];
let i;
let j;
let tmp;
let encKey;
let decKey;
let sbox = this._tables[0][4];
let decTable = this._tables[1];
let keyLen = key.length;
let rcon = 1;
if (keyLen !== 4 && keyLen !== 6 && keyLen !== 8) {
throw new Error('Invalid aes key size');
}
encKey = key.slice(0);
decKey = [];
this._key = [encKey, decKey];
// schedule encryption keys
for (i = keyLen; i < 4 * keyLen + 28; i++) {
tmp = encKey[i - 1];
// apply sbox
if (i % keyLen === 0 || (keyLen === 8 && i % keyLen === 4)) {
tmp = sbox[tmp >>> 24] << 24 ^
sbox[tmp >> 16 & 255] << 16 ^
sbox[tmp >> 8 & 255] << 8 ^
sbox[tmp & 255];
// shift rows and add rcon
if (i % keyLen === 0) {
tmp = tmp << 8 ^ tmp >>> 24 ^ rcon << 24;
rcon = rcon << 1 ^ (rcon >> 7) * 283;
}
}
encKey[i] = encKey[i - keyLen] ^ tmp;
}
// schedule decryption keys
for (j = 0; i; j++, i--) {
tmp = encKey[j & 3 ? i : i - 4];
if (i <= 4 || j < 4) {
decKey[j] = tmp;
} else {
decKey[j] = decTable[0][sbox[tmp >>> 24 ]] ^
decTable[1][sbox[tmp >> 16 & 255]] ^
decTable[2][sbox[tmp >> 8 & 255]] ^
decTable[3][sbox[tmp & 255]];
}
}
}
/**
* Decrypt 16 bytes, specified as four 32-bit words.
*
* @param {Number} encrypted0 the first word to decrypt
* @param {Number} encrypted1 the second word to decrypt
* @param {Number} encrypted2 the third word to decrypt
* @param {Number} encrypted3 the fourth word to decrypt
* @param {Int32Array} out the array to write the decrypted words
* into
* @param {Number} offset the offset into the output array to start
* writing results
* @return {Array} The plaintext.
*/
decrypt(encrypted0, encrypted1, encrypted2, encrypted3, out, offset) {
let key = this._key[1];
// state variables a,b,c,d are loaded with pre-whitened data
let a = encrypted0 ^ key[0];
let b = encrypted3 ^ key[1];
let c = encrypted2 ^ key[2];
let d = encrypted1 ^ key[3];
let a2;
let b2;
let c2;
// key.length === 2 ?
let nInnerRounds = key.length / 4 - 2;
let i;
let kIndex = 4;
let table = this._tables[1];
// load up the tables
let table0 = table[0];
let table1 = table[1];
let table2 = table[2];
let table3 = table[3];
let sbox = table[4];
// Inner rounds. Cribbed from OpenSSL.
for (i = 0; i < nInnerRounds; i++) {
a2 = table0[a >>> 24] ^
table1[b >> 16 & 255] ^
table2[c >> 8 & 255] ^
table3[d & 255] ^
key[kIndex];
b2 = table0[b >>> 24] ^
table1[c >> 16 & 255] ^
table2[d >> 8 & 255] ^
table3[a & 255] ^
key[kIndex + 1];
c2 = table0[c >>> 24] ^
table1[d >> 16 & 255] ^
table2[a >> 8 & 255] ^
table3[b & 255] ^
key[kIndex + 2];
d = table0[d >>> 24] ^
table1[a >> 16 & 255] ^
table2[b >> 8 & 255] ^
table3[c & 255] ^
key[kIndex + 3];
kIndex += 4;
a = a2; b = b2; c = c2;
}
// Last round.
for (i = 0; i < 4; i++) {
out[(3 & -i) + offset] =
sbox[a >>> 24] << 24 ^
sbox[b >> 16 & 255] << 16 ^
sbox[c >> 8 & 255] << 8 ^
sbox[d & 255] ^
key[kIndex++];
a2 = a; a = b; b = c; c = d; d = a2;
}
}
}
/**
* @file decrypter/async-stream.js
*/
import Stream from '../stream';
/**
* A wrapper around the Stream class to use setTiemout
* and run stream "jobs" Asynchronously
*
* @class AsyncStream
* @extends Stream
*/
export default class AsyncStream extends Stream {
constructor() {
super(Stream);
this.jobs = [];
this.delay = 1;
this.timeout_ = null;
}
/**
* process an async job
*
* @private
*/
processJob_() {
this.jobs.shift()();
if (this.jobs.length) {
this.timeout_ = setTimeout(this.processJob_.bind(this),
this.delay);
} else {
this.timeout_ = null;
}
}
/**
* push a job into the stream
*
* @param {Function} job the job to push into the stream
*/
push(job) {
this.jobs.push(job);
if (!this.timeout_) {
this.timeout_ = setTimeout(this.processJob_.bind(this),
this.delay);
}
}
}
/**
* @file decrypter/decrypter.js
*
* An asynchronous implementation of AES-128 CBC decryption with
* PKCS#7 padding.
*/
import AES from './aes';
import AsyncStream from './async-stream';
import {unpad} from 'pkcs7';
/**
* Convert network-order (big-endian) bytes into their little-endian
* representation.
*/
const ntoh = function(word) {
return (word << 24) |
((word & 0xff00) << 8) |
((word & 0xff0000) >> 8) |
(word >>> 24);
};
/**
* Decrypt bytes using AES-128 with CBC and PKCS#7 padding.
*
* @param {Uint8Array} encrypted the encrypted bytes
* @param {Uint32Array} key the bytes of the decryption key
* @param {Uint32Array} initVector the initialization vector (IV) to
* use for the first round of CBC.
* @return {Uint8Array} the decrypted bytes
*
* @see http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
* @see http://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Block_Chaining_.28CBC.29
* @see https://tools.ietf.org/html/rfc2315
*/
export const decrypt = function(encrypted, key, initVector) {
// word-level access to the encrypted bytes
let encrypted32 = new Int32Array(encrypted.buffer,
encrypted.byteOffset,
encrypted.byteLength >> 2);
let decipher = new AES(Array.prototype.slice.call(key));
// byte and word-level access for the decrypted output
let decrypted = new Uint8Array(encrypted.byteLength);
let decrypted32 = new Int32Array(decrypted.buffer);
// temporary variables for working with the IV, encrypted, and
// decrypted data
let init0;
let init1;
let init2;
let init3;
let encrypted0;
let encrypted1;
let encrypted2;
let encrypted3;
// iteration variable
let wordIx;
// pull out the words of the IV to ensure we don't modify the
// passed-in reference and easier access
init0 = initVector[0];
init1 = initVector[1];
init2 = initVector[2];
init3 = initVector[3];
// decrypt four word sequences, applying cipher-block chaining (CBC)
// to each decrypted block
for (wordIx = 0; wordIx < encrypted32.length; wordIx += 4) {
// convert big-endian (network order) words into little-endian
// (javascript order)
encrypted0 = ntoh(encrypted32[wordIx]);
encrypted1 = ntoh(encrypted32[wordIx + 1]);
encrypted2 = ntoh(encrypted32[wordIx + 2]);
encrypted3 = ntoh(encrypted32[wordIx + 3]);
// decrypt the block
decipher.decrypt(encrypted0,
encrypted1,
encrypted2,
encrypted3,
decrypted32,
wordIx);
// XOR with the IV, and restore network byte-order to obtain the
// plaintext
decrypted32[wordIx] = ntoh(decrypted32[wordIx] ^ init0);
decrypted32[wordIx + 1] = ntoh(decrypted32[wordIx + 1] ^ init1);
decrypted32[wordIx + 2] = ntoh(decrypted32[wordIx + 2] ^ init2);
decrypted32[wordIx + 3] = ntoh(decrypted32[wordIx + 3] ^ init3);
// setup the IV for the next round
init0 = encrypted0;
init1 = encrypted1;
init2 = encrypted2;
init3 = encrypted3;
}
return decrypted;
};
/**
* The `Decrypter` class that manages decryption of AES
* data through `AsyncStream` objects and the `decrypt`
* function
*
* @param {Uint8Array} encrypted the encrypted bytes
* @param {Uint32Array} key the bytes of the decryption key
* @param {Uint32Array} initVector the initialization vector (IV) to
* @param {Function} done the function to run when done
* @class Decrypter
*/
export class Decrypter {
constructor(encrypted, key, initVector, done) {
let step = Decrypter.STEP;
let encrypted32 = new Int32Array(encrypted.buffer);
let decrypted = new Uint8Array(encrypted.byteLength);
let i = 0;
this.asyncStream_ = new AsyncStream();
// split up the encryption job and do the individual chunks asynchronously
this.asyncStream_.push(this.decryptChunk_(encrypted32.subarray(i, i + step),
key,
initVector,
decrypted));
for (i = step; i < encrypted32.length; i += step) {
initVector = new Uint32Array([ntoh(encrypted32[i - 4]),
ntoh(encrypted32[i - 3]),
ntoh(encrypted32[i - 2]),
ntoh(encrypted32[i - 1])]);
this.asyncStream_.push(this.decryptChunk_(encrypted32.subarray(i, i + step),
key,
initVector,
decrypted));
}
// invoke the done() callback when everything is finished
this.asyncStream_.push(function() {
// remove pkcs#7 padding from the decrypted bytes
done(null, unpad(decrypted));
});
}
/**
* a getter for step the maximum number of bytes to process at one time
*
* @return {Number} the value of step 32000
*/
static get STEP() {
// 4 * 8000;
return 32000;
}
/**
* @private
*/
decryptChunk_(encrypted, key, initVector, decrypted) {
return function() {
let bytes = decrypt(encrypted, key, initVector);
decrypted.set(bytes, encrypted.byteOffset);
};
}
}
export default {
Decrypter,
decrypt
};
/**
* @file decrypter/index.js
*
* Index module to easily import the primary components of AES-128
* decryption. Like this:
*
* ```js
* import {Decrypter, decrypt, AsyncStream} from './src/decrypter';
* ```
*/
import {decrypt, Decrypter} from './decrypter';
import AsyncStream from './async-stream';
export default {
decrypt,
Decrypter,
AsyncStream
};
......@@ -5,7 +5,7 @@ import Ranges from './ranges';
import {getMediaIndexForTime_ as getMediaIndexForTime, duration} from './playlist';
import videojs from 'video.js';
import SourceUpdater from './source-updater';
import {Decrypter} from './decrypter';
import {Decrypter} from 'aes-decrypter';
import Config from './config';
// in ms
......
......@@ -8,7 +8,7 @@ import document from 'global/document';
import PlaylistLoader from './playlist-loader';
import Playlist from './playlist';
import xhrFactory from './xhr';
import {Decrypter, AsyncStream, decrypt} from './decrypter';
import {Decrypter, AsyncStream, decrypt} from 'aes-decrypter';
import utils from './bin-utils';
import {MediaSource, URL} from 'videojs-contrib-media-sources';
import m3u8 from 'm3u8-parser';
......
// see docs/hlse.md for instructions on how test data was generated
import QUnit from 'qunit';
import {unpad} from 'pkcs7';
import sinon from 'sinon';
import {decrypt, Decrypter, AsyncStream} from '../src/decrypter';
// see docs/hlse.md for instructions on how test data was generated
const stringFromBytes = function(bytes) {
let result = '';
for (let i = 0; i < bytes.length; i++) {
result += String.fromCharCode(bytes[i]);
}
return result;
};
QUnit.module('Decryption');
QUnit.test('decrypts a single AES-128 with PKCS7 block', function() {
let key = new Uint32Array([0, 0, 0, 0]);
let initVector = key;
// the string "howdy folks" encrypted
let encrypted = new Uint8Array([
0xce, 0x90, 0x97, 0xd0,
0x08, 0x46, 0x4d, 0x18,
0x4f, 0xae, 0x01, 0x1c,
0x82, 0xa8, 0xf0, 0x67
]);
QUnit.deepEqual('howdy folks',
stringFromBytes(unpad(decrypt(encrypted, key, initVector))),
'decrypted with a byte array key'
);
});
QUnit.test('decrypts multiple AES-128 blocks with CBC', function() {
let key = new Uint32Array([0, 0, 0, 0]);
let initVector = key;
// the string "0123456789abcdef01234" encrypted
let encrypted = new Uint8Array([
0x14, 0xf5, 0xfe, 0x74,
0x69, 0x66, 0xf2, 0x92,
0x65, 0x1c, 0x22, 0x88,
0xbb, 0xff, 0x46, 0x09,
0x0b, 0xde, 0x5e, 0x71,
0x77, 0x87, 0xeb, 0x84,
0xa9, 0x54, 0xc2, 0x45,
0xe9, 0x4e, 0x29, 0xb3
]);
QUnit.deepEqual('0123456789abcdef01234',
stringFromBytes(unpad(decrypt(encrypted, key, initVector))),
'decrypted multiple blocks');
});
QUnit.test(
'verify that the deepcopy works by doing two decrypts in the same test',
function() {
let key = new Uint32Array([0, 0, 0, 0]);
let initVector = key;
// the string "howdy folks" encrypted
let pkcs7Block = new Uint8Array([
0xce, 0x90, 0x97, 0xd0,
0x08, 0x46, 0x4d, 0x18,
0x4f, 0xae, 0x01, 0x1c,
0x82, 0xa8, 0xf0, 0x67
]);
QUnit.deepEqual('howdy folks',
stringFromBytes(unpad(decrypt(pkcs7Block, key, initVector))),
'decrypted with a byte array key'
);
// the string "0123456789abcdef01234" encrypted
let cbcBlocks = new Uint8Array([
0x14, 0xf5, 0xfe, 0x74,
0x69, 0x66, 0xf2, 0x92,
0x65, 0x1c, 0x22, 0x88,
0xbb, 0xff, 0x46, 0x09,
0x0b, 0xde, 0x5e, 0x71,
0x77, 0x87, 0xeb, 0x84,
0xa9, 0x54, 0xc2, 0x45,
0xe9, 0x4e, 0x29, 0xb3
]);
QUnit.deepEqual('0123456789abcdef01234',
stringFromBytes(unpad(decrypt(cbcBlocks, key, initVector))),
'decrypted multiple blocks');
});
QUnit.module('Incremental Processing', {
beforeEach() {
this.clock = sinon.useFakeTimers();
},
afterEach() {
this.clock.restore();
}
});
QUnit.test('executes a callback after a timeout', function() {
let asyncStream = new AsyncStream();
let calls = '';
asyncStream.push(function() {
calls += 'a';
});
this.clock.tick(asyncStream.delay);
QUnit.equal(calls, 'a', 'invoked the callback once');
this.clock.tick(asyncStream.delay);
QUnit.equal(calls, 'a', 'only invoked the callback once');
});
QUnit.test('executes callback in series', function() {
let asyncStream = new AsyncStream();
let calls = '';
asyncStream.push(function() {
calls += 'a';
});
asyncStream.push(function() {
calls += 'b';
});
this.clock.tick(asyncStream.delay);
QUnit.equal(calls, 'a', 'invoked the first callback');
this.clock.tick(asyncStream.delay);
QUnit.equal(calls, 'ab', 'invoked the second');
});
QUnit.module('Incremental Decryption', {
beforeEach() {
this.clock = sinon.useFakeTimers();
},
afterEach() {
this.clock.restore();
}
});
QUnit.test('asynchronously decrypts a 4-word block', function() {
let key = new Uint32Array([0, 0, 0, 0]);
let initVector = key;
// the string "howdy folks" encrypted
let encrypted = new Uint8Array([0xce, 0x90, 0x97, 0xd0,
0x08, 0x46, 0x4d, 0x18,
0x4f, 0xae, 0x01, 0x1c,
0x82, 0xa8, 0xf0, 0x67]);
let decrypted;
let decrypter = new Decrypter(encrypted,
key,
initVector,
function(error, result) {
if (error) {
throw new Error(error);
}
decrypted = result;
});
QUnit.ok(!decrypted, 'asynchronously decrypts');
this.clock.tick(decrypter.asyncStream_.delay * 2);
QUnit.ok(decrypted, 'completed decryption');
QUnit.deepEqual('howdy folks',
stringFromBytes(decrypted),
'decrypts and unpads the result');
});
QUnit.test('breaks up input greater than the step value', function() {
let encrypted = new Int32Array(Decrypter.STEP + 4);
let done = false;
let decrypter = new Decrypter(encrypted,
new Uint32Array(4),
new Uint32Array(4),
function() {
done = true;
});
this.clock.tick(decrypter.asyncStream_.delay * 2);
QUnit.ok(!done, 'not finished after two ticks');
this.clock.tick(decrypter.asyncStream_.delay);
QUnit.ok(done, 'finished after the last chunk is decrypted');
});