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996fe143 by brandonocasey
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moved ntoh, decrypt, and Decrypter into the same file

1 parent 8cf9c6e1
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Showing 5 changed files with 106 additions and 103 deletions
import Stream from '../stream';
/**
* A wrapper around the Stream class to use setTiemout
* and run stream "jobs" Asynchronously
*/
export default class AsyncStream extends Stream {
constructor() {
super(Stream);
......
import ntoh from './ntoh';
import AES from './aes';
/* eslint-disable max-len */
/**
* Decrypt bytes using AES-128 with CBC and PKCS#7 padding.
* @param encrypted {Uint8Array} the encrypted bytes
* @param key {Uint32Array} the bytes of the decryption key
* @param initVector {Uint32Array} 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
*/
/* eslint-enable max-len */
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;
};
export default decrypt;
import AES from './aes';
import AsyncStream from './async-stream';
import ntoh from './ntoh';
import {unpad} from 'pkcs7';
import decrypt from './decrypt';
export default class Decrypter {
/**
* 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);
};
/* eslint-disable max-len */
/**
* Decrypt bytes using AES-128 with CBC and PKCS#7 padding.
* @param encrypted {Uint8Array} the encrypted bytes
* @param key {Uint32Array} the bytes of the decryption key
* @param initVector {Uint32Array} 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
*/
/* eslint-enable max-len */
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;
};
export class Decrypter {
constructor(encrypted, key, initVector, done) {
let step = Decrypter.STEP;
let encrypted32 = new Int32Array(encrypted.buffer);
......@@ -46,3 +140,7 @@ export default class Decrypter {
// 4 * 8000;
Decrypter.STEP = 32000;
export default {
Decrypter,
decrypt
};
......
import decrypt from './decrypt';
import {decrypt, Decrypter} from './decrypter';
import AsyncStream from './async-stream';
import Decrypter from './decrypter';
export default {
decrypt,
......
/**
* 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);
};
export default ntoh;