1 /* <!-- copyright */
2 /*
3 * aria2 - The high speed download utility
4 *
5 * Copyright (C) 2013 Nils Maier
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 *
21 * In addition, as a special exception, the copyright holders give
22 * permission to link the code of portions of this program with the
23 * OpenSSL library under certain conditions as described in each
24 * individual source file, and distribute linked combinations
25 * including the two.
26 * You must obey the GNU General Public License in all respects
27 * for all of the code used other than OpenSSL. If you modify
28 * file(s) with this exception, you may extend this exception to your
29 * version of the file(s), but you are not obligated to do so. If you
30 * do not wish to do so, delete this exception statement from your
31 * version. If you delete this exception statement from all source
32 * files in the program, then also delete it here.
33 */
34 /* copyright --> */
35
36 #include "InternalARC4Encryptor.h"
37
38 namespace aria2 {
39
init(const unsigned char * key,size_t keyLength)40 void ARC4Encryptor::init(const unsigned char* key, size_t keyLength)
41 {
42 j = 0;
43 for (auto& c : state_)
44 c = j++;
45
46 j = 0;
47 for (i = 0; i < sizeof(state_); ++i) {
48 j = (j + state_[i] + key[i % keyLength]) & 0xff;
49 auto tmp = state_[i];
50 state_[i] = state_[j];
51 state_[j] = tmp;
52 }
53 i = j = 0;
54 }
55
encrypt(size_t len,unsigned char * out,const unsigned char * in)56 void ARC4Encryptor::encrypt(size_t len, unsigned char* out,
57 const unsigned char* in)
58 {
59 for (auto c = 0u; c < len; ++c) {
60 i = (i + 1) & 0xff;
61 j = (j + state_[i]) & 0xff;
62 auto sj = state_[i];
63 auto si = state_[i] = state_[j];
64 state_[j] = sj;
65 out[c] = in[c] ^ state_[(si + sj) & 0xff];
66 }
67 }
68
69 } // namespace aria2
70