1 /* arcfour.c --- The arcfour stream cipher
2 * Copyright (C) 2000-2003, 2005-2006, 2009-2012 Free Software Foundation, Inc.
4 * This file is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published
6 * by the Free Software Foundation; either version 2, or (at your
7 * option) any later version.
9 * This file is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this file; if not, see <http://www.gnu.org/licenses/>.
19 /* Code from Libgcrypt adapted for gnulib by Simon Josefsson. */
22 * For a description of the algorithm, see:
23 * Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1996.
24 * ISBN 0-471-11709-9. Pages 397 ff.
32 arcfour_stream (arcfour_context * context, const char *inbuf, char *outbuf,
35 uint8_t i = context->idx_i;
36 uint8_t j = context->idx_j;
37 char *sbox = context->sbox;
39 for (; length > 0; length--)
49 ^ sbox[(0U + sbox[i] + sbox[j]) % ARCFOUR_SBOX_SIZE]);
57 arcfour_setkey (arcfour_context * context, const char *key, size_t keylen)
60 char *sbox = context->sbox;
62 context->idx_i = context->idx_j = 0;
63 for (i = 0; i < ARCFOUR_SBOX_SIZE; i++)
65 for (i = j = k = 0; i < ARCFOUR_SBOX_SIZE; i++)
68 j = (j + sbox[i] + key[k]) % ARCFOUR_SBOX_SIZE;