rbutil/ipodpatcher/arc4.c

   1 /*
   2  * arc4.c
   3  * Release $Name: MATRIXSSL_1_8_3_OPEN $
   4  *
   5  * ARC4 stream cipher implementation
   6  */
   7 /*
   8  * Copyright (c) PeerSec Networks, 2002-2007. All Rights Reserved.
   9  * The latest version of this code is available at http://www.matrixssl.org
  10  *
  11  * This software is open source; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This General Public License does NOT permit incorporating this software
  17  * into proprietary programs.  If you are unable to comply with the GPL, a
  18  * commercial license for this software may be purchased from PeerSec Networks
  19  * at http://www.peersec.com
  20  *
  21  * This program is distributed in WITHOUT ANY WARRANTY; without even the
  22  * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  23  * See the GNU General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program; if not, write to the Free Software
  27  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  28  * http://www.gnu.org/copyleft/gpl.html
  29  */
  30 /******************************************************************************/
  31
  32 #include "arc4.h"
  33
  34 /*
  35     Some accounts, such as O'Reilly's Secure Programming Cookbook say that no
  36     more than 2^30 bytes should be processed without rekeying, so we
  37     enforce that limit here.  FYI, this is equal to 1GB of data transferred.
  38 */
  39 #define ARC4_MAX_BYTES 0x40000000
  40
  41 /******************************************************************************/
  42 /*
  43     SSL_RSA_WITH_RC4_* cipher callbacks
  44  */
  45 void matrixArc4Init(struct rc4_key_t *ctx, unsigned char *key, int32_t keylen)
  46 {
  47     unsigned char    index1, index2, tmp, *state;
  48     int16_t            counter;
  49
  50     ctx->byteCount = 0;
  51     state = &ctx->state[0];
  52
  53     for (counter = 0; counter < 256; counter++) {
  54         state[counter] = (unsigned char)counter;
  55     }
  56     ctx->x = 0;
  57     ctx->y = 0;
  58     index1 = 0;
  59     index2 = 0;
  60
  61     for (counter = 0; counter < 256; counter++) {
  62         index2 = (key[index1] + state[counter] + index2) & 0xff;
  63
  64         tmp = state[counter];
  65         state[counter] = state[index2];
  66         state[index2] = tmp;
  67
  68         index1 = (index1 + 1) % keylen;
  69     }
  70 }
  71
  72 int32_t matrixArc4(struct rc4_key_t *ctx, unsigned char *in,
  73                    unsigned char *out, int32_t len)
  74 {
  75     unsigned char    x, y, *state, xorIndex, tmp;
  76     int   counter;     /* NOTE BY DAVE CHAPMAN: This was a short in
  77                           the original code, which caused a segfault
  78                           when attempting to process data > 32767
  79                           bytes. */
  80
  81     ctx->byteCount += len;
  82     if (ctx->byteCount > ARC4_MAX_BYTES) {
  83         return -1;
  84     }
  85
  86     x = ctx->x;
  87     y = ctx->y;
  88     state = &ctx->state[0];
  89     for (counter = 0; counter < len; counter++) {
  90         x = (x + 1) & 0xff;
  91         y = (state[x] + y) & 0xff;
  92
  93         tmp = state[x];
  94         state[x] = state[y];
  95         state[y] = tmp;
  96
  97         xorIndex = (state[x] + state[y]) & 0xff;
  98
  99         tmp = in[counter];
 100         tmp ^= state[xorIndex];
 101         out[counter] = tmp;
 102     }
 103     ctx->x = x;
 104     ctx->y = y;
 105     return len;
 106 }
 107
 108 /*****************************************************************************/