drivers/staging/vt6655/rc4.c

   1 /*
   2  * File: rc4.c
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Purpose:
  19  *
  20  * Functions:
  21  *
  22  * Revision History:
  23  *
  24  * Author: Kyle Hsu
  25  *
  26  * Date: Sep 4, 2002
  27  *
  28  */
  29
  30 #if !defined(__RC4_H__)
  31 #include "rc4.h"
  32 #endif
  33
  34 VOID rc4_init(PRC4Ext pRC4, PBYTE pbyKey, UINT cbKey_len)
  35 {
  36     UINT  ust1, ust2;
  37     UINT  keyindex;
  38     UINT  stateindex;
  39     PBYTE pbyst;
  40     UINT  idx;
  41
  42     pbyst = pRC4->abystate;
  43     pRC4->ux = 0;
  44     pRC4->uy = 0;
  45     for (idx = 0; idx < 256; idx++)
  46         pbyst[idx] = (BYTE)idx;
  47     keyindex = 0;
  48     stateindex = 0;
  49     for (idx = 0; idx < 256; idx++) {
  50         ust1 = pbyst[idx];
  51         stateindex = (stateindex + pbyKey[keyindex] + ust1) & 0xff;
  52         ust2 = pbyst[stateindex];
  53         pbyst[stateindex] = (BYTE)ust1;
  54         pbyst[idx] = (BYTE)ust2;
  55         if (++keyindex >= cbKey_len)
  56             keyindex = 0;
  57     }
  58 }
  59
  60 UINT rc4_byte(PRC4Ext pRC4)
  61 {
  62     UINT ux;
  63     UINT uy;
  64     UINT ustx, usty;
  65     PBYTE pbyst;
  66
  67     pbyst = pRC4->abystate;
  68     ux = (pRC4->ux + 1) & 0xff;
  69     ustx = pbyst[ux];
  70     uy = (ustx + pRC4->uy) & 0xff;
  71     usty = pbyst[uy];
  72     pRC4->ux = ux;
  73     pRC4->uy = uy;
  74     pbyst[uy] = (BYTE)ustx;
  75     pbyst[ux] = (BYTE)usty;
  76
  77     return pbyst[(ustx + usty) & 0xff];
  78 }
  79
  80 VOID rc4_encrypt(PRC4Ext pRC4, PBYTE pbyDest,
  81                      PBYTE pbySrc, UINT cbData_len)
  82 {
  83     UINT ii;
  84     for (ii = 0; ii < cbData_len; ii++)
  85         pbyDest[ii] = (BYTE)(pbySrc[ii] ^ rc4_byte(pRC4));
  86 }