drivers/staging/vt6656/rc4.c

   1 /*
   2  * Copyright (c) 1996, 2003 VIA Networking Technologies, Inc.
   3  * All rights reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * File: rc4.c
  20  *
  21  * Purpose:
  22  *
  23  * Functions:
  24  *
  25  * Revision History:
  26  *
  27  * Author: Kyle Hsu
  28  *
  29  * Date: Sep 4, 2002
  30  *
  31  */
  32
  33 #include "rc4.h"
  34
  35 void rc4_init(PRC4Ext pRC4, PBYTE pbyKey, unsigned int cbKey_len)
  36 {
  37         unsigned int  ust1, ust2;
  38         unsigned int  keyindex;
  39         unsigned int  stateindex;
  40         PBYTE pbyst;
  41         unsigned int  idx;
  42
  43         pbyst = pRC4->abystate;
  44         pRC4->ux = 0;
  45         pRC4->uy = 0;
  46         for (idx = 0; idx < 256; idx++)
  47                 pbyst[idx] = (BYTE)idx;
  48         keyindex = 0;
  49         stateindex = 0;
  50         for (idx = 0; idx < 256; idx++) {
  51                 ust1 = pbyst[idx];
  52                 stateindex = (stateindex + pbyKey[keyindex] + ust1) & 0xff;
  53                 ust2 = pbyst[stateindex];
  54                 pbyst[stateindex] = (BYTE)ust1;
  55                 pbyst[idx] = (BYTE)ust2;
  56                 if (++keyindex >= cbKey_len)
  57                         keyindex = 0;
  58         }
  59 }
  60
  61 unsigned int rc4_byte(PRC4Ext pRC4)
  62 {
  63         unsigned int ux;
  64         unsigned int uy;
  65         unsigned int ustx, usty;
  66         PBYTE pbyst;
  67
  68         pbyst = pRC4->abystate;
  69         ux = (pRC4->ux + 1) & 0xff;
  70         ustx = pbyst[ux];
  71         uy = (ustx + pRC4->uy) & 0xff;
  72         usty = pbyst[uy];
  73         pRC4->ux = ux;
  74         pRC4->uy = uy;
  75         pbyst[uy] = (BYTE)ustx;
  76         pbyst[ux] = (BYTE)usty;
  77
  78         return pbyst[(ustx + usty) & 0xff];
  79 }
  80
  81 void rc4_encrypt(PRC4Ext pRC4, PBYTE pbyDest,
  82                         PBYTE pbySrc, unsigned int cbData_len)
  83 {
  84         unsigned int ii;
  85         for (ii = 0; ii < cbData_len; ii++)
  86                 pbyDest[ii] = (BYTE)(pbySrc[ii] ^ rc4_byte(pRC4));
  87 }