crypto/des/ofb_enc.c

   1 /* crypto/des/ofb_enc.c */
   2 /* Copyright (C) 1995-1997 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59 #include "des_locl.h"
  60
  61 /* The input and output are loaded in multiples of 8 bits.
  62  * What this means is that if you hame numbits=12 and length=2
  63  * the first 12 bits will be retrieved from the first byte and half
  64  * the second.  The second 12 bits will come from the 3rd and half the 4th
  65  * byte.
  66  */
  67 void des_ofb_encrypt(in, out, numbits, length, schedule, ivec)
  68 unsigned char *in;
  69 unsigned char *out;
  70 int numbits;
  71 long length;
  72 des_key_schedule schedule;
  73 des_cblock (*ivec);
  74         {
  75         register DES_LONG d0,d1,v0,v1,n=(numbits+7)/8;
  76         register DES_LONG mask0,mask1;
  77         register long l=length;
  78         register int num=numbits;
  79         DES_LONG ti[2];
  80         unsigned char *iv;
  81
  82         if (num > 64) return;
  83         if (num > 32)
  84                 {
  85                 mask0=0xffffffffL;
  86                 if (num >= 64)
  87                         mask1=mask0;
  88                 else
  89                         mask1=(1L<<(num-32))-1;
  90                 }
  91         else
  92                 {
  93                 if (num == 32)
  94                         mask0=0xffffffffL;
  95                 else
  96                         mask0=(1L<<num)-1;
  97                 mask1=0x00000000;
  98                 }
  99
 100         iv=(unsigned char *)ivec;
 101         c2l(iv,v0);
 102         c2l(iv,v1);
 103         ti[0]=v0;
 104         ti[1]=v1;
 105         while (l-- > 0)
 106                 {
 107                 des_encrypt((DES_LONG *)ti,schedule,DES_ENCRYPT);
 108                 c2ln(in,d0,d1,n);
 109                 in+=n;
 110                 d0=(d0^ti[0])&mask0;
 111                 d1=(d1^ti[1])&mask1;
 112                 l2cn(d0,d1,out,n);
 113                 out+=n;
 114                 }
 115         v0=ti[0];
 116         v1=ti[1];
 117         iv=(unsigned char *)ivec;
 118         l2c(v0,iv);
 119         l2c(v1,iv);
 120         v0=v1=d0=d1=ti[0]=ti[1]=0;
 121         }
 122