crypto/cast/c_cfb64.c

   1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   2  * All rights reserved.
   3  *
   4  * This package is an SSL implementation written
   5  * by Eric Young (eay@cryptsoft.com).
   6  * The implementation was written so as to conform with Netscapes SSL.
   7  *
   8  * This library is free for commercial and non-commercial use as long as
   9  * the following conditions are aheared to.  The following conditions
  10  * apply to all code found in this distribution, be it the RC4, RSA,
  11  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  12  * included with this distribution is covered by the same copyright terms
  13  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  14  *
  15  * Copyright remains Eric Young's, and as such any Copyright notices in
  16  * the code are not to be removed.
  17  * If this package is used in a product, Eric Young should be given attribution
  18  * as the author of the parts of the library used.
  19  * This can be in the form of a textual message at program startup or
  20  * in documentation (online or textual) provided with the package.
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  * 3. All advertising materials mentioning features or use of this software
  31  *    must display the following acknowledgement:
  32  *    "This product includes cryptographic software written by
  33  *     Eric Young (eay@cryptsoft.com)"
  34  *    The word 'cryptographic' can be left out if the rouines from the library
  35  *    being used are not cryptographic related :-).
  36  * 4. If you include any Windows specific code (or a derivative thereof) from
  37  *    the apps directory (application code) you must include an acknowledgement:
  38  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  50  * SUCH DAMAGE.
  51  *
  52  * The licence and distribution terms for any publically available version or
  53  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  54  * copied and put under another distribution licence
  55  * [including the GNU Public Licence.]
  56  */
  57
  58 #include <openssl/cast.h>
  59 #include "cast_lcl.h"
  60
  61 /*
  62  * The input and output encrypted as though 64bit cfb mode is being used.
  63  * The extra state information to record how much of the 64bit block we have
  64  * used is contained in *num;
  65  */
  66
  67 void CAST_cfb64_encrypt(const unsigned char *in, unsigned char *out,
  68                         long length, const CAST_KEY *schedule,
  69                         unsigned char *ivec, int *num, int enc)
  70 {
  71     register CAST_LONG v0, v1, t;
  72     register int n = *num;
  73     register long l = length;
  74     CAST_LONG ti[2];
  75     unsigned char *iv, c, cc;
  76
  77     iv = ivec;
  78     if (enc) {
  79         while (l--) {
  80             if (n == 0) {
  81                 n2l(iv, v0);
  82                 ti[0] = v0;
  83                 n2l(iv, v1);
  84                 ti[1] = v1;
  85                 CAST_encrypt((CAST_LONG *)ti, schedule);
  86                 iv = ivec;
  87                 t = ti[0];
  88                 l2n(t, iv);
  89                 t = ti[1];
  90                 l2n(t, iv);
  91                 iv = ivec;
  92             }
  93             c = *(in++) ^ iv[n];
  94             *(out++) = c;
  95             iv[n] = c;
  96             n = (n + 1) & 0x07;
  97         }
  98     } else {
  99         while (l--) {
 100             if (n == 0) {
 101                 n2l(iv, v0);
 102                 ti[0] = v0;
 103                 n2l(iv, v1);
 104                 ti[1] = v1;
 105                 CAST_encrypt((CAST_LONG *)ti, schedule);
 106                 iv = ivec;
 107                 t = ti[0];
 108                 l2n(t, iv);
 109                 t = ti[1];
 110                 l2n(t, iv);
 111                 iv = ivec;
 112             }
 113             cc = *(in++);
 114             c = iv[n];
 115             iv[n] = cc;
 116             *(out++) = c ^ cc;
 117             n = (n + 1) & 0x07;
 118         }
 119     }
 120     v0 = v1 = ti[0] = ti[1] = t = c = cc = 0;
 121     *num = n;
 122 }