cfb64enc.c revision 296465 
1/* crypto/des/cfb64enc.c */
2/* Copyright (C) 1995-1998 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/*
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
67void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out,
68                       long length, DES_key_schedule *schedule,
69                       DES_cblock *ivec, int *num, int enc)
70{
71    register DES_LONG v0, v1;
72    register long l = length;
73    register int n = *num;
74    DES_LONG ti[2];
75    unsigned char *iv, c, cc;
76
77    iv = &(*ivec)[0];
78    if (enc) {
79        while (l--) {
80            if (n == 0) {
81                c2l(iv, v0);
82                ti[0] = v0;
83                c2l(iv, v1);
84                ti[1] = v1;
85                DES_encrypt1(ti, schedule, DES_ENCRYPT);
86                iv = &(*ivec)[0];
87                v0 = ti[0];
88                l2c(v0, iv);
89                v0 = ti[1];
90                l2c(v0, iv);
91                iv = &(*ivec)[0];
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                c2l(iv, v0);
102                ti[0] = v0;
103                c2l(iv, v1);
104                ti[1] = v1;
105                DES_encrypt1(ti, schedule, DES_ENCRYPT);
106                iv = &(*ivec)[0];
107                v0 = ti[0];
108                l2c(v0, iv);
109                v0 = ti[1];
110                l2c(v0, iv);
111                iv = &(*ivec)[0];
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] = c = cc = 0;
121    *num = n;
122}
123