cfb_enc.c revision 296465 
1/* crypto/des/cfb_enc.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 "e_os.h"
60#include "des_locl.h"
61#include <assert.h>
62
63/*
64 * The input and output are loaded in multiples of 8 bits. What this means is
65 * that if you hame numbits=12 and length=2 the first 12 bits will be
66 * retrieved from the first byte and half the second.  The second 12 bits
67 * will come from the 3rd and half the 4th byte.
68 */
69/*
70 * Until Aug 1 2003 this function did not correctly implement CFB-r, so it
71 * will not be compatible with any encryption prior to that date. Ben.
72 */
73void DES_cfb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
74                     long length, DES_key_schedule *schedule,
75                     DES_cblock *ivec, int enc)
76{
77    register DES_LONG d0, d1, v0, v1;
78    register unsigned long l = length;
79    register int num = numbits / 8, n = (numbits + 7) / 8, i, rem =
80        numbits % 8;
81    DES_LONG ti[2];
82    unsigned char *iv;
83#ifndef L_ENDIAN
84    unsigned char ovec[16];
85#else
86    unsigned int sh[4];
87    unsigned char *ovec = (unsigned char *)sh;
88
89    /* I kind of count that compiler optimizes away this assertioni, */
90    assert(sizeof(sh[0]) == 4); /* as this holds true for all, */
91    /* but 16-bit platforms...      */
92
93#endif
94
95    if (numbits <= 0 || numbits > 64)
96        return;
97    iv = &(*ivec)[0];
98    c2l(iv, v0);
99    c2l(iv, v1);
100    if (enc) {
101        while (l >= (unsigned long)n) {
102            l -= n;
103            ti[0] = v0;
104            ti[1] = v1;
105            DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
106            c2ln(in, d0, d1, n);
107            in += n;
108            d0 ^= ti[0];
109            d1 ^= ti[1];
110            l2cn(d0, d1, out, n);
111            out += n;
112            /*
113             * 30-08-94 - eay - changed because l>>32 and l<<32 are bad under
114             * gcc :-(
115             */
116            if (numbits == 32) {
117                v0 = v1;
118                v1 = d0;
119            } else if (numbits == 64) {
120                v0 = d0;
121                v1 = d1;
122            } else {
123#ifndef L_ENDIAN
124                iv = &ovec[0];
125                l2c(v0, iv);
126                l2c(v1, iv);
127                l2c(d0, iv);
128                l2c(d1, iv);
129#else
130                sh[0] = v0, sh[1] = v1, sh[2] = d0, sh[3] = d1;
131#endif
132                if (rem == 0)
133                    memmove(ovec, ovec + num, 8);
134                else
135                    for (i = 0; i < 8; ++i)
136                        ovec[i] = ovec[i + num] << rem |
137                            ovec[i + num + 1] >> (8 - rem);
138#ifdef L_ENDIAN
139                v0 = sh[0], v1 = sh[1];
140#else
141                iv = &ovec[0];
142                c2l(iv, v0);
143                c2l(iv, v1);
144#endif
145            }
146        }
147    } else {
148        while (l >= (unsigned long)n) {
149            l -= n;
150            ti[0] = v0;
151            ti[1] = v1;
152            DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
153            c2ln(in, d0, d1, n);
154            in += n;
155            /*
156             * 30-08-94 - eay - changed because l>>32 and l<<32 are bad under
157             * gcc :-(
158             */
159            if (numbits == 32) {
160                v0 = v1;
161                v1 = d0;
162            } else if (numbits == 64) {
163                v0 = d0;
164                v1 = d1;
165            } else {
166#ifndef L_ENDIAN
167                iv = &ovec[0];
168                l2c(v0, iv);
169                l2c(v1, iv);
170                l2c(d0, iv);
171                l2c(d1, iv);
172#else
173                sh[0] = v0, sh[1] = v1, sh[2] = d0, sh[3] = d1;
174#endif
175                if (rem == 0)
176                    memmove(ovec, ovec + num, 8);
177                else
178                    for (i = 0; i < 8; ++i)
179                        ovec[i] = ovec[i + num] << rem |
180                            ovec[i + num + 1] >> (8 - rem);
181#ifdef L_ENDIAN
182                v0 = sh[0], v1 = sh[1];
183#else
184                iv = &ovec[0];
185                c2l(iv, v0);
186                c2l(iv, v1);
187#endif
188            }
189            d0 ^= ti[0];
190            d1 ^= ti[1];
191            l2cn(d0, d1, out, n);
192            out += n;
193        }
194    }
195    iv = &(*ivec)[0];
196    l2c(v0, iv);
197    l2c(v1, iv);
198    v0 = v1 = d0 = d1 = ti[0] = ti[1] = 0;
199}
200