xref: /openssl/crypto/des/cfb_enc.c (revision fecb3aae)
1 /*
2  * Copyright 1995-2022 The OpenSSL Project Authors. All Rights Reserved.
3  *
4  * Licensed under the Apache License 2.0 (the "License").  You may not use
5  * this file except in compliance with the License.  You can obtain a copy
6  * in the file LICENSE in the source distribution or at
7  * https://www.openssl.org/source/license.html
8  */
9 
10 /*
11  * DES low level APIs are deprecated for public use, but still ok for internal
12  * use.
13  */
14 #include "internal/deprecated.h"
15 
16 #include "internal/e_os.h"
17 #include "des_local.h"
18 #include <assert.h>
19 
20 /*
21  * The input and output are loaded in multiples of 8 bits. What this means is
22  * that if you hame numbits=12 and length=2 the first 12 bits will be
23  * retrieved from the first byte and half the second.  The second 12 bits
24  * will come from the 3rd and half the 4th byte.
25  */
26 /*
27  * Until Aug 1 2003 this function did not correctly implement CFB-r, so it
28  * will not be compatible with any encryption prior to that date. Ben.
29  */
DES_cfb_encrypt(const unsigned char * in,unsigned char * out,int numbits,long length,DES_key_schedule * schedule,DES_cblock * ivec,int enc)30 void DES_cfb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
31                      long length, DES_key_schedule *schedule,
32                      DES_cblock *ivec, int enc)
33 {
34     register DES_LONG d0, d1, v0, v1;
35     register unsigned long l = length;
36     register int num = numbits / 8, n = (numbits + 7) / 8, i, rem =
37         numbits % 8;
38     DES_LONG ti[2];
39     unsigned char *iv;
40 #ifndef L_ENDIAN
41     unsigned char ovec[16];
42 #else
43     unsigned int sh[4];
44     unsigned char *ovec = (unsigned char *)sh;
45 
46     /* I kind of count that compiler optimizes away this assertion, */
47     assert(sizeof(sh[0]) == 4); /* as this holds true for all, */
48     /* but 16-bit platforms...      */
49 
50 #endif
51 
52     if (numbits <= 0 || numbits > 64)
53         return;
54     iv = &(*ivec)[0];
55     c2l(iv, v0);
56     c2l(iv, v1);
57     if (enc) {
58         while (l >= (unsigned long)n) {
59             l -= n;
60             ti[0] = v0;
61             ti[1] = v1;
62             DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
63             c2ln(in, d0, d1, n);
64             in += n;
65             d0 ^= ti[0];
66             d1 ^= ti[1];
67             l2cn(d0, d1, out, n);
68             out += n;
69             /*
70              * 30-08-94 - eay - changed because l>>32 and l<<32 are bad under
71              * gcc :-(
72              */
73             if (numbits == 32) {
74                 v0 = v1;
75                 v1 = d0;
76             } else if (numbits == 64) {
77                 v0 = d0;
78                 v1 = d1;
79             } else {
80 #ifndef L_ENDIAN
81                 iv = &ovec[0];
82                 l2c(v0, iv);
83                 l2c(v1, iv);
84                 l2c(d0, iv);
85                 l2c(d1, iv);
86 #else
87                 sh[0] = v0, sh[1] = v1, sh[2] = d0, sh[3] = d1;
88 #endif
89                 if (rem == 0)
90                     memmove(ovec, ovec + num, 8);
91                 else
92                     for (i = 0; i < 8; ++i)
93                         ovec[i] = ovec[i + num] << rem |
94                             ovec[i + num + 1] >> (8 - rem);
95 #ifdef L_ENDIAN
96                 v0 = sh[0], v1 = sh[1];
97 #else
98                 iv = &ovec[0];
99                 c2l(iv, v0);
100                 c2l(iv, v1);
101 #endif
102             }
103         }
104     } else {
105         while (l >= (unsigned long)n) {
106             l -= n;
107             ti[0] = v0;
108             ti[1] = v1;
109             DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
110             c2ln(in, d0, d1, n);
111             in += 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             d0 ^= ti[0];
147             d1 ^= ti[1];
148             l2cn(d0, d1, out, n);
149             out += n;
150         }
151     }
152     iv = &(*ivec)[0];
153     l2c(v0, iv);
154     l2c(v1, iv);
155     v0 = v1 = d0 = d1 = ti[0] = ti[1] = 0;
156 }
157