1 /* crypto/des/ofb_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 "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(const unsigned char *in, unsigned char *out, int numbits,
68 long length, DES_key_schedule *schedule,
69 DES_cblock *ivec)
70 {
71 register DES_LONG d0,d1,vv0,vv1,v0,v1,n=(numbits+7)/8;
72 register DES_LONG mask0,mask1;
73 register long l=length;
74 register int num=numbits;
75 DES_LONG ti[2];
76 unsigned char *iv;
77
78 if (num > 64) return;
79 if (num > 32)
80 {
81 mask0=0xffffffffL;
82 if (num >= 64)
83 mask1=mask0;
84 else
85 mask1=(1L<<(num-32))-1;
86 }
87 else
88 {
89 if (num == 32)
90 mask0=0xffffffffL;
91 else
92 mask0=(1L<<num)-1;
93 mask1=0x00000000L;
94 }
95
96 iv = &(*ivec)[0];
97 c2l(iv,v0);
98 c2l(iv,v1);
99 ti[0]=v0;
100 ti[1]=v1;
101 while (l-- > 0)
102 {
103 ti[0]=v0;
104 ti[1]=v1;
105 DES_encrypt1((DES_LONG *)ti,schedule,DES_ENCRYPT);
106 vv0=ti[0];
107 vv1=ti[1];
108 c2ln(in,d0,d1,n);
109 in+=n;
110 d0=(d0^vv0)&mask0;
111 d1=(d1^vv1)&mask1;
112 l2cn(d0,d1,out,n);
113 out+=n;
114
115 if (num == 32)
116 { v0=v1; v1=vv0; }
117 else if (num == 64)
118 { v0=vv0; v1=vv1; }
119 else if (num > 32) /* && num != 64 */
120 {
121 v0=((v1>>(num-32))|(vv0<<(64-num)))&0xffffffffL;
122 v1=((vv0>>(num-32))|(vv1<<(64-num)))&0xffffffffL;
123 }
124 else /* num < 32 */
125 {
126 v0=((v0>>num)|(v1<<(32-num)))&0xffffffffL;
127 v1=((v1>>num)|(vv0<<(32-num)))&0xffffffffL;
128 }
129 }
130 iv = &(*ivec)[0];
131 l2c(v0,iv);
132 l2c(v1,iv);
133 v0=v1=d0=d1=ti[0]=ti[1]=vv0=vv1=0;
134 }