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 */
67void des_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
68	     long length, des_key_schedule schedule, des_cblock *ivec)
69	{
70	register DES_LONG d0,d1,vv0,vv1,v0,v1,n=(numbits+7)/8;
71	register DES_LONG mask0,mask1;
72	register long l=length;
73	register int num=numbits;
74	DES_LONG ti[2];
75	unsigned char *iv;
76
77	if (num > 64) return;
78	if (num > 32)
79		{
80		mask0=0xffffffffL;
81		if (num >= 64)
82			mask1=mask0;
83		else
84			mask1=(1L<<(num-32))-1;
85		}
86	else
87		{
88		if (num == 32)
89			mask0=0xffffffffL;
90		else
91			mask0=(1L<<num)-1;
92		mask1=0x00000000L;
93		}
94
95	iv = &(*ivec)[0];
96	c2l(iv,v0);
97	c2l(iv,v1);
98	ti[0]=v0;
99	ti[1]=v1;
100	while (l-- > 0)
101		{
102		ti[0]=v0;
103		ti[1]=v1;
104		des_encrypt1((DES_LONG *)ti,schedule,DES_ENCRYPT);
105		vv0=ti[0];
106		vv1=ti[1];
107		c2ln(in,d0,d1,n);
108		in+=n;
109		d0=(d0^vv0)&mask0;
110		d1=(d1^vv1)&mask1;
111		l2cn(d0,d1,out,n);
112		out+=n;
113
114		if (num == 32)
115			{ v0=v1; v1=vv0; }
116		else if (num == 64)
117				{ v0=vv0; v1=vv1; }
118		else if (num > 32) /* && num != 64 */
119			{
120			v0=((v1>>(num-32))|(vv0<<(64-num)))&0xffffffffL;
121			v1=((vv0>>(num-32))|(vv1<<(64-num)))&0xffffffffL;
122			}
123		else /* num < 32 */
124			{
125			v0=((v0>>num)|(v1<<(32-num)))&0xffffffffL;
126			v1=((v1>>num)|(vv0<<(32-num)))&0xffffffffL;
127			}
128		}
129	iv = &(*ivec)[0];
130	l2c(v0,iv);
131	l2c(v1,iv);
132	v0=v1=d0=d1=ti[0]=ti[1]=vv0=vv1=0;
133	}
134
135