1 /* crypto/cast/c_cfb64.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 <openssl/cast.h>
60 #include "cast_lcl.h"
61 
62 /*
63  * The input and output encrypted as though 64bit cfb mode is being used.
64  * The extra state information to record how much of the 64bit block we have
65  * used is contained in *num;
66  */
67 
CAST_cfb64_encrypt(const unsigned char * in,unsigned char * out,long length,const CAST_KEY * schedule,unsigned char * ivec,int * num,int enc)68 void CAST_cfb64_encrypt(const unsigned char *in, unsigned char *out,
69                         long length, const CAST_KEY *schedule,
70                         unsigned char *ivec, int *num, int enc)
71 {
72     register CAST_LONG v0, v1, t;
73     register int n = *num;
74     register long l = length;
75     CAST_LONG ti[2];
76     unsigned char *iv, c, cc;
77 
78     iv = ivec;
79     if (enc) {
80         while (l--) {
81             if (n == 0) {
82                 n2l(iv, v0);
83                 ti[0] = v0;
84                 n2l(iv, v1);
85                 ti[1] = v1;
86                 CAST_encrypt((CAST_LONG *)ti, schedule);
87                 iv = ivec;
88                 t = ti[0];
89                 l2n(t, iv);
90                 t = ti[1];
91                 l2n(t, iv);
92                 iv = ivec;
93             }
94             c = *(in++) ^ iv[n];
95             *(out++) = c;
96             iv[n] = c;
97             n = (n + 1) & 0x07;
98         }
99     } else {
100         while (l--) {
101             if (n == 0) {
102                 n2l(iv, v0);
103                 ti[0] = v0;
104                 n2l(iv, v1);
105                 ti[1] = v1;
106                 CAST_encrypt((CAST_LONG *)ti, schedule);
107                 iv = ivec;
108                 t = ti[0];
109                 l2n(t, iv);
110                 t = ti[1];
111                 l2n(t, iv);
112                 iv = ivec;
113             }
114             cc = *(in++);
115             c = iv[n];
116             iv[n] = cc;
117             *(out++) = c ^ cc;
118             n = (n + 1) & 0x07;
119         }
120     }
121     v0 = v1 = ti[0] = ti[1] = t = c = cc = 0;
122     *num = n;
123 }
124