xref: /openssl/crypto/des/cfb64enc.c (revision 33388b44)
1 /*
2  * Copyright 1995-2020 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 "des_local.h"
17 
18 /*
19  * The input and output encrypted as though 64bit cfb mode is being used.
20  * The extra state information to record how much of the 64bit block we have
21  * used is contained in *num;
22  */
23 
DES_cfb64_encrypt(const unsigned char * in,unsigned char * out,long length,DES_key_schedule * schedule,DES_cblock * ivec,int * num,int enc)24 void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out,
25                        long length, DES_key_schedule *schedule,
26                        DES_cblock *ivec, int *num, int enc)
27 {
28     register DES_LONG v0, v1;
29     register long l = length;
30     register int n = *num;
31     DES_LONG ti[2];
32     unsigned char *iv, c, cc;
33 
34     iv = &(*ivec)[0];
35     if (enc) {
36         while (l--) {
37             if (n == 0) {
38                 c2l(iv, v0);
39                 ti[0] = v0;
40                 c2l(iv, v1);
41                 ti[1] = v1;
42                 DES_encrypt1(ti, schedule, DES_ENCRYPT);
43                 iv = &(*ivec)[0];
44                 v0 = ti[0];
45                 l2c(v0, iv);
46                 v0 = ti[1];
47                 l2c(v0, iv);
48                 iv = &(*ivec)[0];
49             }
50             c = *(in++) ^ iv[n];
51             *(out++) = c;
52             iv[n] = c;
53             n = (n + 1) & 0x07;
54         }
55     } else {
56         while (l--) {
57             if (n == 0) {
58                 c2l(iv, v0);
59                 ti[0] = v0;
60                 c2l(iv, v1);
61                 ti[1] = v1;
62                 DES_encrypt1(ti, schedule, DES_ENCRYPT);
63                 iv = &(*ivec)[0];
64                 v0 = ti[0];
65                 l2c(v0, iv);
66                 v0 = ti[1];
67                 l2c(v0, iv);
68                 iv = &(*ivec)[0];
69             }
70             cc = *(in++);
71             c = iv[n];
72             iv[n] = cc;
73             *(out++) = c ^ cc;
74             n = (n + 1) & 0x07;
75         }
76     }
77     v0 = v1 = ti[0] = ti[1] = c = cc = 0;
78     *num = n;
79 }
80