1/*
2 * Copyright 1995-2016 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#include "des_local.h"
11
12/*
13 * The input and output are loaded in multiples of 8 bits. What this means is
14 * that if you have numbits=12 and length=2 the first 12 bits will be
15 * retrieved from the first byte and half the second. The second 12 bits
16 * will come from the 3rd and half the 4th byte.
17 */
18void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
19 long length, DES_key_schedule *schedule,
20 DES_cblock *ivec)
21{
22 register DES_LONG d0, d1, vv0, vv1, v0, v1, n = (numbits + 7) / 8;
23 register DES_LONG mask0, mask1;
24 register long l = length;
25 register int num = numbits;
26 DES_LONG ti[2];
27 unsigned char *iv;
28
29 if (num > 64)
30 return;
31 if (num > 32) {
32 mask0 = 0xffffffffL;
33 if (num >= 64)
34 mask1 = mask0;
35 else
36 mask1 = (1L << (num - 32)) - 1;
37 } else {
38 if (num == 32)
39 mask0 = 0xffffffffL;
40 else
41 mask0 = (1L << num) - 1;
42 mask1 = 0x00000000L;
43 }
44
45 iv = &(*ivec)[0];
46 c2l(iv, v0);
47 c2l(iv, v1);
48 ti[0] = v0;
49 ti[1] = v1;
50 while (l-- > 0) {
51 ti[0] = v0;
52 ti[1] = v1;
53 DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
54 vv0 = ti[0];
55 vv1 = ti[1];
56 c2ln(in, d0, d1, n);
57 in += n;
58 d0 = (d0 ^ vv0) & mask0;
59 d1 = (d1 ^ vv1) & mask1;
60 l2cn(d0, d1, out, n);
61 out += n;
62
63 if (num == 32) {
64 v0 = v1;
65 v1 = vv0;
66 } else if (num == 64) {
67 v0 = vv0;
68 v1 = vv1;
69 } else if (num > 32) { /* && num != 64 */
70 v0 = ((v1 >> (num - 32)) | (vv0 << (64 - num))) & 0xffffffffL;
71 v1 = ((vv0 >> (num - 32)) | (vv1 << (64 - num))) & 0xffffffffL;
72 } else { /* num < 32 */
73
74 v0 = ((v0 >> num) | (v1 << (32 - num))) & 0xffffffffL;
75 v1 = ((v1 >> num) | (vv0 << (32 - num))) & 0xffffffffL;
76 }
77 }
78 iv = &(*ivec)[0];
79 l2c(v0, iv);
80 l2c(v1, iv);
81 v0 = v1 = d0 = d1 = ti[0] = ti[1] = vv0 = vv1 = 0;
82}
83