ofb128.c revision 296341 
1/* ====================================================================
2 * Copyright (c) 2008 The OpenSSL Project.  All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in
13 *    the documentation and/or other materials provided with the
14 *    distribution.
15 *
16 * 3. All advertising materials mentioning features or use of this
17 *    software must display the following acknowledgment:
18 *    "This product includes software developed by the OpenSSL Project
19 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
20 *
21 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
22 *    endorse or promote products derived from this software without
23 *    prior written permission. For written permission, please contact
24 *    openssl-core@openssl.org.
25 *
26 * 5. Products derived from this software may not be called "OpenSSL"
27 *    nor may "OpenSSL" appear in their names without prior written
28 *    permission of the OpenSSL Project.
29 *
30 * 6. Redistributions of any form whatsoever must retain the following
31 *    acknowledgment:
32 *    "This product includes software developed by the OpenSSL Project
33 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
34 *
35 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
36 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
37 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
38 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
39 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
41 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
42 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
43 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
44 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
45 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
46 * OF THE POSSIBILITY OF SUCH DAMAGE.
47 * ====================================================================
48 *
49 */
50
51#include <openssl/crypto.h>
52#include "modes_lcl.h"
53#include <string.h>
54
55#ifndef MODES_DEBUG
56# ifndef NDEBUG
57#  define NDEBUG
58# endif
59#endif
60#include <assert.h>
61
62/*
63 * The input and output encrypted as though 128bit ofb mode is being used.
64 * The extra state information to record how much of the 128bit block we have
65 * used is contained in *num;
66 */
67void CRYPTO_ofb128_encrypt(const unsigned char *in, unsigned char *out,
68                           size_t len, const void *key,
69                           unsigned char ivec[16], int *num, block128_f block)
70{
71    unsigned int n;
72    size_t l = 0;
73
74    assert(in && out && key && ivec && num);
75
76    n = *num;
77
78#if !defined(OPENSSL_SMALL_FOOTPRINT)
79    if (16 % sizeof(size_t) == 0) { /* always true actually */
80        do {
81            while (n && len) {
82                *(out++) = *(in++) ^ ivec[n];
83                --len;
84                n = (n + 1) % 16;
85            }
86# if defined(STRICT_ALIGNMENT)
87            if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) !=
88                0)
89                break;
90# endif
91            while (len >= 16) {
92                (*block) (ivec, ivec, key);
93                for (; n < 16; n += sizeof(size_t))
94                    *(size_t *)(out + n) =
95                        *(size_t *)(in + n) ^ *(size_t *)(ivec + n);
96                len -= 16;
97                out += 16;
98                in += 16;
99                n = 0;
100            }
101            if (len) {
102                (*block) (ivec, ivec, key);
103                while (len--) {
104                    out[n] = in[n] ^ ivec[n];
105                    ++n;
106                }
107            }
108            *num = n;
109            return;
110        } while (0);
111    }
112    /* the rest would be commonly eliminated by x86* compiler */
113#endif
114    while (l < len) {
115        if (n == 0) {
116            (*block) (ivec, ivec, key);
117        }
118        out[l] = in[l] ^ ivec[n];
119        ++l;
120        n = (n + 1) % 16;
121    }
122
123    *num = n;
124}
125