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#include <openssl/modes.h>
49
50#include <assert.h>
51#include <string.h>
52
53#include "internal.h"
54
55
56#ifndef STRICT_ALIGNMENT
57#  define STRICT_ALIGNMENT 0
58#endif
59
60void CRYPTO_cbc128_encrypt(const uint8_t *in, uint8_t *out, size_t len,
61                           const void *key, uint8_t ivec[16],
62                           block128_f block) {
63  size_t n;
64  const uint8_t *iv = ivec;
65
66  assert(key != NULL && ivec != NULL);
67  assert(len == 0 || (in != NULL && out != NULL));
68
69  if (STRICT_ALIGNMENT &&
70      ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) {
71    while (len >= 16) {
72      for (n = 0; n < 16; ++n) {
73        out[n] = in[n] ^ iv[n];
74      }
75      (*block)(out, out, key);
76      iv = out;
77      len -= 16;
78      in += 16;
79      out += 16;
80    }
81  } else {
82    while (len >= 16) {
83      for (n = 0; n < 16; n += sizeof(size_t)) {
84        *(size_t *)(out + n) = *(size_t *)(in + n) ^ *(size_t *)(iv + n);
85      }
86      (*block)(out, out, key);
87      iv = out;
88      len -= 16;
89      in += 16;
90      out += 16;
91    }
92  }
93
94  while (len) {
95    for (n = 0; n < 16 && n < len; ++n) {
96      out[n] = in[n] ^ iv[n];
97    }
98    for (; n < 16; ++n) {
99      out[n] = iv[n];
100    }
101    (*block)(out, out, key);
102    iv = out;
103    if (len <= 16) {
104      break;
105    }
106    len -= 16;
107    in += 16;
108    out += 16;
109  }
110
111  memcpy(ivec, iv, 16);
112}
113
114void CRYPTO_cbc128_decrypt(const uint8_t *in, uint8_t *out, size_t len,
115                           const void *key, uint8_t ivec[16],
116                           block128_f block) {
117  size_t n;
118  union {
119    size_t t[16 / sizeof(size_t)];
120    uint8_t c[16];
121  } tmp;
122
123  assert(key != NULL && ivec != NULL);
124  assert(len == 0 || (in != NULL && out != NULL));
125
126  const uintptr_t inptr = (uintptr_t) in;
127  const uintptr_t outptr = (uintptr_t) out;
128  /* If |in| and |out| alias, |in| must be ahead. */
129  assert(inptr >= outptr || inptr + len <= outptr);
130
131  if ((inptr >= 32 && outptr <= inptr - 32) || inptr < outptr) {
132    /* If |out| is at least two blocks behind |in| or completely disjoint, there
133     * is no need to decrypt to a temporary block. */
134    const uint8_t *iv = ivec;
135
136    if (STRICT_ALIGNMENT &&
137        ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) {
138      while (len >= 16) {
139        (*block)(in, out, key);
140        for (n = 0; n < 16; ++n) {
141          out[n] ^= iv[n];
142        }
143        iv = in;
144        len -= 16;
145        in += 16;
146        out += 16;
147      }
148    } else if (16 % sizeof(size_t) == 0) { /* always true */
149      while (len >= 16) {
150        size_t *out_t = (size_t *)out, *iv_t = (size_t *)iv;
151
152        (*block)(in, out, key);
153        for (n = 0; n < 16 / sizeof(size_t); n++) {
154          out_t[n] ^= iv_t[n];
155        }
156        iv = in;
157        len -= 16;
158        in += 16;
159        out += 16;
160      }
161    }
162    memcpy(ivec, iv, 16);
163  } else {
164    /* |out| is less than two blocks behind |in|. Decrypting an input block
165     * directly to |out| would overwrite a ciphertext block before it is used as
166     * the next block's IV. Decrypt to a temporary block instead. */
167    if (STRICT_ALIGNMENT &&
168        ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) {
169      uint8_t c;
170      while (len >= 16) {
171        (*block)(in, tmp.c, key);
172        for (n = 0; n < 16; ++n) {
173          c = in[n];
174          out[n] = tmp.c[n] ^ ivec[n];
175          ivec[n] = c;
176        }
177        len -= 16;
178        in += 16;
179        out += 16;
180      }
181    } else if (16 % sizeof(size_t) == 0) { /* always true */
182      while (len >= 16) {
183        size_t c, *out_t = (size_t *)out, *ivec_t = (size_t *)ivec;
184        const size_t *in_t = (const size_t *)in;
185
186        (*block)(in, tmp.c, key);
187        for (n = 0; n < 16 / sizeof(size_t); n++) {
188          c = in_t[n];
189          out_t[n] = tmp.t[n] ^ ivec_t[n];
190          ivec_t[n] = c;
191        }
192        len -= 16;
193        in += 16;
194        out += 16;
195      }
196    }
197  }
198
199  while (len) {
200    uint8_t c;
201    (*block)(in, tmp.c, key);
202    for (n = 0; n < 16 && n < len; ++n) {
203      c = in[n];
204      out[n] = tmp.c[n] ^ ivec[n];
205      ivec[n] = c;
206    }
207    if (len <= 16) {
208      for (; n < 16; ++n) {
209        ivec[n] = in[n];
210      }
211      break;
212    }
213    len -= 16;
214    in += 16;
215    out += 16;
216  }
217}
218