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#include <openssl/type_check.h>
50
51#include <assert.h>
52#include <string.h>
53
54#include "internal.h"
55
56
57OPENSSL_COMPILE_ASSERT((16 % sizeof(size_t)) == 0, bad_size_t_size_cfb);
58
59void CRYPTO_cfb128_encrypt(const uint8_t *in, uint8_t *out, size_t len,
60                           const void *key, uint8_t ivec[16], unsigned *num,
61                           int enc, block128_f block) {
62  size_t l = 0;
63
64  assert(in && out && key && ivec && num);
65
66  unsigned n = *num;
67
68  if (enc) {
69    while (n && len) {
70      *(out++) = ivec[n] ^= *(in++);
71      --len;
72      n = (n + 1) % 16;
73    }
74#if STRICT_ALIGNMENT
75    if (((uintptr_t)in | (uintptr_t)out | (uintptr_t)ivec) % sizeof(size_t) !=
76        0) {
77      while (l < len) {
78        if (n == 0) {
79          (*block)(ivec, ivec, key);
80        }
81        out[l] = ivec[n] ^= in[l];
82        ++l;
83        n = (n + 1) % 16;
84      }
85      *num = n;
86      return;
87    }
88#endif
89    while (len >= 16) {
90      (*block)(ivec, ivec, key);
91      for (; n < 16; n += sizeof(size_t)) {
92        size_t tmp = load_word_le(ivec + n) ^ load_word_le(in + n);
93        store_word_le(ivec + n, tmp);
94        store_word_le(out + n, tmp);
95      }
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] = ivec[n] ^= in[n];
105        ++n;
106      }
107    }
108    *num = n;
109    return;
110  } else {
111    while (n && len) {
112      uint8_t c;
113      *(out++) = ivec[n] ^ (c = *(in++));
114      ivec[n] = c;
115      --len;
116      n = (n + 1) % 16;
117    }
118    if (STRICT_ALIGNMENT &&
119        ((uintptr_t)in | (uintptr_t)out | (uintptr_t)ivec) % sizeof(size_t) !=
120            0) {
121      while (l < len) {
122        uint8_t c;
123        if (n == 0) {
124          (*block)(ivec, ivec, key);
125        }
126        out[l] = ivec[n] ^ (c = in[l]);
127        ivec[n] = c;
128        ++l;
129        n = (n + 1) % 16;
130      }
131      *num = n;
132      return;
133    }
134    while (len >= 16) {
135      (*block)(ivec, ivec, key);
136      for (; n < 16; n += sizeof(size_t)) {
137        size_t t = load_word_le(in + n);
138        store_word_le(out + n, load_word_le(ivec + n) ^ t);
139        store_word_le(ivec + n, t);
140      }
141      len -= 16;
142      out += 16;
143      in += 16;
144      n = 0;
145    }
146    if (len) {
147      (*block)(ivec, ivec, key);
148      while (len--) {
149        uint8_t c;
150        out[n] = ivec[n] ^ (c = in[n]);
151        ivec[n] = c;
152        ++n;
153      }
154    }
155    *num = n;
156    return;
157  }
158}
159
160
161/* This expects a single block of size nbits for both in and out. Note that
162   it corrupts any extra bits in the last byte of out */
163static void cfbr_encrypt_block(const uint8_t *in, uint8_t *out, unsigned nbits,
164                               const void *key, uint8_t ivec[16], int enc,
165                               block128_f block) {
166  int n, rem, num;
167  uint8_t ovec[16 * 2 + 1]; /* +1 because we dererefence (but don't use) one
168                               byte off the end */
169
170  if (nbits <= 0 || nbits > 128) {
171    return;
172  }
173
174  // fill in the first half of the new IV with the current IV
175  OPENSSL_memcpy(ovec, ivec, 16);
176  // construct the new IV
177  (*block)(ivec, ivec, key);
178  num = (nbits + 7) / 8;
179  if (enc) {
180    // encrypt the input
181    for (n = 0; n < num; ++n) {
182      out[n] = (ovec[16 + n] = in[n] ^ ivec[n]);
183    }
184  } else {
185    // decrypt the input
186    for (n = 0; n < num; ++n) {
187      out[n] = (ovec[16 + n] = in[n]) ^ ivec[n];
188    }
189  }
190  // shift ovec left...
191  rem = nbits % 8;
192  num = nbits / 8;
193  if (rem == 0) {
194    OPENSSL_memcpy(ivec, ovec + num, 16);
195  } else {
196    for (n = 0; n < 16; ++n) {
197      ivec[n] = ovec[n + num] << rem | ovec[n + num + 1] >> (8 - rem);
198    }
199  }
200
201  // it is not necessary to cleanse ovec, since the IV is not secret
202}
203
204// N.B. This expects the input to be packed, MS bit first
205void CRYPTO_cfb128_1_encrypt(const uint8_t *in, uint8_t *out, size_t bits,
206                             const void *key, uint8_t ivec[16], unsigned *num,
207                             int enc, block128_f block) {
208  size_t n;
209  uint8_t c[1], d[1];
210
211  assert(in && out && key && ivec && num);
212  assert(*num == 0);
213
214  for (n = 0; n < bits; ++n) {
215    c[0] = (in[n / 8] & (1 << (7 - n % 8))) ? 0x80 : 0;
216    cfbr_encrypt_block(c, d, 1, key, ivec, enc, block);
217    out[n / 8] = (out[n / 8] & ~(1 << (unsigned int)(7 - n % 8))) |
218                 ((d[0] & 0x80) >> (unsigned int)(n % 8));
219  }
220}
221
222void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
223                             size_t length, const void *key,
224                             unsigned char ivec[16], unsigned *num, int enc,
225                             block128_f block) {
226  size_t n;
227
228  assert(in && out && key && ivec && num);
229  assert(*num == 0);
230
231  for (n = 0; n < length; ++n) {
232    cfbr_encrypt_block(&in[n], &out[n], 8, key, ivec, enc, block);
233  }
234}
235