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 
57 OPENSSL_COMPILE_ASSERT((16 % sizeof(size_t)) == 0, bad_size_t_size);
58 
CRYPTO_cfb128_encrypt(const uint8_t * in,uint8_t * out,size_t len,const void * key,uint8_t ivec[16],int * num,int enc,block128_f block)59 void CRYPTO_cfb128_encrypt(const uint8_t *in, uint8_t *out, size_t len,
60                            const void *key, uint8_t ivec[16], int *num, int enc,
61                            block128_f block) {
62   unsigned int n;
63   size_t l = 0;
64 
65   assert(in && out && key && ivec && num);
66 
67   n = *num;
68 
69   if (enc) {
70     while (n && len) {
71       *(out++) = ivec[n] ^= *(in++);
72       --len;
73       n = (n + 1) % 16;
74     }
75 #if STRICT_ALIGNMENT
76     if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 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 *)(out + n) = *(size_t *)(ivec + n) ^= *(size_t *)(in + n);
93       }
94       len -= 16;
95       out += 16;
96       in += 16;
97       n = 0;
98     }
99     if (len) {
100       (*block)(ivec, ivec, key);
101       while (len--) {
102         out[n] = ivec[n] ^= in[n];
103         ++n;
104       }
105     }
106     *num = n;
107     return;
108   } else {
109     while (n && len) {
110       uint8_t c;
111       *(out++) = ivec[n] ^ (c = *(in++));
112       ivec[n] = c;
113       --len;
114       n = (n + 1) % 16;
115     }
116     if (STRICT_ALIGNMENT && ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) {
117       while (l < len) {
118         unsigned char c;
119         if (n == 0) {
120           (*block)(ivec, ivec, key);
121         }
122         out[l] = ivec[n] ^ (c = in[l]);
123         ivec[n] = c;
124         ++l;
125         n = (n + 1) % 16;
126       }
127       *num = n;
128       return;
129     }
130     while (len >= 16) {
131       (*block)(ivec, ivec, key);
132       for (; n < 16; n += sizeof(size_t)) {
133         size_t t = *(size_t *)(in + n);
134         *(size_t *)(out + n) = *(size_t *)(ivec + n) ^ t;
135         *(size_t *)(ivec + n) = t;
136       }
137       len -= 16;
138       out += 16;
139       in += 16;
140       n = 0;
141     }
142     if (len) {
143       (*block)(ivec, ivec, key);
144       while (len--) {
145         uint8_t c;
146         out[n] = ivec[n] ^ (c = in[n]);
147         ivec[n] = c;
148         ++n;
149       }
150     }
151     *num = n;
152     return;
153   }
154 }
155 
156 
157 /* This expects a single block of size nbits for both in and out. Note that
158    it corrupts any extra bits in the last byte of out */
cfbr_encrypt_block(const uint8_t * in,uint8_t * out,unsigned nbits,const void * key,uint8_t ivec[16],int enc,block128_f block)159 static void cfbr_encrypt_block(const uint8_t *in, uint8_t *out, unsigned nbits,
160                                const void *key, uint8_t ivec[16], int enc,
161                                block128_f block) {
162   int n, rem, num;
163   uint8_t ovec[16 * 2 + 1]; /* +1 because we dererefence (but don't use) one
164                                byte off the end */
165 
166   if (nbits <= 0 || nbits > 128) {
167     return;
168   }
169 
170   /* fill in the first half of the new IV with the current IV */
171   memcpy(ovec, ivec, 16);
172   /* construct the new IV */
173   (*block)(ivec, ivec, key);
174   num = (nbits + 7) / 8;
175   if (enc) {
176     /* encrypt the input */
177     for (n = 0; n < num; ++n) {
178       out[n] = (ovec[16 + n] = in[n] ^ ivec[n]);
179     }
180   } else {
181     /* decrypt the input */
182     for (n = 0; n < num; ++n) {
183       out[n] = (ovec[16 + n] = in[n]) ^ ivec[n];
184     }
185   }
186   /* shift ovec left... */
187   rem = nbits % 8;
188   num = nbits / 8;
189   if (rem == 0) {
190     memcpy(ivec, ovec + num, 16);
191   } else {
192     for (n = 0; n < 16; ++n) {
193       ivec[n] = ovec[n + num] << rem | ovec[n + num + 1] >> (8 - rem);
194     }
195   }
196 
197   /* it is not necessary to cleanse ovec, since the IV is not secret */
198 }
199 
200 /* N.B. This expects the input to be packed, MS bit first */
CRYPTO_cfb128_1_encrypt(const uint8_t * in,uint8_t * out,size_t bits,const void * key,uint8_t ivec[16],int * num,int enc,block128_f block)201 void CRYPTO_cfb128_1_encrypt(const uint8_t *in, uint8_t *out, size_t bits,
202                              const void *key, uint8_t ivec[16], int *num,
203                              int enc, block128_f block) {
204   size_t n;
205   uint8_t c[1], d[1];
206 
207   assert(in && out && key && ivec && num);
208   assert(*num == 0);
209 
210   for (n = 0; n < bits; ++n) {
211     c[0] = (in[n / 8] & (1 << (7 - n % 8))) ? 0x80 : 0;
212     cfbr_encrypt_block(c, d, 1, key, ivec, enc, block);
213     out[n / 8] = (out[n / 8] & ~(1 << (unsigned int)(7 - n % 8))) |
214                  ((d[0] & 0x80) >> (unsigned int)(n % 8));
215   }
216 }
217 
CRYPTO_cfb128_8_encrypt(const unsigned char * in,unsigned char * out,size_t length,const void * key,unsigned char ivec[16],int * num,int enc,block128_f block)218 void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
219                              size_t length, const void *key,
220                              unsigned char ivec[16], int *num, int enc,
221                              block128_f block) {
222   size_t n;
223 
224   assert(in && out && key && ivec && num);
225   assert(*num == 0);
226 
227   for (n = 0; n < length; ++n) {
228     cfbr_encrypt_block(&in[n], &out[n], 8, key, ivec, enc, block);
229   }
230 }
231 
232