1 /* $OpenBSD: cfb128.c,v 1.7 2023/07/08 14:56:54 beck Exp $ */
2 /* ====================================================================
3 * Copyright (c) 2008 The OpenSSL Project. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
15 * distribution.
16 *
17 * 3. All advertising materials mentioning features or use of this
18 * software must display the following acknowledgment:
19 * "This product includes software developed by the OpenSSL Project
20 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
21 *
22 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
23 * endorse or promote products derived from this software without
24 * prior written permission. For written permission, please contact
25 * openssl-core@openssl.org.
26 *
27 * 5. Products derived from this software may not be called "OpenSSL"
28 * nor may "OpenSSL" appear in their names without prior written
29 * permission of the OpenSSL Project.
30 *
31 * 6. Redistributions of any form whatsoever must retain the following
32 * acknowledgment:
33 * "This product includes software developed by the OpenSSL Project
34 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
35 *
36 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
37 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
39 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
40 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
47 * OF THE POSSIBILITY OF SUCH DAMAGE.
48 * ====================================================================
49 *
50 */
51
52 #include <openssl/crypto.h>
53 #include "modes_local.h"
54 #include <string.h>
55
56 #ifndef MODES_DEBUG
57 # ifndef NDEBUG
58 # define NDEBUG
59 # endif
60 #endif
61
62 /* The input and output encrypted as though 128bit cfb mode is being
63 * used. The extra state information to record how much of the
64 * 128bit block we have used is contained in *num;
65 */
66 void
CRYPTO_cfb128_encrypt(const unsigned char * in,unsigned char * out,size_t len,const void * key,unsigned char ivec[16],int * num,int enc,block128_f block)67 CRYPTO_cfb128_encrypt(const unsigned char *in, unsigned char *out,
68 size_t len, const void *key,
69 unsigned char ivec[16], int *num,
70 int enc, block128_f block)
71 {
72 unsigned int n;
73 size_t l = 0;
74
75 n = *num;
76
77 if (enc) {
78 #if !defined(OPENSSL_SMALL_FOOTPRINT)
79 if (16 % sizeof(size_t) == 0)
80 do { /* always true actually */
81 while (n && len) {
82 *(out++) = ivec[n] ^= *(in++);
83 --len;
84 n = (n + 1) % 16;
85 }
86 #ifdef __STRICT_ALIGNMENT
87 if (((size_t)in|(size_t)out|(size_t)ivec) %
88 sizeof(size_t) != 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 *)(ivec + n) ^= *(size_t *)(in +
96 n);
97 }
98 len -= 16;
99 out += 16;
100 in += 16;
101 n = 0;
102 }
103 if (len) {
104 (*block)(ivec, ivec, key);
105 while (len--) {
106 out[n] = ivec[n] ^= in[n];
107 ++n;
108 }
109 }
110 *num = n;
111 return;
112 } while (0);
113 /* the rest would be commonly eliminated by x86* compiler */
114 #endif
115 while (l < len) {
116 if (n == 0) {
117 (*block)(ivec, ivec, key);
118 }
119 out[l] = ivec[n] ^= in[l];
120 ++l;
121 n = (n + 1) % 16;
122 }
123 *num = n;
124 } else {
125 #if !defined(OPENSSL_SMALL_FOOTPRINT)
126 if (16 % sizeof(size_t) == 0)
127 do { /* always true actually */
128 while (n && len) {
129 unsigned char c;
130 *(out++) = ivec[n] ^ (c = *(in++));
131 ivec[n] = c;
132 --len;
133 n = (n + 1) % 16;
134 }
135 #ifdef __STRICT_ALIGNMENT
136 if (((size_t)in|(size_t)out|(size_t)ivec) %
137 sizeof(size_t) != 0)
138 break;
139 #endif
140 while (len >= 16) {
141 (*block)(ivec, ivec, key);
142 for (; n < 16; n += sizeof(size_t)) {
143 size_t t = *(size_t *)(in + n);
144 *(size_t *)(out + n) = *(size_t *)(ivec +
145 n) ^ t;
146 *(size_t *)(ivec + n) = t;
147 }
148 len -= 16;
149 out += 16;
150 in += 16;
151 n = 0;
152 }
153 if (len) {
154 (*block)(ivec, ivec, key);
155 while (len--) {
156 unsigned char c;
157 out[n] = ivec[n] ^ (c = in[n]);
158 ivec[n] = c;
159 ++n;
160 }
161 }
162 *num = n;
163 return;
164 } while (0);
165 /* the rest would be commonly eliminated by x86* compiler */
166 #endif
167 while (l < len) {
168 unsigned char c;
169 if (n == 0) {
170 (*block)(ivec, ivec, key);
171 }
172 out[l] = ivec[n] ^ (c = in[l]);
173 ivec[n] = c;
174 ++l;
175 n = (n + 1) % 16;
176 }
177 *num = n;
178 }
179 }
180 LCRYPTO_ALIAS(CRYPTO_cfb128_encrypt);
181
182 /* This expects a single block of size nbits for both in and out. Note that
183 it corrupts any extra bits in the last byte of out */
184 static void
cfbr_encrypt_block(const unsigned char * in,unsigned char * out,int nbits,const void * key,unsigned char ivec[16],int enc,block128_f block)185 cfbr_encrypt_block(const unsigned char *in, unsigned char *out,
186 int nbits, const void *key,
187 unsigned char ivec[16], int enc,
188 block128_f block)
189 {
190 int n, rem, num;
191 unsigned char ovec[16*2 + 1]; /* +1 because we dererefence (but don't use) one byte off the end */
192
193 if (nbits <= 0 || nbits > 128)
194 return;
195
196 /* fill in the first half of the new IV with the current IV */
197 memcpy(ovec, ivec, 16);
198 /* construct the new IV */
199 (*block)(ivec, ivec, key);
200 num = (nbits + 7)/8;
201 if (enc) /* encrypt the input */
202 for (n = 0; n < num; ++n)
203 out[n] = (ovec[16 + n] = in[n] ^ ivec[n]);
204 else /* decrypt the input */
205 for (n = 0; n < num; ++n)
206 out[n] = (ovec[16 + n] = in[n]) ^ ivec[n];
207 /* shift ovec left... */
208 rem = nbits % 8;
209 num = nbits/8;
210 if (rem == 0)
211 memcpy(ivec, ovec + num, 16);
212 else
213 for (n = 0; n < 16; ++n)
214 ivec[n] = ovec[n + num] << rem |
215 ovec[n + num + 1] >> (8 - rem);
216
217 /* it is not necessary to cleanse ovec, since the IV is not secret */
218 }
219
220 /* N.B. This expects the input to be packed, MS bit first */
221 void
CRYPTO_cfb128_1_encrypt(const unsigned char * in,unsigned char * out,size_t bits,const void * key,unsigned char ivec[16],int * num,int enc,block128_f block)222 CRYPTO_cfb128_1_encrypt(const unsigned char *in, unsigned char *out,
223 size_t bits, const void *key,
224 unsigned char ivec[16], int *num,
225 int enc, block128_f block)
226 {
227 size_t n;
228 unsigned char c[1], d[1];
229
230 for (n = 0; n < bits; ++n)
231 {
232 c[0] = (in[n/8] & (1 << (7 - n % 8))) ? 0x80 : 0;
233 cfbr_encrypt_block(c, d, 1, key, ivec, enc, block);
234 out[n/8] = (out[n/8] & ~(1 << (unsigned int)(7 - n % 8))) |
235 ((d[0] & 0x80) >> (unsigned int)(n % 8));
236 }
237 }
238 LCRYPTO_ALIAS(CRYPTO_cfb128_1_encrypt);
239
240 void
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)241 CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
242 size_t length, const void *key,
243 unsigned char ivec[16], int *num,
244 int enc, block128_f block)
245 {
246 size_t n;
247
248 for (n = 0; n < length; ++n)
249 cfbr_encrypt_block(&in[n], &out[n], 8, key, ivec, enc, block);
250 }
251 LCRYPTO_ALIAS(CRYPTO_cfb128_8_encrypt);
252