Line data Source code
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 : * NOTE: the IV/counter CTR mode is big-endian. The code itself is
64 : * endian-neutral.
65 : */
66 :
67 : /* increment counter (128-bit int) by 1 */
68 : static void ctr128_inc(unsigned char *counter)
69 : {
70 : u32 n = 16;
71 : u8 c;
72 :
73 : do {
74 0 : --n;
75 0 : c = counter[n];
76 0 : ++c;
77 0 : counter[n] = c;
78 0 : if (c)
79 : return;
80 0 : } while (n);
81 : }
82 :
83 : #if !defined(OPENSSL_SMALL_FOOTPRINT)
84 : static void ctr128_inc_aligned(unsigned char *counter)
85 : {
86 : size_t *data, c, n;
87 : const union {
88 : long one;
89 : char little;
90 : } is_endian = {
91 : 1
92 : };
93 :
94 : if (is_endian.little) {
95 : ctr128_inc(counter);
96 : return;
97 : }
98 :
99 : data = (size_t *)counter;
100 : n = 16 / sizeof(size_t);
101 : do {
102 : --n;
103 : c = data[n];
104 : ++c;
105 : data[n] = c;
106 : if (c)
107 : return;
108 : } while (n);
109 : }
110 : #endif
111 :
112 : /*
113 : * The input encrypted as though 128bit counter mode is being used. The
114 : * extra state information to record how much of the 128bit block we have
115 : * used is contained in *num, and the encrypted counter is kept in
116 : * ecount_buf. Both *num and ecount_buf must be initialised with zeros
117 : * before the first call to CRYPTO_ctr128_encrypt(). This algorithm assumes
118 : * that the counter is in the x lower bits of the IV (ivec), and that the
119 : * application has full control over overflow and the rest of the IV. This
120 : * implementation takes NO responsability for checking that the counter
121 : * doesn't overflow into the rest of the IV when incremented.
122 : */
123 0 : void CRYPTO_ctr128_encrypt(const unsigned char *in, unsigned char *out,
124 : size_t len, const void *key,
125 : unsigned char ivec[16],
126 : unsigned char ecount_buf[16], unsigned int *num,
127 : block128_f block)
128 : {
129 : unsigned int n;
130 : size_t l = 0;
131 :
132 : assert(in && out && key && ecount_buf && num);
133 : assert(*num < 16);
134 :
135 0 : n = *num;
136 :
137 : #if !defined(OPENSSL_SMALL_FOOTPRINT)
138 : if (16 % sizeof(size_t) == 0) { /* always true actually */
139 : do {
140 0 : while (n && len) {
141 0 : *(out++) = *(in++) ^ ecount_buf[n];
142 0 : --len;
143 0 : n = (n + 1) % 16;
144 : }
145 :
146 : # if defined(STRICT_ALIGNMENT)
147 : if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) !=
148 : 0)
149 : break;
150 : # endif
151 0 : while (len >= 16) {
152 0 : (*block) (ivec, ecount_buf, key);
153 : ctr128_inc_aligned(ivec);
154 0 : for (; n < 16; n += sizeof(size_t))
155 0 : *(size_t *)(out + n) =
156 0 : *(size_t *)(in + n) ^ *(size_t *)(ecount_buf + n);
157 0 : len -= 16;
158 0 : out += 16;
159 0 : in += 16;
160 : n = 0;
161 : }
162 0 : if (len) {
163 0 : (*block) (ivec, ecount_buf, key);
164 : ctr128_inc_aligned(ivec);
165 0 : while (len--) {
166 0 : out[n] = in[n] ^ ecount_buf[n];
167 0 : ++n;
168 : }
169 : }
170 0 : *num = n;
171 0 : return;
172 : } while (0);
173 : }
174 : /* the rest would be commonly eliminated by x86* compiler */
175 : #endif
176 : while (l < len) {
177 : if (n == 0) {
178 : (*block) (ivec, ecount_buf, key);
179 : ctr128_inc(ivec);
180 : }
181 : out[l] = in[l] ^ ecount_buf[n];
182 : ++l;
183 : n = (n + 1) % 16;
184 : }
185 :
186 : *num = n;
187 : }
188 :
189 : /* increment upper 96 bits of 128-bit counter by 1 */
190 : static void ctr96_inc(unsigned char *counter)
191 : {
192 : u32 n = 12;
193 : u8 c;
194 :
195 : do {
196 0 : --n;
197 0 : c = counter[n];
198 0 : ++c;
199 0 : counter[n] = c;
200 0 : if (c)
201 : return;
202 0 : } while (n);
203 : }
204 :
205 0 : void CRYPTO_ctr128_encrypt_ctr32(const unsigned char *in, unsigned char *out,
206 : size_t len, const void *key,
207 : unsigned char ivec[16],
208 : unsigned char ecount_buf[16],
209 : unsigned int *num, ctr128_f func)
210 : {
211 : unsigned int n, ctr32;
212 :
213 : assert(in && out && key && ecount_buf && num);
214 : assert(*num < 16);
215 :
216 0 : n = *num;
217 :
218 0 : while (n && len) {
219 0 : *(out++) = *(in++) ^ ecount_buf[n];
220 0 : --len;
221 0 : n = (n + 1) % 16;
222 : }
223 :
224 0 : ctr32 = GETU32(ivec + 12);
225 0 : while (len >= 16) {
226 0 : size_t blocks = len / 16;
227 : /*
228 : * 1<<28 is just a not-so-small yet not-so-large number...
229 : * Below condition is practically never met, but it has to
230 : * be checked for code correctness.
231 : */
232 0 : if (sizeof(size_t) > sizeof(unsigned int) && blocks > (1U << 28))
233 : blocks = (1U << 28);
234 : /*
235 : * As (*func) operates on 32-bit counter, caller
236 : * has to handle overflow. 'if' below detects the
237 : * overflow, which is then handled by limiting the
238 : * amount of blocks to the exact overflow point...
239 : */
240 0 : ctr32 += (u32)blocks;
241 0 : if (ctr32 < blocks) {
242 0 : blocks -= ctr32;
243 : ctr32 = 0;
244 : }
245 0 : (*func) (in, out, blocks, key, ivec);
246 : /* (*ctr) does not update ivec, caller does: */
247 0 : PUTU32(ivec + 12, ctr32);
248 : /* ... overflow was detected, propogate carry. */
249 0 : if (ctr32 == 0)
250 : ctr96_inc(ivec);
251 0 : blocks *= 16;
252 0 : len -= blocks;
253 0 : out += blocks;
254 0 : in += blocks;
255 : }
256 0 : if (len) {
257 : memset(ecount_buf, 0, 16);
258 0 : (*func) (ecount_buf, ecount_buf, 1, key, ivec);
259 0 : ++ctr32;
260 0 : PUTU32(ivec + 12, ctr32);
261 0 : if (ctr32 == 0)
262 : ctr96_inc(ivec);
263 0 : while (len--) {
264 0 : out[n] = in[n] ^ ecount_buf[n];
265 0 : ++n;
266 : }
267 : }
268 :
269 0 : *num = n;
270 0 : }
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