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1 /* ====================================================================
2 * Copyright (c) 2008 The OpenSSL Project. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
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
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/)"
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.
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.
30 * 6. Redistributions of any form whatsoever must retain the following
32 * "This product includes software developed by the OpenSSL Project
33 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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 * ====================================================================
51 #include <openssl/crypto.h>
52 #include "modes_lcl.h"
63 * NOTE: the IV/counter CTR mode is big-endian. The code itself is
67 /* increment counter (128-bit int) by 1 */
68 static void ctr128_inc(unsigned char *counter
)
80 #if !defined(OPENSSL_SMALL_FOOTPRINT)
81 static void ctr128_inc_aligned(unsigned char *counter
)
83 size_t *data
, c
, d
, n
;
91 if (is_endian
.little
|| ((size_t)counter
% sizeof(size_t)) != 0) {
96 data
= (size_t *)counter
;
98 n
= 16 / sizeof(size_t);
102 /* did addition carry? */
103 c
= ((d
- c
) ^ d
) >> (sizeof(size_t) * 8 - 1);
109 * The input encrypted as though 128bit counter mode is being used. The
110 * extra state information to record how much of the 128bit block we have
111 * used is contained in *num, and the encrypted counter is kept in
112 * ecount_buf. Both *num and ecount_buf must be initialised with zeros
113 * before the first call to CRYPTO_ctr128_encrypt(). This algorithm assumes
114 * that the counter is in the x lower bits of the IV (ivec), and that the
115 * application has full control over overflow and the rest of the IV. This
116 * implementation takes NO responsibility for checking that the counter
117 * doesn't overflow into the rest of the IV when incremented.
119 void CRYPTO_ctr128_encrypt(const unsigned char *in
, unsigned char *out
,
120 size_t len
, const void *key
,
121 unsigned char ivec
[16],
122 unsigned char ecount_buf
[16], unsigned int *num
,
128 assert(in
&& out
&& key
&& ecount_buf
&& num
);
133 #if !defined(OPENSSL_SMALL_FOOTPRINT)
134 if (16 % sizeof(size_t) == 0) { /* always true actually */
137 *(out
++) = *(in
++) ^ ecount_buf
[n
];
142 # if defined(STRICT_ALIGNMENT)
143 if (((size_t)in
| (size_t)out
| (size_t)ecount_buf
)
144 % sizeof(size_t) != 0)
148 (*block
) (ivec
, ecount_buf
, key
);
149 ctr128_inc_aligned(ivec
);
150 for (n
= 0; n
< 16; n
+= sizeof(size_t))
151 *(size_t *)(out
+ n
) =
152 *(size_t *)(in
+ n
) ^ *(size_t *)(ecount_buf
+ n
);
159 (*block
) (ivec
, ecount_buf
, key
);
160 ctr128_inc_aligned(ivec
);
162 out
[n
] = in
[n
] ^ ecount_buf
[n
];
170 /* the rest would be commonly eliminated by x86* compiler */
174 (*block
) (ivec
, ecount_buf
, key
);
177 out
[l
] = in
[l
] ^ ecount_buf
[n
];
185 /* increment upper 96 bits of 128-bit counter by 1 */
186 static void ctr96_inc(unsigned char *counter
)
198 void CRYPTO_ctr128_encrypt_ctr32(const unsigned char *in
, unsigned char *out
,
199 size_t len
, const void *key
,
200 unsigned char ivec
[16],
201 unsigned char ecount_buf
[16],
202 unsigned int *num
, ctr128_f func
)
204 unsigned int n
, ctr32
;
206 assert(in
&& out
&& key
&& ecount_buf
&& num
);
212 *(out
++) = *(in
++) ^ ecount_buf
[n
];
217 ctr32
= GETU32(ivec
+ 12);
219 size_t blocks
= len
/ 16;
221 * 1<<28 is just a not-so-small yet not-so-large number...
222 * Below condition is practically never met, but it has to
223 * be checked for code correctness.
225 if (sizeof(size_t) > sizeof(unsigned int) && blocks
> (1U << 28))
228 * As (*func) operates on 32-bit counter, caller
229 * has to handle overflow. 'if' below detects the
230 * overflow, which is then handled by limiting the
231 * amount of blocks to the exact overflow point...
233 ctr32
+= (u32
)blocks
;
234 if (ctr32
< blocks
) {
238 (*func
) (in
, out
, blocks
, key
, ivec
);
239 /* (*ctr) does not update ivec, caller does: */
240 PUTU32(ivec
+ 12, ctr32
);
241 /* ... overflow was detected, propagate carry. */
250 memset(ecount_buf
, 0, 16);
251 (*func
) (ecount_buf
, ecount_buf
, 1, key
, ivec
);
253 PUTU32(ivec
+ 12, ctr32
);
257 out
[n
] = in
[n
] ^ ecount_buf
[n
];