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)
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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"
56 * NOTE: the IV/counter CTR mode is big-endian. The code itself is
60 /* increment counter (128-bit int) by 1 */
61 static void ctr128_inc(unsigned char *counter)
73 #if !defined(OPENSSL_SMALL_FOOTPRINT)
74 static void ctr128_inc_aligned(unsigned char *counter)
76 size_t *data, c, d, n;
84 if (is_endian.little || ((size_t)counter % sizeof(size_t)) != 0) {
89 data = (size_t *)counter;
91 n = 16 / sizeof(size_t);
95 /* did addition carry? */
96 c = ((d - c) ^ d) >> (sizeof(size_t) * 8 - 1);
102 * The input encrypted as though 128bit counter mode is being used. The
103 * extra state information to record how much of the 128bit block we have
104 * used is contained in *num, and the encrypted counter is kept in
105 * ecount_buf. Both *num and ecount_buf must be initialised with zeros
106 * before the first call to CRYPTO_ctr128_encrypt(). This algorithm assumes
107 * that the counter is in the x lower bits of the IV (ivec), and that the
108 * application has full control over overflow and the rest of the IV. This
109 * implementation takes NO responsibility for checking that the counter
110 * doesn't overflow into the rest of the IV when incremented.
112 void CRYPTO_ctr128_encrypt(const unsigned char *in, unsigned char *out,
113 size_t len, const void *key,
114 unsigned char ivec[16],
115 unsigned char ecount_buf[16], unsigned int *num,
123 #if !defined(OPENSSL_SMALL_FOOTPRINT)
124 if (16 % sizeof(size_t) == 0) { /* always true actually */
127 *(out++) = *(in++) ^ ecount_buf[n];
132 # if defined(STRICT_ALIGNMENT)
133 if (((size_t)in | (size_t)out | (size_t)ecount_buf)
134 % sizeof(size_t) != 0)
138 (*block) (ivec, ecount_buf, key);
139 ctr128_inc_aligned(ivec);
140 for (n = 0; n < 16; n += sizeof(size_t))
141 *(size_t *)(out + n) =
142 *(size_t *)(in + n) ^ *(size_t *)(ecount_buf + n);
149 (*block) (ivec, ecount_buf, key);
150 ctr128_inc_aligned(ivec);
152 out[n] = in[n] ^ ecount_buf[n];
160 /* the rest would be commonly eliminated by x86* compiler */
164 (*block) (ivec, ecount_buf, key);
167 out[l] = in[l] ^ ecount_buf[n];
175 /* increment upper 96 bits of 128-bit counter by 1 */
176 static void ctr96_inc(unsigned char *counter)
188 void CRYPTO_ctr128_encrypt_ctr32(const unsigned char *in, unsigned char *out,
189 size_t len, const void *key,
190 unsigned char ivec[16],
191 unsigned char ecount_buf[16],
192 unsigned int *num, ctr128_f func)
194 unsigned int n, ctr32;
199 *(out++) = *(in++) ^ ecount_buf[n];
204 ctr32 = GETU32(ivec + 12);
206 size_t blocks = len / 16;
208 * 1<<28 is just a not-so-small yet not-so-large number...
209 * Below condition is practically never met, but it has to
210 * be checked for code correctness.
212 if (sizeof(size_t) > sizeof(unsigned int) && blocks > (1U << 28))
215 * As (*func) operates on 32-bit counter, caller
216 * has to handle overflow. 'if' below detects the
217 * overflow, which is then handled by limiting the
218 * amount of blocks to the exact overflow point...
220 ctr32 += (u32)blocks;
221 if (ctr32 < blocks) {
225 (*func) (in, out, blocks, key, ivec);
226 /* (*ctr) does not update ivec, caller does: */
227 PUTU32(ivec + 12, ctr32);
228 /* ... overflow was detected, propagate carry. */
237 memset(ecount_buf, 0, 16);
238 (*func) (ecount_buf, ecount_buf, 1, key, ivec);
240 PUTU32(ivec + 12, ctr32);
244 out[n] = in[n] ^ ecount_buf[n];