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 "modes_lcl.h"
61 /* NOTE: the IV/counter CTR mode is big-endian. The code itself
62 * is endian-neutral. */
64 /* increment counter (128-bit int) by 1 */
65 static void ctr128_inc(unsigned char *counter) {
78 #if !defined(OPENSSL_SMALL_FOOTPRINT)
79 static void ctr128_inc_aligned(unsigned char *counter) {
81 const union { long one; char little; } is_endian = {1};
83 if (is_endian.little) {
88 data = (size_t *)counter;
89 n = 16/sizeof(size_t);
100 /* The input encrypted as though 128bit counter mode is being
101 * used. The extra state information to record how much of the
102 * 128bit block we have used is contained in *num, and the
103 * encrypted counter is kept in ecount_buf. Both *num and
104 * ecount_buf must be initialised with zeros before the first
105 * call to CRYPTO_ctr128_encrypt().
107 * This algorithm assumes that the counter is in the x lower bits
108 * of the IV (ivec), and that the application has full control over
109 * overflow and the rest of the IV. This implementation takes NO
110 * responsability for checking that the counter doesn't overflow
111 * into the rest of the IV when incremented.
113 void CRYPTO_ctr128_encrypt(const unsigned char *in, unsigned char *out,
114 size_t len, const void *key,
115 unsigned char ivec[16], unsigned char ecount_buf[16],
116 unsigned int *num, block128_f block)
121 assert(in && out && key && ecount_buf && num);
126 #if !defined(OPENSSL_SMALL_FOOTPRINT)
127 if (16%sizeof(size_t) == 0) do { /* always true actually */
129 *(out++) = *(in++) ^ ecount_buf[n];
134 #if defined(STRICT_ALIGNMENT)
135 if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
139 (*block)(ivec, ecount_buf, key);
140 ctr128_inc_aligned(ivec);
141 for (; n<16; n+=sizeof(size_t))
143 *(size_t *)(in+n) ^ *(size_t *)(ecount_buf+n);
150 (*block)(ivec, ecount_buf, key);
151 ctr128_inc_aligned(ivec);
153 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) {
189 void CRYPTO_ctr128_encrypt_ctr32(const unsigned char *in, unsigned char *out,
190 size_t len, const void *key,
191 unsigned char ivec[16], unsigned char ecount_buf[16],
192 unsigned int *num, ctr128_f func)
194 unsigned int n,ctr32;
196 assert(in && out && key && ecount_buf && num);
202 *(out++) = *(in++) ^ ecount_buf[n];
207 ctr32 = GETU32(ivec+12);
209 size_t blocks = len/16;
211 * 1<<28 is just a not-so-small yet not-so-large number...
212 * Below condition is practically never met, but it has to
213 * be checked for code correctness.
215 if (sizeof(size_t)>sizeof(unsigned int) && blocks>(1U<<28))
218 * As (*func) operates on 32-bit counter, caller
219 * has to handle overflow. 'if' below detects the
220 * overflow, which is then handled by limiting the
221 * amount of blocks to the exact overflow point...
223 ctr32 += (u32)blocks;
224 if (ctr32 < blocks) {
228 (*func)(in,out,blocks,key,ivec);
229 /* (*ctr) does not update ivec, caller does: */
230 PUTU32(ivec+12,ctr32);
231 /* ... overflow was detected, propogate carry. */
232 if (ctr32 == 0) ctr96_inc(ivec);
239 memset(ecount_buf,0,16);
240 (*func)(ecount_buf,ecount_buf,1,key,ivec);
242 PUTU32(ivec+12,ctr32);
243 if (ctr32 == 0) ctr96_inc(ivec);
245 out[n] = in[n] ^ ecount_buf[n];