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 "modes.h"
52 #include <string.h>
53
54 #ifndef MODES_DEBUG
55 # ifndef NDEBUG
56 # define NDEBUG
57 # endif
58 #endif
59 #include <assert.h>
60
61 typedef unsigned int u32;
62 typedef unsigned char u8;
63
64 #define STRICT_ALIGNMENT
65 #if defined(__i386) || defined(__i386__) || \
66 defined(__x86_64) || defined(__x86_64__) || \
67 defined(_M_IX86) || defined(_M_AMD64) || defined(_M_X64) || \
68 defined(__s390__) || defined(__s390x__)
69 # undef STRICT_ALIGNMENT
70 #endif
71
72 /* NOTE: the IV/counter CTR mode is big-endian. The code itself
73 * is endian-neutral. */
74
75 /* increment counter (128-bit int) by 1 */
ctr128_inc(unsigned char * counter)76 static void ctr128_inc(unsigned char *counter) {
77 u32 n=16;
78 u8 c;
79
80 do {
81 --n;
82 c = counter[n];
83 ++c;
84 counter[n] = c;
85 if (c) return;
86 } while (n);
87 }
88
89 #if !defined(OPENSSL_SMALL_FOOTPRINT)
ctr128_inc_aligned(unsigned char * counter)90 static void ctr128_inc_aligned(unsigned char *counter) {
91 size_t *data,c,n;
92 const union { long one; char little; } is_endian = {1};
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) return;
107 } while (n);
108 }
109 #endif
110
111 /* The input encrypted as though 128bit counter mode is being
112 * used. The extra state information to record how much of the
113 * 128bit block we have used is contained in *num, and the
114 * encrypted counter is kept in ecount_buf. Both *num and
115 * ecount_buf must be initialised with zeros before the first
116 * call to CRYPTO_ctr128_encrypt().
117 *
118 * This algorithm assumes that the counter is in the x lower bits
119 * of the IV (ivec), and that the application has full control over
120 * overflow and the rest of the IV. This implementation takes NO
121 * responsability for checking that the counter doesn't overflow
122 * into the rest of the IV when incremented.
123 */
CRYPTO_ctr128_encrypt(const unsigned char * in,unsigned char * out,size_t len,const void * key,unsigned char ivec[16],unsigned char ecount_buf[16],unsigned int * num,block128_f block)124 void CRYPTO_ctr128_encrypt(const unsigned char *in, unsigned char *out,
125 size_t len, const void *key,
126 unsigned char ivec[16], unsigned char ecount_buf[16],
127 unsigned int *num, 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 n = *num;
136
137 #if !defined(OPENSSL_SMALL_FOOTPRINT)
138 if (16%sizeof(size_t) == 0) do { /* always true actually */
139 while (n && len) {
140 *(out++) = *(in++) ^ ecount_buf[n];
141 --len;
142 n = (n+1) % 16;
143 }
144
145 #if defined(STRICT_ALIGNMENT)
146 if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
147 break;
148 #endif
149 while (len>=16) {
150 (*block)(ivec, ecount_buf, key);
151 ctr128_inc_aligned(ivec);
152 for (; n<16; n+=sizeof(size_t))
153 *(size_t *)(out+n) =
154 *(size_t *)(in+n) ^ *(size_t *)(ecount_buf+n);
155 len -= 16;
156 out += 16;
157 in += 16;
158 n = 0;
159 }
160 if (len) {
161 (*block)(ivec, ecount_buf, key);
162 ctr128_inc_aligned(ivec);
163 while (len--) {
164 out[n] = in[n] ^ ecount_buf[n];
165 ++n;
166 }
167 }
168 *num = n;
169 return;
170 } while(0);
171 /* the rest would be commonly eliminated by x86* compiler */
172 #endif
173 while (l<len) {
174 if (n==0) {
175 (*block)(ivec, ecount_buf, key);
176 ctr128_inc(ivec);
177 }
178 out[l] = in[l] ^ ecount_buf[n];
179 ++l;
180 n = (n+1) % 16;
181 }
182
183 *num=n;
184 }
185