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