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 #include <openssl/type_check.h>
50
51 #include <assert.h>
52 #include <string.h>
53
54 #include "internal.h"
55 #include "../../internal.h"
56
57
58 // NOTE: the IV/counter CTR mode is big-endian. The code itself
59 // is endian-neutral.
60
61 // increment counter (128-bit int) by 1
ctr128_inc(uint8_t * counter)62 static void ctr128_inc(uint8_t *counter) {
63 uint32_t n = 16, c = 1;
64
65 do {
66 --n;
67 c += counter[n];
68 counter[n] = (uint8_t) c;
69 c >>= 8;
70 } while (n);
71 }
72
73 OPENSSL_STATIC_ASSERT(16 % sizeof(crypto_word_t) == 0,
74 "block cannot be divided into crypto_word_t");
75
76 // The input encrypted as though 128bit counter mode is being used. The extra
77 // state information to record how much of the 128bit block we have used is
78 // contained in *num, and the encrypted counter is kept in ecount_buf. Both
79 // *num and ecount_buf must be initialised with zeros before the first call to
80 // CRYPTO_ctr128_encrypt().
81 //
82 // This algorithm assumes that the counter is in the x lower bits of the IV
83 // (ivec), and that the application has full control over overflow and the rest
84 // of the IV. This implementation takes NO responsibility for checking that
85 // the counter doesn't overflow into the rest of the IV when incremented.
CRYPTO_ctr128_encrypt(const uint8_t * in,uint8_t * out,size_t len,const AES_KEY * key,uint8_t ivec[16],uint8_t ecount_buf[16],unsigned int * num,block128_f block)86 void CRYPTO_ctr128_encrypt(const uint8_t *in, uint8_t *out, size_t len,
87 const AES_KEY *key, uint8_t ivec[16],
88 uint8_t ecount_buf[16], unsigned int *num,
89 block128_f block) {
90 unsigned int n;
91
92 assert(key && ecount_buf && num);
93 assert(len == 0 || (in && out));
94 assert(*num < 16);
95
96 n = *num;
97
98 while (n && len) {
99 *(out++) = *(in++) ^ ecount_buf[n];
100 --len;
101 n = (n + 1) % 16;
102 }
103 while (len >= 16) {
104 (*block)(ivec, ecount_buf, key);
105 ctr128_inc(ivec);
106 for (n = 0; n < 16; n += sizeof(crypto_word_t)) {
107 CRYPTO_store_word_le(out + n, CRYPTO_load_word_le(in + n) ^
108 CRYPTO_load_word_le(ecount_buf + n));
109 }
110 len -= 16;
111 out += 16;
112 in += 16;
113 n = 0;
114 }
115 if (len) {
116 (*block)(ivec, ecount_buf, key);
117 ctr128_inc(ivec);
118 while (len--) {
119 out[n] = in[n] ^ ecount_buf[n];
120 ++n;
121 }
122 }
123 *num = n;
124 }
125
126 // increment upper 96 bits of 128-bit counter by 1
ctr96_inc(uint8_t * counter)127 static void ctr96_inc(uint8_t *counter) {
128 uint32_t n = 12, c = 1;
129
130 do {
131 --n;
132 c += counter[n];
133 counter[n] = (uint8_t) c;
134 c >>= 8;
135 } while (n);
136 }
137
CRYPTO_ctr128_encrypt_ctr32(const uint8_t * in,uint8_t * out,size_t len,const AES_KEY * key,uint8_t ivec[16],uint8_t ecount_buf[16],unsigned int * num,ctr128_f func)138 void CRYPTO_ctr128_encrypt_ctr32(const uint8_t *in, uint8_t *out, size_t len,
139 const AES_KEY *key, uint8_t ivec[16],
140 uint8_t ecount_buf[16], unsigned int *num,
141 ctr128_f func) {
142 unsigned int n, ctr32;
143
144 assert(key && ecount_buf && num);
145 assert(len == 0 || (in && out));
146 assert(*num < 16);
147
148 n = *num;
149
150 while (n && len) {
151 *(out++) = *(in++) ^ ecount_buf[n];
152 --len;
153 n = (n + 1) % 16;
154 }
155
156 ctr32 = CRYPTO_load_u32_be(ivec + 12);
157 while (len >= 16) {
158 size_t blocks = len / 16;
159 // 1<<28 is just a not-so-small yet not-so-large number...
160 // Below condition is practically never met, but it has to
161 // be checked for code correctness.
162 if (sizeof(size_t) > sizeof(unsigned int) && blocks > (1U << 28)) {
163 blocks = (1U << 28);
164 }
165 // As (*func) operates on 32-bit counter, caller
166 // has to handle overflow. 'if' below detects the
167 // overflow, which is then handled by limiting the
168 // amount of blocks to the exact overflow point...
169 ctr32 += (uint32_t)blocks;
170 if (ctr32 < blocks) {
171 blocks -= ctr32;
172 ctr32 = 0;
173 }
174 (*func)(in, out, blocks, key, ivec);
175 // (*func) does not update ivec, caller does:
176 CRYPTO_store_u32_be(ivec + 12, ctr32);
177 // ... overflow was detected, propogate carry.
178 if (ctr32 == 0) {
179 ctr96_inc(ivec);
180 }
181 blocks *= 16;
182 len -= blocks;
183 out += blocks;
184 in += blocks;
185 }
186 if (len) {
187 OPENSSL_memset(ecount_buf, 0, 16);
188 (*func)(ecount_buf, ecount_buf, 1, key, ivec);
189 ++ctr32;
190 CRYPTO_store_u32_be(ivec + 12, ctr32);
191 if (ctr32 == 0) {
192 ctr96_inc(ivec);
193 }
194 while (len--) {
195 out[n] = in[n] ^ ecount_buf[n];
196 ++n;
197 }
198 }
199
200 *num = n;
201 }
202