• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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