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ctr128.c

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1/* $OpenBSD: ctr128.c,v 1.7 2017/08/13 17:46:24 bcook Exp $ */-
2/* ====================================================================-
3 * Copyright (c) 2008 The OpenSSL Project. All rights reserved.-
4 *-
5 * Redistribution and use in source and binary forms, with or without-
6 * modification, are permitted provided that the following conditions-
7 * are met:-
8 *-
9 * 1. Redistributions of source code must retain the above copyright-
10 * notice, this list of conditions and the following disclaimer. -
11 *-
12 * 2. Redistributions in binary form must reproduce the above copyright-
13 * notice, this list of conditions and the following disclaimer in-
14 * the documentation and/or other materials provided with the-
15 * distribution.-
16 *-
17 * 3. All advertising materials mentioning features or use of this-
18 * software must display the following acknowledgment:-
19 * "This product includes software developed by the OpenSSL Project-
20 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"-
21 *-
22 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to-
23 * endorse or promote products derived from this software without-
24 * prior written permission. For written permission, please contact-
25 * openssl-core@openssl.org.-
26 *-
27 * 5. Products derived from this software may not be called "OpenSSL"-
28 * nor may "OpenSSL" appear in their names without prior written-
29 * permission of the OpenSSL Project.-
30 *-
31 * 6. Redistributions of any form whatsoever must retain the following-
32 * acknowledgment:-
33 * "This product includes software developed by the OpenSSL Project-
34 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"-
35 *-
36 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY-
37 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE-
38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR-
39 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR-
40 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,-
41 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT-
42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;-
43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)-
44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,-
45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)-
46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED-
47 * OF THE POSSIBILITY OF SUCH DAMAGE.-
48 * ====================================================================-
49 *-
50 */-
51-
52#include <openssl/crypto.h>-
53#include "modes_lcl.h"-
54#include <string.h>-
55-
56#ifndef MODES_DEBUG-
57# ifndef NDEBUG-
58# define NDEBUG-
59# endif-
60#endif-
61#include <assert.h>-
62-
63/* NOTE: the IV/counter CTR mode is big-endian. The code itself-
64 * is endian-neutral. */-
65-
66/* increment counter (128-bit int) by 1 */-
67static void ctr128_inc(unsigned char *counter) {-
68 u32 n=16;-
69 u8 c;-
70-
71 do {-
72 --n;-
73 c = counter[n];-
74 ++c;-
75 counter[n] = c;-
76 if (c) return;
never executed: return;
cDescription
TRUEnever evaluated
FALSEnever evaluated
0
77 } while (n);
never executed: end of block
nDescription
TRUEnever evaluated
FALSEnever evaluated
0
78}
never executed: end of block
0
79-
80#if !defined(OPENSSL_SMALL_FOOTPRINT)-
81static void-
82ctr128_inc_aligned(unsigned char *counter)-
83{-
84#if BYTE_ORDER == LITTLE_ENDIAN-
85 ctr128_inc(counter);-
86#else-
87 size_t *data, c, n;-
88 data = (size_t *)counter;-
89 n = 16 / sizeof(size_t);-
90 do {-
91 --n;-
92 c = data[n];-
93 ++c;-
94 data[n] = c;-
95 if (c)-
96 return;-
97 } while (n);-
98#endif-
99}
never executed: end of block
0
100#endif-
101-
102/* The input encrypted as though 128bit counter mode is being-
103 * used. The extra state information to record how much of the-
104 * 128bit block we have used is contained in *num, and the-
105 * encrypted counter is kept in ecount_buf. Both *num and-
106 * ecount_buf must be initialised with zeros before the first-
107 * call to CRYPTO_ctr128_encrypt().-
108 *-
109 * This algorithm assumes that the counter is in the x lower bits-
110 * of the IV (ivec), and that the application has full control over-
111 * overflow and the rest of the IV. This implementation takes NO-
112 * responsability for checking that the counter doesn't overflow-
113 * into the rest of the IV when incremented.-
114 */-
115void CRYPTO_ctr128_encrypt(const unsigned char *in, unsigned char *out,-
116 size_t len, const void *key,-
117 unsigned char ivec[16], unsigned char ecount_buf[16],-
118 unsigned int *num, block128_f block)-
119{-
120 unsigned int n;-
121 size_t l=0;-
122-
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 */
16%sizeof(size_t) == 0Description
TRUEnever evaluated
FALSEnever evaluated
0
129 while (n && len) {
nDescription
TRUEnever evaluated
FALSEnever evaluated
lenDescription
TRUEnever evaluated
FALSEnever evaluated
0
130 *(out++) = *(in++) ^ ecount_buf[n];-
131 --len;-
132 n = (n+1) % 16;-
133 }
never executed: end of block
0
134-
135#ifdef __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) {
len>=16Description
TRUEnever evaluated
FALSEnever evaluated
0
140 (*block)(ivec, ecount_buf, key);-
141 ctr128_inc_aligned(ivec);-
142 for (; n<16; n+=sizeof(size_t))
n<16Description
TRUEnever evaluated
FALSEnever evaluated
0
143 *(size_t *)(out+n) =
never executed: *(size_t *)(out+n) = *(size_t *)(in+n) ^ *(size_t *)(ecount_buf+n);
0
144 *(size_t *)(in+n) ^ *(size_t *)(ecount_buf+n);
never executed: *(size_t *)(out+n) = *(size_t *)(in+n) ^ *(size_t *)(ecount_buf+n);
0
145 len -= 16;-
146 out += 16;-
147 in += 16;-
148 n = 0;-
149 }
never executed: end of block
0
150 if (len) {
lenDescription
TRUEnever evaluated
FALSEnever evaluated
0
151 (*block)(ivec, ecount_buf, key);-
152 ctr128_inc_aligned(ivec);-
153 while (len--) {
len--Description
TRUEnever evaluated
FALSEnever evaluated
0
154 out[n] = in[n] ^ ecount_buf[n];-
155 ++n;-
156 }
never executed: end of block
0
157 }
never executed: end of block
0
158 *num = n;-
159 return;
never executed: return;
0
160 } while(0);
never executed: end of block
0
161 /* the rest would be commonly eliminated by x86* compiler */-
162#endif-
163 while (l<len) {
l<lenDescription
TRUEnever evaluated
FALSEnever evaluated
0
164 if (n==0) {
n==0Description
TRUEnever evaluated
FALSEnever evaluated
0
165 (*block)(ivec, ecount_buf, key);-
166 ctr128_inc(ivec);-
167 }
never executed: end of block
0
168 out[l] = in[l] ^ ecount_buf[n];-
169 ++l;-
170 n = (n+1) % 16;-
171 }
never executed: end of block
0
172-
173 *num=n;-
174}
never executed: end of block
0
175-
176/* increment upper 96 bits of 128-bit counter by 1 */-
177static 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;
never executed: return;
cDescription
TRUEnever evaluated
FALSEnever evaluated
0
187 } while (n);
never executed: end of block
nDescription
TRUEnever evaluated
FALSEnever evaluated
0
188}
never executed: end of block
0
189-
190void 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(*num < 16);-
198-
199 n = *num;-
200-
201 while (n && len) {
nDescription
TRUEnever evaluated
FALSEevaluated 9 times by 1 test
Evaluated by:
  • evptest
lenDescription
TRUEnever evaluated
FALSEnever evaluated
0-9
202 *(out++) = *(in++) ^ ecount_buf[n];-
203 --len;-
204 n = (n+1) % 16;-
205 }
never executed: end of block
0
206-
207 ctr32 = GETU32(ivec+12);-
208 while (len>=16) {
len>=16Description
TRUEevaluated 9 times by 1 test
Evaluated by:
  • evptest
FALSEevaluated 9 times by 1 test
Evaluated by:
  • evptest
9
209 size_t blocks = len/16;-
210 /*-
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.-
214 */-
215 if (sizeof(size_t)>sizeof(unsigned int) && blocks>(1U<<28))
sizeof(size_t)...(unsigned int)Description
TRUEevaluated 9 times by 1 test
Evaluated by:
  • evptest
FALSEnever evaluated
blocks>(1U<<28)Description
TRUEnever evaluated
FALSEevaluated 9 times by 1 test
Evaluated by:
  • evptest
0-9
216 blocks = (1U<<28);
never executed: blocks = (1U<<28);
0
217 /*-
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...-
222 */-
223 ctr32 += (u32)blocks;-
224 if (ctr32 < blocks) {
ctr32 < blocksDescription
TRUEnever evaluated
FALSEevaluated 9 times by 1 test
Evaluated by:
  • evptest
0-9
225 blocks -= ctr32;-
226 ctr32 = 0;-
227 }
never executed: end of block
0
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);
never executed: ctr96_inc(ivec);
ctr32 == 0Description
TRUEnever evaluated
FALSEevaluated 9 times by 1 test
Evaluated by:
  • evptest
0-9
233 blocks *= 16;-
234 len -= blocks;-
235 out += blocks;-
236 in += blocks;-
237 }
executed 9 times by 1 test: end of block
Executed by:
  • evptest
9
238 if (len) {
lenDescription
TRUEevaluated 3 times by 1 test
Evaluated by:
  • evptest
FALSEevaluated 6 times by 1 test
Evaluated by:
  • evptest
3-6
239 memset(ecount_buf,0,16);-
240 (*func)(ecount_buf,ecount_buf,1,key,ivec);-
241 ++ctr32;-
242 PUTU32(ivec+12,ctr32);-
243 if (ctr32 == 0) ctr96_inc(ivec);
never executed: ctr96_inc(ivec);
ctr32 == 0Description
TRUEnever evaluated
FALSEevaluated 3 times by 1 test
Evaluated by:
  • evptest
0-3
244 while (len--) {
len--Description
TRUEevaluated 12 times by 1 test
Evaluated by:
  • evptest
FALSEevaluated 3 times by 1 test
Evaluated by:
  • evptest
3-12
245 out[n] = in[n] ^ ecount_buf[n];-
246 ++n;-
247 }
executed 12 times by 1 test: end of block
Executed by:
  • evptest
12
248 }
executed 3 times by 1 test: end of block
Executed by:
  • evptest
3
249-
250 *num=n;-
251}
executed 9 times by 1 test: end of block
Executed by:
  • evptest
9
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