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1 /* | |
2 * ctr_prng.c | |
3 * | |
4 * counter mode based pseudorandom source | |
5 * | |
6 * David A. McGrew | |
7 * Cisco Systems, Inc. | |
8 */ | |
9 /* | |
10 * | |
11 * Copyright(c) 2001-2006 Cisco Systems, Inc. | |
12 * All rights reserved. | |
13 * | |
14 * Redistribution and use in source and binary forms, with or without | |
15 * modification, are permitted provided that the following conditions | |
16 * are met: | |
17 * | |
18 * Redistributions of source code must retain the above copyright | |
19 * notice, this list of conditions and the following disclaimer. | |
20 * | |
21 * Redistributions in binary form must reproduce the above | |
22 * copyright notice, this list of conditions and the following | |
23 * disclaimer in the documentation and/or other materials provided | |
24 * with the distribution. | |
25 * | |
26 * Neither the name of the Cisco Systems, Inc. nor the names of its | |
27 * contributors may be used to endorse or promote products derived | |
28 * from this software without specific prior written permission. | |
29 * | |
30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
31 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
32 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
33 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
34 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, | |
35 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
36 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
37 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
41 * OF THE POSSIBILITY OF SUCH DAMAGE. | |
42 * | |
43 */ | |
44 | |
45 | |
46 #ifdef HAVE_CONFIG_H | |
47 #include <config.h> | |
48 #endif | |
49 | |
50 #include "prng.h" | |
51 | |
52 /* single, global prng structure */ | |
53 | |
54 ctr_prng_t ctr_prng; | |
55 | |
56 err_status_t | |
57 ctr_prng_init(rand_source_func_t random_source) { | |
58 uint8_t tmp_key[32]; | |
59 err_status_t status; | |
60 | |
61 /* initialize output count to zero */ | |
62 ctr_prng.octet_count = 0; | |
63 | |
64 /* set random source */ | |
65 ctr_prng.rand = random_source; | |
66 | |
67 /* initialize secret key from random source */ | |
68 status = random_source(tmp_key, 32); | |
69 if (status) | |
70 return status; | |
71 | |
72 /* initialize aes ctr context with random key */ | |
73 #ifdef OPENSSL | |
74 status = aes_icm_openssl_context_init(&ctr_prng.state, tmp_key, 30); | |
75 #else | |
76 status = aes_icm_context_init(&ctr_prng.state, tmp_key, 30); | |
77 #endif | |
78 if (status) | |
79 return status; | |
80 | |
81 return err_status_ok; | |
82 } | |
83 | |
84 err_status_t | |
85 ctr_prng_get_octet_string(void *dest, uint32_t len) { | |
86 err_status_t status; | |
87 | |
88 /* | |
89 * if we need to re-initialize the prng, do so now | |
90 */ | |
91 if ((aes_icm_bytes_encrypted(&ctr_prng.state) + len) > 0xffff) { | |
92 status = ctr_prng_init(ctr_prng.rand); | |
93 if (status) | |
94 return status; | |
95 } | |
96 ctr_prng.octet_count += len; | |
97 | |
98 /* | |
99 * write prng output | |
100 */ | |
101 status = aes_icm_output(&ctr_prng.state, (uint8_t*)dest, len); | |
102 if (status) | |
103 return status; | |
104 | |
105 return err_status_ok; | |
106 } | |
107 | |
108 err_status_t | |
109 ctr_prng_deinit(void) { | |
110 | |
111 /* nothing */ | |
112 | |
113 return err_status_ok; | |
114 } | |
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