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comparison: netwerk/srtp/src/crypto/rng/ctr_prng.c
netwerk/srtp/src/crypto/rng/ctr_prng.c
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| -1:000000000000 | 0:92dbb4c935c5 |
|---|---|
| 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 #include "prng.h" | |
| 47 | |
| 48 /* single, global prng structure */ | |
| 49 | |
| 50 ctr_prng_t ctr_prng; | |
| 51 | |
| 52 err_status_t | |
| 53 ctr_prng_init(rand_source_func_t random_source) { | |
| 54 uint8_t tmp_key[32]; | |
| 55 err_status_t status; | |
| 56 | |
| 57 /* initialize output count to zero */ | |
| 58 ctr_prng.octet_count = 0; | |
| 59 | |
| 60 /* set random source */ | |
| 61 ctr_prng.rand = random_source; | |
| 62 | |
| 63 /* initialize secret key from random source */ | |
| 64 status = random_source(tmp_key, 32); | |
| 65 if (status) | |
| 66 return status; | |
| 67 | |
| 68 /* initialize aes ctr context with random key */ | |
| 69 status = aes_icm_context_init(&ctr_prng.state, tmp_key, 30); | |
| 70 if (status) | |
| 71 return status; | |
| 72 | |
| 73 return err_status_ok; | |
| 74 } | |
| 75 | |
| 76 err_status_t | |
| 77 ctr_prng_get_octet_string(void *dest, uint32_t len) { | |
| 78 err_status_t status; | |
| 79 | |
| 80 /* | |
| 81 * if we need to re-initialize the prng, do so now | |
| 82 * | |
| 83 * avoid 32-bit overflows by subtracting instead of adding | |
| 84 */ | |
| 85 if (ctr_prng.octet_count > MAX_PRNG_OUT_LEN - len) { | |
| 86 status = ctr_prng_init(ctr_prng.rand); | |
| 87 if (status) | |
| 88 return status; | |
| 89 } | |
| 90 ctr_prng.octet_count += len; | |
| 91 | |
| 92 /* | |
| 93 * write prng output | |
| 94 */ | |
| 95 status = aes_icm_output(&ctr_prng.state, (uint8_t*)dest, len); | |
| 96 if (status) | |
| 97 return status; | |
| 98 | |
| 99 return err_status_ok; | |
| 100 } | |
| 101 | |
| 102 err_status_t | |
| 103 ctr_prng_deinit(void) { | |
| 104 | |
| 105 /* nothing */ | |
| 106 | |
| 107 return err_status_ok; | |
| 108 } |
