1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/netwerk/srtp/src/crypto/rng/ctr_prng.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,108 @@
1.4 +/*
1.5 + * ctr_prng.c
1.6 + *
1.7 + * counter mode based pseudorandom source
1.8 + *
1.9 + * David A. McGrew
1.10 + * Cisco Systems, Inc.
1.11 + */
1.12 +/*
1.13 + *
1.14 + * Copyright(c) 2001-2006 Cisco Systems, Inc.
1.15 + * All rights reserved.
1.16 + *
1.17 + * Redistribution and use in source and binary forms, with or without
1.18 + * modification, are permitted provided that the following conditions
1.19 + * are met:
1.20 + *
1.21 + * Redistributions of source code must retain the above copyright
1.22 + * notice, this list of conditions and the following disclaimer.
1.23 + *
1.24 + * Redistributions in binary form must reproduce the above
1.25 + * copyright notice, this list of conditions and the following
1.26 + * disclaimer in the documentation and/or other materials provided
1.27 + * with the distribution.
1.28 + *
1.29 + * Neither the name of the Cisco Systems, Inc. nor the names of its
1.30 + * contributors may be used to endorse or promote products derived
1.31 + * from this software without specific prior written permission.
1.32 + *
1.33 + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
1.34 + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
1.35 + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
1.36 + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
1.37 + * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
1.38 + * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
1.39 + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
1.40 + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
1.41 + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
1.42 + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.43 + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
1.44 + * OF THE POSSIBILITY OF SUCH DAMAGE.
1.45 + *
1.46 + */
1.47 +
1.48 +
1.49 +#include "prng.h"
1.50 +
1.51 +/* single, global prng structure */
1.52 +
1.53 +ctr_prng_t ctr_prng;
1.54 +
1.55 +err_status_t
1.56 +ctr_prng_init(rand_source_func_t random_source) {
1.57 + uint8_t tmp_key[32];
1.58 + err_status_t status;
1.59 +
1.60 + /* initialize output count to zero */
1.61 + ctr_prng.octet_count = 0;
1.62 +
1.63 + /* set random source */
1.64 + ctr_prng.rand = random_source;
1.65 +
1.66 + /* initialize secret key from random source */
1.67 + status = random_source(tmp_key, 32);
1.68 + if (status)
1.69 + return status;
1.70 +
1.71 + /* initialize aes ctr context with random key */
1.72 + status = aes_icm_context_init(&ctr_prng.state, tmp_key, 30);
1.73 + if (status)
1.74 + return status;
1.75 +
1.76 + return err_status_ok;
1.77 +}
1.78 +
1.79 +err_status_t
1.80 +ctr_prng_get_octet_string(void *dest, uint32_t len) {
1.81 + err_status_t status;
1.82 +
1.83 + /*
1.84 + * if we need to re-initialize the prng, do so now
1.85 + *
1.86 + * avoid 32-bit overflows by subtracting instead of adding
1.87 + */
1.88 + if (ctr_prng.octet_count > MAX_PRNG_OUT_LEN - len) {
1.89 + status = ctr_prng_init(ctr_prng.rand);
1.90 + if (status)
1.91 + return status;
1.92 + }
1.93 + ctr_prng.octet_count += len;
1.94 +
1.95 + /*
1.96 + * write prng output
1.97 + */
1.98 + status = aes_icm_output(&ctr_prng.state, (uint8_t*)dest, len);
1.99 + if (status)
1.100 + return status;
1.101 +
1.102 + return err_status_ok;
1.103 +}
1.104 +
1.105 +err_status_t
1.106 +ctr_prng_deinit(void) {
1.107 +
1.108 + /* nothing */
1.109 +
1.110 + return err_status_ok;
1.111 +}
