1386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari/* 2386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * ctr_prng.c 3386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * 4386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * counter mode based pseudorandom source 5386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * 6386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * David A. McGrew 7386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * Cisco Systems, Inc. 8386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari */ 9386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari/* 10386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * 11386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * Copyright(c) 2001-2006 Cisco Systems, Inc. 12386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * All rights reserved. 13386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * 14386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * Redistribution and use in source and binary forms, with or without 15386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * modification, are permitted provided that the following conditions 16386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * are met: 17386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * 18386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * Redistributions of source code must retain the above copyright 19386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * notice, this list of conditions and the following disclaimer. 20386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * 21386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * Redistributions in binary form must reproduce the above 22386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * copyright notice, this list of conditions and the following 23386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * disclaimer in the documentation and/or other materials provided 24386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * with the distribution. 25386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * 26386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * Neither the name of the Cisco Systems, Inc. nor the names of its 27386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * contributors may be used to endorse or promote products derived 28386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * from this software without specific prior written permission. 29386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * 30386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 31386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 32386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 33386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 34386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 35386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 36386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 37386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 38386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 39386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 40386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 41386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * OF THE POSSIBILITY OF SUCH DAMAGE. 42386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * 43386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari */ 44386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 45386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 46386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari#include "prng.h" 47386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 48386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari/* single, global prng structure */ 49386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 50386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagarictr_prng_t ctr_prng; 51386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 52386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagarierr_status_t 53386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagarictr_prng_init(rand_source_func_t random_source) { 54386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari uint8_t tmp_key[32]; 55386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari err_status_t status; 56386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 57386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari /* initialize output count to zero */ 58386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari ctr_prng.octet_count = 0; 59386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 60386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari /* set random source */ 61386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari ctr_prng.rand = random_source; 62386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 63386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari /* initialize secret key from random source */ 64386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari status = random_source(tmp_key, 32); 65386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari if (status) 66386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari return status; 67386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 68386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari /* initialize aes ctr context with random key */ 69386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari status = aes_icm_context_init(&ctr_prng.state, tmp_key); 70386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari if (status) 71386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari return status; 72386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 73386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari return err_status_ok; 74386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari} 75386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 76386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagarierr_status_t 77386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagarictr_prng_get_octet_string(void *dest, uint32_t len) { 78386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari err_status_t status; 79386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 80386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari /* 81386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * if we need to re-initialize the prng, do so now 82386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * 83386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * avoid 32-bit overflows by subtracting instead of adding 84386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari */ 85386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari if (ctr_prng.octet_count > MAX_PRNG_OUT_LEN - len) { 86386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari status = ctr_prng_init(ctr_prng.rand); 87386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari if (status) 88386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari return status; 89386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari } 90386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari ctr_prng.octet_count += len; 91386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 92386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari /* 93386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari * write prng output 94386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari */ 95386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari status = aes_icm_output(&ctr_prng.state, (uint8_t*)dest, len); 96386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari if (status) 97386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari return status; 98386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 99386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari return err_status_ok; 100386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari} 101386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 102386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagarierr_status_t 103386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagarictr_prng_deinit(void) { 104386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 105386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari /* nothing */ 106386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari 107386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari return err_status_ok; 108386ce4d9144fc190797f4e43a31aeaf76ca2e373Param Reddappagari} 109