1 /** 2 * \file doc_rng.h 3 * 4 * \brief Random number generator (RNG) module documentation file. 5 */ 6 /* 7 * 8 * Copyright The Mbed TLS Contributors 9 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 10 * 11 * This file is provided under the Apache License 2.0, or the 12 * GNU General Public License v2.0 or later. 13 * 14 * ********** 15 * Apache License 2.0: 16 * 17 * Licensed under the Apache License, Version 2.0 (the "License"); you may 18 * not use this file except in compliance with the License. 19 * You may obtain a copy of the License at 20 * 21 * http://www.apache.org/licenses/LICENSE-2.0 22 * 23 * Unless required by applicable law or agreed to in writing, software 24 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 25 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 26 * See the License for the specific language governing permissions and 27 * limitations under the License. 28 * 29 * ********** 30 * 31 * ********** 32 * GNU General Public License v2.0 or later: 33 * 34 * This program is free software; you can redistribute it and/or modify 35 * it under the terms of the GNU General Public License as published by 36 * the Free Software Foundation; either version 2 of the License, or 37 * (at your option) any later version. 38 * 39 * This program is distributed in the hope that it will be useful, 40 * but WITHOUT ANY WARRANTY; without even the implied warranty of 41 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 42 * GNU General Public License for more details. 43 * 44 * You should have received a copy of the GNU General Public License along 45 * with this program; if not, write to the Free Software Foundation, Inc., 46 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 47 * 48 * ********** 49 */ 50 51 /** 52 * @addtogroup rng_module Random number generator (RNG) module 53 * 54 * The Random number generator (RNG) module provides random number 55 * generation, see \c mbedtls_ctr_drbg_random(). 56 * 57 * The block-cipher counter-mode based deterministic random 58 * bit generator (CTR_DBRG) as specified in NIST SP800-90. It needs an external 59 * source of entropy. For these purposes \c mbedtls_entropy_func() can be used. 60 * This is an implementation based on a simple entropy accumulator design. 61 * 62 * The other number generator that is included is less strong and uses the 63 * HAVEGE (HArdware Volatile Entropy Gathering and Expansion) software heuristic 64 * which considered unsafe for primary usage, but provides additional random 65 * to the entropy pool if enables. 66 * 67 * Meaning that there seems to be no practical algorithm that can guess 68 * the next bit with a probability larger than 1/2 in an output sequence. 69 * 70 * This module can be used to generate random numbers. 71 */ 72