RandomNum.h (1635B)
1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */ 3 /* This Source Code Form is subject to the terms of the Mozilla Public 4 * License, v. 2.0. If a copy of the MPL was not distributed with this 5 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */ 6 7 /* Routines for generating random numbers */ 8 9 #ifndef mozilla_RandomNum_h_ 10 #define mozilla_RandomNum_h_ 11 12 #include "mozilla/Maybe.h" 13 #include "mozilla/Types.h" 14 15 namespace mozilla { 16 17 /** 18 * Generate cryptographically secure random bytes using the best facilities 19 * available on the current OS. 20 * 21 * Return value: true if random bytes were copied into `aBuffer` or false on 22 * error. 23 * 24 * Useful whenever a secure random number is needed and NSS isn't available. 25 * (Perhaps because it hasn't been initialized yet) 26 * 27 * Current mechanisms: 28 * Windows: RtlGenRandom() 29 * Android, Darwin, DragonFly, FreeBSD, OpenBSD, NetBSD: arc4random() 30 * Linux: getrandom() if available, "/dev/urandom" otherwise 31 * Other Unix: "/dev/urandom" 32 * 33 */ 34 [[nodiscard]] MFBT_API bool GenerateRandomBytesFromOS(void* aBuffer, 35 size_t aLength); 36 37 /** 38 * Generate a cryptographically secure random 64-bit unsigned number using the 39 * best facilities available on the current OS. 40 */ 41 MFBT_API Maybe<uint64_t> RandomUint64(); 42 43 /** 44 * Like RandomUint64, but always returns a uint64_t or crashes with an assert 45 * if the underlying RandomUint64 call failed. 46 */ 47 MFBT_API uint64_t RandomUint64OrDie(); 48 49 } // namespace mozilla 50 51 #endif // mozilla_RandomNum_h_