From 461e547877da0c04db69e067c923cc4540aab03a Mon Sep 17 00:00:00 2001 From: fanquake Date: Mon, 18 Nov 2019 09:58:10 -0500 Subject: [PATCH 1/2] doc: correct random.h docs after #17270 --- src/random.cpp | 2 +- src/random.h | 14 +++++++------- 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/src/random.cpp b/src/random.cpp index 3e6398f7b49..c78a34ea45e 100644 --- a/src/random.cpp +++ b/src/random.cpp @@ -182,7 +182,7 @@ static uint64_t GetRdSeed() noexcept /* Access to other hardware random number generators could be added here later, * assuming it is sufficiently fast (in the order of a few hundred CPU cycles). * Slower sources should probably be invoked separately, and/or only from - * RandAddSeedSleep (which is called during idle background operation). + * RandAddPeriodic (which is called once a minute). */ static void InitHardwareRand() {} static void ReportHardwareRand() {} diff --git a/src/random.h b/src/random.h index 7768f9d3c50..76b3493c5dc 100644 --- a/src/random.h +++ b/src/random.h @@ -41,17 +41,17 @@ * These entropy sources are slower, but designed to make sure the RNG state contains * fresh data that is unpredictable to attackers. * - * - RandAddSeedSleep() seeds everything that fast seeding includes, but additionally: - * - A high-precision timestamp before and after sleeping 1ms. - * - (On Windows) Once every 10 minutes, performance monitoring data from the OS. - - - Once every minute, strengthen the entropy for 10 ms using repeated SHA512. - * These just exploit the fact the system is idle to improve the quality of the RNG - * slightly. + * - RandAddPeriodic() seeds everything that fast seeding includes, but additionally: + * - A high-precision timestamp + * - Dynamic environment data (performance monitoring, ...) + * - Strengthen the entropy for 10 ms using repeated SHA512. + * This is run once every minute. * * On first use of the RNG (regardless of what function is called first), all entropy * sources used in the 'slow' seeder are included, but also: * - 256 bits from the hardware RNG (rdseed or rdrand) when available. - * - (On Windows) Performance monitoring data from the OS. + * - Dynamic environment data (performance monitoring, ...) + * - Static environment data * - Strengthen the entropy for 100 ms using repeated SHA512. * * When mixing in new entropy, H = SHA512(entropy || old_rng_state) is computed, and From 55b2cb199c276781b6daa5438af2da57dea3ac52 Mon Sep 17 00:00:00 2001 From: fanquake Date: Mon, 18 Nov 2019 10:21:28 -0500 Subject: [PATCH 2/2] random: mark RandAddPeriodic and SeedPeriodic as noexcept The usage of MilliSleep() in SeedPeriodic (previously SeedSleep) was removed in #17270, meaning it, and its users can now be marked noexcept. --- src/random.cpp | 16 +++------------- src/random.h | 2 +- 2 files changed, 4 insertions(+), 14 deletions(-) diff --git a/src/random.cpp b/src/random.cpp index c78a34ea45e..8c33e1260bd 100644 --- a/src/random.cpp +++ b/src/random.cpp @@ -450,17 +450,7 @@ void LockingCallbackOpenSSL(int mode, int i, const char* file, int line) NO_THRE /* A note on the use of noexcept in the seeding functions below: * - * None of the RNG code should ever throw any exception, with the sole exception - * of MilliSleep in SeedSleep, which can (and does) support interruptions which - * cause a boost::thread_interrupted to be thrown. - * - * This means that SeedSleep, and all functions that invoke it are throwing. - * However, we know that GetRandBytes() and GetStrongRandBytes() never trigger - * this sleeping logic, so they are noexcept. The same is true for all the - * GetRand*() functions that use GetRandBytes() indirectly. - * - * TODO: After moving away from interruptible boost-based thread management, - * everything can become noexcept here. + * None of the RNG code should ever throw any exception. */ static void SeedTimestamp(CSHA512& hasher) noexcept @@ -516,7 +506,7 @@ static void SeedStrengthen(CSHA512& hasher, RNGState& rng, int microseconds) noe Strengthen(strengthen_seed, microseconds, hasher); } -static void SeedPeriodic(CSHA512& hasher, RNGState& rng) +static void SeedPeriodic(CSHA512& hasher, RNGState& rng) noexcept { // Everything that the 'fast' seeder includes SeedFast(hasher); @@ -598,7 +588,7 @@ static void ProcRand(unsigned char* out, int num, RNGLevel level) void GetRandBytes(unsigned char* buf, int num) noexcept { ProcRand(buf, num, RNGLevel::FAST); } void GetStrongRandBytes(unsigned char* buf, int num) noexcept { ProcRand(buf, num, RNGLevel::SLOW); } -void RandAddPeriodic() { ProcRand(nullptr, 0, RNGLevel::PERIODIC); } +void RandAddPeriodic() noexcept { ProcRand(nullptr, 0, RNGLevel::PERIODIC); } bool g_mock_deterministic_tests{false}; diff --git a/src/random.h b/src/random.h index 76b3493c5dc..8af616f8ea4 100644 --- a/src/random.h +++ b/src/random.h @@ -88,7 +88,7 @@ void GetStrongRandBytes(unsigned char* buf, int num) noexcept; * * Thread-safe. */ -void RandAddPeriodic(); +void RandAddPeriodic() noexcept; /** * Fast randomness source. This is seeded once with secure random data, but