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author | Pieter Wuille <pieter.wuille@gmail.com> | 2018-12-17 16:04:35 -0800 |
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committer | Pieter Wuille <pieter.wuille@gmail.com> | 2019-01-16 16:31:37 -0800 |
commit | 2ccc3d3aa346e96206281a391bc29874cf5ee7f4 (patch) | |
tree | 9c32dd35ce9134f4268855545ead5714b1a7813f | |
parent | aae8b9bf0f4fd2b801ee72cf191588c8b3a67c3c (diff) | |
download | bitcoin-2ccc3d3aa346e96206281a391bc29874cf5ee7f4.tar.xz |
Abstract out seeding/extracting entropy into RNGState::MixExtract
-rw-r--r-- | src/crypto/sha512.h | 2 | ||||
-rw-r--r-- | src/random.cpp | 60 |
2 files changed, 37 insertions, 25 deletions
diff --git a/src/crypto/sha512.h b/src/crypto/sha512.h index cd1023bc85..4118ac1b18 100644 --- a/src/crypto/sha512.h +++ b/src/crypto/sha512.h @@ -17,7 +17,7 @@ private: uint64_t bytes; public: - static const size_t OUTPUT_SIZE = 64; + static constexpr size_t OUTPUT_SIZE = 64; CSHA512(); CSHA512& Write(const unsigned char* data, size_t len); diff --git a/src/random.cpp b/src/random.cpp index 6b7962aa13..c78848d56e 100644 --- a/src/random.cpp +++ b/src/random.cpp @@ -304,6 +304,34 @@ struct RNGState { { InitHardwareRand(); } + + /** Extract up to 32 bytes of entropy from the RNG state, mixing in new entropy from hasher. */ + void MixExtract(unsigned char* out, size_t num, CSHA512&& hasher) + { + assert(num <= 32); + unsigned char buf[64]; + static_assert(sizeof(buf) == CSHA512::OUTPUT_SIZE, "Buffer needs to have hasher's output size"); + { + LOCK(m_mutex); + // Write the current state of the RNG into the hasher + hasher.Write(m_state, 32); + // Write a new counter number into the state + hasher.Write((const unsigned char*)&m_counter, sizeof(m_counter)); + ++m_counter; + // Finalize the hasher + hasher.Finalize(buf); + // Store the last 32 bytes of the hash output as new RNG state. + memcpy(m_state, buf + 32, 32); + } + // If desired, copy (up to) the first 32 bytes of the hash output as output. + if (num) { + assert(out != nullptr); + memcpy(out, buf, num); + } + // Best effort cleanup of internal state + hasher.Reset(); + memory_cleanse(buf, 64); + } }; RNGState& GetRNGState() @@ -315,38 +343,29 @@ RNGState& GetRNGState() } } -static void AddDataToRng(void* data, size_t len); +static void AddDataToRng(void* data, size_t len, RNGState& rng); void RandAddSeedSleep() { + RNGState& rng = GetRNGState(); + int64_t nPerfCounter1 = GetPerformanceCounter(); std::this_thread::sleep_for(std::chrono::milliseconds(1)); int64_t nPerfCounter2 = GetPerformanceCounter(); // Combine with and update state - AddDataToRng(&nPerfCounter1, sizeof(nPerfCounter1)); - AddDataToRng(&nPerfCounter2, sizeof(nPerfCounter2)); + AddDataToRng(&nPerfCounter1, sizeof(nPerfCounter1), rng); + AddDataToRng(&nPerfCounter2, sizeof(nPerfCounter2), rng); memory_cleanse(&nPerfCounter1, sizeof(nPerfCounter1)); memory_cleanse(&nPerfCounter2, sizeof(nPerfCounter2)); } -static void AddDataToRng(void* data, size_t len) { - RNGState& rng = GetRNGState(); - +static void AddDataToRng(void* data, size_t len, RNGState& rng) { CSHA512 hasher; hasher.Write((const unsigned char*)&len, sizeof(len)); hasher.Write((const unsigned char*)data, len); - unsigned char buf[64]; - { - WAIT_LOCK(rng.m_mutex, lock); - hasher.Write(rng.m_state, sizeof(rng.m_state)); - hasher.Write((const unsigned char*)&rng.m_counter, sizeof(rng.m_counter)); - ++rng.m_counter; - hasher.Finalize(buf); - memcpy(rng.m_state, buf + 32, 32); - } - memory_cleanse(buf, 64); + rng.MixExtract(nullptr, 0, std::move(hasher)); } void GetStrongRandBytes(unsigned char* out, int num) @@ -372,14 +391,7 @@ void GetStrongRandBytes(unsigned char* out, int num) } // Combine with and update state - { - WAIT_LOCK(rng.m_mutex, lock); - hasher.Write(rng.m_state, sizeof(rng.m_state)); - hasher.Write((const unsigned char*)&rng.m_counter, sizeof(rng.m_counter)); - ++rng.m_counter; - hasher.Finalize(buf); - memcpy(rng.m_state, buf + 32, 32); - } + rng.MixExtract(out, num, std::move(hasher)); // Produce output memcpy(out, buf, num); |