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diff --git a/src/net.cpp b/src/net.cpp
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -15,6 +15,7 @@
#include <consensus/consensus.h>
#include <crypto/sha256.h>
#include <netbase.h>
+#include <random.h>
#include <scheduler.h>
#include <ui_interface.h>
#include <util/strencodings.h>
@@ -457,6 +458,10 @@
pszDest ? pszDest : "", false, block_relay_only);
pnode->AddRef();
+ // We're making a new connection, harvest entropy from the time (and our
+ // peer count)
+ RandAddEvent((uint32_t)id);
+
return pnode;
}
@@ -721,8 +726,13 @@
msg.m_message_size = hdr.nMessageSize;
msg.m_raw_message_size = hdr.nMessageSize + CMessageHeader::HEADER_SIZE;
+ // We just received a message off the wire, harvest entropy from the time
+ // (and the message checksum)
+ RandAddEvent(ReadLE32(hash.begin()));
+
msg.m_valid_checksum = (memcmp(hash.begin(), hdr.pchChecksum,
CMessageHeader::CHECKSUM_SIZE) == 0);
+
if (!msg.m_valid_checksum) {
LogPrint(
BCLog::NET, "CHECKSUM ERROR (%s, %u bytes), expected %s was %s\n",
@@ -1130,6 +1140,10 @@
LOCK(cs_vNodes);
vNodes.push_back(pnode);
}
+
+ // We received a new connection, harvest entropy from the time (and our peer
+ // count)
+ RandAddEvent((uint32_t)id);
}
void CConnman::DisconnectNodes() {
diff --git a/src/random.h b/src/random.h
--- a/src/random.h
+++ b/src/random.h
@@ -94,6 +94,14 @@
*/
void RandAddPeriodic() noexcept;
+/**
+ * Gathers entropy from the low bits of the time at which events occur. Should
+ * be called with a uint32_t describing the event at the time an event occurs.
+ *
+ * Thread-safe.
+ */
+void RandAddEvent(const uint32_t event_info) noexcept;
+
/**
* Fast randomness source. This is seeded once with secure random data, but
* is completely deterministic and does not gather more entropy after that.
diff --git a/src/random.cpp b/src/random.cpp
--- a/src/random.cpp
+++ b/src/random.cpp
@@ -10,6 +10,7 @@
#include <wincrypt.h>
#endif
#include <compat/cpuid.h>
+#include <crypto/sha256.h>
#include <crypto/sha512.h>
#include <logging.h> // for LogPrintf()
#include <randomenv.h>
@@ -403,11 +404,43 @@
uint64_t m_counter GUARDED_BY(m_mutex) = 0;
bool m_strongly_seeded GUARDED_BY(m_mutex) = false;
+ Mutex m_events_mutex;
+ CSHA256 m_events_hasher GUARDED_BY(m_events_mutex);
+
public:
RNGState() noexcept { InitHardwareRand(); }
~RNGState() {}
+ void AddEvent(uint32_t event_info) noexcept {
+ LOCK(m_events_mutex);
+
+ m_events_hasher.Write((const uint8_t *)&event_info, sizeof(event_info));
+ // Get the low four bytes of the performance counter. This translates to
+ // roughly the subsecond part.
+ uint32_t perfcounter = (GetPerformanceCounter() & 0xffffffff);
+ m_events_hasher.Write((const uint8_t *)&perfcounter,
+ sizeof(perfcounter));
+ }
+
+ /**
+ * Feed (the hash of) all events added through AddEvent() to hasher.
+ */
+ void SeedEvents(CSHA512 &hasher) noexcept {
+ // We use only SHA256 for the events hashing to get the ASM speedups we
+ // have for SHA256, since we want it to be fast as network peers may be
+ // able to trigger it repeatedly.
+ LOCK(m_events_mutex);
+
+ uint8_t events_hash[32];
+ m_events_hasher.Finalize(events_hash);
+ hasher.Write(events_hash, 32);
+
+ // Re-initialize the hasher with the finalized state to use later.
+ m_events_hasher.Reset();
+ m_events_hasher.Write(events_hash, 32);
+ }
+
/**
* Extract up to 32 bytes of entropy from the RNG state, mixing in new
* entropy from hasher.
@@ -482,7 +515,7 @@
SeedTimestamp(hasher);
}
-static void SeedSlow(CSHA512 &hasher) noexcept {
+static void SeedSlow(CSHA512 &hasher, RNGState &rng) noexcept {
uint8_t buffer[32];
// Everything that the 'fast' seeder includes
@@ -492,6 +525,9 @@
GetOSRand(buffer);
hasher.Write(buffer, sizeof(buffer));
+ // Add the events hasher into the mix
+ rng.SeedEvents(hasher);
+
// High-precision timestamp.
//
// Note that we also commit to a timestamp in the Fast seeder, so we
@@ -519,6 +555,9 @@
// High-precision timestamp
SeedTimestamp(hasher);
+ // Add the events hasher into the mix
+ rng.SeedEvents(hasher);
+
// Dynamic environment data (performance monitoring, ...)
auto old_size = hasher.Size();
RandAddDynamicEnv(hasher);
@@ -535,7 +574,7 @@
SeedHardwareSlow(hasher);
// Everything that the 'slow' seeder includes.
- SeedSlow(hasher);
+ SeedSlow(hasher, rng);
// Dynamic environment data (performance monitoring, ...)
auto old_size = hasher.Size();
@@ -556,7 +595,7 @@
PERIODIC, //!< Called by RandAddPeriodic()
};
-static void ProcRand(uint8_t *out, int num, RNGLevel level) {
+static void ProcRand(uint8_t *out, int num, RNGLevel level) noexcept {
// Make sure the RNG is initialized first (as all Seed* function possibly
// need hwrand to be available).
RNGState &rng = GetRNGState();
@@ -569,7 +608,7 @@
SeedFast(hasher);
break;
case RNGLevel::SLOW:
- SeedSlow(hasher);
+ SeedSlow(hasher, rng);
break;
case RNGLevel::PERIODIC:
SeedPeriodic(hasher, rng);
@@ -595,6 +634,10 @@
ProcRand(nullptr, 0, RNGLevel::PERIODIC);
}
+void RandAddEvent(const uint32_t event_info) noexcept {
+ GetRNGState().AddEvent(event_info);
+}
+
bool g_mock_deterministic_tests{false};
uint64_t GetRand(uint64_t nMax) noexcept {

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