Crypto: added cache for faster key derivation

src/common.h

@@ -47,6 +47,7 @@
 #include <cstdio>
 #include <cstdlib>
 
+#include <array>
 #include <vector>
 #include <string>
 #include <algorithm>

src/crypto.cpp

@@ -20,6 +20,7 @@
 #include "keccak.h"
 #include "uv_util.h"
 #include <random>
+#include <unordered_map>
 
 extern "C" {
 #include "crypto-ops.h"
@@ -108,24 +109,6 @@ bool check_keys(const hash& pub, const hash& sec)
 	return pub == pub_check;
 }
 
-bool generate_key_derivation(const hash& key1, const hash& key2, hash& derivation)
-{
-	ge_p3 point;
-	ge_p2 point2;
-	ge_p1p1 point3;
-
-	if (ge_frombytes_vartime(&point, key1.h) != 0) {
-		return false;
-	}
-
-	ge_scalarmult(&point2, key2.h, &point);
-	ge_mul8(&point3, &point2);
-	ge_p1p1_to_p2(&point2, &point3);
-	ge_tobytes(reinterpret_cast<uint8_t*>(&derivation), &point2);
-
-	return true;
-}
-
 static FORCEINLINE void hash_to_scalar(const uint8_t* data, size_t length, uint8_t(&res)[HASH_SIZE])
 {
 	keccak(data, static_cast<int>(length), res, HASH_SIZE);
@@ -153,9 +136,71 @@ static FORCEINLINE void derivation_to_scalar(const hash& derivation, size_t outp
 	hash_to_scalar(begin, end - begin, res);
 }
 
-// cppcheck-suppress constParameter
+class Cache
-bool derive_public_key(const hash& derivation, size_t output_index, const hash& base, hash& derived_key)
 {
+public:
+	Cache()
+	{
+		uv_mutex_init_checked(&m);
+	}
+
+	~Cache()
+	{
+		uv_mutex_destroy(&m);
+	}
+
+	bool get_derivation(const hash& key1, const hash& key2, hash& derivation)
+	{
+		std::array<uint8_t, HASH_SIZE * 2> index;
+		memcpy(index.data(), key1.h, HASH_SIZE);
+		memcpy(index.data() + HASH_SIZE, key2.h, HASH_SIZE);
+
+		{
+			MutexLock lock(m);
+			auto it = derivations.find(index);
+			if (it != derivations.end()) {
+				derivation = it->second;
+				return true;
+			}
+		}
+
+		ge_p3 point;
+		ge_p2 point2;
+		ge_p1p1 point3;
+
+		if (ge_frombytes_vartime(&point, key1.h) != 0) {
+			return false;
+		}
+
+		ge_scalarmult(&point2, key2.h, &point);
+		ge_mul8(&point3, &point2);
+		ge_p1p1_to_p2(&point2, &point3);
+		ge_tobytes(reinterpret_cast<uint8_t*>(&derivation), &point2);
+
+		{
+			MutexLock lock(m);
+			derivations.emplace(index, derivation);
+		}
+
+		return true;
+	}
+
+	bool get_public_key(const hash& derivation, size_t output_index, const hash& base, hash& derived_key)
+	{
+		std::array<uint8_t, HASH_SIZE * 2 + sizeof(size_t)> index;
+		memcpy(index.data(), derivation.h, HASH_SIZE);
+		memcpy(index.data() + HASH_SIZE, base.h, HASH_SIZE);
+		memcpy(index.data() + HASH_SIZE * 2, &output_index, sizeof(size_t));
+
+		{
+			MutexLock lock(m);
+			auto it = public_keys.find(index);
+			if (it != public_keys.end()) {
+				derived_key = it->second;
+				return true;
+			}
+		}
+
 		uint8_t scalar[HASH_SIZE];
 		ge_p3 point1;
 		ge_p3 point2;
@@ -174,7 +219,30 @@ bool derive_public_key(const hash& derivation, size_t output_index, const hash&
 		ge_p1p1_to_p2(&point5, &point4);
 		ge_tobytes(derived_key.h, &point5);
 
+		{
+			MutexLock lock(m);
+			public_keys.emplace(index, derived_key);
+		}
+
 		return true;
 	}
 
+private:
+	uv_mutex_t m;
+	std::unordered_map<std::array<uint8_t, HASH_SIZE * 2>, hash> derivations;
+	std::unordered_map<std::array<uint8_t, HASH_SIZE * 2 + sizeof(size_t)>, hash> public_keys;
+};
+
+static Cache cache;
+
+bool generate_key_derivation(const hash& key1, const hash& key2, hash& derivation)
+{
+	return cache.get_derivation(key1, key2, derivation);
+}
+
+bool derive_public_key(const hash& derivation, size_t output_index, const hash& base, hash& derived_key)
+{
+	return cache.get_public_key(derivation, output_index, base, derived_key);
+}
+
 } // namespace p2pool

src/side_chain.cpp

@@ -34,7 +34,6 @@
 #include <fstream>
 #include <iterator>
 #include <numeric>
-#include <array>
 
 // Only uncomment it to debug issues with uncle/orphan blocks
 //#define DEBUG_BROADCAST_DELAY_MS 100

src/util.h

@@ -136,4 +136,17 @@ struct hash<p2pool::hash>
 	}
 };
 
+template<size_t N>
+struct hash<std::array<uint8_t, N>>
+{
+	FORCEINLINE size_t operator()(const std::array<uint8_t, N>& value) const
+	{
+		uint64_t result = 0xcbf29ce484222325ull;
+		for (size_t i = 0; i < N; ++i) {
+			result = (result ^ value[i]) * 0x100000001b3ull;
+		}
+		return static_cast<size_t>(result);
+	}
+};
+
 } // namespace std

src/wallet.cpp

@@ -22,7 +22,6 @@
 #include "wallet.h"
 #include "keccak.h"
 #include "crypto.h"
-#include <array>
 
 extern "C" {
 #include "crypto-ops.h"
@@ -81,23 +80,16 @@ static_assert(rev_alphabet.num_symbols == 58, "Check alphabet");
 namespace p2pool {
 
 Wallet::Wallet(const char* address)
-	: m_txkeySec{}
-	, m_outputIndex(std::numeric_limits<size_t>::max())
-	, m_derivation{}
-	, m_ephPublicKey{}
 {
-	uv_mutex_init_checked(&m_lock);
 	decode(address);
 }
 
 Wallet::~Wallet()
 {
-	uv_mutex_destroy(&m_lock);
 }
 
 Wallet::Wallet(const Wallet& w)
 {
-	uv_mutex_init_checked(&m_lock);
 	operator=(w);
 }
 
@@ -108,18 +100,11 @@ Wallet& Wallet::operator=(const Wallet& w)
 		return *this;
 	}
 
-	MutexLock lock(m_lock);
-	MutexLock lock2(w.m_lock);
-
 	m_prefix = w.m_prefix;
 	m_spendPublicKey = w.m_spendPublicKey;
 	m_viewPublicKey = w.m_viewPublicKey;
 	m_checksum = w.m_checksum;
 	m_type = w.m_type;
-	m_txkeySec = w.m_txkeySec;
-	m_outputIndex = w.m_outputIndex;
-	m_derivation = w.m_derivation;
-	m_ephPublicKey = w.m_ephPublicKey;
 
 	return *this;
 }
@@ -204,8 +189,6 @@ bool Wallet::assign(const hash& spend_pub_key, const hash& view_pub_key, Network
 		return false;
 	}
 
-	MutexLock lock(m_lock);
-
 	m_prefix = 0;
 	m_spendPublicKey = spend_pub_key;
 	m_viewPublicKey = view_pub_key;
@@ -213,43 +196,19 @@ bool Wallet::assign(const hash& spend_pub_key, const hash& view_pub_key, Network
 
 	m_type = type;
 
-	m_txkeySec = {};
-	m_outputIndex = std::numeric_limits<size_t>::max();
-	m_derivation = {};
-	m_ephPublicKey = {};
-
 	return true;
 }
 
-bool Wallet::get_eph_public_key(const hash& txkey_sec, size_t output_index, hash& eph_public_key)
+bool Wallet::get_eph_public_key(const hash& txkey_sec, size_t output_index, hash& eph_public_key) const
 {
-	MutexLock lock(m_lock);
-
 	hash derivation;
-	bool derivation_changed = false;
-
-	if (txkey_sec == m_txkeySec) {
-		derivation = m_derivation;
-	}
-	else {
 	if (!generate_key_derivation(m_viewPublicKey, txkey_sec, derivation)) {
 		return false;
 	}
-		m_derivation = derivation;
-		m_txkeySec = txkey_sec;
-		derivation_changed = true;
-	}
 
-	if (!derivation_changed && (output_index == m_outputIndex)) {
-		eph_public_key = m_ephPublicKey;
-	}
-	else {
 	if (!derive_public_key(derivation, output_index, m_spendPublicKey, eph_public_key)) {
 		return false;
 	}
-		m_outputIndex = output_index;
-		m_ephPublicKey = eph_public_key;
-	}
 
 	return true;
 }

src/wallet.h

@@ -39,7 +39,7 @@ public:
 	FORCEINLINE const hash& spend_public_key() const { return m_spendPublicKey; }
 	FORCEINLINE const hash& view_public_key() const { return m_viewPublicKey; }
 
-	bool get_eph_public_key(const hash& txkey_sec, size_t output_index, hash& eph_public_key);
+	bool get_eph_public_key(const hash& txkey_sec, size_t output_index, hash& eph_public_key) const;
 
 	FORCEINLINE bool operator<(const Wallet& w) const { return m_spendPublicKey < w.m_spendPublicKey; }
 	FORCEINLINE bool operator==(const Wallet& w) const { return m_spendPublicKey == w.m_spendPublicKey; }
@@ -50,12 +50,6 @@ private:
 	hash m_viewPublicKey;
 	uint32_t m_checksum;
 	NetworkType m_type;
-
-	mutable uv_mutex_t m_lock;
-	hash m_txkeySec;
-	size_t m_outputIndex;
-	hash m_derivation;
-	hash m_ephPublicKey;
 };
 
 } // namespace p2pool