fortuna: properly handle reseeds

* move reseed_ctr and related member functions to Accumulator

* create a std::shared_ptr<Accumulator> to Fortuna's internal
  Accumulator object and feed that into SeedFileManager instead of a
  reference, which used to get copied to a new object in SeedFileManager

* make Accumulator non-copyable, since it's only to be created once.
  instead, a shared_ptr is used to facilitate multiple-access

* handle concurrency in Accumulator as the reseed_ctr-related functions
  can now be accessed from both Fortuna and SeedFileManager, declare mtx
  as mutable (since it's also used in a const function)

* use std::scoped_lock in 'initialize_prng()' to safely lock both mutexes

accumulator.cpp

@@ -28,6 +28,21 @@ Accumulator::Accumulator() noexcept {
 Accumulator::~Accumulator() noexcept {}
 
 
+auto Accumulator::set_reseed_ctr_to_null() -> void {
+	std::lock_guard<std::mutex> lg(mtx);
+	this->reseed_ctr = 0x00;
+}
+
+auto Accumulator::incr_reseed_ctr() -> void {
+	std::lock_guard<std::mutex> lg(mtx);
+	{ ++this->reseed_ctr; }
+}
+
+auto Accumulator::get_reseed_ctr() const -> uint64_t {
+	std::lock_guard<std::mutex> lg(mtx);
+	return this->reseed_ctr;
+}
+
 auto Accumulator::_p_pools_equal(
 	std::shared_ptr<std::array<accumulator::Pool, Accumulator::NUM_OF_POOLS>>
 		p_pools) const -> bool {
@@ -84,6 +99,7 @@ auto Accumulator::get_random_data(const unsigned int& n_bytes) -> std::string {
 
 auto Accumulator::call_reseed(const std::string& seed) -> void {
 	try {
+		incr_reseed_ctr();
 		this->Gen->reseed(seed);
 	}
 	catch (std::exception& e) {

accumulator.h

@@ -12,6 +12,7 @@
 #include <cstdint>
 #include <exception>
 #include <memory>
+#include <mutex>
 #include <vector>
 
 namespace fortuna {
@@ -22,6 +23,9 @@ private:
 	static constexpr const uint8_t MAX_SOURCES{255};
 	static constexpr const uint8_t NUM_OF_POOLS{32};
 
+	mutable std::mutex mtx; // used in const fun
+	uint64_t reseed_ctr{0x00};
+
 	std::vector<uint8_t> entropy_sources{};
 	fortuna::generator::Generator* Gen;
 	std::shared_ptr<std::array<accumulator::Pool, Accumulator::NUM_OF_POOLS>>
@@ -33,6 +37,12 @@ protected:
 public:
 	constexpr static const unsigned int init_pool_num{0};
 
+	auto set_reseed_ctr_to_null() -> void;
+
+	auto incr_reseed_ctr() -> void;
+
+	auto get_reseed_ctr() const -> uint64_t;
+
 	auto _p_pools_equal(
 		std::shared_ptr<std::array<accumulator::Pool,
 								   Accumulator::NUM_OF_POOLS>> p_pools) const
@@ -82,6 +92,9 @@ public:
 
 	Accumulator() noexcept;
 	~Accumulator() noexcept;
+	Accumulator(const Accumulator&) = delete; // no copy
+	Accumulator(Accumulator&) = delete;
+	Accumulator& operator=(const Accumulator&) = delete;
 
 }; // class Accumulator
 

fortuna.cpp

@@ -86,7 +86,7 @@ auto Fortuna::random_data(unsigned int n_bytes) -> void {
 			// if (R.pools[0].get_s_byte_count() >= min_pool_size &&
 			// elapsed > R.Gen.reseed_interval) {
 			for (int i = 0; i < static_cast<int>(pools_to_use); ++i) {
-				if (this->R.reseed_ctr %
+				if (this->get_reseed_ctr() %
 						static_cast<uint64_t>(pow(2, static_cast<double>(i))) ==
 					0) {
 					s.append(fortuna::Util::do_sha(
@@ -101,8 +101,8 @@ auto Fortuna::random_data(unsigned int n_bytes) -> void {
 			s.clear();
 		}
 
-		fmt::print("[i] fortuna: reseed ctr {}\n", R.reseed_ctr);
-		if (R.reseed_ctr == 0) {
+		fmt::print("[i] fortuna: reseed ctr {}\n", get_reseed_ctr());
+		if (get_reseed_ctr() == 0) {
 			fmt::print("[!] ERROR: reseed ctr is 0, PRNG not seeded!\n");
 			throw std::runtime_error("illegal state, PRNG not seeded");
 		}
@@ -179,9 +179,9 @@ auto Fortuna::seed_file_manager_service() -> void {
 	std::unique_lock<std::mutex> mtx_l(mtx);
 	std::unique_lock<std::mutex> a_ul(mtx_accu);
 
-	assert(this->accumulator._p_pools_equal(this->R._p_pools));
+	assert(this->_p_accumulator->_p_pools_equal(this->R._p_pools));
 
-	SeedFileManager sfm(this->accumulator);
+	SeedFileManager sfm(this->_p_accumulator);
 
 	a_ul.unlock();
 	mtx_l.unlock();
@@ -244,7 +244,7 @@ auto Fortuna::urandom_entropy_src_service() -> void {
 			if (this->R._p_pools) {
 				// make sure they're pointing to the same chunk of data
 				// I know, debug-only
-				assert(this->accumulator._p_pools_equal(this->R._p_pools));
+				assert(this->_p_accumulator->_p_pools_equal(this->R._p_pools));
 
 				ues.event(adder);
 			}

fortuna.h

@@ -22,7 +22,7 @@ public:
 	std::mutex mtx;
 	std::mutex mtx_random_data;
 	std::mutex mtx_p_pools;
-	std::mutex mtx_accu;
+	mutable std::mutex mtx_accu; // used in const fun, too
 	std::mutex print_mtx;
 	std::thread th_gen;
 	std::thread th_accu;
@@ -36,53 +36,47 @@ public:
 	[[optimize_for_synchronized]] auto random_data(unsigned int) -> void;
 
 	auto set_reseed_ctr_to_null() -> void {
-		std::lock_guard<std::mutex> lg(mtx);
-		Fortuna::R.null_da_ctr();
+		std::scoped_lock sl(mtx_accu, print_mtx);
+		this->_p_accumulator->set_reseed_ctr_to_null();
+		fmt::print("reseed_ctr set to 0x00\n");
 	}
 
 	auto incr_reseed_ctr() -> void {
-		std::lock_guard<std::mutex> lg(mtx);
-		++Fortuna::R.reseed_ctr;
+		std::scoped_lock sl(mtx, mtx_accu);
+		this->_p_accumulator->incr_reseed_ctr();
 	}
 
 	auto get_reseed_ctr() const -> uint64_t {
-		return R.reseed_ctr;
+		std::lock_guard<std::mutex> lg(mtx_accu);
+		return this->_p_accumulator->get_reseed_ctr();
 	}
 
 	auto initialize_prng() -> void {
-		// TODO(me): handle the reseeds here as per Cryptography Engineering,
-		// p. 153
-		set_reseed_ctr_to_null();
-		std::unique_lock<std::mutex> p_ul(print_mtx);
-
-		std::scoped_lock sl(mtx_accu, mtx_p_pools);
 		try {
-			R.initialize_pools();
-			fmt::print("[i] fortuna: pools initialized\n");
-			p_ul.unlock();
-			accumulator.set_pools_ptr(R._p_pools);
-			accumulator.set_gen(R.Gen);
+			set_reseed_ctr_to_null();
 
-			// FIXME: bogus first reseed here, P_0 definitely hasn't collected
-			// enough entropy by now
-			incr_reseed_ctr();
+			std::scoped_lock sl(mtx_accu, mtx_p_pools);
 
-			p_ul.lock();
-			fmt::print("first reseed\n");
-			p_ul.unlock();
+			{
+				std::lock_guard<std::mutex> lg(print_mtx);
 
-			std::unique_lock<std::mutex> ul(mtx);
-			R.Gen.reseed("fortuna");
-			ul.unlock();
+				R.initialize_pools();
+				fmt::print("[i] fortuna: pools initialized\n");
+			}
+
+			this->_p_accumulator->set_pools_ptr(R._p_pools);
+			this->_p_accumulator->set_gen(R.Gen);
+
+			this->sync_point.count_down();
 		}
 		catch (std::exception& e) {
-			p_ul.try_lock();
+			std::lock_guard<std::mutex> lg(print_mtx);
 			fmt::print(
 				"{}\n[!] fortuna: fatal error, PRNG initialization FAILED!\n\n",
 				e.what());
 		}
-		p_ul.try_lock();
-		this->sync_point.count_down();
+
+		std::lock_guard<std::mutex> lg(print_mtx);
 		fmt::print("[*] fortuna: PRNG initialized\n");
 	}
 
@@ -104,11 +98,6 @@ public:
 		~R_state() noexcept = default;
 
 	protected:
-		auto null_da_ctr() -> void {
-			reseed_ctr = 0x00;
-			fmt::print("reseed_ctr set to 0x00\n");
-		}
-
 		auto initialize_pools() -> void {
 			for (unsigned int i = accumulator::Accumulator::init_pool_num;
 				 i < Fortuna::NUM_OF_POOLS;
@@ -119,7 +108,6 @@ public:
 
 	private:
 		generator::Generator Gen;
-		uint64_t reseed_ctr{0x00};
 
 		// da_pools is to be used solely for creating a shared_ptr of the
 		// object: _p_pools. any further access to the structure should be
@@ -136,7 +124,8 @@ public:
 	}; // class R_state
 
 	fortuna::Fortuna::R_state R;
-	fortuna::accumulator::Accumulator accumulator;
+	std::shared_ptr<accumulator::Accumulator> _p_accumulator{
+		std::make_shared<accumulator::Accumulator>()};
 
 }; // class Fortuna
 

seed_file_management.cpp

@@ -21,8 +21,9 @@
 namespace fortuna {
 
 SeedFileManager::SeedFileManager(
-	const fortuna::accumulator::Accumulator& da_accumulator) noexcept {
-	this->accumulator = da_accumulator;
+	std::shared_ptr<fortuna::accumulator::Accumulator>
+		da_accumulator) noexcept {
+	this->_p_accumulator = da_accumulator;
 }
 SeedFileManager::~SeedFileManager() noexcept {
 	set_job_running(false); // RIP, well, yeah, not running when the obj dies
@@ -108,7 +109,7 @@ auto SeedFileManager::update_seed_file() -> void {
 							 buff.SizeInBytes() *
 								 8); // we need the size in bits
 
-		accumulator.call_reseed(str_buff);
+		this->_p_accumulator->call_reseed(str_buff);
 		write_seed_file();
 	}
 	catch (std::exception& e) {
@@ -123,7 +124,7 @@ auto SeedFileManager::write_seed_file() -> void {
 
 	fortuna::SeedFileManager::IS_RUNNING = true;
 	CryptoPP::SecByteBlock buff{config.seed_f_length};
-	const std::string da_buff{accumulator.get_random_data(
+	const std::string da_buff{this->_p_accumulator->get_random_data(
 		static_cast<unsigned int>(config.seed_f_length))};
 
 	assert(da_buff.length() % 2 == 0);

seed_file_management.h

@@ -26,8 +26,8 @@ public:
 	auto is_job_running() const -> bool;
 	auto do_stuff() -> void;
 
-	explicit SeedFileManager(
-		const fortuna::accumulator::Accumulator& accumulator) noexcept;
+	explicit SeedFileManager(std::shared_ptr<fortuna::accumulator::Accumulator>
+								 accumulator) noexcept;
 	~SeedFileManager() noexcept;
 
 protected:
@@ -38,7 +38,7 @@ private:
 	mutable std::recursive_mutex mtx;
 	std::atomic<bool> IS_RUNNING{false};
 	DoTask do_task;
-	fortuna::accumulator::Accumulator accumulator;
+	std::shared_ptr<fortuna::accumulator::Accumulator> _p_accumulator;
 
 	auto seed_file_exists() const -> bool;
 	auto write_seed_file() -> void;