fortuna: handle reseeds+clear pools for seed

* actually clear out entropy of the pools before a reseed
* correctly prepare the seed for the reseed
* add a couple of helper methods to Pool that assist with getting
  length, retrieving and clearing of the collected entropy
* catch exceptions in main(), handle them gracefully

fortuna.cpp

@@ -36,13 +36,25 @@ namespace fortuna {
 			)
 		};
 		fmt::print("last_reseed: {} ago\n", elapsed);
+		const int pools_to_use{ffsll(static_cast<int>(get_reseed_ctr()))};
 		std::string s;
 
-		if (sizeof(R.pools[0]) >= min_pool_size && elapsed > R.Gen.reseed_interval) {
+		if (R.pools[0].get_s_length() >= min_pool_size && elapsed > R.Gen.reseed_interval) {
+			#pragma omp parallel for
+			for (int i = 0; i < static_cast<int>(pools_to_use); ++i) {
+				if (R.reseed_ctr % static_cast<int>(pow(2,i)) == 0) {
+					try {
+						s.append(fortuna::Util::do_sha(R.pools[i].get_s()));
+						R.pools[i].clear_pool();
+					} catch(std::exception& e) {
+						fmt::print("{}\n", e.what());
+					}
+				}
+			}
 			incr_reseed_ctr();
-			// TODO(me): Append the hashes of all the pools we will use to s
-			R.Gen.reseed(fortuna::Util::do_sha(s));
+			R.Gen.reseed(s);
 			R.last_reseed = std::chrono::steady_clock::now();
+			s.clear();
 		}
 
 		std::string n{R.Gen.generate_random_data(n_bytes)};

fortuna.h

@@ -29,6 +29,10 @@ public:
 		++Fortuna::R.reseed_ctr;
 	}
 
+	auto get_reseed_ctr() const -> uint64_t {
+		return R.reseed_ctr;
+	}
+
 	auto initialize_prng() -> void {
 		// TODO(me): handle the reseeds here as per Cryptography Engineering,
 		// p. 153
@@ -63,10 +67,7 @@ public:
 
 	private:
 		generator::Generator Gen;
-		#pragma GCC diagnostic push
-		#pragma GCC diagnostic ignored "-Wpedantic"
-		unsigned __int128 reseed_ctr;
-		#pragma GCC diagnostic pop
+		uint64_t reseed_ctr{0x00};
 		accumulator::Pool pools[num_of_pools];
 
 		std::chrono::steady_clock::time_point last_reseed;

main.cpp

@@ -1,10 +1,13 @@
 #include "fortuna.h"
 
-#include <fmt/core.h>
-
 int main() {
 	fmt::print("[*] doing evil stuff\n");
 	fortuna::Fortuna f;
-	f.random_data(4); // number of bytes requested
+	try {
+		f.random_data(4); // number of bytes requested
+	} catch (std::exception& e) {
+		fmt::print("[!] exiting due to \"{}\"\n", e.what());
+		exit(0);
+	}
 	return 0;
 }

pool.h

@@ -25,6 +25,7 @@ public:
 		set_id(id);
 	}
 
+	// add entropy contained in a random event of 1 to 32 bytes
 	auto add_entropy(const uint source, const std::vector<char> &event) -> int {
 		std::string event_str;
 		const size_t event_size{event.size()};
@@ -58,6 +59,19 @@ public:
 		return 0;
 	}
 
+	auto get_s_length() const -> uint64_t {
+		// returns total length of entropy contained in this pool
+		return this->s.length();
+	}
+
+	auto get_s() const -> std::string {
+		return this->s;
+	}
+
+	auto clear_pool() -> void {
+		this->s.clear();
+	}
+
 protected:
 	auto set_s(const std::string& entropy_s) -> void {
 		try {