Implemented authentication.

Near feature complete.

Signature.hpp

@@ -0,0 +1,9 @@
+#pragma once
+#include <vector>
+#include <array>
+
+using Digest    = std::array<uint8_t, 32>;
+using Signature = std::array<uint8_t, 64>;
+
+//Ripped from https://github.com/pratikd650/Teensy_U2F/blob/master/Teensy_U2F.cpp
+void appendSignatureAsDER(std::vector<uint8_t> &response, const Signature &signature);