Add error codes for signing error checks

include/jwt/error_codes.hpp

@@ -0,0 +1,44 @@
+#ifndef CPP_JWT_ERROR_CODES_HPP
+#define CPP_JWT_ERROR_CODES_HPP
+
+#include <system_error>
+
+namespace jwt {
+/**
+ * All the algorithm errors
+ */
+enum class AlgorithmErrc
+{
+  SigningErr = 1,
+  VerificationErr,
+  NoneAlgorithmUsed, // Not an actual error!
+};
+
+/**
+ * Algorithm error conditions
+ */
+enum class AlgorithmFailureSource
+{
+};
+
+
+/**
+ */
+std::error_code make_error_code(AlgorithmErrc err);
+
+} // END namespace jwt
+
+
+/**
+ * Make the custom enum classes as error code
+ * adaptable.
+ */
+namespace std
+{
+  template <>
+  struct is_error_code_enum<jwt::AlgorithmErrc> : true_type {};
+}
+
+#include "jwt/impl/error_codes.ipp"
+
+#endif