+/// \class fides
+///
+/// \brief Interaction with a Fides database.
+///
+/// A fides object manages a database of public keys and certificates.
+/// New certificates can be created, certificates can be imported and exported,
+/// and queries can be done on the database.
+
+
+/// Creates a new handle on a Fides database.
+//
+/// Will load the private key, known public keys and certificates.
+/// After that it will calculate the trust value of all keys.
+///
+/// @param dir Directory where Fides stores the keys and certificates.
+/// If no directory is specified, the following environment variables
+/// are used, in the given order:
+/// - \$FIDES_HOME
+/// - \$HOME/.fides
+/// - \$WPD/.fides
+fides::fides(const std::string &dir): homedir(dir) {