+extern std::string make_digest (std::string filename, boost::function<void (float)> *);
+extern std::string content_kind_to_string (ContentKind kind);
+extern ContentKind content_kind_from_string (std::string kind);
+extern bool empty_or_white_space (std::string s);
+extern boost::shared_ptr<XYZFrame> decompress_j2k (uint8_t* data, int64_t size, int reduce);
+
+extern void init ();
+
+extern void sign (xmlpp::Element* parent, CertificateChain const & certificates, boost::filesystem::path signer_key, bool interop);
+extern void add_signature_value (xmlpp::Element* parent, CertificateChain const & certificates, boost::filesystem::path signer_key, std::string const & ns);
+extern void add_signer (xmlpp::Element* parent, CertificateChain const & certificates, std::string const & ns);