+extern std::string make_digest (std::string filename);
+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 opj_image_t* decompress_j2k (uint8_t* data, int64_t size, int reduce);
+extern boost::shared_ptr<ARGBFrame> xyz_to_rgb (opj_image_t* xyz_frame, boost::shared_ptr<const GammaLUT>, boost::shared_ptr<const GammaLUT>);
+
+extern void init ();
+
+extern void sign (xmlpp::Element* parent, CertificateChain const & certificates, std::string const & signer_key);
+extern void add_signature_value (xmlpp::Element* parent, CertificateChain const & certificates, std::string const & signer_key, std::string const & ns);
+extern void add_signer (xmlpp::Element* parent, CertificateChain const & certificates, std::string const & ns);
+
+extern int base64_decode (std::string const & in, unsigned char* out, int out_length);