char *silc_pkcs_silc_encode_identifier(char *username, char *host,
                                           char *realname, char *email,
                                           char *org, char *country,
                                           char *version);

    Encodes and returns SILC public key identifier.  If some of the
    arguments are NULL those are not encoded into the identifier string.
    Protocol says that at least username and host must be provided.
    Caller must free the returned identifier string.