SilcUInt32 silc_utf8_encoded_len(const unsigned char *bin,
                                     SilcUInt32 bin_len,
                                     SilcStringEncoding bin_encoding);

    Returns the length of UTF-8 encoded string if the `bin' of
    encoding of `bin_encoding' is encoded with silc_utf8_encode.
    Returns zero (0) on error.