The function returns a string containing base64 encoded binary key data. It is used to extract symmetric or asymmetric keys. So if key is asymmetric (RSA or DSA) the second parameter designate which part to extract private or public.
The function returns serialized key material.
The 'ServerPrivate.pfx' is a own RSA key so we exporting public part to supply to some party to encrypt data for us.
SQL> select xenc_key_serialize ('ServerPrivate.pfx', 1); callret VARCHAR _______________________________________________________________________________ MIGJAoGBAMuSqCUCsie6RGUPBdtyM3fPF+yN5ot34i9/IPmjfmlSOlOQ/A9eYClJyvxRVDEHkkNFJWUzPWVRDoIEsUsYgBA6ls8qfai6XdWYoB/2dFB/08tT5uJajNleSF5sjJrjcPvmvn7k1SrVFtCIILioihtGpR2Dpp26MFjfffAnLhiDAgMBAAE= 1 Rows. -- 1 msec.