How to check Oracle database connection encryption type
Don't confuse Oracle Advanced Security with encrypted SSL client connections to the database.  The Advanced Security option is comprised of two main features, Data Radaction and Transparent Data Encryption.  TDE is the encryption of data within tables, so that if someone captures the datafiles they won't be able to read table data in the clear inside the file.

An encrypted SSL connection between a client and the database is just part of the Oracle Net Services and is included with every version.  The Oracle documentation explains how to set that up.

To answer your question, run this query:

SELECT sys_context('USERENV', 'NETWORK_PROTOCOL') as network_protocol FROM dual;


If you are connected via SSL you will get the response

NETWORK_PROTOCOL
----------------
tcps


If you get "tcp," then you are on a non-SSL connection.