It depends on exactly what you are looking for. If you license the Advanced Security Option (an extra cost above and beyond the enterprise edition license), you can use [urhttp://www.oracle.com/technetwork/database/options/advanced-security/index-099011.html]Transparent Data Encryption (TDE) to encrypt data at rest or network encryption to encrypt the data between the client and the server. If you don't want to license the Advanced Security Option and you're only concerned about data at rest, you can use the dbms_crypto package to manually encrypt data. That will require that you build your own key management infrastructure, it will require (or at least very strongly encourage) data model changes, and it will be less efficient than TDE. But it saves on licensing costs.