Which encrypted data type is automatically used in Oracle Autonomous Database?

In Oracle Autonomous Database, Transparent Data Encryption (TDE) is the default and automatically applied encryption method used to secure data at rest. TDE protects sensitive data by encrypting database files without requiring any changes to the application code or the way the applications interact with the database. This seamless integration ensures that data is encrypted on disk, providing enhanced security for stored data without compromising performance.

TDE is effective in protecting data against unauthorized access, particularly in scenarios where physical media may be lost or stolen. It ensures that the data remains encrypted in the underlying storage system and only becomes accessible to authorized users through the database management system itself.

The other encryption methods mentioned, while important in different contexts, do not serve the same purpose within Oracle Autonomous Database. Symmetric and asymmetric encryption algorithms are generally applied for secure communication and data exchange rather than as a default method for securing data at rest. Hash encryption, on the other hand, is primarily used for verifying data integrity rather than encrypting data itself. Thus, TDE is the most suitable and relevant choice for encryption in this particular context.