Data-at-rest

To protect sensitive data while at rest (data-at-rest) in Oracle database data files and in backup files the Oracle database's Transparent Database Encryption (TDE) feature should be used. (See Oracle Database Advanced Security Guide document - https://docs.oracle.com/en/database/oracle/oracle-database/19/asoag/introduction-to-transparent-data-encryption.html#GUID-62AA9447-FDCD-4A4C-B563-32DE04D55952 or related document for your database and version).

Note:

TDE is enabled and used by default in Oracle Cloud's PaaS Database Cloud Service for securing data files and backup files within the cloud. (See https://docs.oracle.com/en/cloud/paas/database-dbaas-cloud/csdbi/data-security.html).