You can encrypt sensitive credential data in the SYS.LINK$ and SYS.SCHEDULER$_CREDENTIAL system tables.
By default, the credential data in the SYS.LINK$ and SYS.SCHEDULER$_CREDENTIAL system tables is obfuscated. However, because of the availability of many types of de-obfuscation algorithms, Oracle recommends that you encrypt this sensitive credential data. To check the status the data dictionary credentials, you can query the DICTIONARY_CREDENTIALS_ENCRYPT data dictionary view.
The encryption of sensitive credential data in these two system tables uses Transparent Data Encryption. Encryption of credential data uses the AES256 algorithm. To encrypt credential data, you do not need an Oracle Advanced Security Option license, but you must be granted the SYSKM administrative privilege and the database must have an open keystore.
