You can now have the encryption keys used for the primary and standby databases to be available in the primary and standby regions respectively so that it provides protection against a single point of failure for the OCI Vault key. This is possible if the keys are in OCI Virtual Private Vault. So, a cross-region Data Guard can be set up between two databases if their keys are residing in a virtual private vault (VPV) and are managed by the OCI Vault service.

For more information, see:

• To administer Vault encryption keys
• Customer-Managed Keys in Exadata Cloud Infrastructure
• Prerequisites for Using Oracle Data Guard with Exadata Cloud Infrastructure