How can I enforce and manage transparent data encryption on SQL Databases involved in replication and Always On AGs?

To enforce and manage Transparent Data Encryption (TDE) on SQL Databases involved in replication and Always On Availability Groups (AGs), consider the following points:

1. Managing TDE for Database Restores: When restoring databases to lower environments or between servers, ensure that the TDE certificate used to encrypt the database is backed up and available. This is crucial because the database encryption key (DEK) is protected by this certificate. You can manage TDE using the Azure portal or PowerShell, and it is recommended to maintain backups of the server certificates to prevent data loss if the certificate becomes unavailable.
2. Managing TDE in Transactional Replication: For databases involved in transactional replication, TDE must be enabled separately on the distribution and subscriber databases. When setting up replication, ensure that TDE is enabled on all databases that will participate in the replication process. Additionally, during the initial data distribution for transactional replication, you can enable encryption to protect the communication channel.

For Always On AGs, you can add encrypted databases to the availability group. Ensure that the master key and certificates are created on all secondary replicas before creating the DEK on the primary replica. This setup will help maintain encryption across all replicas in the availability group.

References:

• TDE and replication
• TDE and availability groups