Today in our Virtual Chapter meeting for VCDBA, I presented on SQL Server Encryption including TDE. The question was posed as to whether or not the TDE would take affect if the mirror was established first and then you enabled TDE on the database. I was not sure at the time only because I had not done any tests, so I did not want to say yes or no unless I could substantiate it.
I set off to do some tests. First I created a Mirrored database using the demo code from the VC presentation.
use master GO CREATE DATABASE [TESTTDE] ON PRIMARY ( NAME = N'TESTTDE', FILENAME = N'C:\sqldata\S1\TESTTDE.mdf' , SIZE = 10240KB , FILEGROWTH = 10240KB ) LOG ON ( NAME = N'TESTTDE_log', FILENAME = N'C:\sqldata\S1\TESTTDE_log.ldf' , SIZE = 10240KB , FILEGROWTH = 10240KB ) GO
Now once the database is created on instance 1 I backed up the database and a log backup. Then restored it to the second instance with it’s log with no recovery. Once it was primed and ready, I established a mirror and saw the database was synchronized. Now the trick is to use create the components to establish the Encryption Hierarchy.
USE master; GO CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'INSTANCE1_Use1Strong2Password3Here!'; go CREATE CERTIFICATE MyServerCert WITH SUBJECT = 'My DEK Certificate' GO
Now that we have the MASTER KEY and the Certificate in place, you need to backup the certificate to a set of files and restore it to the second instance.
BACKUP CERTIFICATE MyServerCert TO FILE='C:\SQLBACKUP\MyserverCert.cer' WITH PRIVATE KEY (FILE='C:\SQLBACKUP\MyServerCert.pvk', ENCRYPTION BY PASSWORD='My1Secure2Password!') GO
NOW CHANGE TO THE SECOND INSTANCE
-- Make sure that you change to the second instance USE master; GO CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'INSTANCE2_Use1Strong2Password3Here!'; GO CREATE CERTIFICATE MyServerCert FROM FILE = 'C:\SQLBACKUP\MyServerCert.cer' WITH PRIVATE KEY (FILE = 'C:\SQLBACKUP\MyServerCert.pvk', DECRYPTION BY PASSWORD = 'My1Secure2Password!'); GO
Now that you have the Encryption Hierarchy established for both instances, let’s encrypt the database.
-- Make sure that you are in the Principal instance -- or this will not work because you won't be able -- to USE TESTTDE on the Mirror USE TESTTDE GO CREATE DATABASE ENCRYPTION KEY WITH ALGORITHM = AES_128 ENCRYPTION BY SERVER CERTIFICATE MyServerCert; GO ALTER DATABASE TESTTDE SET ENCRYPTION ON; GO
What will happen in the Mirror is that it will encrypt the database, even though you won’t be able to see it. When it is fully encrypted, and you fail the database over in the Mirror, it will indicate that the database is encrypted. On the Principal you can see it with the query below.
SELECT db.name, db.is_encrypted, dm.encryption_state, dm.percent_complete, dm.key_algorithm, dm.key_length FROM sys.databases db LEFT OUTER JOIN sys.dm_database_encryption_keys dm ON db.database_id = dm.database_id;
Now for the Log Shipping copy
To establish the test for the Log Shipping, do the same as you did for the mirror but restore the Full, then the Log with Standby so that you can see that it flags it as encrypted. First establish the Log Shipping without encryption set up, and once you are in Standby on the Shipped side, you can use the existing Certificate to test the idea of encryption afterwards.
- CREATE DATABASE
- SET Recovery Model to Full
- Backup Database
- Backup Log
- Change to second instance
- RESTORE DATABASE with NORECOVERY
- RESTORE LOG WITH STANDBY
- Change to first instance
- USE TESTTDELOGSHIPPING
- CREATE DATABASE ENCRYPTION KEY
- ALTER DATABASE TESTTDELOGSHIPPING SET ENCRYPTION ON
- BACKUP LOG
- Change to second instance
- RESTORE LOG TESTTDELOGSHIPPING WITH STANDBY
- Run the above query to see if the database is encrypted. You will see is_encrypted = 1
This shows that the Mirroring and Log Shipping processes are affected by the Database Encryption Process.