Restoring database with TDE to a 2nd instance

  • winston Smith

    SSCoach

    Points: 19484

    I was unsure of how to do this so i done some googling and a few tests of my own, and although i am successful, i have a few questions. heres what i did:

    On Instance 1 I created a master key, created a server cert, backed up the server cert and encrypted it with a password. I then created a db encryption key using the server cert and enabled TDE, and took a backup. no problems

    use master

    GO

    --create master key

    create master key encryption by password = 'strong_Passw0rD'

    GO

    --create server certificate

    Create certificate ServerCert with subject = 'server cert for use with TDE'

    GO

    --backup server cert, encrypting it by password

    Backup certificate ServerCert to file = 'C:\cert_Backups\servercert.cer'

    with private key (file = 'C:\cert_Backups\servercert.key',encryption By Password = 'strong_Passw0rD')

    go

    use security_testing

    GO

    --create db encryption key which is encrypted by the serverCert

    create database encryption key with algorithm = AES_128

    encryption by server certificate ServerCert

    GO

    --enable encryption

    Alter database security_testing

    set encryption on

    GO

    --backup encrypted database

    backup database security_testing

    to disk = 'C:\cert_Backups\db_bak\security_testing_encrypted_bak.bak'

    On instance 2, i tried to restore the backup, this failed, so i created a new server master key, and then restored the server cert and had no problems restoring the backup:

    --try to restore database on 2nd instance

    RESTORE DATABASE [TDE_Restore] FROM DISK = N'C:\cert_Backups\db_bak\security_testing_encrypted_bak.bak' WITH FILE = 1,

    MOVE N'Security_Testing' TO N'C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\DATA\TDE_Restore.mdf',

    MOVE N'Security_Testing_log' TO N'C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\DATA\TDE_Restore_1.LDF', NOUNLOAD, STATS = 10

    GO

    --cannot restore database.

    --trying to restore keys first.

    USE master

    GO

    CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'TDEtesting123'

    GO

    CREATE CERTIFICATE serverCert FROM FILE = 'C:\cert_Backups\servercert.cer'

    WITH PRIVATE KEY (FILE = 'C:\cert_Backups\servercert.key', DECRYPTION BY PASSWORD = 'strong_Passw0rD')

    GO

    RESTORE DATABASE [TDE_Restore] FROM DISK = N'C:\cert_Backups\db_bak\security_testing_encrypted_bak.bak' WITH FILE = 1,

    MOVE N'Security_Testing' TO N'C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\DATA\TDE_Restore.mdf',

    MOVE N'Security_Testing_log' TO N'C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\DATA\TDE_Restore_1.LDF', NOUNLOAD, STATS = 10

    GO

    --Success

    My question surrounds the server master key. i thought i should have to backup the server master key from instance 1 and restore it to instance 2 in order to be able to restore the server cert and thus the database. as you can see above, i dont, as i created a completely new server master key on instance 2 with a completely different password. what is the purpose of the server master key in this case?

    Question 2 is where does the Service Master Key fit into all this?

  • Roy Ernest

    SSC-Dedicated

    Points: 38707

    If my understanding is correct, Master key just protect the private key of certificates and asymmetric keys that are present in the DB. It is the certificate that matters in TDE.

    That is my understanding

    -Roy

  • winston Smith

    SSCoach

    Points: 19484

    Roy Ernest (9/29/2009)


    If my understanding is correct, Master key just protect the private key of certificates and asymmetric keys that are present in the DB. It is the certificate that matters in TDE.

    That is my understanding

    to protect the cert from what though? If i have the cert and the password to decrypt the cert, theres no way a master key can protect it, but the master key is still required to create the server certificate ( and prob keys in the db, have not checked this yet though).

  • npranj

    SSCrazy

    Points: 2323

    Master key is created at instance level and hence it is absolutely OK to create a master key for the destination database instance which you did.

    The Certificate and Keys becaked up from the source database server are the ones that will be used to encrypt.

  • pramod.singh 40121

    SSC Rookie

    Points: 47

    Please check the below link for restoring with server master key.

    http://blogs.msdn.com/b/ai/archive/2012/09/24/enabling-tde-transparent-data-encryption-on-all-user-databases.aspx

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