SQL Server offers various security features to protect your data, and one of them is Transparent Database Encryption (TDE). TDE helps in encrypting the data at rest, providing an additional layer of security for your sensitive information. In this blog post, we will discuss how to enable TDE when using SQL Server Mirroring.

Recently, I had a customer who was working with SQL Server 2008 R2 and wanted to enable TDE on their server. Although I initially thought of recommending AlwaysOn, it was not feasible for them due to the application’s compatibility limitations. So, I decided to guide them on enabling TDE with minimal downtime.

When using SQL Server Database Mirroring, there are a few steps that need to be implemented before enabling mirroring. Let’s go through these steps:

Step 1: Create a Master Key on the Mirror Server

The first step involves creating a Master Key on the Mirror server. This key is used to encrypt the certificate that will be created in the next step. Here’s an example of how to create the Master Key:

USE master;
GO
CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'some strong password #1';
GO

Note that the password used here doesn’t have to be the same as the one for the master key on the principal instance.

Step 2: Backup the Certificate on the Principal Server

The next step is to backup the certificate used for encryption on the principal server. This certificate will be used to create a certificate on the mirror server. Here’s an example of how to backup the certificate:

USE master;
GO
BACKUP CERTIFICATE MyPrinServerCert TO FILE = 'path_and_file_name.cer'
WITH PRIVATE KEY (FILE = 'path_and_file_name.pvk',
ENCRYPTION BY PASSWORD = 'your strong password #2');
GO

Make sure to replace ‘path_and_file_name’ with the appropriate file path and name.

Step 3: Create a Certificate on the Mirror Server

After backing up the certificate, you need to copy the certificate file and the key file to the mirror server. Then, create a certificate using these two files. Here’s an example of how to create the certificate:

USE master;
GO
CREATE CERTIFICATE MyPrinServerCert
FROM FILE = 'path_and_file_name.cer'
WITH PRIVATE KEY (FILE = 'path_and_file_name.pvk',
DECRYPTION BY PASSWORD = 'your strong password #2');
GO

Ensure that the password provided in this step matches the password provided when backing up the certificate on the principal server.

It’s important to note that these steps are not limited to SQL Server Mirroring and can be applied to other scenarios like log-shipping or AlwaysOn as well. If you’re working with TDE inside SQL Server, have you ever used similar scripts in your environments?

Implementing Transparent Database Encryption (TDE) with SQL Server Mirroring can help enhance the security of your data. By following the steps outlined in this blog post, you can enable TDE and protect your sensitive information.