Encrypting Data at Rest with TDE in SQL Server

Transparent Data Encryption (TDE) is a feature in SQL Server that allows you to encrypt the entire database, including the data and log files, to protect sensitive data from unauthorized access.

Here’s an example of how to implement TDE at the database level using the “CREATE CERTIFICATE” and “BACKUP CERTIFICATE” commands:

Create a master key:

USE master;
GO

CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'mysecretpassword';
GO

This creates a master key that is used to encrypt and decrypt the certificate that will be used for TDE.

Create a certificate:

USE mydatabase;
GO

CREATE CERTIFICATE mydatabase_cert
WITH SUBJECT = 'mydatabase TDE certificate';
GO

This creates a certificate that will be used to encrypt the database.

Create a database encryption key:

USE mydatabase;
GO

CREATE DATABASE ENCRYPTION KEY
WITH ALGORITHM = AES_256
ENCRYPTION BY SERVER CERTIFICATE mydatabase_cert;
GO

This creates a database encryption key that is used to encrypt the database.

Enable TDE on the database:

USE mydatabase;
GO
ALTER DATABASE mydatabase
SET ENCRYPTION ON;
GO

This enables TDE on the database.

Backup the certificate:

BACKUP CERTIFICATE mydatabase_cert
TO FILE = 'C:\mydatabase_cert.cer'
WITH PRIVATE KEY (
    FILE = 'C:\mydatabase_privatekey.pvk',
    ENCRYPTION BY PASSWORD = 'mysecretpassword'
);

This backs up the certificate and private key to a file. The private key is encrypted using the master key password.

It’s important to store the backup certificate files in a secure location and never loose it. This is critical because if you lose the certificate files, you will lose access to the encrypted data and will not be able to restore the database.

It’s worth noting that TDE encrypts the data at rest, meaning data that is stored on disk, and not data that is being transmitted over the network, so it’s important to use other security measures such as firewalls, VPNs, and secure communication protocols to protect the data during transmission.

It’s also important to keep in mind that TDE can have a slight performance impact, especially during backups and restores. So, it’s important to monitor the performance of your database after enabling TDE and make adjustments as necessary.

It’s important to test the TDE implementation in a test environment before moving it to production, as well as test the restore process to make sure that the certificate is working properly.

It’s also important to keep the SQL Server and the TDE certificate updated and to replace the certificate before it expires.