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You can take several precautions to help secure the database, such as designing a secure system, encrypting confidential assets, and building a firewall around the database servers. However, in a scenario where the physical media (such as drives or backup tapes) are stolen, a malicious party can restore or attach the database and browse the data. One solution is to encrypt the sensitive data in the database and protect the keys used to encrypt the data with a certificate. This prevents anyone without the keys from using the data, but this kind of protection must be planned in advance.
Transparent Data Encryption (TDE) enables you to encrypt sensitive data, such as credit card numbers, stored in tables and FileGroups. Encrypted data is transparently decrypted for a database user or application that has access to data. TDE helps protect data stored on media in the event that the storage media or data file is stolen. SQL Server uses authentication, authorization, and auditing mechanisms to secure data in the database but not in the operating system data files where data is stored. To protect these data files, SQL Server provides TDE. TDE encrypts sensitive data stored in data files. To prevent unauthorized decryption, TDE stores the encryption keys in a security module external to the database.
TDE performs real-time I/O encryption and decryption of the data and log files. The encryption uses a database encryption key (DEK), which is stored in the database boot record for availability during recovery. The DEK is a symmetric key secured by using a certificate stored in the master database of the server or an asymmetric key protected by an EKM module. TDE protects data at rest, meaning the data and log files. It provides the ability to comply with many laws, regulations, and guidelines established in various industries. This enables software developers to encrypt data by using AES and 3DES encryption algorithms without changing existing applications.
Encryption of the database file is performed at the page level. The pages in an encrypted database are encrypted before they are written to disk and decrypted when read into memory. TDE does not increase the size of the encrypted database.
Benefits of using TDE include the following:
- As a security administrator, you can be sure that sensitive data is safe in case the storage media or data file is stolen.
- Implementing TDE helps you address security-related regulatory compliance issues.
- You do not need to create triggers or views to decrypt data for the authorized user or application. Data from tables is transparently decrypted for the database user and application.
- Database users and applications need not be aware that the data they are accessing is stored in encrypted form. Data is transparently decrypted for the database users and applications.
- Applications need not be modified to handle encrypted data. Data encryption and decryption are managed by the database.
- Key management operations are automated. The user or application does not need to manage encryption keys.
To learn more about TDE, see the Transparent Data Encryption (TDE) help topic in the MSDN library.
To use TDE, follow these steps in SQL Server Management Studio.
- Create a master key.
- Create or obtain a certificate protected by the master key.
- Create a database encryption key and protect it by the certificate.
- Set the database to use encryption.
Example of TDE
You can use the SQL commands below to configure TDE. You can choose the password for the master key, and when backing up the master key, you can choose the folder and file name.
USE masterGO/* Verify master key */SELECT * FROM sys.symmetric_keys WHERE name LIKE '%MS_DatabaseMasterKey%'GO/* if there are no records found, then it means there was no predefined Master Key. To create a Master Key, you can execute the below mentioned TSQL code. */ /* Create master key */CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'rev$$@admin';GO/* Backup master key */OPEN MASTER KEY DECRYPTION BY PASSWORD = 'rev$$@admin';GOBACKUP MASTER KEY TO FILE = 'D:\mssqlbackup\master\masterkey.mk' ENCRYPTION BY PASSWORD = 'rev$$@admin';GO/* Create Certificate */CREATE CERTIFICATE rev_cert WITH SUBJECT = 'REV Server Certificate';GO/* Verify Certificate */SELECT * FROM sys.certificates where [name] = 'rev_cert'GO/* Backup certificate */BACKUP CERTIFICATE rev_cert TO FILE = 'D:\mssqlbackup\master\rev.cer' WITH PRIVATE KEY ( FILE = 'D:\mssqlbackup\master\rev.pvk', ENCRYPTION BY PASSWORD = 'rev$$@admin');GO--use rev databaseUSE revGO/* Create Encryption key */CREATE DATABASE ENCRYPTION KEY WITH ALGORITHM = AES_256 ENCRYPTION BY SERVER CERTIFICATE rev_cert;GO/* Encrypt database */ALTER DATABASE revdb SET ENCRYPTION ON;GO/* Verify Encryption */SELECT DB_NAME(database_id) AS DatabaseName,Encryption_State AS EncryptionState,key_algorithm AS Algorithm,key_length AS KeyLengthFROM sys.dm_database_encryption_keysGOSELECT NAME AS DatabaseName,IS_ENCRYPTED AS IsEncrypted FROM sys.databases where name ='revdb'GO
FAQs
TDE encrypts the storage of an entire database by using a symmetric key called the Database Encryption Key (DEK).
How to check if transparent data encryption is enabled in SQL Server? ›
dm_database_encryption_keys; This query will return the encryption status of all databases on the SQL Server. The encryption_state column will show the status of TDE for each database. A status of 'Encrypted' (encryption_state = 3) indicates that TDE is enabled.
What are the advantages of using TDE transparent data encryption in SQL Server? ›
Advantages of TDE
- Fairly simple to implement.
- No changes to the application tier required.
- Is invisible to the user.
- Works with high availability features, such as mirroring, AlwaysOn and log shipping.
- Works with older versions of SQL Server, back to 2008.
Enable TDE
- Create a master key.
- Create or obtain a certificate protected by the master key.
- Create a database encryption key and protect it by using the certificate.
- Set the database to use encryption.
One disadvantage of TDE is that it does not protect data in transit. Data is only encrypted when it is at rest in the database. If data is transmitted over a network, it can be intercepted and read by an attacker. Another disadvantage of TDE is that it does not protect against SQL injection attacks.
Which SQL items are protected with SQL TDE? ›
TDE encrypts the entire file stored on disk, so administrators do not have granular control over cell-level or column-level encryption. All disk I/O activity is encrypted, so it's an “all or nothing” feature for SQL Server databases.
How to enable TDE in Azure SQL Server? ›
As a quick note here: for both Azure Synapse and Azure SQL, you can set TDE encryption on through the Azure Portal. When you click on an Azure SQL database, there is an option under settings called Data Encryption under the Security settings.
Which version of SQL Server has TDE encryption? ›
Microsoft offers TDE as part of its Microsoft SQL Server 2008, 2008 R2, 2012, 2014, 2016, 2017 and 2019.
How long does it take to enable TDE in SQL Server? ›
Enabling TDE is not instantaneous, the SQL Server Encryption Scanner has to read all the underlying database pages and encrypt them, For a 30 TB database it might take multiple days for SQL Server to encrypt the entire database and we as DBAs should monitor the encryption progress making sure there are no side effects.
How to check encryption status in SQL Server? ›
How to tell if encryption is working?
- Open a new query window in SQL Server Management Studio (SSMS) and connect to the SQL Server instance.
- Execute the following T-SQL command to check the value of encrypt_option column. For encrypted connections the value will be TRUE .
When to use Transparent Data Encryption. Transparent Data Encryption (TDE) protects data at rest, such as backups on physical media. It prevents access to data in scenarios like improper disposal of disk drives or attempts to restore databases from snapshots or copies.
What is the impact of TDE in SQL? ›
Microsoft states that enabling TDE usually has a performance overhead of 2–4%.
What is the alternative to TDE in SQL? ›
NetLib Security Encryptionizer for SQL Server
Encryptionizer is a cost-effective alternative to SQL Server's built-in TDE without the need for additional upgrades or maintenance.
How do I enable encryption in SQL Server? ›
Open SQL Server Management Studio
On the Object Explorer toolbar, click Connect, and then click Database Engine. On the Connection Properties tab, click Encrypt connection.
How to remove TDE from a database in SQL Server? ›
Turning off TDE and removing TDE setup
- In SQL Server Management Studio, navigate to Databases > TestDatabase.
- Right-click TestDatabase, then select Tasks > Manage Database Encryption….
- Ensure Set Database Encryption On is deselected, then click OK.
- Wait for the decryption process to finish.
Transparent Data Encryption (often abbreviated to TDE) is a technology employed by Microsoft, IBM and Oracle to encrypt database files. TDE offers encryption at file level. TDE enables the encryption of data at rest, encrypting databases both on the hard drive and consequently on backup media.
What is the difference between transparent data encryption and always encrypted? ›
To simplify: TDE secures all of the database files on disk, hence the term "at rest". Since encryption and decryption are done by the database engine, it's transparent to all clients. Always Encrypted is more granular, specific data elements/columns store encrypted data which requires a "key" to translate.
What is the difference between transparent data encryption and data masking? ›
Two key differences between masking and encryption are the following: Masked data remains usable, but original values can't be recovered. Encrypted data is challenging to work with but can be recovered with the correct encryption key.
Which two does the master key encrypt with transparent data encryption? ›
This TDE master encryption key is used to encrypt the TDE tablespace encryption key, which in turn is used to encrypt and decrypt data in the tablespace.
