ALTER DATABASE ENCRYPTION KEY (Transact-SQL)

**APPLIES TO:** SQL Server (starting with 2008) Azure SQL Database Azure SQL Data Warehouse Parallel Data Warehouse

Alters an encryption key and certificate that is used for transparently encrypting a database. For more information about transparent database encryption, see Transparent Data Encryption (TDE).

Transact-SQL Syntax Conventions

Syntax

-- Syntax for SQL Server  
  
ALTER DATABASE ENCRYPTION KEY  
      REGENERATE WITH ALGORITHM = { AES_128 | AES_192 | AES_256 | TRIPLE_DES_3KEY }  
   |  
   ENCRYPTION BY SERVER   
    {  
        CERTIFICATE Encryptor_Name |  
        ASYMMETRIC KEY Encryptor_Name  
    }  
[ ; ]  

-- Syntax for Parallel Data Warehouse  
  
ALTER DATABASE ENCRYPTION KEY  
    {  
      {  
        REGENERATE WITH ALGORITHM = { AES_128 | AES_192 | AES_256 | TRIPLE_DES_3KEY }  
        [ ENCRYPTION BY SERVER CERTIFICATE Encryptor_Name ]  
      }  
      |  
      ENCRYPTION BY SERVER   CERTIFICATE Encryptor_Name    
    }  
[ ; ]  

Arguments

REGENERATE WITH ALGORITHM = { AES_128 | AES_192 | AES_256 | TRIPLE_DES_3KEY }
Specifies the encryption algorithm that is used for the encryption key.

ENCRYPTION BY SERVER CERTIFICATE Encryptor_Name
Specifies the name of the certificate used to encrypt the database encryption key.

ENCRYPTION BY SERVER ASYMMETRIC KEY Encryptor_Name
Specifies the name of the asymmetric key used to encrypt the database encryption key.

Remarks

The certificate or asymmetric key that is used to encrypt the database encryption key must be located in the master system database.

When the database owner (dbo) is changed, the database encryption key does not have to be regenerated.

After a database encryption key has been modified twice, a log backup must be performed before the database encryption key can be modified again.

Permissions

Requires CONTROL permission on the database and VIEW DEFINITION permission on the certificate or asymmetric key that is used to encrypt the database encryption key.

Examples

The following example alters the database encryption key to use the AES_256 algorithm.

-- Uses AdventureWorks  
  
ALTER DATABASE ENCRYPTION KEY  
REGENERATE WITH ALGORITHM = AES_256;  
GO  

See Also

Transparent Data Encryption (TDE)
SQL Server Encryption
SQL Server and Database Encryption Keys (Database Engine)
Encryption Hierarchy
ALTER DATABASE SET Options (Transact-SQL)
CREATE DATABASE ENCRYPTION KEY (Transact-SQL)
DROP DATABASE ENCRYPTION KEY (Transact-SQL)
sys.dm_database_encryption_keys (Transact-SQL)