--- title: "ALTER MASTER KEY (Transact-SQL) | Microsoft Docs" ms.custom: "" ms.date: "03/14/2017" ms.prod: "sql" ms.prod_service: "sql-data-warehouse, database-engine, pdw, sql-database" ms.service: "" ms.component: "t-sql|statements" ms.reviewer: "" ms.suite: "sql" ms.technology: - "database-engine" ms.tgt_pltfrm: "" ms.topic: "language-reference" f1_keywords: - "ALTER MASTER KEY" - "ALTER_MASTER_KEY_TSQL" dev_langs: - "TSQL" helpviewer_keywords: - "REGENERATE phrase" - "ALTER MASTER KEY statement" - "decryption [SQL Server], Database Master Key" - "FORCE option" - "encryption [SQL Server], Database Master Key" - "database master key [SQL Server], modifying" - "cryptography [SQL Server], Database Master Key" - "modifying Database Master Key" - "service master key [SQL Server], modifying" - "DROP ENCRYPTION BY SERVICE MASTER KEY phrase" ms.assetid: 8ac501c3-4280-4d5b-b58a-1524fa715b50 caps.latest.revision: 49 author: "edmacauley" ms.author: "edmaca" manager: "craigg" ms.workload: "On Demand" monikerRange: ">= aps-pdw-2016 || = azuresqldb-current || = azure-sqldw-latest || >= sql-server-2016 || = sqlallproducts-allversions" --- # ALTER MASTER KEY (Transact-SQL) [!INCLUDE[tsql-appliesto-ss2008-asdb-asdw-pdw-md](../../includes/tsql-appliesto-ss2008-asdb-asdw-pdw-md.md)] Changes the properties of a database master key. ![Topic link icon](../../database-engine/configure-windows/media/topic-link.gif "Topic link icon") [Transact-SQL Syntax Conventions](../../t-sql/language-elements/transact-sql-syntax-conventions-transact-sql.md) ## Syntax ``` -- Syntax for SQL Server ALTER MASTER KEY ::= | ::= [ FORCE ] REGENERATE WITH ENCRYPTION BY PASSWORD = 'password' ::= ADD ENCRYPTION BY { SERVICE MASTER KEY | PASSWORD = 'password' } | DROP ENCRYPTION BY { SERVICE MASTER KEY | PASSWORD = 'password' } ``` ``` -- Syntax for Azure SQL Database -- Note: DROP ENCRYPTION BY SERVICE MASTER KEY is not supported on Azure SQL Database. ALTER MASTER KEY ::= | ::= [ FORCE ] REGENERATE WITH ENCRYPTION BY PASSWORD = 'password' ::= ADD ENCRYPTION BY { SERVICE MASTER KEY | PASSWORD = 'password' } | DROP ENCRYPTION BY { PASSWORD = 'password' } ``` ``` -- Syntax for Azure SQL Data Warehouse and Parallel Data Warehouse ALTER MASTER KEY ::= | ::= [ FORCE ] REGENERATE WITH ENCRYPTION BY PASSWORD ='password' ::= ADD ENCRYPTION BY SERVICE MASTER KEY | DROP ENCRYPTION BY SERVICE MASTER KEY ``` ## Arguments PASSWORD ='*password*' Specifies a password with which to encrypt or decrypt the database master key. *password* must meet the Windows password policy requirements of the computer that is running the instance of [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)]. ## Remarks The REGENERATE option re-creates the database master key and all the keys it protects. The keys are first decrypted with the old master key, and then encrypted with the new master key. This resource-intensive operation should be scheduled during a period of low demand, unless the master key has been compromised. [!INCLUDE[ssSQL11](../../includes/sssql11-md.md)] uses the AES encryption algorithm to protect the service master key (SMK) and the database master key (DMK). AES is a newer encryption algorithm than 3DES used in earlier versions. After upgrading an instance of the [!INCLUDE[ssDE](../../includes/ssde-md.md)] to [!INCLUDE[ssSQL11](../../includes/sssql11-md.md)] the SMK and DMK should be regenerated in order to upgrade the master keys to AES. For more information about regenerating the SMK, see [ALTER SERVICE MASTER KEY (Transact-SQL)](../../t-sql/statements/alter-service-master-key-transact-sql.md). When the FORCE option is used, key regeneration will continue even if the master key is unavailable or the server cannot decrypt all the encrypted private keys. If the master key cannot be opened, use the [RESTORE MASTER KEY](../../t-sql/statements/restore-master-key-transact-sql.md) statement to restore the master key from a backup. Use the FORCE option only if the master key is irretrievable or if decryption fails. Information that is encrypted only by an irretrievable key will be lost. The DROP ENCRYPTION BY SERVICE MASTER KEY option removes the encryption of the database master key by the service master key. ADD ENCRYPTION BY SERVICE MASTER KEY causes a copy of the master key to be encrypted using the service master key and stored in both the current database and in master. ## Permissions Requires CONTROL permission on the database. If the database master key has been encrypted with a password, knowledge of that password is also required. ## Examples The following example creates a new database master key for `AdventureWorks` and reencrypts the keys below it in the encryption hierarchy. ``` USE AdventureWorks2012; ALTER MASTER KEY REGENERATE WITH ENCRYPTION BY PASSWORD = 'dsjdkflJ435907NnmM#sX003'; GO ``` ## Examples: [!INCLUDE[ssSDWfull](../../includes/sssdwfull-md.md)] and [!INCLUDE[ssPDW](../../includes/sspdw-md.md)] The following example creates a new database master key for `AdventureWorksPDW2012` and re-encrypts the keys below it in the encryption hierarchy. ``` USE master; ALTER MASTER KEY REGENERATE WITH ENCRYPTION BY PASSWORD = 'dsjdkflJ435907NnmM#sX003'; GO ``` ## See Also [CREATE MASTER KEY (Transact-SQL)](../../t-sql/statements/create-master-key-transact-sql.md) [OPEN MASTER KEY (Transact-SQL)](../../t-sql/statements/open-master-key-transact-sql.md) [CLOSE MASTER KEY (Transact-SQL)](../../t-sql/statements/close-master-key-transact-sql.md) [BACKUP MASTER KEY (Transact-SQL)](../../t-sql/statements/backup-master-key-transact-sql.md) [RESTORE MASTER KEY (Transact-SQL)](../../t-sql/statements/restore-master-key-transact-sql.md) [DROP MASTER KEY (Transact-SQL)](../../t-sql/statements/drop-master-key-transact-sql.md) [Encryption Hierarchy](../../relational-databases/security/encryption/encryption-hierarchy.md) [CREATE DATABASE (SQL Server Transact-SQL)](../../t-sql/statements/create-database-sql-server-transact-sql.md) [Database Detach and Attach (SQL Server)](../../relational-databases/databases/database-detach-and-attach-sql-server.md)