CREATE ASYMMETRIC KEY (Transact-SQL)

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics SQL database in Microsoft Fabric

Creates an asymmetric key in the database.

This feature is incompatible with database export using Data Tier Application Framework (DACFx). You must drop all asymmetric keys before exporting.

Transact-SQL syntax conventions

Note

This syntax is not supported by serverless SQL pool in Azure Synapse Analytics.

Syntax

CREATE ASYMMETRIC KEY asym_key_name   
   [ AUTHORIZATION database_principal_name ]  
   [ FROM <asym_key_source> ]  
   [ WITH <key_option> ] 
   [ ENCRYPTION BY <encrypting_mechanism> ] 
   [ ; ]
  
<asym_key_source>::=  
     FILE = 'path_to_strong-name_file'  
   | EXECUTABLE FILE = 'path_to_executable_file'  
   | ASSEMBLY assembly_name  
   | PROVIDER provider_name  
  
<key_option> ::=  
   ALGORITHM = <algorithm>  
      |  
   PROVIDER_KEY_NAME = 'key_name_in_provider'  
      |  
      CREATION_DISPOSITION = { CREATE_NEW | OPEN_EXISTING }  
  
<algorithm> ::=  
      { RSA_4096 | RSA_3072 | RSA_2048 | RSA_1024 | RSA_512 }   
  
<encrypting_mechanism> ::=  
    PASSWORD = 'password'   

Arguments

asym_key_name
Is the name for the asymmetric key in the database. Asymmetric key names must comply with the rules for identifiers and must be unique within the database.

AUTHORIZATION database_principal_name
Specifies the owner of the asymmetric key. The owner cannot be a role or a group. If this option is omitted, the owner will be the current user.

FROM asym_key_source
Specifies the source from which to load the asymmetric key pair.

FILE = 'path_to_strong-name_file'
Specifies the path of a strong-name file from which to load the key pair. Limited to 260 characters by MAX_PATH from the Windows API.

Note

This option is not available in a contained database.

EXECUTABLE FILE = 'path_to_executable_file'
Specifies the path of an assembly file from which to load the public key. Limited to 260 characters by MAX_PATH from the Windows API.

Note

This option is not available in a contained database.

ASSEMBLY assembly_name
Specifies the name of a signed assembly that has already been loaded into the database from which to load the public key.

PROVIDER provider_name
Specifies the name of an Extensible Key Management (EKM) provider. The provider must be defined first using the CREATE PROVIDER statement. For more information about external key management, see Extensible Key Management (EKM).

ALGORITHM = <algorithm>
Five algorithms can be provided; RSA_4096, RSA_3072, RSA_2048, RSA_1024, and RSA_512.

RSA_1024 and RSA_512 are deprecated. To use RSA_1024 or RSA_512 (not recommended) you must set the database to database compatibility level 120 or lower.

PROVIDER_KEY_NAME = 'key_name_in_provider'
Specifies the key name from the external provider.

CREATION_DISPOSITION = CREATE_NEW
Creates a new key on the Extensible Key Management device. PROVIDER_KEY_NAME must be used to specify key name on the device. If a key already exists on the device the statement fails with error.

CREATION_DISPOSITION = OPEN_EXISTING
Maps a SQL Server asymmetric key to an existing Extensible Key Management key. PROVIDER_KEY_NAME must be used to specify key name on the device. If CREATION_DISPOSITION = OPEN_EXISTING is not provided, the default is CREATE_NEW.

ENCRYPTION BY PASSWORD = 'password'
Specifies the password with which to encrypt the private key. If this clause is not present, the private key will be encrypted with the database master key. password is a maximum of 128 characters. password must meet the Windows password policy requirements of the computer that is running the instance of SQL Server.

Remarks

An asymmetric key is a securable entity at the database level. In its default form, this entity contains both a public key and a private key. When executed without the FROM clause, CREATE ASYMMETRIC KEY generates a new key pair. When executed with the FROM clause, CREATE ASYMMETRIC KEY imports a key pair from a file, or imports a public key from an assembly or DLL file.

By default, the private key is protected by the database master key. If no database master key has been created, a password is required to protect the private key.

The private key can be 512, 1024, or 2048 bits long.

Asymmetric Keys used for TDE are limited to a private key size of 3072 bits.

Permissions

Requires CREATE ASYMMETRIC KEY permission on the database. If the AUTHORIZATION clause is specified, requires IMPERSONATE permission on the database principal, or ALTER permission on the application role. Only Windows logins, SQL Server logins, and application roles can own asymmetric keys. Groups and roles cannot own asymmetric keys.

Examples

A. Creating an asymmetric key

The following example creates an asymmetric key named PacificSales09 by using the RSA_2048 algorithm, and protects the private key with a password.

CREATE ASYMMETRIC KEY PacificSales09   
    WITH ALGORITHM = RSA_2048   
    ENCRYPTION BY PASSWORD = '<enterStrongPasswordHere>';   
GO  

B. Creating an asymmetric key from a file, giving authorization to a user

The following example creates the asymmetric key PacificSales19 from a key pair stored in a file, and assigns ownership of the asymmetric key to user Christina. The private key is protected by the database master key, which must be created prior to creating the asymmetric key.

CREATE ASYMMETRIC KEY PacificSales19  
    AUTHORIZATION Christina  
    FROM FILE = 'c:\PacSales\Managers\ChristinaCerts.tmp';  
GO  

C. Creating an asymmetric key from an EKM provider

The following example creates the asymmetric key EKM_askey1 from a key pair stored in an Extensible Key Management provider called EKM_Provider1, and a key on that provider called key10_user1.

CREATE ASYMMETRIC KEY EKM_askey1   
    FROM PROVIDER EKM_Provider1  
    WITH   
        ALGORITHM = RSA_2048,   
        CREATION_DISPOSITION = CREATE_NEW  
        , PROVIDER_KEY_NAME  = 'key10_user1' ;  
GO  

See Also

ALTER ASYMMETRIC KEY (Transact-SQL)
DROP ASYMMETRIC KEY (Transact-SQL)
ASYMKEYPROPERTY (Transact-SQL)
ASYMKEY_ID (Transact-SQL)
Choose an Encryption Algorithm
Encryption Hierarchy
Extensible Key Management Using Azure Key Vault (SQL Server)