SignByAsymKey (Transact-SQL)

Signs plaintext with an asymmetric key

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SignByAsymKey(Asym_Key_ID,@plaintext [ ,'password' ] )


  • Asym_Key_ID
    Is the ID of an asymmetric key in the current database. Asym_Key_ID isint.

  • **@plaintext**
    Is a variable of type nvarchar, char, varchar, or nchar containing data that will be signed with the asymmetric key.

  • password
    Is the password with which the private key is protected. password is nvarchar(128).

Return Types

varbinary with a maximum size of 8,000 bytes.


Requires CONTROL permission on the asymmetric key.


The following example creates a table, SignedData04, in which to store plaintext and its signature. It next inserts a record in the table, signed with asymmetric key PrimeKey, which is first decrypted with password 'pGFD4bb925DGvbd2439587y'.

-- Create a table in which to store the data
CREATE TABLE [SignedData04]( Description nvarchar(max), Data nvarchar(max), DataSignature varbinary(8000) );
-- Store data together with its signature
DECLARE @clear_text_data nvarchar(max);
set @clear_text_data = N'Important numbers 2, 3, 5, 7, 11, 13, 17, 
      19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79,
      83, 89, 97';
INSERT INTO [SignedData04] 
    VALUES( N'data encrypted by asymmetric key ''PrimeKey''',
    @clear_text_data, SignByAsymKey( AsymKey_Id( 'PrimeKey' ),
    @clear_text_data, N'pGFD4bb925DGvbd2439587y' ));