ENCRYPTBYPASSPHRASE (Transact-SQL)

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance

Encrypt data with a passphrase using the TRIPLE DES algorithm with a 128 key bit length.

Transact-SQL syntax conventions

Syntax

EncryptByPassPhrase ( { 'passphrase' | @passphrase }   
    , { 'cleartext' | @cleartext }  
  [ , { add_authenticator | @add_authenticator }  
    , { authenticator | @authenticator } ] )  

Arguments

passphrase
A passphrase from which to generate a symmetric key.

@passphrase
A variable of type nvarchar, char, varchar, binary, varbinary, or nchar containing a passphrase from which to generate a symmetric key.

cleartext
The cleartext to be encrypted.

@cleartext
A variable of type nvarchar, char, varchar, binary, varbinary, or nchar containing the cleartext. Maximum size is 8,000 bytes.

add_authenticator
Indicates whether an authenticator will be encrypted together with the cleartext. 1 if an authenticator will be added. int.

@add_authenticator
Indicates whether a hash will be encrypted together with the cleartext.

authenticator
Data from which to derive an authenticator. sysname.

@authenticator
A variable containing data from which to derive an authenticator.

Return Types

varbinary with maximum size of 8,000 bytes.

Remarks

A passphrase is a password that includes spaces. The advantage of using a passphrase is that it is easier to remember a meaningful phrase or sentence than to remember a comparably long string of characters.

This function does not check password complexity.

Examples

The following example updates a record in the SalesCreditCard table and encrypts the value of the credit card number stored in column CardNumber_EncryptedbyPassphrase, using the primary key as an authenticator.

USE AdventureWorks2022;  
GO  
-- Create a column in which to store the encrypted data.  
ALTER TABLE Sales.CreditCard   
    ADD CardNumber_EncryptedbyPassphrase VARBINARY(256);   
GO  
-- First get the passphrase from the user.  
DECLARE @PassphraseEnteredByUser NVARCHAR(128);  
SET @PassphraseEnteredByUser   
    = 'A little learning is a dangerous thing!';  
  
-- Update the record for the user's credit card.  
-- In this case, the record is number 3681.  
UPDATE Sales.CreditCard  
SET CardNumber_EncryptedbyPassphrase = EncryptByPassPhrase(@PassphraseEnteredByUser  
    , CardNumber, 1, CONVERT(varbinary, CreditCardID))  
WHERE CreditCardID = '3681';  
GO  

See Also

DECRYPTBYPASSPHRASE (Transact-SQL)
Encryption Hierarchy