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title DECRYPTBYCERT (Transact-SQL) | Microsoft Docs
ms.custom
ms.date 03/06/2017
ms.prod sql-non-specified
ms.reviewer
ms.suite
ms.technology
database-engine
ms.tgt_pltfrm
ms.topic language-reference
f1_keywords
DecryptByCert_TSQL
DECRYPTBYCERT
dev_langs
TSQL
helpviewer_keywords
certificates [SQL Server], decryption
decryption [SQL Server], certificates
DECRYPTBYCERT function
ms.assetid 4950d787-40fa-4e26-bce8-2cb2ceca12fb
caps.latest.revision 38
author BYHAM
ms.author rickbyh
manager jhubbard

DECRYPTBYCERT (Transact-SQL)

[!INCLUDEtsql-appliesto-ss2008-asdb-xxxx-xxx_md]

Decrypts data with the private key of a certificate.

Topic link icon Transact-SQL Syntax Conventions

Syntax

  
DecryptByCert ( certificate_ID , { 'ciphertext' | @ciphertext }   
    [ , { 'cert_password' | @cert_password } ] )  

Arguments

certificate_ID
Is the ID of a certificate in the database. certificate_ID is int.

ciphertext
Is a string of data that has been encrypted with the public key of the certificate.

@ciphertext
Is a variable of type varbinary that contains data that has been encrypted with the certificate.

cert_password
Is the password that was used to encrypt the private key of the certificate. Must be Unicode.

@cert_password
Is a variable of type nchar or nvarchar that contains the password that was used to encrypt the private key of the certificate. Must be Unicode.

Return Types

varbinary with a maximum size of 8,000 bytes.

Remarks

This function decrypts data with the private key of a certificate. Cryptographic transformations that use asymmetric keys consume significant resources. Therefore, EncryptByCert and DecryptByCert are not suited for routine encryption of user data.

Permissions

Requires CONTROL permission on the certificate.

Examples

The following example selects rows from [AdventureWorks2012].[ProtectedData04] that are marked as data encrypted by certificate JanainaCert02. The example decrypts the ciphertext with the private key of certificate JanainaCert02, which it first decrypts with the password of the certificate, pGFD4bb925DGvbd2439587y. The decrypted data is converted from varbinary to nvarchar.

SELECT convert(nvarchar(max), DecryptByCert(Cert_Id('JanainaCert02'),  
    ProtectedData, N'pGFD4bb925DGvbd2439587y'))  
FROM [AdventureWorks2012].[ProtectedData04]   
WHERE Description   
    = N'data encrypted by certificate '' JanainaCert02''';  
GO  

See Also

ENCRYPTBYCERT (Transact-SQL)
CREATE CERTIFICATE (Transact-SQL)
ALTER CERTIFICATE (Transact-SQL)
DROP CERTIFICATE (Transact-SQL)
BACKUP CERTIFICATE (Transact-SQL)
Encryption Hierarchy