在存储过程中使用密码打开对称密钥

Question

我正在尝试编写一个存储过程来解密一些由对称密钥加密的数据，该对称密钥是用带有密码的非对称密钥加密的。

OPEN SYMMETRIC KEY密码需要一个字符串文字，所以我不得不使用EXEC sp_executesql. 有一个更好的方法吗？

DECLARE @open nvarchar(200), @close nvarchar(200)
SET @open = 'OPEN SYMMETRIC KEY skey DECRYPTION BY ASYMMETRIC KEY akey WITH PASSWORD = ' + quotename(@password,'''') + ';';
SET @close = 'CLOSE SYMMETRIC KEY skey;';

EXEC sp_executesql @open

SELECT [TransactionID],Convert(varchar(max),DECRYPTBYKEY([EncryptedText])) as DecryptedText FROM [dbo].[TestTable];

EXEC sp_executesql @close

如果您使用错误的密码执行它，则会引发以下错误：

Msg 15466, Level 16, State 1, Line 1
An error occurred during decryption.
Msg 15315, Level 16, State 1, Line 1
The key 'skey' is not open. Please open the key before using it.

我应该EXEC sp_executesql @open用 a包装TRY ... CATCH并返回NULL还是有（更）优雅的处理方式？

编辑：处理使用错误密码调用此过程的人的最佳方法是什么？

Answer 1

使用密钥的示例，检查您的数据和代码：

CREATE ASYMMETRIC KEY akey WITH ALGORITHM = RSA_2048 
ENCRYPTION BY PASSWORD = 'aaa123'
GO
CREATE SYMMETRIC KEY skey WITH ALGORITHM = AES_256 ENCRYPTION BY ASYMMETRIC KEY akey
GO

DECLARE @t TABLE(plain VARCHAR(100), ciphered VARBINARY(MAX), unciphered VARCHAR(100))

INSERT @t(plain)
VALUES('11111'), ('22222'), ('33333')

OPEN SYMMETRIC KEY skey DECRYPTION BY ASYMMETRIC KEY akey WITH PASSWORD = 'aaa123'

UPDATE @t SET Ciphered = ENCRYPTBYKEY(KEY_GUID('skey'), plain)


UPDATE @t SET unciphered = CAST(DECRYPTBYKEY(ciphered) AS VARCHAR)

SELECT * FROM @t

CLOSE SYMMETRIC KEY skey
DROP SYMMETRIC KEY skey
DROP ASYMMETRIC KEY akey

为了正确记录错误的密码解密尝试，请尝试以下示例，使用变量@password：

CREATE ASYMMETRIC KEY akey WITH ALGORITHM = RSA_2048 
ENCRYPTION BY PASSWORD = 'aaa123'
GO
CREATE SYMMETRIC KEY skey WITH ALGORITHM = AES_256 ENCRYPTION BY ASYMMETRIC KEY akey
GO

DECLARE @t TABLE(plain VARCHAR(100), ciphered VARBINARY(MAX), unciphered VARCHAR(100))

INSERT @t(plain)
VALUES('11111'), ('22222'), ('33333')

OPEN SYMMETRIC KEY skey DECRYPTION BY ASYMMETRIC KEY akey WITH PASSWORD = 'aaa123'

UPDATE @t SET Ciphered = ENCRYPTBYKEY(KEY_GUID('skey'), plain)
CLOSE SYMMETRIC KEY skey

DECLARE @open nvarchar(200), @close nvarchar(200), @password VARCHAR(20) = 'aaa123x'
SET @open = 'OPEN SYMMETRIC KEY skey DECRYPTION BY ASYMMETRIC KEY akey WITH PASSWORD = ' + quotename(@password,'''') + ';';
SET @close = 'CLOSE SYMMETRIC KEY skey;';
BEGIN TRY 
  EXEC sp_executesql @open
  UPDATE @t SET unciphered = CAST(DECRYPTBYKEY(ciphered) AS VARCHAR)
  SELECT * FROM @t
  EXEC sp_executesql @close
END TRY BEGIN CATCH 
  SELECT 'Do whatever you want to do here with this caller. Suspicious caller: '+SUSER_SNAME()+', at: '+CAST(GETDATE() AS VARCHAR)
END CATCH

DROP SYMMETRIC KEY skey
DROP ASYMMETRIC KEY akey