sql-server - "Invalid use of a side-effecting operator ' OPEN SYMMETRIC KEY 打开对称 key 时出现 ' within a function."错误

Question

我正在尝试在两个函数内打开对称 key 。像这样:

CREATE FUNCTION DECRYPTDATA 
(
    @CipherText NVARCHAR(MAX)
)
RETURNS NVARCHAR(MAX)
AS
BEGIN
    DECLARE @Result NVARCHAR(MAX)
    OPEN SYMMETRIC KEY MyKEY DECRYPTION BY CERTIFICATE MyCERT
    SELECT @Result = CONVERT(VARCHAR(MAX),DECRYPTBYKEY(@CipherText))
    RETURN @Result

END
GO
CREATE FUNCTION ENCRYPTDATA 
(
    @Text NVARCHAR(MAX)
)
RETURNS NVARCHAR(MAX)
AS
BEGIN
    DECLARE @Result NVARCHAR(MAX)
    OPEN SYMMETRIC KEY MyKEY DECRYPTION BY CERTIFICATE MyCERT
    SELECT @Result = ENCRYPTBYKEY(Key_GUID('MyKEY'),@Text)
    RETURN @Result

END
GO

但我收到此错误:

Invalid use of a side-effecting operator 'OPEN SYMMETRIC KEY' within a function.

为什么会发生这种情况？

Answer 1

实际上，您可以在函数中执行此操作，而无需使用 DECRYPTBYKEYAUTOCERT 打开对称 key 。功能:

Decrypts by using a symmetric key that is automatically decrypted with a certificate.

以下示例演示了这一点:

CREATE MASTER KEY ENCRYPTION
BY PASSWORD = 'sm_long_password@'
GO

CREATE CERTIFICATE CERT_01
WITH SUBJECT = 'CERT_01'
GO

CREATE SYMMETRIC KEY SK_01
WITH ALGORITHM = AES_256 ENCRYPTION
BY CERTIFICATE CERT_01
GO

CREATE FUNCTION [dbo].[TEST] (@encryptedValue VARBINARY(256))
RETURNS NVARCHAR(128)
AS
BEGIN;
    RETURN CONVERT(NVARCHAR(128),DECRYPTBYKEYAUTOCERT(CERT_ID('CERT_01'), NULL, @encryptedValue));
END
GO


DECLARE @encryptedValue VARBINARY(256);


OPEN SYMMETRIC KEY SK_01 DECRYPTION
BY CERTIFICATE CERT_01

SET @encryptedValue = ENCRYPTBYKEY(KEY_GUID('SK_01'), N'Stack Overflow')

CLOSE SYMMETRIC KEY SK_01;


SELECT [dbo].[TEST] (@encryptedValue);


DROP FUNCTION [dbo].[TEST];
DROP SYMMETRIC KEY SK_01;
DROP CERTIFICATE CERT_01;
DROP MASTER KEY;