[RESOLVED] Error creating a function

[usamaalam]

Hello everybody,

I am trying to create the following function but it gives error "Invalid use of side-effecting or time-dependent operator in 'OPEN SYMMETRIC KEY' within a function."

CREATE FUNCTION GetEncryptedPassword
(
	@Password VARCHAR(10)
)
RETURNS VARBINARY
AS
BEGIN

	OPEN SYMMETRIC KEY PasswordFieldKey
	DECRYPTION BY CERTIFICATE PasswordFieldCertificate;

	RETURN EncryptByKey(Key_GUID('PasswordFieldKey'),@Password)
END
GO

Can we figure out why it's giving this error?

Thanks.