In SQL Server, the CLOSE SYMMETRIC KEY statement is used to close a symmetric key that has been opened in the current session. When you open a symmetric key, it allows you to encrypt and decrypt data using that key. Once you are done using the key, it is a good practice to close it in order to free up resources and improve security.
Here is the syntax for the CLOSE SYMMETRIC KEY statement:
CLOSE SYMMETRIC KEY key_name;
- key_name: This is the name of the symmetric key you want to close. This key must be one that you previously opened during the session.
Example
Here’s an example illustrating how to use the CLOSE SYMMETRIC KEY statement:
1. Open the symmetric key.
2. Perform some operations (like encryption or decryption).
3. Close the symmetric key.
-- Assuming you have a symmetric key named 'MySymmetricKey'
-- First, open the symmetric key
OPEN SYMMETRIC KEY MySymmetricKey
DECRYPTION BY PASSWORD = 'YourStrongPassword';
-- Now perform operations with the key (e.g., encrypt or decrypt data)
-- Close the symmetric key
CLOSE SYMMETRIC KEY MySymmetricKey;
Important Notes
- The symmetric key must be opened in the current session before you can close it.
- If you try to close a symmetric key that is not open, an error will occur.
- Closing the symmetric key removes access to it for the duration of that session until it is opened again.
Make sure to follow appropriate security practices when handling encryption keys, including managing permissions and access.