The CREATE ASYMMETRIC KEY statement in SQL Server is used to create a new asymmetric key, which can be used for encryption and other cryptographic operations. An asymmetric key consists of a public key and a private key, which are used for secure data encryption, decryption, and digital signatures.
Here is the basic syntax for creating an asymmetric key:
CREATE ASYMMETRIC KEY key_name
WITH ALGORITHM = algorithm_name
[ ENCRYPTION BY PASSWORD = 'password' ]
[ FOR ENCRYPTION | FOR SIGNATURE ]
Parameters
- key_name: The name you want to give to the asymmetric key.
- ALGORITHM: The algorithm to use for the key. Common options include RSA_2048, RSA_3072, and RSA_4096.
- ENCRYPTION BY PASSWORD: (Optional) A password to protect the private key. It adds an extra layer of security.
- FOR ENCRYPTION | FOR SIGNATURE: (Optional) Indicates whether the key is intended for encryption or for creating digital signatures.
Example
Below is an example of how to create an asymmetric key:
CREATE ASYMMETRIC KEY MyAsymmetricKey
WITH ALGORITHM = RSA_2048
ENCRYPTION BY PASSWORD = 'YourStrongPassword!'
FOR ENCRYPTION;
Explanation of the Example
1. Key Name: The key is named MyAsymmetricKey.
2. Algorithm: The RSA algorithm with a key size of 2048 bits is chosen.
3. Password Protection: The private key is protected with a password (YourStrongPassword!).
4. Purpose: The key is created specifically for encryption purposes.
Additional Notes
1. Permissions: You need CREATE ASYMMETRIC KEY permissions in the database to execute this command.
2. Key Management: Properly manage and secure the keys after creation, especially the private key, to maintain the security of your encryption operations.
3. Using the Key: After creating the key, you can use it for encryption and decryption operations, or for signing and verifying data.
Using the Key for Encryption
Once the key is created, you can use it in combination with the ENCRYPTBYKEY function to encrypt data or the DECRYPTBYKEY function to decrypt data, typically after opening the key with OPEN ASYMMETRIC KEY.
Closing the Key
After performing operations with the asymmetric key, you can close it using:
CLOSE ASYMMETRIC KEY MyAsymmetricKey;
This ensures that the key is securely closed and cannot be used until opened again.
Conclusion
The CREATE ASYMMETRIC KEY statement is a crucial part of implementing secure encryption solutions in SQL Server. Always remember to follow best practices for cryptographic key management.