There are several methods to encrypt table values in SQL Server. One of the most common methods is to use built-in encryption functions such as ENCRYPTBYPASSPHRASE and DECRYPTBYPASSPHRASE.
Here’s an example of how to encrypt the values in a table column called “CreditCardNumber” using the ENCRYPTBYPASSPHRASE function:
— Create a passphrase
DECLARE @passphrase NVARCHAR(256) = ‘mysecretkey’;
— Create a new column for the encrypted data
ALTER TABLE Customers
ADD EncryptedCreditCardNumber VARBINARY(256);
— Update the table to encrypt the data
UPDATE Customers
SET EncryptedCreditCardNumber = ENCRYPTBYPASSPHRASE(@passphrase, CreditCardNumber);
— Drop the original column
ALTER TABLE Customers
DROP COLUMN CreditCardNumber;
— Rename the encrypted column
EXEC sp_rename ‘Customers.EncryptedCreditCardNumber’, ‘CreditCardNumber’, ‘COLUMN’;
In this example, we first create a passphrase, which is used as the encryption key. We then create a new column called “EncryptedCreditCardNumber” and use the ENCRYPTBYPASSPHRASE function to encrypt the values in the “CreditCardNumber” column. We then drop the original column and rename the encrypted column to its original name.
To decrypt the data, you can use the DECRYPTBYPASSPHRASE function:
— Declare the passphrase
DECLARE @passphrase NVARCHAR(256) = ‘mysecretkey’;
— Decrypt the data
SELECT CreditCardNumber, CAST(DECRYPTBYPASSPHRASE(@passphrase, CreditCardNumber) AS NVARCHAR(50)) AS ‘DecryptedCreditCardNumber’
FROM Customers
It’s worth noting that this method uses symmetric key encryption, which means that the same key is used for both encryption and decryption. Another method is to use Asymmetric key encryption where the encryption key is different from the decryption key.
It’s also important to store the passphrase securely and to backup the encryption keys in a safe place.
It’s highly recommended to use the built-in encryption functions of SQL Server, like Always Encrypted or Transparent Data Encryption (TDE) which provides more secure and robust encryption.
