How to: Encrypt a Column of Data

USE AdventureWorks;
GO

--If there is no master key, create one now.
IF NOT EXISTS
(SELECT * FROM sys.symmetric_keys WHERE symmetric_key_id = 101)
CREATE MASTER KEY ENCRYPTION BY
PASSWORD = '23987hxJKL969#ghf0%94467GRkjg5k3fd117r$$#1946kcj$n44nhdlj'
GO

CREATE CERTIFICATE HumanResources037
WITH SUBJECT = 'Employee Social Security Numbers';
GO

CREATE SYMMETRIC KEY SSN_Key_01
WITH ALGORITHM = AES_256
ENCRYPTION BY CERTIFICATE HumanResources037;
GO

USE [AdventureWorks];
GO

-- Create a column in which to store the encrypted data.
ALTER TABLE HumanResources.Employee
ADD EncryptedNationalIDNumber varbinary(128);
GO

-- Open the symmetric key with which to encrypt the data.
OPEN SYMMETRIC KEY SSN_Key_01
DECRYPTION BY CERTIFICATE HumanResources037;

-- Encrypt the value in column NationalIDNumber with symmetric
-- key SSN_Key_01. Save the result in column EncryptedNationalIDNumber.
UPDATE HumanResources.Employee
SET EncryptedNationalIDNumber = EncryptByKey(Key_GUID('SSN_Key_01'), NationalIDNumber);
GO

-- Verify the encryption.
-- First, open the symmetric key with which to decrypt the data.
OPEN SYMMETRIC KEY SSN_Key_01
DECRYPTION BY CERTIFICATE HumanResources037;
GO

-- Now list the original ID, the encrypted ID, and the
-- decrypted ciphertext. If the decryption worked, the original
-- and the decrypted ID will match.
SELECT NationalIDNumber, EncryptedNationalIDNumber
AS 'Encrypted ID Number',
CONVERT(nvarchar, DecryptByKey(EncryptedNationalIDNumber))
AS 'Decrypted ID Number'
FROM HumanResources.Employee;
GO

USE AdventureWorks;
--If there is no master key, create one now.
IF NOT EXISTS
(SELECT * FROM sys.symmetric_keys WHERE symmetric_key_id = 101)
CREATE MASTER KEY ENCRYPTION BY
PASSWORD = '23987hxJKL95QYV4369#ghf0%lekjg5k3fd117r$$#1946kcj$n44ncjhdlj'
GO

CREATE CERTIFICATE Sales09
WITH SUBJECT = 'Customer Credit Card Numbers';
GO

CREATE SYMMETRIC KEY CreditCards_Key11
WITH ALGORITHM = AES_256
ENCRYPTION BY CERTIFICATE Sales09;
GO

-- Create a column in which to store the encrypted data.
ALTER TABLE Sales.CreditCard
ADD CardNumber_Encrypted varbinary(128);
GO

-- Open the symmetric key with which to encrypt the data.
OPEN SYMMETRIC KEY CreditCards_Key11
DECRYPTION BY CERTIFICATE Sales09;

-- Encrypt the value in column CardNumber using the
-- symmetric key CreditCards_Key11.
-- Save the result in column CardNumber_Encrypted.
UPDATE Sales.CreditCard
SET CardNumber_Encrypted = EncryptByKey(Key_GUID('CreditCards_Key11')
, CardNumber, 1, HashBytes('SHA1', CONVERT( varbinary
, CreditCardID)));
GO

-- Verify the encryption.
-- First, open the symmetric key with which to decrypt the data.

OPEN SYMMETRIC KEY CreditCards_Key11
DECRYPTION BY CERTIFICATE Sales09;
GO

-- Now list the original card number, the encrypted card number,
-- and the decrypted ciphertext. If the decryption worked,
-- the original number will match the decrypted number.

SELECT CardNumber, CardNumber_Encrypted
AS 'Encrypted card number', CONVERT(nvarchar,
DecryptByKey(CardNumber_Encrypted, 1 ,
HashBytes('SHA1', CONVERT(varbinary, CreditCardID))))
AS 'Decrypted card number' FROM Sales.CreditCard;
GO