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如何：加密資料行

這個主題說明您可以使用對稱加密來加密資料行的兩種方式。在下面的範例中，純文字正本在資料表中保持不變。這保留 AdventureWorks 範例資料庫的功能，可讓您體驗這些範例所示範的功能。在部署環境中，只儲存加密資料。

[!附註]

Windows XP 或 Windows Server 2000 上不支援使用 AES 的加密。在不支援 AES 的系統上執行下列程式碼範例之前，您應該將 "AES_256" 變更為 "DES"。

範例

A. 簡單對稱加密

下列程式碼顯示如何使用對稱金鑰加密資料行。

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

B. 包含驗證器的對稱加密

下列程式碼將示範如何使用包含驗證器的對稱加密來加密資料行。

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