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Procedura: Crittografia di una colonna di dati

In questo argomento vengono illustrati due modi in cui è possibile crittografare una colonna di dati tramite la crittografia simmetrica. Negli esempi seguenti, il testo normale originale resta inalterato nella tabella. In tal modo è possibile provare la funzionalità dimostrata in questi esempi senza inficiare la funzionalità del database di esempio AdventureWorks. In un ambiente di produzione, vengono archiviati solo i dati crittografati.

[!NOTA]

La crittografia tramite AES non è supportata in Windows XP o Windows Server 2000. Prima di eseguire questi esempi di codice in un sistema che non supporta AES, è necessario modificare "AES_256" in "DES".

Esempi

A. Crittografia simmetrica semplice

Nel codice seguente viene illustrato come crittografare una colonna utilizzando una chiave simmetrica.

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. Crittografia simmetrica che include un autenticatore

Nel codice seguente viene illustrato come crittografare una colonna utilizzando la crittografia simmetrica che include un autenticatore.

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