I was reading about encryption in database (SQL Server) and came across an MS article()

In the article, they created a master key, then created a certificate via that using AES_256 algorithm and then encrypted/decrypted the data via above certificate.

But as long as both keys & certificates are there in same database server, anyone who gets access to the server can always decrypt the data. Then where is the security? I might not understood it properly so posted this here to get proper idea to use encryption at database side and protect keys.

I followed below queries.

CREATE MASTER KEY ENCRYPTION BY PASSWORD = '<some strong password>'; 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
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1 Answer

After having a discussion with microsoft people, i got below article which fulfills my need.

Ref:

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