Encrypt column of data

@sapator wrote:

Hi I'm reading on encryption in SQL 2012 by a column of data.
https://technet.microsoft.com/en-us/library/ms179331(v=sql.110).aspx
I have seen that you must create a master key and a certificate.
I'm cannot understand however the decryption.
There is no indication of passing some key and if is not the case (probably) then how the permissions are used in order to decrypt?

OPEN SYMMETRIC KEY SSN_Key_01
   DECRYPTION BY CERTIFICATE HumanResources037;
GO
.......etc
 CONVERT(nvarchar, DecryptByKey(EncryptedNationalIDNumber))  . 

OK but how do we know who has permissions to decrypt?
Any help?
Thanks

Also I would like to encrypt per value entered and not the whole column. Do I need to create a trigger that will encrypt the inserted value? If, so how? There is only a column encryption example here.
I could use PASSPHRASE encryption. I have done it in the past but I prefer to use something new and - thus more secure.

Read full topic