How does data encryption work in Nav 2009

Hi - Let me start by stating for the record I am not a developer!  My question relates to data encryption within Nav.  I believe it was first introduced in Nav 2009 - (although I know that it can be applied to previous versions by the same technology). In my example the bank account details are encrypted.  I do not believe that this is anything to do with set up but is it something that can be turned on/off. Is it applied at SQL Db level?  Can anyone point me in the direction of where I can read more up about how the encryption is applied etc.