Having seen a fully developed ATM provider way back in 1980 that was eventually purchased by a large bank. The secret aspects are a joke. In fact a VISA fraud investigation group worked in and around the general area of the ATM Company and not once did the investigtors approach the security issue as device specific. The methods used by most thieves tended to be along the lines of scamming the system from a structural standpoint. The software was nothing more than an additional set of issue neither the investigators nor the ATM development group understood. The cost to obtain someones money is cheap. Especially when it is conned and lied out of them.