Automated Teller Machines are a wonderful example taking the traditional model and using technology to cut costs and increase convenience to the consumer. They are a wonderful example because they do this in a secure fashion. We all know that 100% security is not even the goal, but 100% control of the system over which the transaction occurs is. Some of the literature on Financial Transaction Cards (FTCs) demonstrate the level of effort that was put into maintaining 100% control of the system. For an example of such literature, see SMART CARDS by Jerome Svigals (1985 Macmillan Publishing, NY ISBN: 0-02-948900-8). Page 36 starts a discussion on identifying components and their impact on the weakness of the system as well as what additional measures were taken to mitigate these risks.

The ATM system allows the bank to transact business with the customer in a secure environment. The bank has full control over its computers as well as its privately owned and operated communications network. The bank also has full control over the terminals on which the customer transacts business. Not only has the bank hardened the security of these systems but it has gone so far as to authenticate the user at the terminal with a physical token (FTC) and PIN. Proprietary ATM networks were a good example of a system which has "acceptable risks" associated with it.

This is not to say that the model is not without its share of risk. There are a number of attacks that could be made by attaching a "rouge device" to the network and with today's more open network model, security may not be quite up to par. The very basic "high level" design however, at least asserts some level of control over every component in the model and we can talk about making the model more or less secure.