AUTOMATED TELLER MACHINE COMMUNICATION SECURITY AND RELIABILITY
INTRODUCTION
An automated teller machine (ATM) is a computerized telecommunications device that provides the clients of a financial institution with access to financial transactions in a public space without the need for a cashier, human clerk or bank teller. On most modern ATMs, the customer
is identified by inserting a plastic ATM card with a magnetic stripe or a plastic smart card with a chip that contains a unique card number and some security information.
Authentication is provided by the customer entering a personal identification number (PIN).
Using an ATM, customers can access their bank accounts in order to make cash withdrawals and check their account balances as well as purchase cell phone prepaid credit. ATMs are known by various other names including automated transaction machine, automated banking machine, cash point (in Britain), money machine, bank machine, cash machine, hole'in'the'wall, bancomat
(in various countries in Europe and Russia), etc.
Most ATMs are connected to interbank networks, enabling people to withdraw and deposit money from machines not belonging to the bank where they have their account or in the country where their accounts are held (enabling cash withdrawals in local currency). Some examples of interbank networks include PULSE, PLUS, cirrus, interac, inter switch
STAR, and LINK. ATMs rely on authorization of a financial transaction by the card
issuer or other authorizing institution via the communications network. This is often performed through an ISO 8583 messaging system. ATMs typically connect directly to their host or ATM controller via either ADSL or dial'up modem over a telephone line or directly via a leased
line. Leased lines are preferable to POTs lines because they require less time to establish a connection. Leased lines may be comparatively expensive to operate versus a POTs line meaning less'trafficked machines will usually rely on a dial'up modem. That dilemma may be solved as high'
speed internet VPN connections become more ubiquitous. Common lower' level layer communication protocols used by ATMs to communicate back to bank include SNA over SDLC, TC500 over Async, X.25, and TCP/IP over Ethernet. In addition to methods employed for transaction security and secrecy, all communications traffic between the ATM and the transaction
processor may also be encrypted via methods such as SSL.
