TECHNICAL FIELD

Customers can perform financial transactions, such as withdraw cash, deposit cash, pay for a product or service, obtain account information, etc., at automatic teller machines (ATM), vending machines, and payment systems. Such systems comprise various input devices, such as card readers and PIN pads, which are configured to accept data necessary to process the payment. The customer may provide certain payment data by presenting a payment card bearing a magnetic stripe or chip to a payment card reader. Data stored on the payment card may include one or more of the following: a Primary Account Number (PAN), the cardholder's name, a service code, and the card's expiration date. Also, if required to complete the transaction, the customer may enter account information such as a personal identification number (PIN) using a PIN entry device (e.g., a PIN pad). The system communicates the data to a remote host system responsible for the customer's account for verification.

Fraud poses continuing challenges to customers, merchants, and banks, among others. One example of such fraud is known as “skimming,” which generally refers to any unauthorized attempt to acquire data associated with a transaction at an input device. Such data can include credit or debit card numbers, PINs, or other account information. Those of skill in the art are familiar with examples of techniques used to “skim” transaction data, which often involve the placement of an inconspicuous device capable of capturing data in the vicinity of an input device. For instance, fraudsters may overlay a data capture device resembling a card reader or keypad on the actual card reader or keypad so that, when a user completes a transaction, the overlaid device simultaneously captures the user's account information. In some cases, the data capture device also transmits the captured data to the fraudsters. To further avoid detection, skimmers have also placed data-capture devices within an input device or behind a bezel or fascia in which an input device is mounted. In other cases, fraudsters have installed small, unobtrusive cameras in the vicinity of a PIN pads to capture PINs.

Attempts have been made to combat fraud caused by skimming. Known methods include ultrasonic monitoring of an area in front of a card reader or for changes in “acoustic impedance.” Other methods include narrowband monitoring for electrical emissions and attempts at electronic “jamming” of a skimming device overlaid on an input device. As those of skill in the art are aware, however, these methods suffer from a variety of drawbacks. With the ultrasonic monitoring method, for example, temperature and humidity compensation can complicate attempts to detect a change in “acoustic impedance” in the area surrounding the mouth of a payment card reader. Further, ultrasonic monitoring of the area in front of the card reader has limited resolution, it cannot monitor the card reader interior, and the potential locations of ultrasonic transceivers are constrained by the layout of the card reader bezel.

