SafePay: Protecting against credit card forgery with existing magnetic card readers

Existing magnetic cards adopt plain text to store confidential information, thus being vulnerable to an untrusted credit card reader or a skimming device. To tackle the problem, researchers have proposed several new techniques such as integrated circuit card (IC card) and mobile wallet applications [1]; however, none of them can support existing magnetic card readers thereby facing backwards compatibility issue. In this paper, to combat such credit card information leakages and remain backwards compatible, we propose SafePay, a system that transforms disposable credit card information to electrical current and drives a magnetic card chip to simulate the behavior of a physical magnetic card. We have implemented a prototype system of SafePay by a mobile phone and a prototype magnetic card chip. In the evaluation, we show that the current cost is about $0.5 excluding the phone, and the cost can be even lowered if manufactured in large scale. We also evaluated the prototype in experimental environment such as oscilloscope and real-world scenarios such as vending machines. The results show that the physical signal in oscilloscope is the same as the theoretical value, and meanwhile, we can successfully buy products in all the tested real-world scenarios.