An Experimental Study of Human Body Magnetic Communication

Near field communication (NFC), which emerged only a decade ago, has been rapidly adopted in business services including point-of-sale (POS) systems, identification, ticketing, and various other types of services. Compared with other competitive technologies, NFC achieves physical-level security but sacrifices convenience. For example, NFC cannot achieve device-free or hands-free payment transactions like the service provided by PayPal called PayPal Beacon, which utilizes Bluetooth low energy (BLE) technology. In this thesis, a low-cost wearable device was developed that can achieve better physical-level security than NFC provides. This system is compatible with existing NFC-based POS systems and can help users realize a convenient, hands-free payment transaction. Specifically, a custom NFC wristband was designed to channel its magnetic field through the human arm. By confining the magnetic field in NFC to the area around body, the possibility of communication sniffing and hijacking can be reduced and improvement in security can be achieved. To evaluate this approach, various experiments were conducted in different configurations. The results showed that the communication range for the human body channel was greater than that of the air and water channels. In addition, this study demonstrated that the human body is a naturally secure channel in comparison to air and water channels, as nearby interference was minimized during magnetic-based human body communication