The Inverse Square Law and Near Field Communication

A. Braeken, P. Leemans, M. Vanophalvens

Vrije Universiteit Brussel

Near field communication (NFC) is a short-range wireless communication technology, very popular in identification and payment systems. Resistance against different types of security attacks requires the existence of a secure channel. Instead of using operational intensive cryptographic computations, a secure channel can be theoretically obtained based on the superposition principle when sender and receiver send a signal at exactly the same time. In this paper, we show that due to the inverse square law, the attacker can clearly identify the signal of the most nearby device if (s)he is not exactly placed in the middle.