Blink 'Em All: Scalable, User-Friendly and Secure Initialization of Wireless Sensor Nodes

Wireless sensor networks have several useful applications in commercial and defense settings, as well as user-centric personal area networks. To establish secure (point-to-point and/or broadcast) communication channels among the nodes of a wireless sensor network is a fundamental security task. To this end, a plethora of so-called key pre-distribution schemes have been proposed in the past, e.g., [25][9][19][8][5]. All these schemes, however, rely on shared secret(s), which are assumed to be pre-loaded onto the sensor nodes, e.g., during the manufacturing process. In this paper, we consider the problem of user-assisted secure initialization of sensor network necessary to bootstrap key pre-distribution. This is a challenging problem due to the level of user burden involved in initializing multiple (often large number of) sensor nodes and lack of input and output user-interfaces on sensor motes. We propose a novel method for secure sensor node initialization based on a visual out-of-band channel that utilizes minimal output interface in the form of LED(s) already available on most off-the-shelf sensor motes. The proposed method requires only a little extra cost, is efficient and reasonably scalable. Moreover, based on a usability study that we conducted, the method turns out to be quite user-friendly and easy to administer by everyday computer users.