Secret keys from entangled sensor motes

Abstract

Key management in wireless sensor networks does not only face typical, but also several new challenges. The scale, resource limitations, and new threats such as node capture and compromise necessitate the use of an on-line key generation, where secret keys are generated by the nodes themselves. However, the cost of such schemes is high since their secrecy is based on computational complexity. Recently, several research contributions justified that the wireless channel itself can be used to generate information-theoretic secure keys between two parties. By exchanging sampling messages during movement, a bit string can be derived that is only known to the involved entities. Yet, movement is not the only possibility to generate randomness. The channel response is also strongly dependent on the frequency of the transmitted signal. In our work, we introduce a protocol for key generation based on the frequency-selectivity of channel fading. The great practical advantage of this approach is that we do not rely on node movement as the source of randomness. Thus, the frequent case of a sensor network with static motes is supported. Furthermore, the error correction property of the proposed protocol mitigates the effects of measurement errors and other temporal effects, giving rise to a key agreement rate of over 97%. We show the applicability of our protocol by implementing it on MICAz motes, and evaluate its robustness and secrecy through experiments and analysis.

Extracting secret key from wireless link dynamics in vehicular environments

“…Group key extraction is considered in [13], and the key extraction in [14] is for securing implantable medical devices. Other key extraction approaches [8], [15] are also proposed specifically for the mote platform. There has also been much work on protecting WLANs and sensor networks [16]- [19].…”

“…Due to the nature of wireless fading, Eve cannot get any information about the dynamics experienced by Alice and Bob, which has been verified [5], [8], [15]. In addition, the information exposed by information reconciliation has been removed by privacy amplification.…”

Secret Key Generation Rate vs. Reconciliation Cost Using Wireless Channel Characteristics in Body Area Networks

“…Wireless sensor devices have been specifically considered in [11] and [4]. In the first, the authors implement and test a ranking method on TelosB wireless motes which are randomly moved, to extract keys at very high rate.…”

“…In the first, the authors implement and test a ranking method on TelosB wireless motes which are randomly moved, to extract keys at very high rate. In [4], the authors vary channel frequency to vary channel response for MICAz motes and satisfactorily extract keys with high rate of key agreement. They specifically consider stationary deployments.…”

Collaborative secret key extraction leveraging Received Signal Strength in mobile wireless networks

“…However, previous works on RSS based secret key generation mainly focused on improving the secret bit generation rate between a pair of wireless devices (by exploiting temporal and spatial variations of radio channel [7], [8], multiple antenna diversity [9], and multiple frequencies [10]). The problem of using RSS to perform key generation among multiple wireless devices to ensure secure group communication remains as a challenge.…”