RoK: A robust key pre-distribution protocol for multi-phase wireless sensor networks

Abstract

Wireless sensor networks are usually deployed to operate for a long period of time. Because nodes are battery-operated, they eventually run out of power and new nodes need to be periodically deployed to assure network connectivity. This type of networks is referred to as Multi-phase WSN in the literature [1]. Current key pre-distribution schemes, such as [2] and [3], are not adapted to multi-stage WSN. With these schemes, the security of the WSN degrades with time, since the proportion of corrupted links gradually increases. In this paper, we propose a new pre-distribution scheme adapted to multi-phase WSN. In the proposed scheme, the pre-distributed keys have limited lifetimes and are refreshed periodically. As a result, a network that is temporarily attacked (i.e. the attacker is active only during a limited amount of time) automatically self-heals, i.e. recovers its initial state when the attack stops. In contrast, with existing schemes, an attacker that corrupts a certain amount of nodes compromises a given fraction of the total number of secure channels. This ratio remains constant until the end of the network, even if the attacker stops its action. Furthermore, with our scheme, a network that is constantly attacked (i.e. the attacker regularly corrupts nodes of the network, without stopping) is much less impacted than a network that uses existing key pre-distribution protocols. With these schemes, the number of compromised links constantly increases until all the links are compromised. With our proposal, the proportion of compromised links is limited and constant.