Energy efficient key management protocols to secure sensor networks

In sensor networks, large numbers of tiny sensor nodes communicate remotely or locally among themselves to accomplish a wide range of applications. However, such a network poses serious security protocol design challenges due to the ad hoc nature of the communication and constraints such as limited energy, processor speed and memory. To secure such a wireless network, the efficient key management techniques are important. Existing techniques assume energy and memory equipped nodes. This dissertation proposes energy efficient group key management protocols for secure sensor networks.; First we propose a group key management protocol for hierarchical sensor networks where instead of using pre-deployed keys, each sensor node generates a partial key dynamically using a function. The function takes partial keys of its children as arguments. In the second protocol, we propose an Energy and Communication Efficient Group key management (ECEG) scheme which reduces the usage of memory, communication and energy in sensors. This scheme is designed based on the idea that each node is pre-loaded with a key chain and an elliptic curve. The next key management protocol is based on securing cluster heads in sensor networks. As the cluster head does data aggregation and takes important decision on the behalf of a group, hence it is crucial to provide enhanced security to the cluster head when compared to general nodes. In the last scheme we propose a protocol called RBASH (Role Based Hierarchical Sensor Networks) which provides role-based multi-level security in sensor networks. Each group is organized in such a way that, they can have different roles and depending on their roles, can have different levels of access.; The success of each of these schemes in providing security and being energy efficient is experimentally evaluated through the simulations using TinyOs and TOSSIM. This includes, analyzing the time and energy consumption in broadcasting partial keys and group key under two sensor routing protocols (Tiny-AODV and Tiny-Diffusion) by varying the number of nodes and key sizes. Some of the other experiments include evaluation of the packet loss in the network, packet delivery time for partial and group key computation, energy consumption and comparison with the existing scheme like muTESLA.