Recent advances in development of low-cost wireless sensor platforms open up opportunities for novel wireless sensor network (WSN) applications. Likewise emerge security concerns of WSNs receiving closer attention of research community. Well known security threats in WSNs range from Denial-of-Service (DoS), Replay and Sybil attacks to those targeted at violating data integrity and confidentiality. Public-key cryptography (PKC) as a countermeasure to potential attacks, although originally treated infeasible for resource-constrained sensor nodes, has shown its eligibility for WSNs in the past few years. However, different security and performance requirements, energy consumption issues, as well as varying hardware capabilities of sensor motes pose a challenge of finding the most efficient security protocol for a particular WSN application and scenario. In this paper, we propose to use the Host Identity Protocol (HIP) as the main component for building network-layer security in WSNs. Comb...