Hamzeh Ghasemzadeh - Electrical Engineering Department Islamic Azad University of Damavand Tehran, Iran
Ali Payandeh - ICT Department Malek-e-Ashtar University Tehran, Iran
Mohammad Reza Aref - Electrical Engineering Department Sharif University of technology Tehran, Iran

Due to hostile environment and wireless communication channel, security mechanisms are essential for wireless sensor networks (WSNs). Existence of a pair of shared key is a prerequisite for many of these security mechanisms; a task that key management system addresses. Recently, an energy efficient method based on public key cryptography (PKC) was proposed. We analyze this protocol and show that it is vulnerable to denial of service (DOS) attacks and adversary can exhaust memory and battery of nodes. Then, we analyze this protocol and show that using a more knowledgeable BS this vulnerability can be solved very efficiently. Based on this observation we propose a modified version of the protocol that achieves immediate authentication and can prevent DOS attacks. We show that the improved protocol achieves immediate authentication at the expense of 1.82 mj extra energy consumption while retaining other desirable characteristics of the basic method.

key management system; public key cryptography; denial of service; broadcast authentication