User Authentication for Hiererchical Wireless Sensor Networks

Wireless sensor networks (WSNs) have a vast field of applications, including environment monitoring, battlefield surveillance and target tracking systems. As WSNs are usually deployed in remote or hostile environments and nodes are prone to compromise attacks, the adoption of key management is extremely important. Most queries in WSN applications are issued at the point of the base station or gateway node of the network. However, there is a great need to access the real-time data inside the network from the nodes because the real-time data may no longer be accessed through the base station only but also by the legal user with authority. To support the requirement, recently Das et al. proposed a dynamic password-based user authentication scheme for hierarchical WSNs. The purposes of this paper are to show Das et al.'s scheme has a security problem of password guessing attack with lost smart card and to provide a remedy for the scheme. For this, we will give a security analysis of Das et al.'s scheme focused on the offline password guessing attack with the assumption that the attacker could steal user's smart card and read the memory on it. Then, we will propose a user authentication scheme for hierarchical WSNs to solve the security problem in Das et al.'s scheme. Our scheme inherits the advantages from Das et al.'s scheme but solves the problems in it.