Wireless Sensor Networks are by its nature prone to various forms of security attacks. Authentication and secure communication have become the need of the day. Due to single point failure of a sink node or base station, mobile sinks are better in many wireless sensor networks applications for efficient data collection or aggregation, localized sensor reprogramming and for revoking compromised sensors. The existing sytems that make use of key predistribution schemes for pairwise key establishment between sensor nodes and mobile sinks, deploying mobile sinks for data collection has drawbacks. Here, an attacker can easily obtain many keys by capturing a few nodes and can gain control of the network by deploying a node preloaded with some compromised keys that will be the replica of compromised mobile sink. We propose an efficient three level key predistribution framework that uses any pairwise key predistribution in different levels. The new framework has two set of key pools one set of keys for the mobile sink nodes to access the sensor network and other set of keys for secure communication among the sensor nodes. It reduces the damage caused by mobile sink replication attack and stationary access node replication attack. To further reduce the communication time it uses a shortest distance to make pair between the nodes for comunication. Through results, we show that our security framework has a higher network resilience to a mobile sink replication attack as compared to the polynomial pool-based scheme with less communication tim
