Secure time synchronization is a key requirement for many sophisticated application running on these networks. Most of the existing secure time synchronization protocols incur high communication and storage costs and are subject to a few known security attacks. In wireless sensor network (WSN), lifetime of the network is determined by the amount of energy consumption by the nodes. To improve the lifetime of the network, nodes are organized into clusters, in which the cluster head (CH) collects and aggregates the data. A special node called mobile data collector (MDC) is used to collect the data from the CH and transfer it to the base station (BS) By using proposed method MDC authenticated to CH by computing shared secret keys on the fly. Once the MDC and CH are authenticated, all the sensor nodes in the cluster are synchronized, time synchronization reduce the communication and storage requirements of each CH. Security analysis of this proposed system shows that it is highly robust against different attacks namely compromised CH, reply attack, message manipulation attack as well as pulse delay attack
