Secure Distributed Data Storage In Wireless Sensor Networks

In delay tolerant networks (DTN), reputation-based routing schemes attract much attention in recent years because of their high security and low overhead. But the existing reputation-based schemes encounter a key problem that the reputation maintained by a node is usually out of date because of the long delivery delay. The outdated reputation can’t be used directly to evaluate the current reputation of a target node. Hence, how to predict a node’s current reputation accurately according to reputation history is a very important issue. In this paper, we propose a Markov chain based reputation evaluation scheme (MRES for short).In MRES, a source node first collects the reputation of a target node from its neighbors. Each collected reputation includes a time-stamp. Second, when the node collects enough reputation, it starts to remove the unreliable reputation according to its own reputation table, and then it constructs a state transition matrix with the collected reputation. Third, the node uses the state transition matrix and the latest reputation to predict the reputation of the target node. Finally, it evaluates target node’s reputation through probability theory.When the entries in source node’s reputation table are not enough, the proceeding of removing unreliable reputation will be not secure enough. We propose MIRES (Markov chain based iterative reputation evaluation Scheme) to solve this problem. MIRES is an extension to MRES. It uses an iterative strategy to remove the unreliable reputation. Through calculating the inconsistency of every node, the iterative strategy can detect the malicious node easily and effectively.The results show that, MRES and MIRES can reduce the negative effect of delay and predict the reputation of the target node accurately in comparison with existing reputation-based schemes. Furthermore, they are robust against malicious nodes.