Secure and resilient clock synchronization in wireless sensor networks

Abstract

Abstract-Wireless sensor networks have received a lot of attention recently due to its wide applications. An accurate and synchronized clock time is crucial in many sensor network applications. Several clock synchronization schemes have been proposed for wireless sensor networks recently to address the resource constraints in such networks. However, most of these techniques assume benign environments, but cannot survive malicious attacks in hostile environments, especially when there are compromised nodes. As an exception, a recent work attempts to detect malicious attacks against clock synchronization, and aborts when an attack is detected. Though this approach can prevent incorrect clock synchronization due to attacks, it will lead to denial of clock synchronization in such situations.This paper adopts a model where all the sensor nodes synchronize their clocks to a common source, which is assumed to be well synchronized to the external clock. This paper seeks techniques to provide redundant ways for each node to synchronize its clock with the common source, so that it can tolerate partially missing or false synchronization information provided by compromised nodes. Two types of techniques are developed using this general method: level-based clock synchronization and diffusion-based clock synchronization. Targeted at static sensor networks, the level-based clock synchronization constructs a level hierarchy initially, and uses (or reuses) this level hierarchy for multiple rounds of clock synchronization. The diffusion-based clock synchronization attempts to synchronize all the clocks without relying on any structure assumptions and, thus, can be used for dynamic sensor networks. This paper further investigates how to use multiple clock sources for both approaches to increase the resilience against compromise of source nodes. The analysis in this paper indicates that both level-based and diffusion-based approaches can tolerate up to colluding malicious source nodes and colluding malicious nodes among the neighbors of each normal node, where and are two system parameters. This paper also presents the results of simulation studies performed to evaluate the proposed techniques. These results demonstrate that the level-based approach has less overhead and higher precision, but less coverage, than the diffusion-based approach.

Reference Broadcast-Based Secure Time Synchronization for Industrial Wireless Sensor Networks

“…As a consequence, a feedback closed loop security-aware PTP is achieved. Sun et al [29] provided redundant ways and multiple time sources for each node to synchronize with the time source. Each node computes the source clock offsets with all its neighbors and chooses the median as the source clock offset.…”

Competent Time Synchronization Mac Protocols to Attain High Performance of Wireless Sensor Networks for Secure Communication

“…The Level Diffusion Based Clock Synchronization protocol [31] presents the synchronization of all sensors' clocks without depending on any configuration conditions in dynamic system settings. Even though this protocol has a wide transmission range, it suffers from much overhead and less accuracy.…”