Public auditing protocol with dynamic update and privacy-preserving properties in fog-to-cloud-based IoT applications

Along with the rapid development of Internet-of-Things (IoT), fog-to-cloud computing is now popularly considered as a new paradigm to support kinds of IoT applications. Like traditional cloud storage, fog-to-cloud storage also suffers from many security threatens. One of most important concerns is how to check the integrity of outsourced IoT data (in cloud server). Although fruitful auditing schemes were proposed for traditional cloud storage, few of them can be directly applied in the fog-to-cloud setting. In the recent work of Tian et al., for the first time, they considered this problem. However, in their protocol, the computational complexity and communication overhead are very high for mobile sinks or fog node, which has constraint computational ability. Moreover, the dynamic update function was not considered in their work. In this paper, we follow the line of Tian et al. and re-consider the public auditing technique in fog-to-cloud-based IoT scenarios. Based on the linearly homomorphic proxy re-signature technique, we propose a new public auditing protocol, which does not only support dynamic update of IoT data but also preserves the privacy against third party auditor. Performance analysis shows that our protocol outperforms that of Tian et al. and hence is rather practical for fog-to-cloud-based applications.