Analysis of One Scheme for Enabling Cloud Storage Auditing with Verifiable Outsourcing of Key Updates

Cloud computing supports a paradigm shift from local to network-centric computing and enables customers with limited computational resources to outsource large-scale computational tasks to the cloud, such as linear equations and linear programming. Recently, Yu et al. [IEEE TIFS, 11(6), 2016, 1362-1375] have proposed a scheme for cloud storage auditing with verifiable outsourcing of key updates. In this note, we remark that Yu et al.’s scheme has two inherent weaknesses: 1) it does not truly mitigate the client’s computational burden for key updates; 2) it does not ensure confidentiality since the files uploaded to the cloud by the client are eventually not encrypted at all.