Comments on “Efficient Public Verification of Data Integrity for Cloud Storage Systems From Indistinguishability Obfuscation”

Abstract

Recently, Zhang et al. proposed a novel public data integrity verification scheme for the cloud storage using indistinguishability obfuscation ( $iO$ ), and extend it to support batch verification and data dynamic operations ( IEEE Transactions on Information Forensics and Security , vol. 12, no. 3, pp. 676–688, Mar. 2017). However, we find that the scheme has two flaws: (a) the self-checking of the uploaded blocks and tags in Store phase is not reliable, i.e., it is easy to generate invalid block-tag pairs without being detected; (b) the extended scheme for data dynamic operations suffers from a chosen message attack, i.e., if some uploaded blocks match a certain pattern, the cloud storage is able to replace any existing block by a forged one without being detected, which violates the scheme’s security model. Then, we provide solutions to these problems while preserving all the desirable features of the original scheme.