Secure and efficient privacy-preserving public auditing scheme for cloud storage

Recently, Worku et al. pointed out that the work “privacy-preserving public auditing for data storage security in cloud computing” proposed by Wang et al. is insecure and their second work “privacypreserving public auditing for secure cloud the storage” is inefficient. Thus, they offered a secure and efficient-privacy public auditing scheme for cloud storage. They claimed that their system is provably secure in the random oracle model and the operation is effective. However, after crypto-analysis, we found that the scheme cannot reach the security goal, it has the existential forgery attack. We, therefore, alter it to incorporate the desired privacy preserving requirement, which is very significant in a privacy-preserving public auditing protocol for cloud storage.