Cloud computing provides a convenient, scalable, and cost-effective data storage solution that is particularly attractive to small organizations who lack internal information technology (IT) resources. However, this new solution also introduces new challenges, in particular, being able to demonstrate that data hosted in the cloud is indeed still in place, accessible, and secure. Yang and Jia discuss the issues involved and options available for auditing cloud storage solutions.

Some historical background is presented and several methods of cloud data storage auditing are discussed. The methods covered are message authentication code (MAC) hash functions; Rivest-Sharmir-Adleman (RSA)-based homomorphic methods; and Boneh-Lynn-Shacham (BLS)-based homomorphic methods. The security of the auditing methods, as well as their performance in terms of storage overheads, communications costs, and computational complexity, are discussed and compared. Finally, challenges to the design of efficient auditing protocols, where the cloud data is not static and where group collaboration is involved, are discussed. The authors then summarize in a conclusion and provide thorough references.

An interesting and detailed discussion of a nontrivial and often overlooked aspect of any decision to store large volumes of important information in cloud storage.