An improved dynamic provable data possession model

Cloud computing is becoming increasingly popular. Many companies, organizations and individuals choose to outsource their computing demands and storage demands. In order to ensure the integrity of the data in the Cloud, especially the dynamic files which can be updated online, we propose an improved dynamic provable data possession model: It divides file into blocks, generates a tag for each block, computes a hash value for each tag, uses tags to ensure the integrity of the file blocks, and uses hash values to ensure the integrity of the tags. Compared with previous works, it reduces the computational and communication complexity from logn to constant. Although client needs to store some secret values which may create some additional storage expense, it only takes up about 0.02% of the original file size. Hence it is acceptable in most cases.