Homomorphic Tags Based Cloud Storage Integrity Verification Techniques

With the development of technology and computer performance, an increasing number of clients choose to outsource their data to remote cloud storage. It offers clients great convenience, relieving them from heavy burden of storage and management. However, this entails a sacrifice of actual control of these files for clients. Remote servers may suffer from disk failure for uncertain reasons or even delete rarely accessed data to sell the storage to other clients. Cloud crashes all around the world, which brings heavy lost to countries and enterprises. Dishonest servers always choose to hide these accidents to save their reputation.When clients want to retrieve their files, it’s always too late to know that these files are lost.For issues above, researchers proposed several RIC(Remote Integrity Checking)schemes to resolve it, and schemes based on homomorphic tags are proposed, including later PDP(Provable Data Possession) and POR(Proofs of retrievability). These schemes are mostly based on RSA or BLS homomorphic tags, which are not so efficient. Therefore,they always seems limited when used in real cloud settings.In this research, we propose cloud integrity verification scheme ECPDP based on elliptic curve cryptography and homomorphic tags. Compared with classical PDP with1024 bit security parameter, we can reach the same safety level using only 160 bit security parameter, which resulting in lower computation and communication cost. We provide two safety level schemes: one is strongly safe that can guarantee each block is integrity, and the other can only guarantee the total value of several blocks but more efficient. The schemes also use the idea of sampling, reducing the communication cost without sacrificing the detection rate. Compared with PDP in the experiment, we find that the metadate on the client side reduces 84% and the computation cost reduces 13%. We also propose schemes that support public and dynamic verification to enable them more practical in real cloud.We make use of BLS to achieve public verification, and use the hash tree authentication structure to reach dynamic verification. We also provide new researching direction like retrievability and robustness.Based on the work above, we make performance and security analysis, which showsthat our schemes are more lightweight and the cost does not grow linearly with the file.Therefore, this scheme has lower communication and computation cost with better security guarantee.