Dynamic Storage Proof (PoS) is a useful cryptographic primitive that enables a user to check the integrity of outsourced files and to efficiently update the files on a cloud server. Although researchers have proposed many dynamic PoS schemes in single-user environments, the problem has not been sufficiently investigated in multi-user environments. DeyPoS Deduplicatable Dynamic Proof of Storage for Multi-User Environments A practical multi-user cloud storage system needs a secure client-side cross-user deduplication technique that allows a user to skip the upload process and get file ownership immediately when other owners of the same files upload them to the cloud server. None of the existing dynamic PoSs can support this technique to the best of our knowledge.

In this DeyPoS Deduplicatable Dynamic Proof of Storage for Multi-User Environments paper, we introduce the concept of deduplicable dynamic storage proof and propose an efficient construction called DeyPoS, simultaneously achieving dynamic PoS and secure cross-user deduplication. We exploit a novel tool called Homomorphic Authenticated Tree (HAT) in view of the challenges of structure diversity and private tag generation. We prove the safety of our construction, and the theoretical analysis and experimental results show that our construction is effective in practice.

Advantages

• It is an efficient authenticated structure.
• It is the first practical deduplicatable dynamic PoS scheme called DeyPoS and proved its security in the random oracle model.
• The theoretical and experimental results show that our DeyPoS implementation is efficient,
• Performs better especially when the file size and the number of the challenged blocks are large.