Dynamic Proof of Storage (PoS) is a useful cryptographic primitive that allows a user to
check the integrity and efficiently update the files in a cloud server. There has been many solutions proposed
for Dynamic Proof of Storage in singleuser environment but for multi user problems is still unsolvable. A
multi-user cloud storage system needs the secure client side cross user deduplication technique, which
allows a user to stop the uploading process and gain the ownership of the files immediately, when other
owners of the same files have uploaded them to the cloud server.As we know, none of the existing dynamic
PoSs can support this technique. In this paper, we elaborate the concept of deduplicatable dynamic proof of
storage and propose an efficient construction called DeyPoS, to achieve dynamic Proof of Storage and
secure cross-user deduplication, simultaneously.To build a novel tool called Homomorphic Authenticated
Tree (HAT) to address challenges such as structure diversity and private tag generation.Hence we prove the
security of our construction, and the theoretical analysis and experimental results show that our research is
practically valid and applicable.