Abstract: Cloud Storage has been commonly used by many users, deduplication is a one of the technique used in such cloud storages. Basic idea of deduplication is that there should be only single instance of a file stored in the servers even if it is used by millions of users. Although deduplication increases storage consumption, the technique itself is not very reliable. Likewise, when the user uploads some file security concern of confidentiality of that file also arises. With the above security concerns keeping in mind we put forward this paper with an idea of creating a reliable distributed deduplication system. With our system we target to improve reliability of files with them scattered across multiple serves. With our new covert sharing mechanism we also meet the security requirements of data confidentiality and consistency, all of this without using any cryptography mechanism of any sort. Our tests show that this system is secured as it fulfills our security threat model. As a proof of concept, we implement the system we put forward and show that the incurred operating cost is very limited in realistic environments.

Keywords: Deduplication, distributed storage system, reliability, covert sharing.