As the volume of data increases, so does the demand for online storage services, from simple backup services to cloud storage infrastructures. Although deduplication is most effective when applied across multiple users, cross-user deduplication has serious privacy implications. Some simple mechanisms can enable cross-user deduplication while greatly reducing the risk of data leakage. Cloud storage refers to scalable and elastic storage capabilities delivered as a service using Internet technologies with elastic provisioning and usebased pricing that doesn't penalize users for changing their storage consumption without notice.