Enabling Encrypted Delta Compression for Outsourced Storage Systems via Preserving Similarity

Outsourcing storage to the cloud can relieve pressure on storage capacity, wherein encrypted deduplication is often used to perform deduplication on encrypted data, for ensuring both storage efficiency and security. However, encrypted deduplication only removes duplicate encrypted data without considering non-duplicate but very similar ones. In this paper, we propose EDelta, which is the first to enable encrypted delta compression so as to further reduce redundancy of similar encrypted data atop encrypted deduplication, by means of preserving similarity after encryption. We also propose two methods to speed up the encryption process of encrypted delta compression. We prototype EDelta in cloud environments and our experimental results based on real-world datasets show that EDelta can achieve an additional data reduction ratio by up to 45.0% on top of encrypted deduplication.