BLAST: Applying Streaming Ciphers Into Outsourced Cloud Storage

Providing secure and efficient outsourced storage is a precursor to widespread cloud deployment and availability. For this purpose, existing designs mainly rely on block ciphers, although stream ciphers are more computationally-efficient than block ciphers. This paper presents a construction of secure storage, BLAST, enhanced with a stream cipher rather than a block cipher with a novel block accessible encryption mechanism based on streaming ciphers. In BLAST, a hierarchical tree generated in the form of an n-level quad tree is created for each user during the registration phase of the storage system. When a user wants to access the outsourced storage, the user can access their data after encrypting or decrypting it using a sequence of key stream frames derived from the hierarchical tree. The experimental results show that the proposed system achieves significant improved performance than normal streaming/block cipher-based secure storage system in terms of throughput and access latency.