An ORAM-based privacy preserving data sharing scheme for cloud storage

Data sharing is one of the basic applications for cloud storage, which is inherently suitable for scalability and multitenancy feature of cloud computing. Generally, for security and privacy concerns, clients tend to conceal (e.g. encrypt) their data content. However, access patterns, usually generated by behavior of users in sharing data rather than data content itself, may cause severe sensitive information leakage . Recently, oblivious random access memory (ORAM) has drawn increasingly attention as it is an ideal cryptographic tool for access pattern hiding. However, the existing ORAM-based data sharing schemes involve various deficiencies, either in high complexity for computation or heavy reliance of complex cryptography primitives. Inspired by the former schemes, in this paper we propose a novel ORAM based data sharing scheme with high security guarantee and high efficiency. The scheme can prevent the data block from arbitrary modification through Shuffle Correctness Proof. The security of the scheme is based on the IND-CPA security of encryption scheme, the unforgeability of Identity-Based signature and the security properties of basic Path-ORAM. Analysis shows that the scheme has the optimal computation and communication complexity.