NC-Audit: Auditing for network coding storage

Network coding-based storage has recently received a lot of attention in the network coding community. Independently, another body of work has proposed integrity checking schemes for cloud storage, none of which, however, is customized for network coding storage or can efficiently support repair. In this work, we bridge the gap between these currently disconnected bodies of work, and we focus on the (novel) advantage of network coding for integrity checking. We propose NC-Audit - a remote data integrity checking scheme, designed specifically for network coding-based storage cloud. NC-Audit provides a unique combination of desired properties: (i) efficient checking of data integrity (ii) efficient support for repairing failed nodes (iii) full support for modification of outsourced data and (iv) protection against information leakage when checking is performed by a third party. The key ingredient of the design of NC-Audit is a novel combination of SpaceMac, a homomorphic MAC scheme for network coding, and NCrypt, a novel CPA-secure encryption scheme that is compatible with SpaceMac. Our evaluation of a Java implementation of NC-Audit shows that an audit costs the storage node and the auditor only a few milliseconds of computation time, and lower bandwidth than prior work.