Multi-level Access and Information Leakage in Scalable Cloud Storage

International audienceCodes providing multi-level access have received substantial research attention because of their capabilities to combat server failures in cloud storage. We provide a general construction that is both sufficient and necessary for reaching the well-known singleton bound for multi-level accessible codes. We present a general decoding protocol as well. Based on this result, we derive the lower bound on information leakage, which is viewed as the amount of information conveyed from unintended local clouds to the central cloud about their own local messages. We introduce a code construction based on Cauchy Reed-Solomon (CRS) codes, and prove that this construction achieves the lower bound on the information leakage