A Source-Joint Encryption Scheme for Asymmetric Multilevel Diversity Coding Systems

In many communication networks, users may obtain messages with different levels of importance distributed from multiple available sources, which can be modeled by multilevel diversity coding systems (MDCS). However, previous studies on MDCS have not provided any secure encoding scheme that can be applied to arbitrary access structures and security levels. Additionally, the threats of unauthorized eavesdropping and key leakage have not been fully considered. To solve these problems, this paper proposes a secure-joint encryption scheme for secure asymmetric MDCS (S-AMDCS), which can be applied to systems with arbitrary number of encoders and security levels. The secrecy of the proposed scheme does not depend on the secure keys. It achieves threshold perfect secrecy through the (k,n) threshold secret sharing (SS) scheme, and prevents unauthorized eavesdropping between users through source-joint coding. The secrecy and the efficiency optimality of the proposed scheme are proved.