Security against passive attacks on network coding system - A survey

Network coding is a progressive information dissemination technology for network communications. Since its emergence at the turn of the millennium, network coding has reached more and more applications. In this survey article, we present a comprehensive review of the researches on secure network coding against passive attack. Studies in this area address problems such as: “If an eavesdropper can wiretap a few packets from a network coding system, how should the system be designed to protect useful information from being divulged?” According to protection strength, we establish a security hierarchy with four grades for network coding systems. For each grade, we collect and investigate existing schemes extensively. The essence of each scheme is expounded, such as key ideas, encryptions, or precoding matrix constructions, etc. Especially, the hardship of cryptanalysis is emphasized. Moreover, advantages and disadvantages are evaluated and compared between these schemes. In spite of single source networks, studies on theoretical possibilities and practical techniques for multisource networks are covered. Countermeasures against traffic analysis attacks are included. Finally, we suggest several open problems and promising methods for the future study.