Research On Security Protocols Of Broadband Satellite Networks

In recent years, accessing to Internet via satellite, as an essential component of air-space-ground integrated information networks in the future, has become a trend of satellite communication development. The integration of satellite communication and Internet expands Internet utilization districts and enriches functions and attributes of satellite communication. There are some technical chanllenges existing in interoperations between satellite communication system and terrestrial Internet infrastructure. The performance deterioration of TCP/IP applying to satellite networks has been researched in detail, and different kinds of effective TCP performance enhancing techniques have been proposed. However, IPSec and IKE matching TCP/IP and supplying security service in terrestrial Internet have still some applicable problems when transplanting to broadband satellite networks, such as incompatibility with TCP performance enhancing techniques. So, designing and analysing applicable security protocol are key points of broadband satellite network researches.The dissertation researches security methods of broadband satellite networks with supporting TCP performance enhancing technique in depth by referring to the latest researches. It enriches security framework of broadband satellite networks which implements TCP performance enhancing techniques and makes positive achievement and reference value for air-space-ground integrated information network's theory. Aiming at network-layer security protocol and authenticated key exchange protocol designs, the dissertation concentrates on the following aspects:Firstly, the confliction between transportation performance enhancing technique and IPSec is analysed, and a flexible changeable zone IPSec (CZ-IPSec) protocol is proposed. By converting traditional static zone mapping to changeable dynamic mapping and designing corresponding composite security association and processing flows, CZ-IPSec is enabled to support TCP performance enhancing techniques, and fulfill TCP effencicy improvement. CZ-IPSec is proved by analysis and test results that its bandwidth overheads and processing time delay are not unacceptable. Thus, reasonable tradeoff is achieved by designing CZ-IPSec at the cost of unacceptable overheads and authorith permission of TCP performance enhancing proxy gaining accessing to TCP/IP header, HTTP header and link address contents.Secondly, satellite Internet authenticated key exchange protocol (SIKE) is proposed on account of solving initiator identity exposure and cookie exchange invalidation against denial of service (DoS) attacks in broadband satellite networks. SIKE provides active identity protection for protocol initiator. By designing difficulty adjusting value and range value at server terminal, fine-grained difficulty client puzzle based on one-way hash function is embedded in SIKE. Validity of the fine-grained difficulty client puzzle is proved by test. The form of SIKE embedding puzzle-solution exchange is given as well as capability analysis against DoS attacks.Thirdly, session key security of SIKE is formally analysed. On basis of existing references, HMAC-DDH assumption is proposed for adapting to SIKE's key extraction calculation. HMAC-DDH assumption is weaker than DDH, and it would hold if the DH group contains a large enough DDH subgroup. So, protocol reducing to HMAC-DDH assumption is more secure than the protocol reducing to DDH assumption. It is proved that SIKE has session key consistency, and the session key and random chosen key are indistinguishable. Session key consistency and indistinguishability between session key and random chosed key bring about session key security of SIKE.Finally, provable secure tri-party and qradri-party authenticated key exchange protocols (STIKE and SQIKE) are proposed for supporting CZ-IPSec in broadband satellite networks. Unlike existing researches, the design integrates 2-party key exchange into tri-party or quadric-party key exchange according to particular requirements of CZ-IPSec. Therefore, research in the dissertation brings forth new ideas to analyzing formally this particular kind of protocols. Considering reducing message transportation quantity, especially messages via satellite links, snooping function of performance enhancing proxy is utilized. Based on extensions of CK model and BCP model respectively, STIKE and SQIKE are proposed and proven session key secure. STIKE and SQIKE satify various terms of security attribute requirement, and their message transportation quatity and calculation are discussed in addition.