入侵容忍的Quorum系统及其可生存性分析

针对入侵容忍系统的一致性问题,提出一种基于Quorum结构的系统构建方法。以可信实时计算基为平台,采用同步和异步混合的时间模型,实现了客户端的读写协议、服务器的数据更新协议和数据复制协议。构造了入侵容忍的对称Quorum系统、对称网格Quorum系统和非对称Quorum系统,从系统预期失效时间的角度分析了3种入侵容忍Quorum系统的可生存性,得出预期失效时间变化趋势与门限值、系统规模之间的关系。与其他Quorum系统相比,在规模相同的情况下,提出的非对称入侵容忍Quorum系统的可生存性最高,高于f屏蔽Quorum系统,对称网格入侵容忍Quorum系统的可生存性高于常规网格Quorum系统。

Intrusion-tolerant Quorum system and survivability analysis

To solve the consistency problem of intrusion-tolerant system, a method to build the system based on Quorum was proposed in this paper. The hybrid model of synchronous and asynchronous time was adopted, and the trusted timely computing base used as a platform to implement the intrusion-tolerant protocols, i.e., read-write protocols in clients and update-copy protocols in servers. Three types of intrusion-tolerant systems named symmetrical Quorum system, symmetrical grid Quorum system and asymmetrical Quorum system were built and proved to be reasonable. The survivability of these intrusion-tolerant Quorum systems was analyzed from the perspective of expected time to failure(ETF). Some factors that will affect the expected time to failure were analyzed, so as to obtain the relationship between threshold, system size and the expected time to failure. Compared with the other Quorum systems, the proposed asymmetrical intrusion tolerant Quorum system has the highest survivability, while symmetrical intrusion tolerant Quorum system is of higher survivability than that of f-mask Quorum system and symmetrical grid intrusion tolerant Quorum system is of higher survivability than that of general Quorum system.