Abstract: The hypothesis of independent failure is incomplete to evaluate the reliability in intrusion-tolerance system of diverse redundancy.This paper analyzes the reliability in intrusion-tolerance system based on the probability methodology.The results show that the system reliability relies on the subsystems’ reliabilities and their inner relations under attacks.An evaluation model is also proposed.Compared with the system reliability under independence hypothesis，this model includes three possible cases，and the evaluation results in examples demonstrate the completeness of our model.

Key words: intrusion-tolerance, diversity, redundancy, reliability

摘要： 在评估多样性冗余的容侵系统可靠性时，通常假设各个子系统的失效是相互独立的，从而使得评估结果存在片面性。针对这一问题，使用概率的方法对多样性冗余的容侵系统可靠性进行了分析。结果表明，容侵系统的可靠性不仅与子系统的可靠性有关，而且还依赖于在攻击行为下子系统之间的内在联系。在此基础上，提出了容侵系统可靠性的评估模型。该模型对系统可靠性的评估结果涵括了大于、等于以及小于相互独立假设条件下系统可靠性三种情况。最后通过实例分析验证了模型评估结果的全面性。

关键词: 入侵容忍, 多样性, 冗余, 可靠性