Abstract: Aiming at the lack of security assessment in cloud environment, a cloud-based security modeling method was proposed, and a Security-Performance (S-P) association model in cloud environment was established. Firstly, a model was constructed for virtual machines, the most important component of the cloud system, to evaluate its security. The model fully reflected the impact of security mechanisms and malicious attacks on virtual machines. Secondly, based on the relationship between virtual machine and cloud system, an indicator was proposed for assessing the security of the cloud system. Thirdly, a hierarchical modeling method was proposed to establish an S-P association model. Queuing theory was used to model the performance of cloud computing systems, and the relationship between security and performance was established based on Bayesian theory and association analysis, and a new index for evaluating the association of complex S-P was proposed. Experimental results verify the correctness of the theoretical model and reveal the dynamic change rule of performance caused by safety factors.

Key words: cloud computing, security modeling, performance modeling, Markov model, queuing theory

摘要： 针对云环境缺乏安全性评估的问题，提出一种评估系统安全性的建模方法，并建立了云环境下的安全性-性能（S-P）关联模型。首先，针对云系统中最重要的组成部分，即虚拟机，建立了评估其安全性的模型，该模型充分反映了安全机制和恶意攻击两个安全因素对虚拟机的影响；随后基于虚拟机与云系统之间的关系，提出评估云系统安全性的指标；其次，提出一种分层建模方法来建立S-P关联模型。利用队列理论对云计算系统的性能进行建模，然后基于贝叶斯理论和相关分析建立了安全性和性能之间的关联关系，并提出评估复杂S-P相关性的新指标。实验结果验证了理论模型的正确性，并揭示了安全因素引起的性能动态变化规律。

关键词: 云计算, 安全性建模, 性能建模, 马尔可夫模型, 排队论