Abstract: Because of the cloud computings characteristics of being dynamic and open, continuous malicious attacks happen frequently. With the idea of trusted cloud, a defense system model based on trust for cloud computing was constructed to guarantee the cloud security. Through real-time monitoring, users behavior evidences could be obtained and standardized; a new method for users trust evaluation based on fuzzy Analytic Hierarchy Process (AHP) was presented, which gradually determined the weights of behavior evidences, achieved quantitative assessment of behavioral trust; so as to provide great security defense for users. Besides, multiple detection engines were used to conduct a comprehensive inspection of suspicious files and to make integrated decisions. The experimental results show the system model can effectively eliminate the malicious behaviors from undesirable users, reduce users damages caused by virus and achieve a two-way defense for both cloud and client.

Key words: cloud security, trusted cloud, trust, behavioral evidence, Fuzzy Analytic Hierarchy Process (FAHP), multiple detection engine

摘要： 由于云计算的动态性和开放性，云环境中频频出现恶意攻击行为，为了保障云计算的安全，结合可信云的思想，提出一个云计算下基于信任的防御系统模型。该模型通过实时监控获取用户的行为证据并加以规范；提出一种新的基于模糊层次分析法（FAHP）的用户行为信任评估方法，逐步确定各行为证据的权重，实现行为信任的科学量化评估；利用多种检测引擎对可疑文件进行全面检测和综合决策，为云中用户提供最大限度的安全防御。实验结果表明，该系统模型能有效消除不良用户的恶意攻击行为、降低病毒等给用户带来的损失，达到云端和客户端双向防御的目的。

关键词: 云安全, 可信云, 信任, 行为证据, 模糊层次分析法, 多检测引擎