Abstract: The open environment in cloud computing is much more complex and unpredictable, and can not fully adapt to the new application of computer network such as cloud computing. Combining such security measures of dynamic user behavior trust, effectively confirming the untrusted cloud terminal users and correctly analyzing their abnormal behavior are the basis to ensure cloud security in complex and dynamic environment This paper adopted the method of fuzzy analytic network process(FANP) based on triangular fuzzy numbers, which can reflect the fuzziness of expert evaluation through using fuzzy numbers, and weaken the subjectivity of simply using ANP. The paper also gave a quantization calculation to the weight of each attribute in order to make the evaluation results more objective. The evaluation results provide a quantitative analysis foundation for security control based on dynamic trust and provide the quantitative basis for service providers who adopt a more safe strategy in response to a user's requesting.

Key words: Fuzzy analytic network process, User behavior, Trust evaluation, Cloud computing