关键词: 安全标记, 安全级别, 可信度, 证据, 等级保护

Abstract: This paper analyzes problem of BLP model which is applied to multi-level network，and puts forward access control of multi-level network based on trust evaluation.The method collects evidences of access history of subject from audit systems in the same secure domain，then evaluates trust degree of subject about violating confidentiality rule by evidences，and adjusts secure label of subject and being of object，which can not only increase flexibility and availability but also reduce risk of information system by misuse of credible subject’s authority? in BLP model.

Key words: secure label, secure level, trust degree, evidence, classified security protection