he Minimum Criteria of Covert Channels'''' Existence and its Application
隐通道存在的最小条件及其应用

Covert channels can leak confidential information under the supervision of security mechanism,so its threat is very serious. By research on the working principle of covert channels,the minimum criteria of its existence had been formally proved. Based on it,the taxonomy for the methods of search and elimination in covert channels was given. Furthermore,each method's correctness and deficiency were represented theoretically. These were not only offered the theory bedrock for the work of search and eliminate covert channels,but also given a frame for develop new search and elimination methods in covert channels.