Abstract: Information declassification aims at secure release of sensitive information.Existing security specifications and enforcement mechanisms of declassification policies focus on sequential programs,and they can not be directlytransplanted to multithreaded environments for that attackers can take advantage of some properties of thread scheduling to derive sensitive information.To this end,a two-dimension declassification policy in multithreaded environments was proposed,based on the multi-threaded programming language model and thread scheduling model,effectively ensuring that appropriate information is released at the appropriate point of programs.Moreover,dynamic monitoring mechanisms of the policy in multithreaded environments were presented,and the soundness of enforcements was proved.

Key words: Information flow,Multithreaded environments,Confidentiality,Non-interference