To　achieve　the　multilevel　security　goal　some　models　had　been　developed　such　as　BLP　since　1970s.　These　models　can＇t　successfully　work　in　network　environment　nowadays　due　to　the　difficulty　to　make　the　labels　of　subjects　and　objects　unaltered　across　different　computers.　Recent　years　many　researchers　put　forward　cryptographic　solutions　to　address　multilevel　security　problem.　But　the　key　management　schemes　in　real　systems　were　always　difficult　problems　that　made　those　solutions　unfeasible.　The　trusted　computing　technologies　are　great　advancement　in　computer　architecture　and　should　be　a　powerful　tool　to　securely　manage　the　keys.　This　paper　proposes　a　new　approach　on　the　base　of　the　capabilities　provided　by　TPM　(Trusted　Platform　Module)　to　implement　a　sound　cryptographic　algorithm.　The　new　approach　enforces　a　mandatory　access　control　policy　in　network　environment　and　is　especially　suited　for　classified　organizations.　©　2007　IEEE.