In　the　process　of　formal　analysis　based　on　strand　space　model,　it　is　generally　based　on　the　assumption　that　the　cryptographic　algorithm　used　in　protocol　is　secure.　By　introducing　an　insecure　signature　algorithm,　we　extend　the　penetrator　model　of　strand　space　and　improve　the　authentication　test　method　based　on　parameters　consistency,　and　then　extend　the　expression　and　analysis　ability　of　the　strand　space　method.　Making　use　of　the　improved　method,　we　analyze　the　Linear　MAKEP　protocol　proposed　by　Wong　in　2001.　The　results　show　that　the　protocol　is　not　security　under　the　new　penetrator　model.　Consequently,　we　provide　a　simple　improved　mode.　©　2010　IEEE.