As　the　network　technologies　have　rapidly　developed　in　recent　years,　many　Internet　of　Things　(IoT)　based　services　and　applications　have　walked　into　our　daily　lives;　one　of　these　is　the　medical　information　system.　In　the　early　days,　medical　information　was　recorded　and　stored　in　article　form.　It　contains　a　patient　identity　background,　past　medical　history,　and　records　of　medical　payment.　With　the　development　of　medical　technology,　medical　information　is　now　stored　and　transmitted　electronically.　Medical　information　may　be　a　person＇s　most　private　information,　but　due　to　network　operation　errors　or　hacking　attacks,　there　has　been　a　crisis　of　large-scale　leakage　of　these　personal　privacy　data　in　the　past.　In　any　cases,　how　to　protect　this　medical　information　and　ensure　the　privacy　of　patients　has　become　a　topic　worthy　of　research.　Therefore,　many　kinds　of　literature　discussed　how　to　improve　medical　information　systems.　In　addition,　how　to　effectively　treat　patients　when　accidents　happen　is　also　a　topic　worthy　of　research.　Therefore,　combined　with　IoT　technologies　and　medical　devices,　it　has　been　opened　a　whole　new　future　for　medical　information　system.　This　study　focuses　on　security　and　privacy　issues　to　design　a　security　scheme　for　healthcare　environments　when　a　person　encountered　physical　emergency.　Mobile　devices　and　cloud　computing　are　combined　into　the　proposed　platform.　The　proposed　scheme　can　defend　against　impersonation　attack,　man-in-middle　attack,　and　replay　attack.　The　modal　logic　is　used　to　verify　the　proposed　scheme.　By　using　digital　signature　and　SVO　logic　mechanism,　the　proposed　scheme　is　proven　with　nonrepudiation.