There is a rapid development in the area of Information Communication Technology (ICT). Mobile devices (e.g., PDA, mobile phone, and notebook PC) become necessary for a modern life. Users can use them to access many applications, for example online shopping, mobile pay TV, internet banking, which have been deployed on internet or wireless networks easily. Therefore, secure communications in such wireless environments are more and more important because that protects communication between users and servers from unlawful adversaries.