Many new applications, such as Mobile crowdsensing, burden mobile devices with heavy computation which severely affects the user's experience due to high battery consumption and delayed responses. Cloud computing was expected to solve heavy computation problems, so researchers tried to connect it to mobile networks, but always hindered by the expensive nature of mobile access networks from money, power, delay and other viewpoints. In our previous work, we have proposed a mobile cloud architecture that succeeded in merging the two technologies into a homogeneous one by overcoming the expensive nature of access networks. In this work we are going to extend this architecture by proposing a unified Authentication and Key Agreement mechanism suitable for both mobile mutual authentication and cloud's authentication and Single-Sign-On