The development of applications and services of mobile phone has created a phenomenon of spying and deception through these mobiles. So, it is necessary to think of finding solutions to overcome this problem. In this book, we propose a new method to protect data sent between mobile phones. This method depends on one of the available services to mobile phones, such as Global Position System (GPS), Wireless Fidelity (Wi-Fi) by using the coordinate that are read through these services. The security analysis practical implementation, shows that the probability to break this key is almost impossible due to the dynamic coordinates and (DTD) and adjusting the length of the Random key. Our proposed solution is tested in real time using (J2ME) software where the experimental study shows that the cipher text (message) can only be decrypted under the restriction interval of (DTD). In this book, we proposed an algorithm which is more effective, practical, and promising for data transmission in mobile environment.compared with existing solutions.