In our days the mobile phone is the most popular telecommunication device. A few years ago we could use just simple programs, but today we need to use complex mobile applications, and sometimes we need to connect devices to each other with a wireless standard. Nowadays more and more platforms turn up, which grant effective environment for developing complex applications. One of the most popular platforms is Java Micro Edition. The dissertation is based on this platform thus the first chapters shows the capabilities and architecture of it, and describes the goals of the project. One of the most widely-used wireless standards is Bluetooth, which was designed to connect small devices to each other. The third chapter of the dissertation shows the capabilities and the architecture of this standard and presents how it is possible to create a connection with it. The use of wireless connection without encryption is unsafe thus the next chapter presents the motivation of encryption algorithms, afterwards it presents today’s popular algorithms. The theoretical part is followed by plans of a demo application. The plans describe how and what components build up the demo application. The application is based on the above-mentioned technologies and shows their operation in practice. Thereafter the steps of the application implementation follow. The subsequent chapter including the results tests which demonstrates the correct operation of the application. The last chapter summarizes the dissertation and describes the experiences of the work, finally describes what opportunities may arise to upgrade the demo application.