The goal of this thesis was to create a safe Bluetooth Chat application on Android platform. The application makes a Bluetooth-based encrypted communication between users. The simple manageability and the security were the two most important aspects by planning the program. The program stores the user’s login data and conversations. If the language of the phone is Hungarian, then the program writes all text in Hungarian, if any other languages, then the program use the default English language.
The thesis contains the presentation of the Android platform from developer perspective. It presents the structure of the Android architecture and the lifecycle of the applications. The most commonly used basic elements and user interface elements are described too. Since the program constitutes communication via Bluetooth, therefore, the thesis presents the steps of implementing communication and the Android classes, which implements the Bluetooth communication.
Because of the application encrypts the messages, the thesis contains an overview chapter from the encryption. This chapter describes the basics of the cryptography, and the cipher techniques and in so many words the AES encryption, which is used in the program. A separate chapter describes the encryption classes, which are supported by the Android platform. This chapter presents the implemented encryption module, which uses the previous classes.
The thesis presents how the program works from both users and programmers point of view. The thesis illustrates the functions of the program with pictures. The UML diagrams facilitate to see through the functions of the program.