Porting and securing an ad-hoc library for mobile devices

Abstract

Today, almost everyone carries a mobile device, which is used for various purposes such as communicating with friends or watching videos on an online video sharing platform. However, it requires the presence of a centralised access point, which is not always available. This restriction could be avoided by transitioning to ad hoc wireless communications, where devices would communicate with each other directly. Even so, there are few resources available for the development of ad hoc applications. This master thesis presents the port of a Java mobile ad hoc library to Dart. Therefore, the ported library could be used by the Flutter framework, which allows to develop ad hoc mobile apps regardless of the mobile platforms used. Since the Java mobile ad hoc library is based on a layered architecture, each layer has been individually ported one by one. Another wireless technology, Bluetooth Low Energy, has been explored and used instead of Bluetooth Classic. Despite having a lower data rate, Bluetooth Low Energy is still used to overcome the limitation of Wi-Fi Direct, which is the non-support for multi-hop communications. Then, a new layer has been introduced and implemented, which is responsible for encryption and decryption of data. As a result, a key management system is needed and the on-demand self-organised public key management has been chosen and implemented for end-to-end secure communication. To provide secure communication beyond the end-to-end secure communication, the CRTDH group key agreement has been implemented and provides the possibility to have secure group communications. Study in the literature has shown that the symmetric cryptography ChaCha20 has proven to be very efficient in terms of computation time and energy consumption.