Mesh Messaging is a wireless Instant Messaging service that can communicate among devices without the need of any network infrastructures. It is useful for scenarios, such as disasters and overcrowded events. Technologies for similar purposes have been developed over the years, the trending solutions are usually based on P2P connections between devices. However, the Mesh Messaging applications in the market are often found not secure enough to protect the messages transferred via the connections. Wi-Fi Aware is a new technology for wireless P2P connection in a nearby area without any routers or cellular stations. It is supported in Android system and has security mechanisms for its connections. Meanwhile, Briar is an open-source Instant Messaging application, which has carefully designed protocols for serverless and secure communications. Combining the security features of Wi-Fi Aware and Briar is an attempt of building a secure Mesh Messaging service on Android smartphones.

In the Thesis, relevant concepts and technologies are reviewed. A demo Mesh Messaging Android application is built, with a new implemented Wi-Fi Aware transport plugin for Briar. Evaluation of the demo is performed, the implementation and the involved security protocols are analyzed.