Anix: Anonymous Blackout-Resistant Microblogging with Message Endorsing

Repressive governments are increasingly resorting to Internet shutdowns to control the flow of information during political unrest. In response, messaging apps built on top of mobile-based mesh networks have emerged as important communication tools for citizens and activists. While different flavors of these apps exist, those featuring microblogging functionalities are attractive for swiftly informing and mobilizing individuals. However, most apps fail to simultaneously uphold user anonymity while providing safe ways for users to build trust in others and the messages flowing through the mesh. We introduce Anix, a blackout-resistant app with two novel features: remote trust establishment and anonymous message endorsing. Anix also leverages a set of identity revocation primitives for the fine-grained management of trust relationships and to provide enhanced anonymity. Our evaluation of Anix through comprehensive micro-benchmarks and simulations showcases its practicality and resilience in shutdown scenarios.