Moby: A Blackout-Resistant Anonymity Network for Mobile Devices
Amogh Pradeep, Hira Javaid, Ryan Williams, Antoine Rault, David Choffnes,
Stevens Le Blond, and Bryan Ford
Proceedings on Privacy Enhancing Technologies
March 16, 2022
Abstract:
Internet blackouts are challenging environments for anonymity and censorship
resistance. Existing popular anonymity networks (e.g., Freenet, I2P, Tor)
rely on Internet connectivity to function, making them impracticable during
such blackouts. In such a setting, mobile ad-hoc networks can provide
connectivity, but prior communication protocols for ad-hoc networks are not
designed for anonymity and attack resilience. We address this need by
designing, implementing, and evaluating Moby, a blackout-resistant anonymity
network for mobile devices. Moby provides end-to-end encryption, forward
secrecy and sender-receiver anonymity. It features a bi-modal design of
operation, using Internet connectivity when available and ad-hoc networks dur-
ing blackouts. During periods of Internet connectivity, Moby functions as a
regular messaging application and bootstraps information that is later used in
the absence of Internet connectivity to achieve secure anonymous
communications. Moby incorporates a model of trust based on users’ contact
lists, and a trust establishment protocol that mitigates flooding attacks. We
perform an empirically informed simulation-based study based on cellphone
traces of 268,596 users over the span of a week for a large cellular provider
to determine Moby’s feasibility and present our findings. Last, we implement
and evaluate the Moby client as an Android app.
Paper:
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