MobiHydra: Pragmatic and Multi-level Plausibly Deniable Encryption Storage for Mobile Devices

Nowadays, smartphones have started being used as a tool to collect and spread politically sensitive or activism information. The exposure of the possession of such sensitive data shall pose a risk in severely threatening the life safety of the device owner. For instance, the data owner may be caught and coerced to give away the encryption keys so that the encryption alone is inadequate to mitigate such risk. In this work, we present MobiHydra, a pragmatic plausibly deniable encryption (PDE) scheme featuring multi-level deniability on mobile devices, to circumvent the coercive attack. MobiHydra is pragmatic in that it remarkably supports hiding opportunistic data without necessarily rebooting the device. In addition, MobiHydra favourably mitigates the so-called booting-time defect, which is a whistle-blower to expose the usage of PDE in previous solutions. We implement a prototype for MobiHydra on Google Nexus S. The evaluation results demonstrate that MobiHydra introduces very low overhead compared with other PDE solutions for mobile devices.