Reconciling user privacy and implicit authentication for mobile devices ?
We propose the first protocols that preserve user privacy for implicit authentication on mobile devices. User profiles are stored in encrypted format. No trusted third parties are required. We propose two protocols that are secure against adversaries capturing a device in 2 cases depending on whether or not they tamper with the device. We show that implementations of the two protocols can be efficient enough to run on modern smart-phones in around 300 ms and 2.5 s, respectively. We give security definitions and reductionist proofs of security for both protocols, ensuring user privacy in both cases.
user privacy implicit authentication homomorphic encryption provable security behavioural features