Weak security, excessive personal data collection for user profiling, and a poor user experience are just a few of the many problems that mobile authentication solutions suffer from. Despite being an interesting platform, mobile devices are still not being used to their full potential for authentication. n-Auth is a firm step in unlocking the full potential of mobile devices in authentication, by improving both security and usability whilst respecting the privacy of the user. Our focus is on the combined usage of several strong cryptographic techniques with secure HCI design principles to achieve a better user experience. We specified and built n-Auth, for which robust Android and iOS apps are openly available through the official stores.

We approach RFID privacy both from modelling and protocol point of view. Our privacy model avoids the drawbacks of several proposed RFID privacy models that either suffer from insufficient generality or put forward unrealistic assumptions regarding the adversary's ability to corrupt tags. Furthermore, our model can handle multiple readers and introduces two new privacy notions to capture the recently discovered insider attackers. We analyse multiple existing RFID protocols, demonstrating the easy applicability of our model, and propose a new wide-forward-insider private RFID authentication protocol. This protocol provides sufficient privacy guarantees for most practical applications and is the most efficient of its kind, it only requires two scalar-EC point multiplications.

We propose a new distance bounding protocol, which builds upon the private RFID authentication protocol by Peeters and Hermans [25]. In contrast to most distance-bounding protocols in literature, our construction is based on public-key cryptography. Public-key cryptography (specifically Elliptic Curve Cryptography) can, contrary to popular belief, be realized on resource constrained devices such as RFID tags. Our protocol is wide-forward-insider private, achieves distance-fraud resistance and near-optimal mafia-fraud resistance. Furthermore, it provides strong impersonation security even when the number of time-critical rounds supported by the tag is very small. The computational effort for the protocol is only four scalar-EC point multiplications. Hence the required circuit area is minimal because only an ECC coprocessor is needed: no additional cryptographic primitives need to be implemented.