UACAP: A Unified Auxiliary Channel Authentication Protocol

Rene Mayrhofer, Jürgen Fuß, Iulia Ion

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Authenticating spontaneous interactions between devices and users is challenging for several reasons: the wireless (and therefore invisible) nature of device communication, the heterogeneous nature of devices, and lack of appropriate user interfaces in mobile devices, and the requirement for unobtrusive user interaction. The most promising approach that has been proposed in literature involves the exploitation of the so-called auxiliary channels for authentication to bridge the gap between usability and security. This concept has spawned the independent development of various authentication methods and research prototypes, that, unfortunately, remain hard to compare and interchange and are rarely available to potential application developers. We present a novel, unified cryptographic authentication protocol framework (UACAP) to unify these approaches on using auxiliary channels and analyze its security properties. This protocol and a selection of auxiliary channels aimed at authentication of mobile devices has been implemented and released in an open-source ubiquitous authentication toolkit (OpenUAT). We also present an initial user study evaluating four of these channels.

Original languageEnglish
Article number6152259
Pages (from-to)710-721
Number of pages12
JournalIEEE Transactions on Mobile Computing
Issue number4
Publication statusPublished - 2013


  • Network architecture and design/wireless communication
  • algorithm/protocol design and analysis
  • human-centered computing
  • information systems applications/ miscellaneous
  • mobile applications
  • mobile environments
  • security and protection/authentication
  • ubiquitous computing


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