Alphanumeric authentication, by means of a secret, is not only a powerful mechanism, in theory, but prevails over all its competitors in practice. However, it is clearly inadequate in a world where increasing numbers of systems and services require people to authenticate in a shared space, while being actively observed. This new reality places pressure on a password mechanism never intended for use in such a context. Asterisks may obfuscate alphanumeric characters on entry but popular systems, e.g. Apple iPhone and Nintendo Wii, regularly require users to use an on-screen keyboard for character input. This may not be a real concern within the context of secluded space but inadvertly reveals a secret within shared space. Such a secret has an economic cost in terms of replacement, recall and revenue, all of which affect the financial return of the offending systems and services.#R##N##R##N#In this paper, we present and evaluate a graphical authentication mechanism, Tetrad, which appears to have the potential to address these specific concerns.
['Karen Renaud', 'Joseph Maguire']
Armchair authentication