Authentication Schemes - Comparison and Effective Password Spaces

Text passwords are ubiquitous in authentication. Despite this ubiquity, they have been the target of much criticism. One alternative to the pure recall text passwords are graphical authentication schemes. The different proposed schemes harness the vast visual memory of the human brain and exploit cued-recall as well as recognition in addition to pure recall. While graphical authentication in general is promising, basic research is required to better understand which schemes are most appropriate for which scenario (incl. security model and frequency of usage). This paper presents a comparative study in which all schemes are configured to the same effective password space (as used by large Internet companies). The experiment includes both, cued-recall-based and recognition-based schemes. The results demonstrate that recognition-based schemes have the upper hand in terms of effectiveness and cued-recall-based schemes in terms of efficiency. Thus, depending on the scenario one or the other approach is more appropriate. Both types of schemes have lower reset rates than text passwords which might be of interest in scenarios with limited support capacities