Author(s): Kaczmarek, T; Kobsa, A; Sy, R; Tsudik, G | Abstract: User errors while performing security-critical tasks can lead to undesirable or even disastrous consequences. One major factor influencing mistakes and failures is complexity of such tasks, which has been studied extensively in prior research. Another important issue which hardly received any attention is the impact of both accidental and intended distractions on users performing security-critical tasks. In particular, it is unclear whether, and to what extent, unexpected sensory cues (e.g., auditory or visual) can influence user behavior and or trigger mistakes. Better understanding of the effects of intended distractions will help clarify their role in adversarial models. As part of the research effort described in this paper, we administered a range of naturally occurring -- yet unexpected -- sounds while study participants attempted to perform a security-critical task. We found that, although these auditory cues lowered participants' failure rates, they had no discernible effect on their task completion times. To this end, we overview some relevant literature that explains these somewhat counter-intuitive findings. Conducting a thorough and meaningful study on user errors requires a large number of participants, since errors are typically infrequent and should not be instigated more than once per subject. To reduce the effort of running numerous subjects, we developed a novel experimental setup that was fully automated and unattended. We discuss our experience with this setup and highlight the pros and cons of generalizing its usage.
A fairly common modern setting entails users, each in possession of a personal wireless device, wanting to communicate securely, via their devices. If these users (and their devices) have no prior association, a new security context must be established. In order to prevent potential attacks, the initial context (association) establishment process must involve only the intended devices and their users. A number of methods for initial secure association of two devices have been proposed; their usability factors have been explored and compared extensively. However, a more challenging problem of initial secure association of a group of devices (and users) has not received much attention. Although a few secure group association methods have been proposed, their usability aspects have not been studied, especially, in a comparative manner. This paper discusses desirable features and evaluation criteria for secure group association, identifies suitable methods and presents a comparative usability study. Results show that some simple methods (e.g., peer- or leader-based number comparisons) are quite attractive for small groups, being fast, reasonably secure and well-received by users.