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.
@cite_12 examined usability of device pairing in a group setting, where up to 6 users tried to connect their devices to one another, and found that group effort decreased the expected rate of security and non-security failures. Although, an inherent insecurity of conformity'' was also identified, wherein users would deliberately lie about an observed string in order to fit in'' with the majority opinion of a group.
@cite_12
2148165512 2096768518 15257636 2144454907
Secure Device Pairing is the bootstrapping of secure communication between two previously unassociated devices over a wireless channel. The human-imperceptible nature of wireless communication, lack of any prior security context, and absence of a common trust infrastructure open the door for Man-in-the-Middle (aka Evil Twin) attacks. A number of methods have been proposed to mitigate these attacks, each requiring user assistance in authenticating information exchanged over the wireless channel via some human-perceptible auxiliary channels, e.g., visual, acoustic or tactile. In this paper, we present results of the first comprehensive and comparative study of eleven notable secure device pairing methods. Usability measures include: task performance times, ratings on System Usability Scale (SUS), task completion rates, and perceived security. Study subjects were controlled for age, gender and prior experience with device pairing. We present overall results and identify problematic methods for certain classes of users as well as methods best-suited for various device configurations. 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. We explore the use of extrinsic motivation to improve the state of user-centered security mechanisms. Specifically, we study applications of scores as user incentives in the context of secure device pairing. We develop a scoring functionality that can be integrated with traditional pairing approaches. We then report on a usability study that we performed to evaluate the effect of scoring on the performance of users in comparison operations. Our results demonstrate that individuals are likely to commit fewer errors and show more acceptance when working with the scoring based pairing approach. Framing pairing as a game and providing feedback to users in the form of a score is an efficient way to improve pairing security, particularly among users such as children who may not be aware of the consequences of their decisions while performing security tasks. Initiating and bootstrapping secure, yet low-cost, ad-hoc transactions is an important challenge that needs to be overcome if the promise of mobile and pervasive computing is to be fulfilled. For example, mobile payment applications would benefit from the ability to pair devices securely without resorting to conventional mechanisms such as shared secrets, a Public Key Infrastructure (PKI), or trusted third parties. A number of methods have been proposed for doing this based on the use of a secondary out-of-band (OOB) channel that either authenticates information passed over the normal communication channel or otherwise establishes an authenticated shared secret which can be used for subsequent secure communication. A key element of the success of these methods is dependent on the performance and effectiveness of the OOB channel, which usually depends on people performing certain critical tasks correctly. In this paper, we present the results of a comparative usability study on methods that propose using humans to implement the OOB channel and argue that most of these proposals fail to take into account factors that may seriously harm the security and usability of a protocol. Our work builds on previous research in the usability of pairing methods and the accompanying recommendations for designing user interfaces that minimise human mistakes. Our findings show that the traditional methods of comparing and typing short strings into mobile devices are still preferable despite claims that new methods are more usable and secure, and that user interface design alone is not sufficient in mitigating human mistakes in OOB channels.