Two-factor authentication (2F) aims to enhance resilience of password-based authentication by requiring users to provide an additional authentication factor, e.g., a code generated by a security token. However, it also introduces non-negligible costs for service providers and requires users to carry out additional actions during the authentication process. In this paper, we present an exploratory comparative study of the usability of 2F technologies. First, we conduct a pre-study interview to identify popular technologies as well as contexts and motivations in which they are used. We then present the results of a quantitative study based on a survey completed by 219 Mechanical Turk users, aiming to measure the usability of three popular 2F solutions: codes generated by security tokens, one-time PINs received via email or SMS, and dedicated smartphone apps (e.g., Google Authenticator). We record contexts and motivations, and study their impact on perceived usability. We find that 2F technologies are overall perceived as usable, regardless of motivation and or context of use. We also present an exploratory factor analysis, highlighting that three metrics -- ease-of-use, required cognitive efforts, and trustworthiness -- are enough to capture key factors affecting 2F usability.
Another line of work has focused on password managers . @cite_16 compared the usability of two password managers (PwdHash and Password Multiplier), pointing to a few usability issues in both implementations and showing that users were often uncomfortable relinquishing control'' to password managers. @cite_6 studied the usability of three password managers (LastPass, KeePassMobile, and Roboform2Go), with a focus on mobile phone users. They concluded that users preferred portable, stand-alone managers over cloud-based ones, despite the better usability of the latter, as they were not comfortable giving control of their passwords to an online entity.
@cite_16 @cite_6
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Proposed in response to the growing number of passwords users have to memorize, password managers allow to store one's credentials, either on a third-party server (online password manager), or on a portable device (portable password manager) such as a mobile phone or a USB key. In this paper, we present a comparative usability study of three popular password managers: an online manager (LastPass), a phone manager (KeePassMobile) and a USB manager (Roboform2Go). Our study provides valuable insights on average users' perception of security and usability of the three password management approaches. We find, contrary to our intuition, that users overall prefer the two portable managers over the online manager, despite the better usability of the latter. Also, surprisingly, our non-technical pool of users shows a strong inclination towards the phone manager. These findings can generally be credited to the fact that the users were not comfortable giving control of their passwords to an online entity and preferred to manage their passwords themselves on their own portable devices. Our results prompt the need for research on developing user-friendly and secure phone managers, owing to the ubiquity of mobile phones. We present a usability study of two recent password manager proposals: PwdHash (, 2005) and Password Multiplier (, 2005). Both papers considered usability issues in greater than typical detail, the former briefly reporting on a small usability study; both also provided implementations for download. Our study involving 26 users found that both proposals suffer from major usability problems. Some of these are not "simply" usability issues, but rather lead directly to security exposures. Not surprisingly, we found the most significant problems arose from users having inaccurate or incomplete mental models of the software. Our study revealed many interesting misunderstandings D for example, users reporting a task as easy even when unsuccessful at completing that task; and believing their passwords were being strengthened when in fact they had failed to engage the appropriate protection mechanism. Our findings also suggested that ordinary users would be reluctant to optin to using these managers: users were uncomfortable with "relinquishing control" of their passwords to a manager, did not feel that they needed the password managers, or that the managers provided greater security. The underlying issues relating to the usability and security of multiple passwords are largely unexplored. However, we know that people generally have difficulty remembering multiple passwords. This reduces security since users reuse the same password for different systems or reveal other passwords as they try to log in. We report on a laboratory study comparing recall of multiple text passwords with recall of multiple click-based graphical passwords. In a one-hour session (short-term), we found that participants in the graphical password condition coped significantly better than those in the text password condition. In particular, they made fewer errors when recalling their passwords, did not resort to creating passwords directly related to account names, and did not use similar passwords across multiple accounts. After two weeks, participants in the two conditions had recall success rates that were not statistically different from each other, but those with text passwords made more recall errors than participants with graphical passwords. In our study, click-based graphical passwords were significantly less susceptible to multiple password interference in the short-term, while having comparable usability to text passwords in most other respects. In this paper, we propose and evaluate Use Your Illusion, a novel mechanism for user authentication that is secure and usable regardless of the size of the device on which it is used. Our system relies on the human ability to recognize a degraded version of a previously seen image. We illustrate how distorted images can be used to maintain the usability of graphical password schemes while making them more resilient to social engineering or observation attacks. Because it is difficult to mentally "revert" a degraded image, without knowledge of the original image, our scheme provides a strong line of defense against impostor access, while preserving the desirable memorability properties of graphical password schemes. Using low-fidelity tests to aid in the design, we implement prototypes of Use Your Illusion as i) an Ajax-based web service and ii) on Nokia N70 cellular phones. We conduct a between-subjects usability study of the cellular phone prototype with a total of 99 participants in two experiments. We demonstrate that, regardless of their age or gender, users are very skilled at recognizing degraded versions of self-chosen images, even on small displays and after time periods of one month. Our results indicate that graphical passwords with distorted images can achieve equivalent error rates to those using traditional images, but only when the original image is known.