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Sarah Pearman, Nicholas Munson, Leeyat Slyper, Lujo Bauer, Serge Egelman, Arnab Kumar, Charu Sharma, Jeremy Thomas, Nicolas Christin.  2016.  Risk Compensation in Home-User Computer Security Behavior: A Mixed-Methods Exploratory Study. SOUPS 2016: 12th Symposium on Usable Privacy and Security.

Risk homeostasis theory claims that individuals adjust their behaviors in response to changing variables to keep what they perceive as a constant accepted level of risk [8]. Risk homeostasis theory is used to explain why drivers may drive faster when wearing seatbelts. Here we explore whether risk homeostasis theory applies to end-user security behaviors. We use observed data from over 200 participants in a longitudinal in-situ study as well as survey data from 249 users to attempt to determine how user security behaviors and attitudes are affected by the presence or absence of antivirus software. If risk compensation is occurring, users might be expected to behave more dangerously in some ways when antivirus is present. Some of our preliminary data suggests that risk compensation may be occurring, but additional work with larger samples is needed. 

Joshua Tan, Lujo Bauer, Joseph Bonneau, Lorrie Cranor, Jeremy Thomas, Blase Ur.  2017.  Can Unicorns Help Users Compare Crypto Key Fingerprints? CHI '17 Proceedings of the 2017 CHI Conference on Human Factors in Computing Systems.

Many authentication schemes ask users to manually compare compact representations of cryptographic keys, known as fingerprints. If the fingerprints do not match, that may signal a man-in-the-middle attack. An adversary performing an attack may use a fingerprint that is similar to the target fingerprint, but not an exact match, to try to fool inattentive users. Fingerprint representations should thus be both usable and secure. We tested the usability and security of eight fingerprint representations under different configurations. In a 661-participant between-subjects experiment, participants compared fingerprints under realistic conditions and were subjected to a simulated attack. The best configuration allowed attacks to succeed 6% of the time; the worst 72%. We find the seemingly effective compare-and-select approach performs poorly for key fingerprints and that graphical fingerprint representations, while intuitive and fast, vary in performance. We identify some fingerprint representations as particularly promising.

Blase Ur, Patrick Gage Kelley, Saranga Komanduri, Joel Lee, Michael Maass, Michelle L. Mazurek, Timothy Passaro, Richard Shay, Timothy Vidas, Lujo Bauer et al..  2012.  How Does Your Password Measure Up? The Effect of Strength Meters on Password Creation 21st USENIX Security Symposium.

To help users create stronger text-based passwords, many web sites have deployed password meters that provide visual feedback on password strength. Although these meters are in wide use, their effects on the security and usability of passwords have not been well studied. We present a 2,931-subject study of password creation in the presence of 14 password meters. We found that meters with a variety of visual appearances led users to create longer passwords. However, significant increases in resistance to a password-cracking algorithm were only achieved using meters that scored passwords stringently. These stringent meters also led participants to include more digits, symbols, and uppercase letters. Password meters also affected the act of password creation. Participants who saw stringent meters spent longer creating their password and were more likely to change their password while entering it, yet they were also more likely to find the password meter annoying. However, the most stringent meter and those without visual bars caused participants to place less importance on satisfying the meter. Participants who saw more lenient meters tried to fill the meter and were averse to choosing passwords a meter deemed “bad” or “poor.” Our findings can serve as guidelines for administrators seeking to nudge users towards stronger passwords.