User-chosen passwords reflecting common strategies and patterns ease memorisation but offer uncertain and often weak security, while system-assigned passwords provide higher security guarantee but suffer from poor memorability. We thus examine the technique to enhance password memorability that incorporates a scientific understanding of long-term memory. In particular, we examine the efficacy of providing users with verbal cues—real-life facts corresponding to system-assigned keywords. We also explore the usability gain of including images related to the keywords along with verbal cues. In our multi-session lab study with 52 participants, textual recognition-based scheme offering verbal cues had a significantly higher login success rate (94.23%) compared to the control condition, i.e. textual recognition without verbal cues (61.54%). When users were provided with verbal cues, adding images contributed to faster recognition of the assigned keywords, and thus had an overall improvement in usability. So, we conducted a field study with 54 participants to further examine the usability of graphical recognition-based scheme offering verbal cues, which showed an average login success rate of 98% in a real-life setting and an overall improvement in login performance with more login sessions. These findings show a promising research direction to gain high memorability for system-assigned passwords.

Given the choice, users produce passwords reflecting common strategies and patterns that ease recall but offer uncertain and often weak security. System-assigned passwords provide measurable security but suffer from poor memorability. To address this usability-security tension, we argue that systems should assign random passwords but also help with memorization and recall. We investigate the feasibility of this approach with CuedR, a novel cued-recognition authentication scheme that provides users with multiple cues (visual, verbal, and spatial) and lets them choose the cues that best fit their learning process for later recognition of system-assigned keywords. In our lab study, all 37 of our participants could log in within three attempts one week after registration (mean login time: 38.0 seconds). A pilot study on using multiple CuedR passwords also showed 100% recall within three attempts. Based on our results, we suggest appropriate applications for CuedR, such as financial and e-commerce accounts.

Despite advances in biometrics and other technologies, passwords remain the most commonly used means of authentication in computer systems. Users maintain different security levels for different passwords. In this study, we examine the degree of similarity among passwords of different security levels of a user. We conducted a laboratory experiment with 80 students from the University of Texas at Arlington (UTA). We asked the subjects to construct new passwords for websites of different security levels. We collected the lower-level passwords (e.g., passwords for online news sites) constructed by the subjects, combined them with a comprehensive wordlist, and performed dictionary attacks on their constructed passwords from the higher-level sites (e.g., banking websites). We could successfully crack almost one-third of their constructed passwords from the higher-level sites with this method. This suggests that, if a user's lower-level password is leaked, it can be used effectively by an attacker to crack some of the user's higher-level passwords.