Usability of Humanly Computable Passwords
This addresses security issues for users who rely on password reuse, but it is incremental as it builds on existing theoretical work.
The study tackled the problem of password reuse by evaluating the usability of humanly computable password strategies, finding that with training, participants could calculate an eight-character password for a new website in under 20 seconds.
Reusing passwords across multiple websites is a common practice that compromises security. Recently, Blum and Vempala have proposed password strategies to help people calculate, in their heads, passwords for different sites without dependence on third-party tools or external devices. Thus far, the security and efficiency of these "mental algorithms" has been analyzed only theoretically. But are such methods usable? We present the first usability study of humanly computable password strategies, involving a learning phase (to learn a password strategy), then a rehearsal phase (to login to a few websites), and multiple follow-up tests. In our user study, with training, participants were able to calculate a deterministic eight-character password for an arbitrary new website in under 20 seconds.