Human-Generated and Machine-Generated Ratings of Password Strength: What Do Users Trust More?

Proactive password checkers have been widely used to persuade users to select stronger passwords by providing machine-generated strength ratings of passwords. If such ratings do not match human-generated ratings of human users, there can be a loss of trust in PPCs. In order to study the effectiveness of PPCs, it would be useful to investigate how human users perceive such machine- and human-generated ratings in terms of their trust, which has been rarely studied in the literature. To fill this gap, we report a large-scale crowdsourcing study with over 1,000 workers. The participants were asked to choose which of the two ratings they trusted more. The passwords were selected based on a survey of over 100 human password experts. The results revealed that participants exhibited four distinct behavioral patterns when the passwords were hidden, and many changed their behaviors significantly after the passwords were disclosed, suggesting their reported trust was influenced by their own judgments.