Clear, Unambiguous Password Policies: An Oxymoron?

Abstract

Password policies – documents which regulate how users must create and manage their passwords – can have complex and unforeseen consequences on organizational security. Since these policies attempt to govern user behavior, users must be clear as to what is expected of them for a policy to be effective. While a culprit of misinterpretation, policy ambiguity also prevents researchers from comparing and contrasting policy statements. To tackle ambiguity, we developed a formal language for stating what behavior is and is not allowed when creating, managing, and changing passwords. This formal language lends itself to policy analysis and visualization. A corpus of 41 password policies was translated into the formal language and analyzed. Having these clear, unambiguous policy statements enables us to explore password policies in much greater detail, discuss the relative merits of different statements, compare and contrast policies, and begin to examine the interplay between usability and security in password policies.