Modeling Aggregate Security with User Agents that Employ Password Memorization Techniques

We discuss our ongoing work with an agent-based password simulation which models how site-enforced password requirements affect aggregate security when people interact with multiple authentication systems. We model two password memorization techniques: passphrase generation and spaced repetition. Our simulation suggests system-generated passphrases lead to lower aggregate security across services that enforce even moderate password requirements. Furthermore, allowing users to expand their password length over time via spaced repetition increases aggregate security.