In this article, we discuss how we use neural networks to accurately measure password strength, and how we use this capability to build effective password meters. First, we show how neural networks can be used to guess passwords and how we leveraged this method to build a password guesser to better model guessing attacks. We report our measurements of the effectiveness of neural networks at guessing passwords, demonstrating that they outperform other popular methods of modeling adversarial password guessing. We then show how we developed a password guesser that can be compressed so that it is practical for client-side use inside a Web page. Finally, we describe how we designed and built a password meter, based on neural networks, that gives more accurate and helpful guidance to users for creating passwords that are resistant to guessing attack.
