Abstract-Text-based passwords remain the dominant authentication method in computer systems, despite significant advancement in attackers' capabilities to perform password cracking. In response to this threat, password composition policies have grown increasingly complex. However, there is insufficient research defining metrics to characterize password strength and using them to evaluate password-composition policies. In this paper, we analyze 12,000 passwords collected under seven composition policies via an online study. We develop an efficient distributed method for calculating how effectively several heuristic password-guessing algorithms guess passwords. Leveraging this method, we investigate (a) the resistance of passwords created under different conditions to guessing; (b) the performance of guessing algorithms under different training sets; (c) the relationship between passwords explicitly created under a given composition policy and other passwords that happen to meet the same requirements; and (d) the relationship between guessability, as measured with password-cracking algorithms, and entropy estimates. Our findings advance understanding of both password-composition policies and metrics for quantifying password security.
Guessability is the measure of the time needed to "guess" a given password by an efficient password cracking algorithm REF .
Guess Again (and Again and Again): Measuring Password Strength by Simulating Password-Cracking Algorithms
2012 IEEE Symposium on Security and Privacy
2012 IEEE Symposium on Security and Privacy
Computer Science