Unrevealed Patterns in Password Databases Part One: Analyses of Cleartext Passwords

  • Norbert Tihanyi
  • Attila Kovács
  • Gergely Vargha
  • Ádám Lénárt
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 9393)


In this paper we present a regression based analyses of cleartext passwords moving towards an efficient password cracking methodology. Hundreds of available databases were examined and it was observed that they had similar behavior regardless of their size: password length distribution, entropy, letter frequencies form similar characteristics in each database. Exploiting these characteristics a huge amount of cleartext passwords were analyzed in order to be able to design more sophisticated brute-force attack methods. New patterns are exposed by analyzing millions of cleartext passwords.


Password analyzing Patterns Cracking method 



We would like to thank the opportunity to the Hungarian NSA to grant access to unpublished Hungaraian databases that can not be found on the internet. Databases are originated from different vulnerability assessments and security hardening projects conducted by the National Security Authority of Hungary. For this project only truncated databases were provided. It means that databases do not contain any additional personal information about users, so it cannot be determined to whom the password belongs to. Password analysis and publication of this article is made with the authorization of the Hungarian NSA.


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Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  • Norbert Tihanyi
    • 1
    • 2
    • 3
  • Attila Kovács
    • 2
  • Gergely Vargha
    • 1
    • 3
  • Ádám Lénárt
    • 1
    • 3
  1. 1.HUNGUARD Ltd.BudapestHungary
  2. 2.Department of Computer AlgebraEötvös Loránd UniversityBudapestHungary
  3. 3.National Security Authority of HungaryCyber Defence Management AuthorityBudapestHungary

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