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UNIX Password Security - Ten Years Later

  • David C. Feldmeier
  • Philip R. Karn
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 435)

Abstract

Passwords in the UNIX operating system are encrypted with the crypt algorithm and kept in the publicly-readable file /etc/passwd. This paper examines the vulnerability of UNIX to attacks on its password system. Over the past 10 years, improvements in hardware and software have increased the crypts/second/dollar ratio by five orders of magnitude. We reexamine the UNIX password system in light of these advances and point out possible solutions to the problem of easily found passwords. The paper discusses how the authors built some high-speed tools for password cracking and what elements were necessary for their success. These elements are examined to determine if any of them can be removed from the hands of a possible system infiltrator, and thus increase the security of the system. We conclude that the single most important step that can be taken to improve password security is to increase password entropy.

Keywords

Smart Card Table Lookup Data Encryption Standard Plain Text Attack UNIX Operating System 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1990

Authors and Affiliations

  • David C. Feldmeier
    • 1
  • Philip R. Karn
    • 1
  1. 1.BellcoreMorristown

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