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Toward Usable, Robust Memometric Authentication: an Evaluation of Selected Password Generation Assistance Peter Thomas Henry

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Toward Usable, Robust Memometric Authentication: an Evaluation of Selected Password Generation Assistance Peter Thomas Henry Florida State University Libraries Electronic Theses, Treatises and Dissertations The Graduate School 2007 Toward Usable, Robust Memometric Authentication: An Evaluation of Selected Password Generation Assistance Peter Thomas Henry Follow this and additional works at the FSU Digital Library. For more information, please contact [email protected] THE FLORIDA STATE UNIVERSITY COLLEGE OF INFORMATION TOWARD USABLE, ROBUST MEMOMETRIC AUTHENTICATION: AN EVALUATION OF SELECTED PASSWORD GENERATION ASSISTANCE By PETER THOMAS HENRY A Dissertation submitted to the College of Information in partial fulfillment of the requirements for the degree of Doctor of Philosophy Degree Awarded: Summer Semester, 2007 Copyright © 2007 Peter Thomas Henry All Rights Reserved The members of the Committee approve the dissertation of Peter Thomas Henry defended on May 21, 2007. ______________________________ Charles R. McClure Professor Directing Dissertation ______________________________ Michael Burmester Outside Committee Member ______________________________ John Carlo Bertot Committee Member ______________________________ Gary Burnett Committee Member Approved: _______________________ Lawrence C. Dennis, Dean College of Information The Office of Graduate Studies has verified and approved the above named committee members. ii ACKNOWLEDGEMENTS This dissertation was possible in large part because of the guidance of my committee members, and I want to express my deep appreciation of their help during all stages of the process. Dr. Michael Burmester assisted me immensely with all issues mathematic and cryptographic. Dr. Gary Burnett eased me into compliance with the English language, and in many ways increased the overall usability of this usability research. Dr. John Carlo Bertot graciously provided methodological guidance throughout the development of the research. Finally, the Chairman of my committee, Dr. Charles McClure was by far my greatest source of guidance and encouragement. I am grateful to all the participants of this study. I demanded a lot from them to complete eleven distinct steps and to use passwords that were far longer than usual. They must remain anonymous to the reader, even if their passwords cannot. I owe much gratitude to the many friends and colleagues who have helped me during my studies. They include such computer scientists as Leo Kermes, Sahil Cooner, Dr. Peter Jorgensen, Keeffee Haynes, and Dr. Breno DeMedeiros; such colleagues and teachers as Linda Most, Tommy Snead, David Miner, Dr. Corrine Jorgensen, and Dr. Darrell Burke. The highest gratitude belongs to Judie Mulholland, who inspired me to go for the doctorate and helped me in countless ways. I would also like to thank my friends and family, who know full well what they have gone through, for all their support. Special thanks and love always to my dedicated parents, Robert and Janet Henry, who encouraged me from higher and drier regions. iii TABLE OF CONTENTS List of Tables ..................................................................................................................................v List of Figures .............................................................................................................................. vii Abstract ....................................................................................................................................... viii 1. INTRODUCTION ....................................................................................................................1 2. LITERATURE REVIEW .......................................................................................................26 3. METHODOLOGY .................................................................................................................65 4. PASSWORD STRENGTH TESTING ...................................................................................83 5. PASSWORD-GENERATION SCHEME TESTING .............................................................98 6. GENERATION STAGE TREATMENT ASSESSMENT ...................................................121 7. CONCEPTUAL FRAMEWORK ASSESSMENT ...............................................................132 8. CONCLUSION .....................................................................................................................145 APPENDIX A: GLOSSARY ......................................................................................................165 APPENDIX B: HUMAN SUBJECTS APPROVAL ..................................................................168 APPENDIX C: THINK-ALOUD PROTOCOL .........................................................................169 APPENDIX D: FINAL QUESTIONNAIRE ..............................................................................172 APPENDIX E: GROUP 1 PROTOCOL ....................................................................................173 APPENDIX F: GROUP 2 PROTOCOL .....................................................................................176 APPENDIX G: GROUP 3 PROTOCOL ....................................................................................180 APPENDIX H: GROUP 4 PROTOCOL ....................................................................................183 REFERENCES ...........................................................................................................................187 BIOGRAPHICAL SKETCH ......................................................................................................197 iv LIST OF TABLES Table 2.1: Computation times with a PDP-11/70 .........................................................................33 Table 2.2: The Effect of Search Space on Cracking Time ...........................................................35 Table 2.3: Attack Times versus Password Length ........................................................................35 Table 2.4: Attack Times on Representative Passwords ................................................................36 Table 2.5: Password Restrictions of Common Operating Systems ..............................................38 Table 2.6: Frequency of English Letters .......................................................................................42 Table 2.7: Frequency of Numbers in Written English ..................................................................43 Table 2.8: Frequencies of English letters at Word Boundaries ....................................................43 Table 2.9: The Effect of Search Space on Entropy .......................................................................45 Table 2.10: Results of Password Attacks, by Test Group .............................................................57 Table 2.11: Responses to Email Survey .......................................................................................58 Table 3.1: Research Design ..........................................................................................................66 Table 3.2: Subject Groups by Treatment ......................................................................................69 Table 3.3: Relation of Research Questions to Data Collection Methods .....................................71 Table 4.1: The Effect of Search Space on Entropy .......................................................................89 Table 4.2: Reinhold’s Survey Results ...........................................................................................92 Table 4.3 Engelfriet’s Passphrase Security Scores .......................................................................93 Table 4.5: Entropy Scores of Selected Passwords ........................................................................95 Table 5.1: Analysis of Five Password-generation Schemes .......................................................103 Table 5.2: Selected Passwords by Generation Scheme ..............................................................106 Table 5.3: Study Passwords by Scheme .....................................................................................107 Table 5.4: Authentication Failure Rate by Scheme ....................................................................111 v Table 5.5: Manual Password Resets ...........................................................................................112 Table 5.6: Participants completing each Step .............................................................................113 Table 5.7: Dropouts by Scheme ..................................................................................................113 Table 5.8: Password Generation Scheme by Reason ..................................................................116 Table 5.9: Plaintext Password Failure by Scheme ......................................................................118 Table 5.10: Final Scheme Choice ...............................................................................................119 Table 6.1: Participants completing each Step .............................................................................122 Table 6.2: Subject Groups by Treatment ....................................................................................124 Table 6.3: Authentication Failure Rate by Group .......................................................................126 Table 6.4: Password Resets by Group ........................................................................................130 Table 7.1: Episodic v. Semantic Memory ...................................................................................134
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