Jeremy Clark Panic Passwords: Authenticating under duress Urs Hengartner
© Universal Pictures International 2007. Used under the fair dealings clause in the Canada Copyright Act.
Outline <ul><li>Definitions </li></ul><ul><li>Threat Model: </li></ul><ul><ul><li>Dimensions </li></ul></ul><ul><ul><li>As...
Definitions Password Space
Definitions Password Space Regular
Definitions Password Space Regular Panic
Definitions Password Space Regular Panic Invalid
literature review
Literature Review <ul><li>No thorough attention from the  academic community </li></ul><ul><li>Off-the-shelf  alarm system...
a threat model
Participants <ul><li>Alice:  subject entering her password </li></ul><ul><li>Bob:  entity receiving Alice’s password </li>...
Assumptions <ul><li>Kerckhoffs' principle:  Oscar knows system </li></ul><ul><li>Observational principle:  Oscar sees pass...
Parameter 1: Coercion <ul><li>Oscar threatens Alice with  retribution  if he can determine that Alice entered a panic pass...
Parameter 1: Coercion <ul><li>If Oscar cannot tell if Alice enters a panic password, then Alice cannot prove to him, for m...
Parameter 2: Persistence <ul><li>Oscar could be  persistent  in his attack </li></ul><ul><li>Oscar could have a limited ti...
Parameter 3: Bob’s Action <ul><li>Bob could take some server-side,  unobserved reaction  upon receiving a panic password <...
Parameter 4: Oscar’s Goal <ul><li>Oscar may want to  prevent  a panic password from being entered  at all </li></ul><ul><l...
some categories of attacks
Unrecoverable reactions  B $
Unrecoverable reactions <ul><li>Oscar wants to gain entry to a premise secured with an alarm </li></ul><ul><li>Alice can d...
2P System Password Space Regular Panic Invalid
Unrecoverable reactions  B $
Non-Persistent Attacks  A B B $
Non-Persistent Attacks <ul><li>An ATM issues marked bills if a panic PIN is entered </li></ul><ul><li>Oscar can tell the d...
Non-Persistent Attacks  A B B $
2P-Lock System Password Space Regular Panic Invalid
2P-Lock System Within a window of time: No Lock Lock upon second password Lock upon second password No Lock
2P-Lock System Within a window of time: No Lock Lock upon second password Lock upon second password No Lock Different set ...
Persistent Attacks  A B B $
Persistent Attacks <ul><li>An online voting system spoils any ballots that are cast using a panic password </li></ul><ul><...
Persistent Attacks  A B B $
P-Compliment System Password Space Regular Panic
P-Compliment System Password Space Regular Panic
Password Space Regular Panic Invalid
Password Space Regular Panic Invalid
Alice knows: 1 regular and 1 rule for separating panic from invalid Regular Panic Invalid
A System  A B B $
concluding remarks
Future Directions <ul><li>Expand the  parameters  for the threat model </li></ul><ul><li>Find new  rules  for unlimited pa...
Concluding Remarks
Questions?
 
Title <ul><li>Body </li></ul>  A B B $
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HotSec 2008 Presentation

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"Panic Passwords: Authenticating under Duress" by Jeremy Clark and Urs Hengartner (University of Waterloo)

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  • Joint work
  • HotSec 2008 Presentation

    1. 1. Jeremy Clark Panic Passwords: Authenticating under duress Urs Hengartner
    2. 2. © Universal Pictures International 2007. Used under the fair dealings clause in the Canada Copyright Act.
    3. 3. Outline <ul><li>Definitions </li></ul><ul><li>Threat Model: </li></ul><ul><ul><li>Dimensions </li></ul></ul><ul><ul><li>Assumptions </li></ul></ul><ul><li>Categories of Attacks </li></ul><ul><li>Concluding Remarks </li></ul>
    4. 4. Definitions Password Space
    5. 5. Definitions Password Space Regular
    6. 6. Definitions Password Space Regular Panic
    7. 7. Definitions Password Space Regular Panic Invalid
    8. 8. literature review
    9. 9. Literature Review <ul><li>No thorough attention from the academic community </li></ul><ul><li>Off-the-shelf alarm systems have built in panic passwords </li></ul><ul><li>Some patents have panic passwords as a component </li></ul><ul><li>They use a basic scheme with limited applicability </li></ul>
    10. 10. a threat model
    11. 11. Participants <ul><li>Alice: subject entering her password </li></ul><ul><li>Bob: entity receiving Alice’s password </li></ul><ul><li>Oscar: adversary coercing Alice </li></ul><ul><li>Assume Bob is trustworthy and not in collusion with Oscar </li></ul>
    12. 12. Assumptions <ul><li>Kerckhoffs' principle: Oscar knows system </li></ul><ul><li>Observational principle: Oscar sees password entered </li></ul><ul><li>Iteration principle: Multiple authentications can be forced </li></ul><ul><li>Forced-randomization principle: Oscar can control the order of passwords to be entered </li></ul>
    13. 13. Parameter 1: Coercion <ul><li>Oscar threatens Alice with retribution if he can determine that Alice entered a panic password </li></ul><ul><li>Called a screening attack or blackmail </li></ul>
    14. 14. Parameter 1: Coercion <ul><li>If Oscar cannot tell if Alice enters a panic password, then Alice cannot prove to him, for money, that she is entering a regular password </li></ul><ul><li>Called signalling or bribery </li></ul>$
    15. 15. Parameter 2: Persistence <ul><li>Oscar could be persistent in his attack </li></ul><ul><li>Oscar could have a limited timeframe in which to conduct his attack and thus be non-persistent </li></ul>Persistent Non-persistent
    16. 16. Parameter 3: Bob’s Action <ul><li>Bob could take some server-side, unobserved reaction upon receiving a panic password </li></ul><ul><li>Bob could respond differently to Alice—a difference that could be observed by Oscar </li></ul>Unobservable Reaction Observable Response A B B
    17. 17. Parameter 4: Oscar’s Goal <ul><li>Oscar may want to prevent a panic password from being entered at all </li></ul><ul><li>Oscar may not care if a panic password is entered, as long as a regular password is entered at some point </li></ul> 
    18. 18. some categories of attacks
    19. 19. Unrecoverable reactions  B $
    20. 20. Unrecoverable reactions <ul><li>Oscar wants to gain entry to a premise secured with an alarm </li></ul><ul><li>Alice can deactivate the alarm with a password </li></ul><ul><li>If Alice uses a panic password, the authorities are alerted </li></ul> B $
    21. 21. 2P System Password Space Regular Panic Invalid
    22. 22. Unrecoverable reactions  B $
    23. 23. Non-Persistent Attacks  A B B $
    24. 24. Non-Persistent Attacks <ul><li>An ATM issues marked bills if a panic PIN is entered </li></ul><ul><li>Oscar can tell the difference after analysing the bills—thus he wants to escape with at least some unmarked bills </li></ul> A B B $
    25. 25. Non-Persistent Attacks  A B B $
    26. 26. 2P-Lock System Password Space Regular Panic Invalid
    27. 27. 2P-Lock System Within a window of time: No Lock Lock upon second password Lock upon second password No Lock
    28. 28. 2P-Lock System Within a window of time: No Lock Lock upon second password Lock upon second password No Lock Different set of bills Same behaviour
    29. 29. Persistent Attacks  A B B $
    30. 30. Persistent Attacks <ul><li>An online voting system spoils any ballots that are cast using a panic password </li></ul><ul><li>Oscar should not be able to coerce Alice’s vote, nor should Alice be able to verifiably sell her vote to Oscar </li></ul> A B B $
    31. 31. Persistent Attacks  A B B $
    32. 32. P-Compliment System Password Space Regular Panic
    33. 33. P-Compliment System Password Space Regular Panic
    34. 34. Password Space Regular Panic Invalid
    35. 35. Password Space Regular Panic Invalid
    36. 36. Alice knows: 1 regular and 1 rule for separating panic from invalid Regular Panic Invalid
    37. 37. A System  A B B $
    38. 38. concluding remarks
    39. 39. Future Directions <ul><li>Expand the parameters for the threat model </li></ul><ul><li>Find new rules for unlimited panic passwords </li></ul><ul><li>A password exchange protocol that can distinguish regular, panic, and invalid passwords (given they will be hashed/MACed) </li></ul><ul><li>Usability studies ! </li></ul>
    40. 40. Concluding Remarks
    41. 41. Questions?
    42. 43. Title <ul><li>Body </li></ul>  A B B $

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