Method for private personal identification number management

• US 7,162,456 B2
• Filed: 06/05/2002
• Issued: 01/09/2007
• Est. Priority Date: 06/05/2002
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: de Jong, Eduard
• Primary Examiner(s): Abdi; Kambiz
• Application Number:
  US10/164,658
• Publication Number:
  US 20030229791A1
• Time in Patent Office: 1,679 Days
• Field of Search: 705/1, 705/67, 705/72, 705/50, 726/6, 726/27, 726/21, 713/180
• US Class Current: 705/72
• CPC Class Codes: G06F 21/31 User authentication
• CPC Class Codes: G06F 21/316 by observing the pattern of computer usage, e.g. typical user behaviour
• CPC Class Codes: G06F 21/604 Tools and structures for managing or administering access control systems
• CPC Class Codes: G06F 2221/2101 Auditing as a secondary aspect
• CPC Class Codes: G06F 2221/2147 Locking files
• CPC Class Codes: G06Q 20/382 insuring higher security of transaction
• CPC Class Codes: G06Q 20/4012 Verifying personal identification numbers [PIN]
• CPC Class Codes: G06Q 30/018 Certifying business or products

Abstract

A method for private personal identification number (PIN) management comprises ascertaining a first delay period of a preceding PIN. The first delay period is greater than zero if the preceding PIN does not match a validated PIN and the first delay period equals zero if the preceding PIN matches the validated PIN. The method also includes receiving a current PIN after at least the first delay period and delaying for a second delay period if the current PIN does not match the validated PIN. The second delay period is greater than the first delay period.

Claims

1. A method for private personal identification number (PIN) management, comprising:

ascertaining whether a first delay period of a preceding PIN has expired wherein said delay period of said preceding PIN is a period of time that must expire before a current PIN can be received, and said first delay period greater than zero if upon said preceding PIN does not matching a validated PIN, said first delay period equal to zero if said preceding PIN matches said validated PIN;

receiving a said current PIN after at least expiration of said first delay period; and

determining whether said current PIN matches said validated PIN; and

delaying for changing said a second delay period to a new delay period longer than said delay period for said preceding PIN if upon said current PIN does not matching said validated PIN, and transferring to said ascertaining, said second delay period greater than said first delay period wherein said current PIN becomes said preceding PIN and said new delay period is said delay period of said preceding PIN upon said changing transferring to said ascertaining so that when said current PIN does not match said validated PIN, before receipt of an another access attempt is permitted said delay period is increased in duration with each successive failed access attempt.

2. The method of claim 1, further comprising granting access to a service having restricted access when said current PIN matches said validated PIN.

3. A method for private personal identification number (PIN) management, the method comprising:

determining whether a delay period for receiving a request for a service has expired;

receiving a first said request for a said service having restricted access upon expiration of said delay period, said first request comprising a first PIN entered by a user;

matching said first PIN with another second PIN that has been validated;

allowing access to said service based at least on said matching;

incrementing an exponent if upon said first PIN does not matching said another second PIN; and

delaying for a said delay period that is based at least on said exponent if upon said first PIN does not matching said another second PIN; and

repeating said determining, said receiving, said matching, said incrementing wherein said incrementing increments said exponent, and delaying until said matching finds a match so that when said PIN does not match said another PIN, before receipt of an another access attempt is permitted, said delay period is increased exponentially in duration with each successive failed access attempt; and

allowing access to said service based at least on said matching.

4. The method of claim 3 wherein said delaying further comprises recording the start of said delay.

5. The method of claim 3 wherein said delaying further comprises recording the end of said delay.

6. The method of claim 5, further comprising resuming said delay if when said end has not been recorded.

7. The method of claim 3, further comprising initializing said exponent to 0 if when said first PIN matches said second another PIN.

8. The method of claim 3 wherein said delaying further comprises:

initializing a counter to the value “

1”

;

left-shifting said counter based at least on the value of said exponent, the least significant bit of said counter being populated with the value “

0”

upon each left-shift operation; and

delaying for a predetermined time and decrementing said counter while said counter is nonzero.

9. The method of claim 3 wherein said delaying further comprises:

initializing a counter to “

1”

;

left-shifting said counter based at least on the value of said exponent, the least significant bit of said counter being populated with the value “

1”

upon each left-shift operation; and

delaying for a predetermined time and decrementing said counter while said counter is nonzero.

10. The method or claim 3 wherein said receiving further comprises:

storing said first PIN in a persistent mutable memory; and

marking said stored first PIN as untested.

11. The method of claim 10 wherein said delaying further comprises:

storing said exponent in said persistent mutable memory before initiation of said delaying; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delay.

12. The method of claim 3 wherein said receiving further comprises:

storing said first PIN in a persistent mutable memory; and

marking said stored first PIN as untested; and

said delaying further comprises;

storing said exponent in said persistent mutable memory upon initiation of said delaying; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delaying.

13. The method of claim 12 wherein said storing said first PIN further comprises:

allocating an entry in a list of entries in said persistent mutable memory; and

storing said first PIN in said allocated entry.

14. The method of claim 12 wherein said matching further comprises marking said stored first PIN with the result of the test.

15. The method of claim 12 wherein said delaying further comprises:

storing said exponent with said stored first PIN;

performing a delay determined by said stored exponent; and

marking said stored first PIN as tested successfully and said delaying completed by setting said stored exponent to 0.

16. A method for private personal identification number (PIN) management wherein the method allows access to any service that is not PIN-protected, the method comprising:

receiving a first access request for a service, said first request comprising a first PIN entered by a user;

allowing access to said service if said service is not PIN-protected;

determining a PIN status if when said service is PIN-protected, said determining including delaying for a delay period, which that increases exponentially with each successive failed access request, before receiving another access request; and

allowing access to said service based at least on said PIN status it when said service is PIN-protected.

17. The method of claim 16 wherein said determining further comprises:

ascertaining a first PIN test result;

indicating a successful PIN status if when said first PIN test result indicates a successful PIN test;

testing said first PIN against a second PIN stored in a memory if when said first PIN test result is unavailable or if when said first PIN test result indicates an unsuccessful PIN test, said second PIN comprising a PIN that has been validated;

ascertaining a second PIN test result after said testing;

indicating a successful PIN status if when said second PIN test result indicates a successful PIN test; and

indicating an unsuccessful PIN status if when said second PIN test result indicates an unsuccessful PIN test.

18. The method of claim 17 wherein

said delaying comprises:

storing an exponent in a persistent mutable memory before initiation of said delaying; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delaying; and

said ascertaining a first PIN test result comprises;

determining the presence of an end-of-delay marker in said persistent mutable memory; and

delaying for a delay period that is based at least on said stored exponent if when said marker is not present in said persistent mutable memory.

19. The method of claim 17 wherein

said delaying comprises:

storing an exponent in a persistent mutable memory before initiation of said delaying; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delaying; and

said ascertaining a second PIN test result is based at least on the presence of said end-of-delay marker in said persistent mutable memory and on the result of said testing.

20. The method of claim 17 wherein

said first PIN test result comprises a flag stored in a non-persistent mutable memory;

and

said second PIN test result comprises a flag stored in a non-persistent mutable memory.

21. The method of claim 20 wherein said flag indicates an unsuccessful PIN test upon initialization of said non-persistent mutable memory.

22. The method of claim 17 wherein said testing further comprises:

incrementing an exponent and delaying a delay period that is based at least on said exponent if when said first PIN does not match said second PIN;

marking a session PIN flag to indicate a successful PIN test if when said first PIN matches said second PIN; and

setting said exponent value to “

0”

if when said first PIN matches said second PIN.

23. The method of claim 17 wherein

said delaying comprises:

storing an exponent in a persistent mutable memory before initiation of said delay, said exponent stored in a last entry of a buffer comprising a plurality of entries, each entry comprising a PIN, an exponent and an attempt reference ID, said attempt reference ID associated with a session used to enter said PIN; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delaying;

said ascertaining a first PIN test result comprises;

determining the presence of said end-of-delay marker in said persistent mutable memory; and

delaying for a delay period that is based at least on said exponent if when said marker is not present in said persistent mutable memory; and

said ascertaining a second PIN test result is based at least on the presence of said end-of-delay marker in said persistent mutable memory and on the result of said testing.

24. The method of claim 23, further comprising delaying for a delay period that is based at least on said exponent of said last entry if when the current delaying has been interrupted.

25. The method of claim 23 wherein said last entry is validated if when said exponent of said last entry is 0.

26. The method of claim 23 wherein said last entry is invalid if when said exponent of said lest entry is nonzero.

27. The method of claim 23, further comprising indicating a previous delay has been interrupted if when the exponent of a buffer entry immediately preceding said last buffer does not equal the exponent of said last buffer entry.

28. The method of claim 23, further comprising indicating said last entry is associated with said current session if when the session ID of said last buffer entry equals the session ID of the current session.

29. The method of claim 23 wherein said testing further comprises:

recording a PIN compare attempt in said buffer;

delaying if when said first PIN does not match the PIN in a validated entry; and

marking a delay result in said buffer.

30. The method of claim 29 wherein said recording further comprises:

determining empty entries in said buffer;

determining the last entered entry in said buffer based at least on the entry number of each entry in said buffer;

creating a new entry comprising an exponent that equals one plus the exponent of said last entered entry;

storing said new entry in one of a said empty entries; and

marking said new entry as the last entry.

31. The method of claim 30 wherein said delaying further comprises:

locating a validated entry in said buffer, said validated entry having an exponent value of 0;

loading the PIN value from said last buffer entry; and

delaying for a delay period that is based at least on said exponent value read from said last entry.

32. The method of claim 29 wherein said marking a delay result further comprises:

copying the buffer entry stored immediately prior to said delaying to create a new entry;

setting the exponent value of said new entry to 0 if when said first PIN equals said second PIN; and

storing said new entry in said persistent mutable memory.

33. The method of claim 17 wherein

said delaying comprises:

storing said exponent in said persistent mutable memory before initiation of said delay, said exponent stored in a last entry of a buffer comprising a plurality of entries, each entry comprising a scrambled PIN, an exponent and an attempt reference ID, said attempt reference ID associated with a session used to enter said PIN; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delaying;

said ascertaining a first PIN test result comprises;

determining the presence of said end-of-delay marker in said persistent mutable memory; and

delaying for a delay period that is based at least on said exponent if when said marker is not present in said persistent mutable memory; and

said ascertaining a second PIN test result is based at least on the presence of said end-of-delay marker in said persistent mutable memory and on the result of said testing.

34. The method of claim 33, further comprising delaying for a delay period that is based at least on said exponent in said last entry if when the current delay has been interrupted.

35. The method of claim 33 wherein said last entry is validated if when said exponent of said last entry is 0.

36. The method of claim 33 wherein said last entry is invalid if when said exponent of said last entry is nonzero.

37. The method of claim 33, further comprising indicating a previous delay has been interrupted if when the exponent of an entry immediately preceding said last does not equal the exponent of said last entry.

38. The method of claim 33, further comprising indicating said last entry is associated with said current session if when the session ID of said last entry equals the session ID of the current session.

39. The method of claim 33 wherein said testing further comprises:

recording a PIN compare attempt in said buffer;

delaying if when a first scrambled PIN does not match a second scrambled PIN that has been validated, said first scrambled PIN comprising said first PIN scrambled with a first key, said second scrambled PIN comprising a second PIN scrambled with said first key, said second scrambled PIN and said first key stored in a validated entry; and

marking a delay result in said buffer.

40. The method of claim 39 wherein said first key comprises a randomized key.

41. The method of claim 39 wherein said first key comprises a session ID.

42. The method of claim 39 wherein said recording further comprises:

determining empty entries in said buffer;

determining the last entered entry in said buffer based at least on the entry number of each entry in said buffer;

creating a new entry comprising a PIN that equals said first PIN, said new entry further comprising an exponent that equals one plus the exponent of said last entered entry. scrambling the PIN of said new entry with a second key;

storing said new entry in one of said empty entries; and

marking said new entry as the last entry.

43. The method of claim 42 wherein said delaying further comprises:

locating said validated entry in said buffer;

loading said first PIN from said last entry;

scrambling said first PIN with said first key to create said first scrambled PIN; and

delaying for a delay period that is based at least on said exponent value read from said last entry.

44. The method of claim 43 wherein said scrambling said first PIN further comprises applying an exclusive “

OR”

operation to said first PIN and said first key.

45. The method of claim 43 wherein said delaying for a delay period further comprises performing a number of unit delays, said number is based at least on said exponent, each of said unit delays comprising:

initializing a result to 0; and

applying a bit-wise exclusive “

OR”

operation to said result, said first scrambled PIN and said second scrambled PIN.

46. The method of claim 39 wherein said marking a delay result further comprises:

copying said PIN compare attempt entry to create a new entry;

setting the exponent value of said new entry to 0 if when said result is 0; and

storing said new entry in said persistent mutable memory.

47. A program storage device readable by a machine, embodying a program of instructions executable by the machine to perform a method for private personal identification number (PIN) management, the method comprising:

ascertaining whether a first delay period of a preceding PIN has expired wherein said delay period of said preceding PIN is a period of time that must expire before a current PIN can be received, and said first delay period greater than zero if upon said preceding PIN does not matching a validated PIN, said first delay period equal to zero if said preceding PIN matches said validated PIN;

receiving a said current PIN after at least expiration of said first delay period; and

determining whether said current PIN matches said validated PIN; and

delaying for changing said a second delay period to a new delay period longer than said delay period for said preceding PIN if upon said current PIN does not matching said validated PIN, and transferring to said ascertaining, said second delay period greater than said first delay period wherein said current PIN becomes said preceding PIN and said new delay period is said delay period of said preceding PIN upon said changing transferring to said ascertaining so that when said current PIN does not match said validated PIN, before receipt of an another access attempt is permitted said delay period is increased in duration with each successive failed access attempt.

48. The program storage device of claim 47, said method further comprising granting access to a service having restricted access when said current PIN matches said validated PIN.

49. A program storage device readable by a machine, embodying a program of instructions executable by the machine to perform a method for private personal identification number (PIN) management, the method comprising:

determining whether a delay period for receiving a request for a service has expired;

receiving a first said request for a said service having restricted access upon expiration of said delay period, said first request comprising a first PIN entered by a user;

matching said first PIN with another second PIN that has been validated;

allowing access to said service based at least on said matching;

incrementing an exponent if upon said first PIN does not matching said another second PIN; and

delaying for a said delay period that is based at least on said exponent if upon said first PIN does not matching said another second PIN; and

repeating said determining, said receiving, said matching, said incrementing wherein said incrementing increments said exponent, and delaying until said matching finds a match so that when said PIN does not match said another PIN, before receipt of an another access attempt is permitted, said delay period is increased exponentially in duration with each successive failed access attempt; and

allowing access to said service based at least on said matching.

50. The program storage device of claim 49 wherein said delaying further comprises recording the start of said delay.

51. The program storage device of claim 49 wherein said delaying further comprises recording the end of said delay.

52. The program storage device of claim 51 wherein said method further comprises resuming said delay if when said end has not been recorded.

53. The program storage device of claim 49 wherein said method further comprises initializing said exponent to 0 if when said first PIN matches said second another PIN.

54. The program storage device of claim 49 wherein said delaying further comprises:

initializing a counter to the value “

1”

;

left-shifting said counter based at least on the value of said exponent, the least significant bit of said counter being populated with the value “

0”

upon each left-shift operation; and

delaying for a predetermined time and decrementing said counter while said counter is nonzero.

55. The program storage device of claim 49 wherein said delaying further comprises:

initializing a counter to “

1”

;

left-shifting said counter based at least on the value of said exponent, the least significant bit of said counter being populated with the value “

1”

upon each left-shift operation; and

delaying for a predetermined time and decrementing said counter while said counter is nonzero.

56. The program storage device of claim 49 wherein said receiving further comprises:

storing said first PIN in a persistent mutable memory; and

marking said stored first PIN as untested.

57. The program storage device of claim 56 wherein said delaying further comprises:

storing said exponent in said persistent mutable memory before initiation of said delaying; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delay.

58. The program storage device of claim 49 wherein said receiving further comprises:

storing said first PIN in a persistent mutable memory; and

marking said stored first PIN as untested; and

said delaying further comprises;

storing said exponent in said persistent mutable memory upon initiation of said delaying; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delaying.

59. The program storage device of claim 58 wherein said storing said first PIN further comprises:

allocating an entry in a list of entries in said persistent mutable memory; and

storing said first PIN in said allocated entry.

60. The program storage device of claim 58 wherein said matching further comprises marking said stored first PIN with the result of the test.

61. The program storage device of claim 58 wherein said delaying further comprises:

storing said exponent with said stored first PIN;

performing a delay determined by said stored exponent; and

marking said stored first PIN as tested successfully and said delaying completed by setting said stored exponent to 0.

62. A program storage device readable by a machine, embodying a program of instructions executable by the machine to perform a method for private personal identification number (PIN) management wherein the method allows access to any service that is not PIN-protected, receiving a first access request for a service, said first request comprising a first PIN entered by a user;

allowing access to said service if said service is not PIN-protected;

determining a PIN status if when said service is PIN-protected, said determining including

delaying for a delay period, which that increases exponentially with each successive failed access request, before receiving another access request; and

allowing access to said service based at least on said PIN status if when said service is PIN-protected.

63. The program storage device of claim 62 wherein said determining further comprises:

ascertaining a first PIN test result;

indicating a successful PIN status if when said first PIN test result indicates a successful PIN test;

testing said first PIN against a second PIN stored in a memory if when said first PIN test result is unavailable or if when said first PIN test result indicates an unsuccessful PIN test, said second PIN comprising a PIN that has been validated;

ascertaining a second PIN test result after said testing;

indicating a successful PIN status if when said second PIN test result indicates a successful PIN test; and

indicating an unsuccessful PIN status if when said second PIN test result indicates an unsuccessful PIN test.

64. The program storage device of claim 63 wherein

said delaying comprises:

storing an exponent in a persistent mutable memory before initiation of said delaying; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delaying; and

said ascertaining a first PIN test result comprises;

determining the presence of an end-of-delay marker in said persistent mutable memory; and

delaying for a delay period that is based at least on said stored exponent if when said marker is not present in said persistent mutable memory.

65. The program storage device of claim 63 wherein

said delaying comprises:

storing an exponent in a persistent mutable memory before initiation of said delaying; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delaying; and

said ascertaining a second PIN test result is based at least on the presence of said end-of-delay marker in said persistent mutable memory and on the result of said testing.

66. The program storage device of claim 63 wherein

said first PIN test result comprises a flag stored in a non-persistent mutable memory;

and

said second PIN test result comprises a flag stored in a non-persistent mutable memory.

67. The program storage device of claim 66 wherein said flag indicates an unsuccessful PIN test upon initialization of said non-persistent mutable memory.

68. The program storage device of claim 63 wherein said testing further comprises:

incrementing an exponent and delaying a delay period that is based at least on said exponent if when said first PIN does not match said second PIN;

marking a session PIN flag to indicate a successful PIN test if when said first PIN matches said second PIN; and

setting said exponent value to “

0”

if when said first PIN matches said second PIN.

69. The program storage device of claim 63 wherein

said delaying comprises:

storing an exponent in a persistent mutable memory before initiation of said delay, said exponent stored in a last entry of a buffer comprising a plurality of entries, each entry comprising a PIN, an exponent and an attempt reference ID, said attempt reference ID associated with a session used to enter said PIN; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delaying;

said ascertaining a first PIN test result comprises;

determining the presence of said end-of-delay marker in said persistent mutable memory; and

delaying for a delay period that is based at least on said exponent if when said marker is not present in said persistent mutable memory; and

said ascertaining a second PIN test result is based at least on the presence of said end-of-delay marker in said persistent mutable memory and on the result of said testing.

70. The program storage device of claim 69 wherein said method further comprises delaying for a delay period that is based at least on said exponent of said last entry if when the current delay has been interrupted.

71. The program storage device of claim 69 wherein said last entry is validated if when said exponent of said last entry is 0.

72. The program storage device of claim 69 wherein said last entry is invalid if when said exponent of said last entry is nonzero.

73. The program storage device of claim 69 wherein said method further comprises indicating a previous delay has been interrupted if when the exponent of a buffer entry immediately preceding said lest buffer does not equal the exponent of said last buffer entry.

74. The program storage device of claim 69 wherein said method further comprises indicating said last entry is associated with said current session if when the session ID of said last buffer entry equals the session ID of the current session.

75. The program storage device of claim 69 wherein said testing further comprises:

recording a PIN compare attempt in said buffer;

delaying if when said first PIN does not match the PIN in a validated entry; and

marking a delay result in said buffer.

76. The program storage device of claim 75 wherein said recording further comprises:

determining empty entries in said buffer;

determining the last entered entry in said buffer based at least on the entry number of each entry in said buffer;

creating a new entry comprising an exponent that equals one plus the exponent of said last entered entry;

storing said new entry in one of said empty entries; and

marking said new entry as the last entry.

77. The program storage device of claim 76 wherein said delaying further comprises:

locating a validated entry in said buffer, said validated entry having an exponent value of 0;

loading the PIN value from said last buffer entry; and

delaying for a delay period that is based at least on said exponent value read from said last entry.

78. The program storage device of claim 75 wherein said marking a delay result further comprises:

creating a new buffer entry that equals the buffer entry stored immediately prior to said delaying;

setting the exponent value of said new entry to 0 if when said first PIN equals said second PIN; and

storing said new entry in said persistent mutable memory.

79. The program storage device of claim 63 wherein

said delaying comprises:

storing said exponent in said persistent mutable memory before initiation of said delay, said exponent stared in the lest entry of a buffer comprising a plurality of entries, each entry comprising a scrambled PIN, an exponent and an attempt reference ID, said attempt reference ID associated with a session used to enter said PIN; and

storing an end-of-delay marker in said persistent mutable memory after completion of said delaying;

said ascertaining a first PIN test result comprises;

determining the presence of said end-of-delay marker in said persistent mutable memory; and

delaying for a delay period that is based at least on said exponent if when said marker is not present in said persistent mutable memory; and

said ascertaining a second PIN test result is based at least on the presence of said end-of-delay marker in said persistent mutable memory and on the result of said testing.

80. The program storage device of claim 79 wherein said method further comprises delaying for a delay period that is based at least on said exponent in said last entry if when the current delay has been interrupted.

81. The program storage device of claim 79 wherein said last entry is validated if when said exponent of said last entry is 0.

82. The program storage device of claim 79 wherein said last entry is invalid if when said exponent of said last entry is nonzero.

83. The program storage device of claim 79 wherein said method further comprises indicating a previous delay has been interrupted if when the exponent of an entry immediately preceding said last does not equal the exponent of said last entry.

84. The program storage device of claim 79 wherein said method further comprises indicating said last entry is associated with said current session if when the session ID of said last entry equals the session ID of the current session.

85. The program storage device of claim 79 wherein said testing further comprises:

recording a PIN compare attempt in said buffer;

delaying if when a first scrambled PIN does not match a second scrambled PIN that has been validated, said first scrambled PIN comprising said first PIN scrambled with a first key, said second scrambled PIN comprising a second PIN scrambled with said first key, said second scrambled PIN and said first key stored in a validated entry; and

marking a delay result in said buffer.

86. The program storage device of claim 85 wherein said first key comprises a randomized key.

87. The program storage device of claim 85 wherein said first key comprises a session ID.

88. The program storage device of claim 85 wherein said recording further comprises:

determining empty entries in said buffer;

determining the last entered entry in said buffer based at least on the entry number of each entry in said buffer;

creating a new entry comprising a PIN that equals said first PIN, said new entry further comprising an exponent that equals one plus the exponent of said last entered entry;

scrambling the PIN of said new entry with a second key;

storing said new entry in one of said empty entries; and

marking said new entry as the last entry.

89. The program storage device of claim 88 wherein said delaying further comprises:

locating said validated entry in said buffer;

loading said first PIN from said last entry;

scrambling said first PIN with said first key to create said first scrambled PIN; and

delaying for a delay period that is based at least on said exponent value read from said last entry.

90. The program storage device of claim 89 wherein said scrambling said first PIN further comprises applying an exclusive “

OR”

operation to said first PIN and said first key.

91. The program storage device of claim 89 wherein said delaying for a delay period further comprises performing a number of unit delays, said number is based at least on said exponent, each of said unit delays comprising:

initializing a result to 0; and

applying a bit-wise exclusive “

OR”

operation to said result, said first scrambled PIN and said second scrambled PIN.

92. The program storage device of claim 85 wherein said marking a delay result further comprises:

copying said PIN compare attempt entry to create a new entry;

setting the exponent value of said new entry to 0 if when said result is 0; and

storing said new entry in said persistent mutable memory.