in reply to Regex Match for 3 repeated word characters

Does your bank realize that rule 3 makes passwords easier to guess/crack? Forcing at least one numeric character greatly reduces the search space as well.

Abigail

  • Comment on Re: Regex Match for 3 repeated word characters

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Re: Re: Regex Match for 3 repeated word characters
by antirice (Priest) on May 08, 2003 at 03:49 UTC
    Abigail is correct and as such is my time for fun with math (woohoo!). 

    Number of possible passwords lost by forcing one character to be alpha
+: 1111100000000
Number of possible passwords lost by forcing one character to be numer
+ic: 9.92461065750669e+16
Number of possible passwords lost by forcing at least one character to
+ be alpha and one to be numeric: 9.92472176750669e+16

    [download]
    Hmmm...that's quite a few passwords.

    Updated: Doing math after 10PM isn't one of my strong points.

    antirice    
    The first rule of Perl club is - use Perl
    The     ith rule of Perl club is - follow rule i - 1 for i > 1

[reply]
[d/l]

      The number isn't quite that high. Consider: 

      Total Possible - Actual Possible = Total Lost
(36^8 + 36^9 + 36^10 + 36^11 + 36^12) - ((36^6 + 36^7 + 36^8 + 36^9 + 
+36^10)*10*26) = TL
36^6 * ((36^2 + 36^3 + 36^4 + 36^5 + 36^6) - ((36^0 + 36^1 + 36^2 + 36
+^3 + 36^4)*10*26)) = TL
36^6 * (2,238,976,080 - 449,177,300) = TL
3,896,002,369,298,350,080 = Total Lost

      [download]

      Although 19 digits is hardly a trivial amount (-:

[reply]
[d/l]
Re: Re: Regex Match for 3 repeated word characters
by hsweet (Pilgrim) on May 08, 2003 at 14:20 UTC
    Never thought of that. Maybe they had trouble parsing those characters or didn't think it all the way through

    Time flies like an arrow, fruit flies like banannas

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