RE: Password Cracking Challenge...

From: Michael Wojcik (Michael.Wojcik_at_microfocus.com)
Date: 07/28/03

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    To: vuln-dev@securityfocus.com
Date: Mon, 28 Jul 2003 14:19:14 -0700

    > From: David Riley [mailto:oscar@the-rileys.net]
    > Sent: Monday, July 28, 2003 4:47 PM
    >
    > It is a good starting point, and that's what I thought of as well.
    > However, the cutoff here seems to be 8 bytes instead of 7. I'm still
    > looking at it, but the encoding of the second chunk seems
    > dependent on the
    > first (e.g. the "321" chunk of "Pa$$word321" is different than that of
    > "Password321".

    That, plus the fact that the first 8 bytes of the hashes for "Password123"
    and "Password321" are the same, suggests to me a 64-bit block cipher running
    in some chaining mode. DES in CBC mode, for example.

    The fact that all the hashes are 128 bits would suggest that the algorithm
    either discards characters after the 16th, or perhaps that it uses the first
    and last block of cipher output as the hash (which would be a little
    better). It'd be nice to have two sample vectors of 17-byte passwords, only
    differing in the 17th byte, to check.

    I'll leave further speculation to the actual cryptanalysts (assuming any of
    them find this sufficiently interesting to bother). 

    -- 
Michael Wojcik
Principal Software Systems Developer, Micro Focus
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