Re: CRC32 vd MD5

From: andrea.glorioso@binary-only.com
Date: Sun Jan 05 2003 - 02:42:48 PST

  • Next message: David Pick: "Re: CRC32 vd MD5"

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    >>>>> "jm" == admin  <adminat_private> writes:
    
        jm> Furthermore, would it be realistically possible to change data
        jm> in  an image whose   authenticity   is based solely on   CRC32
        jm> value(s) without changing the  values in question, and thereby
        jm> arousing suspicion?
    
    CRC32 is not a cryptographic hash, and it's  immunity to tampering and
    forging is quite weak.   I'm  not a  cryptographic expert, so  I can't
    expose the whys and hows of the tampering process,  but a quick search
    on google revealed this:
    
    - - http://perlmonks.thepen.com/112024.html
    
      "The code below takes an arbitrary string, and adds some junk on the
      end of it to make the CRC come out to any arbitrary value."
    
    So it doesn't seem so  hard to tamper with the  file content and still
    have  a "valid" crc32 checksum.   I personally wouldn't use crc32-only
    based FIDS.
    
    Best regards,
    
    - --
    Andrea Glorioso                   andrea.glorioso@binary-only.com
    Binary Only                           http://www.binary-only.com/
    Via A. Zanolini, 7/b                  Tel:     +39-348.921.43.79
    40126 Bologna                         Fax:     +39-051-930.31.133
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