2 files, 2 sizes, identical md5sums - Setup

This is a discussion on 2 files, 2 sizes, identical md5sums - Setup ; Hi, Is it possible to have 2 files that are different sizes, but have the same md5sum value? TIA, -T...

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Thread: 2 files, 2 sizes, identical md5sums

  1. 2 files, 2 sizes, identical md5sums

    Hi,

    Is it possible to have 2 files that are different sizes, but have the
    same md5sum value?

    TIA,
    -T

  2. Re: 2 files, 2 sizes, identical md5sums

    gamename wrote:
    > Hi,
    >
    > Is it possible to have 2 files that are different sizes, but have the
    > same md5sum value?
    >

    Quite possible, though rather unlikely.

  3. Re: 2 files, 2 sizes, identical md5sums


    >Is it possible to have 2 files that are different sizes, but have the
    >same md5sum value?


    Yes, but it's very very ... very unlikely.

    In particular, it's very hard for a bad-guy to make a second file
    with the same md5sum. One idea is to be hard to forge documents
    for example a check with a big payment starting with a valid check,
    or to install malware in software distributions.

    --
    These are my opinions, not necessarily my employer's. I hate spam.


  4. Re: 2 files, 2 sizes, identical md5sums

    On Apr 22, 2:11 pm, gamename wrote:
    > Hi,
    >
    > Is it possible to have 2 files that are different sizes, but have the
    > same md5sum value?
    >
    > TIA,
    > -T


    The odds of this happening are very rare indeed. The md5 hash is
    calculated via a mathematical algorithm and has a set length. I will
    not jump into the finer details of the algorithm, but yes it can
    happen.

    - Dominic Salemno

  5. Re: 2 files, 2 sizes, identical md5sums

    gamename writes:

    >Hi,


    >Is it possible to have 2 files that are different sizes, but have the
    >same md5sum value?


    Yes. Any two files, each of arbitrary size (at least one >40 bytes)
    will have roughly a
    1/1000000000000000000000000000000000000000 chance of having the same MD5
    sum.



    >TIA,
    >-T


  6. Re: 2 files, 2 sizes, identical md5sums

    gamename writes:
    >Is it possible to have 2 files that are different sizes, but have the
    >same md5sum value?


    > Yes. Any two files, each of arbitrary size (at least one >40 bytes) will
    > have roughly a 1/1000000000000000000000000000000000000000 chance of
    > having the same MD5 sum.


    Which means that if you can test a million files a second you will need on
    the order of 10000000000000000000000000 years to find a match.
    --
    John Hasler
    john@dhh.gt.org
    Dancing Horse Hill
    Elmwood, WI USA

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