Re: Complex Theoretical One Way Hash Question

Matthew Harrison wrote:
I wish to know if it is possible to embed an MD5 of an image (e.g. a
JPEG) in the image such that the MD5 is human readable in the image AND
is an MD5 of the modified image including the readable MD5.

That is - if I execute an MD5 hash sum off the entire image, that MD5
has will be the same as the MD5 shown in human readable format in the
image (I don't mean a JPEG tag, I mean literally on the image canvas
itself).

The questions:
1. Is it theoretically possible ?
2. Is it feasible ?
3. Has it already been done ?
4. Would other one way hash algorithms be more suited ?


It's possible to find two random 260 byte blocks with the same MD5
starting from any initial hash value, so you can fill a file with n
blocks and have 2^n permutations to work with. If you can get a JPEG,
GIF, etc. decoder to interpret each block as a pixel, you're set. The
compute time will be large; 2^33 operations for each block IIRC, but
probably feasible. There may be some tricks you can pull with other
image or page description formats to interpret each block as a bit and
then hex code it and print it. To keep it interesting you just have to
be careful not to choose a sufficiently advanced filetype that can both
print quines and compute MD5s...

.

Relevant Pages

  • Re: Complex Theoretical One Way Hash Question
    ... JPEG) in the image such that the MD5 is human readable in the image AND ... is an MD5 of the modified image including the readable MD5. ... You can't do this without breaking the hash. ... possible collisions. ...
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  • Re: Complex Theoretical One Way Hash Question
    ... JPEG) in the image such that the MD5 is human readable in the image AND ... is an MD5 of the modified image including the readable MD5. ... That is - if I execute an MD5 hash sum off the entire image, ...
    (sci.crypt)
  • Re: Complex Theoretical One Way Hash Question
    ... JPEG) in the image such that the MD5 is human readable in the image AND ... is an MD5 of the modified image including the readable MD5. ... Would other one way hash algorithms be more suited? ... It is it suppose dto be cryptographically secure, ...
    (sci.crypt)
  • Re: Complex Theoretical One Way Hash Question
    ... JPEG) in the image such that the MD5 is human readable in the image AND ... is an MD5 of the modified image including the readable MD5. ... image depend on the hash; so you have a circular dependency that there ...
    (sci.crypt)
  • Complex Theoretical One Way Hash Question
    ... I wish to know if it is possible to embed an MD5 of an image (e.g. a JPEG) in the image such that the MD5 is human readable in the image AND is an MD5 of the modified image including the readable MD5. ... That is - if I execute an MD5 hash sum off the entire image, that MD5 has will be the same as the MD5 shown in human readable format in the image. ... Would other one way hash algorithms be more suited? ...
    (sci.crypt)
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