[OWASP_PHPSEC] [Offtopic] Decrypting information out of an image

Maarten Hoogveld m.hoogveld at elevate.nl
Fri Oct 4 09:10:51 UTC 2013

Hi Shivam,

You could dive into converting the image in a 2-D array of intensity values
and maybe even extracting the R, G and B channels separately. Then analyze
that data for patterns and slight deviations which could indicate
steganography of some sort.
However, I would first pick the low hanging fruit and just look at the
image. I see that the image is white with a very light grid. You could try
to load the image in gimp <http://www.gimp.org/> or
paint.net<http://www.getpaint.net/>and see if you can see something
more when you zoom in so you can see
individual pixels or adjust contrast, etc.
Good luck!

Met vriendelijke groet, Kind regards,
Maarten Hoogveld
Elevate BV

On Thu, Oct 3, 2013 at 10:08 PM, Shivam Dixit <shivamd001 at gmail.com> wrote:

> Hello all
> Not much discussions on this list nowdays, so I thought of sharing one of
> the questions which I came across recently in college CTF, and was unable
> to solve it.
> The question is the image below :
> https://docs.google.com/file/d/0B4G8EjUmqNchUlg1cGI3UFl4SEE/edit?usp=sharing
> (Image is white, with some grids)
> I have to decrypt some information out of it. I am not able to think from
> where to start. I am *not* good at Image processing. Please give me some
> suggestions on how to start ?
> --
> *Cheers,*
> *Shivam*
> _______________________________________________
> OWASP_PHP_Security_Project mailing list
> OWASP_PHP_Security_Project at lists.owasp.org
> https://lists.owasp.org/mailman/listinfo/owasp_php_security_project
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