[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*
>
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