Matryoshka Dolls: We have a winner!

We have a winner

I want to thank everyone for participating in last week’s puzzle.  I would also like to announce that we have a winner.

ropers was the first (and only) person to successfully reveal the hidden message: “Open the pod bay doors, HAL.”

Hi Zach,

This is a reply to the Matryoshka Dolls Sunday Hacker Puzzle.
The tentative solution/command I've found is:

Open the pod bay doors, HAL.

However, I'm a bit unsure if that's really the <strong>*whole*</strong> solution and
all there is to this riddle -- or if there's yet more to find (see
below).

To get to this point, I have:

1. Recognized the RussianDolls.ppm file as a portable pixmap picture
in binary format with the P6 (0x5036) magic number and looked at it in
the GIMP. I noted that there were eleven red babushkas.

2. Run strings(1) on the .ppm file and looked at the output, where I
saw the Rar! magic number and the secret.txt.gpg file name.

3. Used manual file carving ( cf.
<a href="http://en.wikipedia.org/wiki/File_carving">http://en.wikipedia.org/wiki/File_carving</a> ) to isolate the RAR file.
(This proved unnecessary, as the .ppm will also open just fine as a
RAR if simply renamed to RussianDolls.rar. That's a known phenomenon
and an old trick with both RAR and ZIP files for hosting files at
imageboards.) I extracted the secret.txt.gpg file from the RAR file.

4. Used Scalpel ( <a href="http://www.digitalforensicssolutions.com/Scalpel/">http://www.digitalforensicssolutions.com/Scalpel/</a> )
to automatically care the shit out of RussianDolls.ppm, but all I got
that way was a shed full of .pgp files, which are probably just false
positives.

5. Looked at the RussianDolls.ppm file with a hex editor and noted the
DEADBEEF magic number at 0xe0, which corresponds to pixels 69x0y
(FFFFDE) and 70x0y (ADBEEF). I decrypted the secret.txt.gpg file with
the lowercase deadbeef password and found it to contain the
aforementioned command from "2001: A Space Odyssey" (Stanley Kubrick,
1968) in figlet(6)'s default ASCII art font.

But reading your hints page
<a href="http://thehelpfulhacker.net/2010/02/02/sunday-hacker-puzzle-matryoshka-dolls-hints/">http://thehelpfulhacker.net/2010/02/02/sunday-hacker-puzzle-matryoshka-dolls-hints/</a>
 confused me and made me doubt whether I've found the solution. You
emphasised the visual difference between the original image and your
version. Sure, pixels 69x0y and 70x0y are different from the original
image you referenced, but the most noticeable difference is the
missing shadow and the prominent structure/square to the left of the
largest babushka: <a href="http://i.imgur.com/Vk5R0.png">http://i.imgur.com/Vk5R0.png</a>
But when I calculated the hex offset that corresponds to that location
24x168y -- starting at 0x0y(!) with 345 pixels per row (in this
345x292 picture) and 3 bytes per pixel (in the binary ppm format),
that's 15 bytes (=offset at beginning of file before binary pixel data
starts, occupied by 50 36 0A 33 34 35 20 32 39 32 0A 32 35 35 0A) +
(168(!) rows * 345 columns + 24(!) _more_ columns in the next row) * 3
bytes = (168*345+24)*3+15 = 173967 bytes = 0x2A78F, I didn't find
anything noteworthy there.

So maybe the entire missing shadows and prominent squares are
incidental, and you were really just referring to FFFFDEADBEEF at
pixels 69x0y and 70x0y?

I don't want to get a better chance than anyone else, but maybe you
could publicly drop a hint that might make it clearer at what point
the chase is finished and whether the 2001 quote is the solution
(without giving it away, of course)?

Many thanks and kind regards,
--ropers

As noted, there was some confusion which i cleared up in subsequent posts.

Thanks for playing

I had a great time with this puzzle and really enjoyed the responses from everyone.  I’ve learned how to make these puzzles better.  Hopefully some of you have learned some new skills or put some old ones to the test.

I look forward to doing something like this again, in the near future.  If anyone has requests/suggestions, please let me know - zach@thehelpfulhacker.net