DEF CON 18 Crypto Challenge Ciphertexts • About Ⓘ

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DEF CON 18 Crypto Challenge Ciphertexts

This is some of the source material for G. Mark Hardy’s DEF CON 18 Crypto Challenge. It’s obviously not possible to archive the contest exactly, so I’m just going to provide the pertinent ciphertexts and clues here. I’ll keep them hidden (blue on blue) so that you can’t accidentally see the next stage until you actively highlight the text.

Try not to look too far ahead, because even the intervening text may give too much away.

First Ciphertext

The first stage had participants looking for “Gold” on the DEF CON CD. Eventually, a diligent searcher was expected to find a folder in the Speakers directory called “William-LeGrand,” with only a single file inside. No presentations, no supporting information, just the single file called “au.bug” (Au, of course, being the chemical symbole for the element Gold). Note that both the file name, and the folder it’s sitting in, are clues that can be searched for on the internet to get some additional insights into the first puzzle’s solution.


Hidden Message

The eventual result of the previous stage was to lead you back to G. Mark’s presentation. The plan had been for the PDF to be locked such that you needed a password to search, highlight, or do other operations on it, but they weren’t able to make that happen due to (as I understand it) policies from the company who mastered the CD. So this step was probably easier than it was supposed to be. The result from the last stage should have lead you to the file, given you a password, and given you a hint which, when googled, would have told you the text to search for.

Congratulations. You have just discovered the secret message. Your patience has been rewarded.
Go to my website subdirectory reciprocal of this page number to six places.

Website Clue

The above clue was on page 47. So, once you’ve figured out the clue, and gone to G. Mark Hardy’s website, you’d get the next stage of the puzzle.


Email Response

After solving the second crypto puzzle, you’d be instructed to send an email to another G. Mark address for another clue. In case you didn’t get the clue quite right, you could also get a message from the website. I’ll give both — the website helper clue, and the actual emailed response.

Web “almost, but not quite” clue:

Good job on the research.
Bad job on the contacting.
Think of another way
To use this number
To contact the dead.

Email response:

You're almost there.
People have been asking who is this man since the year bin Laden was born.
He has vowed to stop the motor of the world.
His location is highly classified.
But I bet you can find him.
Find the city that bears his name.
Dial his highly classified phone number there.
You will learn the answer.

That was the last bit. Everything you need to make the final leap is in that clue. Once you think you’ve figured it out, go back to my writeup and see if you were right. Good luck, this was the hardest step to make!