THC Steganographic Challenge

Introduction

The Hacker's Choice has set up a steganographic challenge divided into 6 stages. It is your task to complete each stage by investigating, analyzing and extracting steganographically embedded content hidden in the web site www.thc.org.

If you complete a stage, you will receive further instructions and get information on how to enter the highscore below. You will win a very nice prize if you solve stage 6. We will ship the prize for free, wherever you live.

That's it. There are no further instructions or a registration. Your task is to work with this little information. Proof real skills and gain the fame you deserve. Give it a try. Stage 1, 2 and 3 are really easy to solve! Hunt for the hidden information!

Who will be the first that reaches stage 1? Who can continue to stage 2? Who will be king of the hill and rule?

Solution

The steganographic challenge has been officially terminated on the 9th of August 2004. The Hacker's Choice hopes you had some fun and a great time. Following is the solution to all 6 available stages.

Stage 1-5

Stage	1	2	3	4	5
Stegotext Image
Embedded Message	msg1.txt	msg2.txt	msg3.txt	msg4.txt	msg5.txt
Steganographic Algorithm	JSteg	Steghide	JPHide & Seek	Outguess	F5
Steganographic Password		milandri	fielding	starkwell	massaro

Stage 6

Message 5 contains the following text

   0791c8c7 311bb69c 729936e4 79e13dd6 af48ad03 9299bdb6 fe66df50 ed8afc5f
   c0b484c3 8c491813 0f8cab98 ac80d6a0 36015b4f 0eeaed2c e548bc7e ecddca2a
   ec69ae4e db6ac442 2808778b 194cf54b fc28a96f 686c2553 89fa626d f17ec34d
   3ba3844c ba0f4341 5fa79c3c d3da6d8b 40e925c9 c2b13d05 469d3e6f c0ca4ea4
   e1eb4a03 3929e358 9669d2b7 b5262ea1 d1cdc8eb 2360edb4 ec76e9e7 8d561b5e
   acfdf632 ae56c407

• The cipher used to encrypted the message is the non-American clone of DES.
• The key that was used to encrypt the message is an English synonym in lower case letters.
• The key for the encrypted content is 256 bit wide containing one ASCII character per 32 bit little-endian integer

It is obvious that the above text was encrypted using the Soviet GOST cipher (gost.c). A bruteforce attack over a dictionary with 8 letter, lower case, English words (about 8h) reveals the key "autobahn".

The final message in plaintext looks like this

   536d6172 742e204b 75646f73 20746f20 796f752e 20496620 796f7520 73656e64
   20746865 20776f72 64202764 72616b65 2f72696e 67270a74 6f20506c 61736d6f
   6964203c 706c6173 6d6f6964 40746863 2e6f7267 3e2c2049 2077696c 6c207365
   6e642079 6f752061 20726561 6c0a6765 726d616e 20626565 7220666f 72206672
   65652e20 486f6e65 73746c79 21205468 61742773 20796f75 72207072 697a652e
   20202020 0a00474f

   Smart. Kudos to you. If you send the word 'drake/ring'
   to Plasmoid <plasmoid@thc.org>, I will send you a real
   german beer for free. Honestly! That's your prize. 

News

*2004-08-09
Official end of the Steganographic Challenge
We hope you had some fun and like to tease you for the upcoming Cryptographic Challenge.

* 2004-04-14
After 14 days Kevin is the second person who reached stage 5.

* 2004-04-06
Please don't mail Plasmoid for hints. If he ever will give tips then for people at stage 4 or 5. ;)

* 2004-04-02
Woah! While the crowd slowly enters stage 1, Aki is currently heading for stage 5.

* 2004-04-01
Only 4 hours after starting the challenge Aki reached already stage 2. Keep up the good work.

* 2004-04-01
Official start of the Steganographic Challenge.
The challenge starts. Have fun.

* 2004-03-30
The challenge has been prepared and uploaded to the THC web site.

Highscore

Contact

The organizer of the challenge and your contact for questions is Plasmoid (plasmoid at thc dot org). Cheers!

Last Update: 2004-08-09, Plasmoid