The solution of the first Steemit Crypto Challenge

Today i figured out the last part of the crypto challenge, and by doing so i won it. The last question from @timsaid was that i write about it :)

A lot of contribution was done by @rznag who i know well. He asked me to help him with the last part. Also a lot was solved by @raymonjohnstone. So i share the price with @rznag and @raymonjohnstone.

I am pentester and have some forensic knowledge. But that does not mean i know it all or that it was easy.

First a short summary how the challenge progressed till the last question. If you just want to see the solution of the last part, skip to the end of this post.

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The first clue concealed in the cover image is on the bottom right. Using image manipulation software i.e. Photoshop, reveals this hint.

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Now the bin is coming into play. This is a hint to pastebin.com. Using the code from the cover imagine you will find http://pastebin.com/B6Pm52ts

This was solved by @raymonjohnstone

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well done cryptofriend you came one step closer kRS3Slu6TZw

In the pastebin you will find the follwing: kRS3Slu6TZw
@raymonjohnstone came to the conclustion that this is a Youtube link.

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In the comments to the video you will see the next hint. Nh5LTQ2x

@rznag found out that this again is a pastebin with the following message:

I wonder where you got to know from me.
Things will get complicated now

WMS UGJJ YJUYWQ DGLB KC GL RFC NYQR G AYL ZC APCYRCB GL RFC NPCQCLR ZSR RFC DSRSPC AYL LCTCP RYGLR KC UFYR YK G

Write me an Email with the codeword and you will get the final task:

²×žš+\¯*m¡ÈZ–W§æ­‚Š •éšŠWhµÊ&

The first part was finding out what those random letters mean.
It is Caesar Cipher

The Caesar cipher is another example of Roman ingenuity. First described by the Roman historian Suetonius, it     was used by Julius Caesar to communicate secretly with his army: If he had anything confidential to say, he wrote it in cipher, that is, by so changing the order of the letters of the alphabet, that not a word could be made out. If anyone wishes to decipher these, and get at their meaning, he must substitute the fourth letter of the alphabet, namely D, for A, and so with the others."  Suetonius, Life of Julius Caesar

So WMS UGJJ YJUYWQ DGLB KC GL RFC NYQR G AYL ZC APCYRCB GL RFC NPCQCLR ZSR RFC DSRSPC AYL LCTCP RYGLR KC UFYR YK G

becomes

YOU WILL ALWAYS FIND ME IN THE PAST I CAN BE CREATED IN THE PRESENT BUT THE FUTURE CAN NEVER TAINT ME WHAT AM I

The correct answer here? History.

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And this is where i came in

²×žš+\¯*m¡ÈZ–W§æ­‚Š •éšŠWhµÊ&

Should be a email address. Well it looked very odd.

I checked different hashes like sha 1, sha256 etc. but it looked nothing like it.

It did look a little like the output i get when using a encryption method (plugin). i used it on IRC channels. When both parties have the password you get normal text. For outsiders it looks alien. But you need a key for it. So that could not be it.

But it had me thinking. In exchange (mail server) you encode emails with base64. So i played around with that. I did get some results that looked a little like the challenge text.
string base64 -d

echo string base64 gives you something funny that looked like what i found on the pastebin

test | base64 -d
dGVzdAo=

It did not solve it yet tough. @rznag and i already found out the day before that the text was in ISO- 8859-15. We already played with that but did not get the result we needed. That was because we did not think about encoding that night.

So this is what need to be done. (code.txt is the original text with the strange code)

iconv -f utf16 -t iso-8859-15  code.txt > code_iso.txt
base64 code_iso.txt
cat code_iso.txt
steemitcryptochallengeatgooglemaildotcom

So now we have the email address.

You can also do it online at several website. Here is one http://rumkin.com/tools/cipher/base64.php

while i am writing this the next challenge is already underway. https://steemit.com/steemitcryptochallenge/@timsaid/the-steemit-crypto-challenge-2

I had a lot of fun solving it. Good luck to the participants on the current challenge.