# This seems strange

Yesterday, after physics, I looked into my history book and found this strange note:

IMPORTANT SECRET MESSAGE
Dtzw Htruzyjw mfx gjjs jshwduyji. Knsi tzy ymj htwwjhy pjd. F qnyyqj mnsy: nrlzw ity htr xqfxm LRVfn

After I solved the riddle, I felt a bit angry because the message was promoting a website but it was a StackExchange website so everything was ok for me

Can you Find oUt What the name oF the stAckexchange website is? (Tip: you might need imgur)

• Wait... why would you look into your history book after physic? That seems suspicious.... – North Apr 9 '18 at 18:44
• @North i am a student and they are school books. And hints – MEE - Reinstate Monica Apr 9 '18 at 19:49
• in the first image rot13()Gur gvzr qvivqrq ol gur qbyynef tvirf gur ebg xrl jvgu n yvggyr punatr. – Alan Hoover Apr 9 '18 at 22:59
• @AlanHoover yes, but the only way to get there is to have already solved that part :S – WELZ Apr 10 '18 at 0:59

and

using ROT12

you get :

THECORRECTSOLUTIONISQUANTUMCOMPUTINGSTACKEXCHANGE

THE CORRECT SOLUTION IS QUANTUM COMPUTING STACKEXCHANGE

This is my first answer. Sorry if any wrong format, bad english or other mistakes.

• My intended solution was: 1. find out that there is an imgur with the capital leters from the last sentence 2. go to my profile page, click on the Get it in a blue moon (=impossible) question, divide the qid by six, the modulo 26 is 5, 26 - 5=21. This is the intended rot. 3. decrypt the message and go to the page. Take the time (20:56:22) and concat them, modulo 26 gives 14, the 26-14=12, the rot required to decrypt the final message. – MEE - Reinstate Monica Apr 10 '18 at 17:18
• Sorry, but i didn't thought as far as go to your profile. I've tried all method I know with the time (20:56:22) and ended with 14. With 9781 too. And the missing "d" at address look curious. Thanks, I'll be more careful next time. – nathoenk Apr 11 '18 at 2:08

If you take the:

Capital letters from your last sentence (minus the first one C): FUWFA which can be converted to an imgur link by messing with the case http://i.stack.imgur.com/fUwFa.png
Which brings up:

Which brings up:

HvsQcffsqhGczihwcbWgEiobhiaQcadihwbuGhoqySlqvobus

And if you:

Take the Capital letters from the address you get :HQGWEQGS

• I am sorry but this is not the right direction. Maybe there is some other hint in the image allowing you to decrypt the adress. And you also don't explain correctly why you can decrypt it via rot21. – MEE - Reinstate Monica Apr 9 '18 at 17:41
• Ummm why do we exactly have to answer why? Any decipherer can crack that even without a computer by simply brute-forcing it. Also the fact that F stands by itself makes it obvious that F=A or F=I. Using F=A, you can simply decode it very easily. Seems to be an unnecessary step to me to try and explain Why a rot21 works (maybe because it decodes it?) – North Apr 9 '18 at 18:30
• @North but there is an hint inside the question and your solution is not complete if you can't explain why it is correct. Hint: the capitalized characters in the last sentence (except C) give you a new imgur link that will allow you to find out what you need to do (by the way history is a hint too) – MEE - Reinstate Monica Apr 9 '18 at 18:41
• @North you got the right picture. What has something to do with SE and history and impossible... – MEE - Reinstate Monica Apr 9 '18 at 19:51

By decrypting it using rot21 you get:

"Your Computer has been encrypted. Find out the correct key. A little hint: imgur dot com slash GMQai."

This was easily deciphered by finding out that f=a, working backwards from there. Find the opposite of rot6, decrypts it.
Thanks to @Welz, the second imgur picture gives you the rot # it was encrypted to --> "You'll only get sixth... if F=A, that uses a rot6 cipher.

• yes, but it does not contain the hint the last sentence gives and you have not explained why rot21 and what the answer to my question is. – MEE - Reinstate Monica Apr 9 '18 at 17:27
• Fudge I can't go to the imgur website, its blocked for me. – North Apr 9 '18 at 17:28
• this still does not explain why this decryption is correct in the context of the riddle (tip: look at the last sentence) – MEE - Reinstate Monica Apr 9 '18 at 17:33
• Updated the answer @MEE – North Apr 9 '18 at 20:27
• oh There is an shortcut. The sixth on the picture was originally something different 😀 – MEE - Reinstate Monica Apr 10 '18 at 5:23