Over the Wire - Krypton 3

Krypton 3

Objectives
Well done. You’ve moved past an easy substitution cipher.
The main weakness of a simple substitution cipher is repeated use of a simple key. In the previous exercise you were able to introduce arbitrary plaintext to expose the key. In this example, the cipher mechanism is not available to you, the attacker.
However, you have been lucky. You have intercepted more than one message. The password to the next level is found in the file ‘krypton4’. You have also found 3 other files. (found1, found2, found3)
You know the following important details:

• The message plaintexts are in English (*** very important) - They were produced from the same key (*** even better!)
• 
  

Solution



ok so I used a bit of a cheat on this one, but as long as I have the internet available might as well use it right?

I used the encrypted text of found2 a plugged it into a decrypter which used letter frequency to find the mono-alphabetic key for the text
and found this is the key for this encrption 

Thanks to this site (https://www.guballa.de/substitution-solver)

abcdefghijklmnopqrstuvwxyz 
qazwsxedcrfvtgbyhnujmikolp  

then I got the encrypted key

krypton3@krypton:/krypton/krypton3$ cat krypton4KSVVW BGSJD SVSIS VXBMN YQUUK BNWCU ANMJS

and plugged that into a substitution key

welld oneth eleve lfour passw ordis brutewell done the level four password is bruteBRUTE

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