Tuesday, May 29, 2012

Wargames.My 2011 - crypto100

Players given this code.


Hint given was : I like big,long and yellow
the first thing came in my mind once read the hint was = banana!!..so the answer/passphrase should be monkey.

I googled a little bit about type of ciphers that need a passphrase/key to decrypt it.
I found vignere ciphers.Then try to use online cracker available to crack it, and wollah~ lucky me :D
Flag is = themonkeyisjumpingaroundinthejungle

Here's a python code made by johnburn to solve this challenge. its a dictionary attack btw.

charset   = 'abcdefghijklmnopqrstuvwxyz'
encoded = 'fvrwslwslswhgacsremfberbubgrihgbtvi'

keys = open("wordlist.txt", "r")
for key in  keys.read().split('\n'):
    message = ''
    for i in range(len(encoded)) :
        p = charset.index(encoded[i])
        k = charset.index(key[i % len(key)])
        if k - p < 0 :
                   message += charset[((p - k) + 26) % len(charset)]
        else :
                   message += charset[(p - k) % len(charset)]
    if message[:-2].count('the')>1:
        print 'The key: ' + key        
        print 'The message: ' + message