yuvadm / matasano-cryptopals Goto Github PK

Hi there,

The solution of challenge 4 is another one. I won't quote it here.

Since you are using your challenge3.py file, the ciphers all end up to be the same as used in challenge 3, because of the line:

chrs = [chr(ord(s) ^ i) for s in x.decode('hex')]

Here x always is the same in challenge3.py, though the function parameter is s.

I changed that to (and added a .rstrip() because of the new line character at the end of a line in a file)

s = s.rstrip()

chrs = [chr(ord(l) ^ i) for l in s.decode('hex')]

Then you still need to adapt your scoring.
I used the following function where the index of the letter in NIOATE is the weight/score of the letter.
A hint: Using your own scoring function, you can print out the list of results and search for "now" to get the solution.

ETAOIN = 'etaoinshrdlucmfywgpbvkxqjz'
NIOATE = ETAOIN[::-1]
def characterFrequency(word):
    #letters = filter(lambda x: 'a'<=x<='z' or 'A'<=x<='Z', word)
    #return float(len(letters)) / len(word)
    score = 0
    for l in word.lower():
        if l in NIOATE:
            score += NIOATE.find(l) + 1
    return score

I hope that helps.

Best regards,
normoes