import base64 
base64.b64encode("49276d206b696c6c696e6720796f757220627261696e206c696b65206120706f69736f6e6f7573206d757368726f6f6d".decode("hex"))

from itertools import cycle

def xor_mb(message, key):
    return''.join(chr(ord(m_byte)^ord(k_byte)) for m_byte,k_byte in zip(message, cycle(key)))

xor_mb("1c0111001f010100061a024b53535009181c".decode('hex'), "686974207468652062756c6c277320657965".decode('hex')).encode('hex')

from collections import Counter
message = "1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736".decode('hex')
cnt = Counter(message)
cnt.most_common(3)
for vv in cnt.most_common(7):
    for char in "ETAOIN SHRDLU".lower():
        key = chr(ord(vv[0]) ^ ord(char))
        print key, xor_mb(message, key)

import string
from collections import Counter
from itertools import cycle

def xor_mb(message, key):
        return''.join(chr(ord(m_byte)^ord(k_byte)) for m_byte,k_byte in zip(message, cycle(key)))

printset = set(string.printable)
messages = open("4.txt", 'r').readlines()

for line in messages:
    message = line.rstrip().decode('hex')
    cnt = Counter(message)
    for vv in cnt.most_common(3):
            for char in "ETAOINSHRDLU".lower():
                key = chr(ord(vv[0]) ^ ord(char))
                temp = xor_mb(message, key)
                if set(temp).issubset(printset) and temp[-1] == "\n":
                    print key, temp

import math
import string

from collections import Counter
from itertools import cycle


# Source http://jsbin.com/kaxoxajige/1/edit?js,output
expected = [0.08167,0.01492,0.02782,0.04253,0.12702,0.02228,0.02015,0.06094,0.06966,0.00153,0.00772,
0.04025,0.02406,0.06749,0.07507,0.01929,0.00095,0.05987,0.06327,0.09056,0.02758,0.00978,
0.02360,0.00150,0.01974,0.00074]


# Source -h https://hflog.wordpress.com/2014/04/01/how-to-perform-a-chi-squared-goodness-of-fit-test-in-python

def gf(x):
    #Play with these values to adjust the error of the approximation.
    upper_bound=100.0
    resolution=1000000.0    
    step=upper_bound/resolution
    val=0
    rolling_sum=0
    while val<=upper_bound:
        rolling_sum+=step*(val**(x-1)*2.7182818284590452353602874713526624977**(-val))
        val+=step
    return rolling_sum


def ilgf(s,z):
    val=0
    for k in range(0,100):
        val+=(((-1)**k)*z**(s+k))/(math.factorial(k)*(s+k))
    return val


def chisquarecdf(x,k):
    return 1-ilgf(k/2,x/2)/gf(k/2)


def chisquare(observed_values,expected_values):
    test_statistic=0
    for observed, expected in zip(observed_values, expected_values):
        test_statistic+=(float(observed)-float(expected))**2/float(expected)
    df=len(observed_values)-1
    return test_statistic, chisquarecdf(test_statistic,df)


def frequency(message):
    message = message.lower().strip(" ")
    freq = []
    length = len(message)
    for char in "abcdefghijklmnopqrstuvwxyz":
        freq.append(float(message.count(char)) / length)
    return freq


def xor_mb(message, key):
        return''.join(chr(ord(m_byte)^ord(k_byte)) for m_byte,k_byte in zip(message, cycle(key)))


printset = set(string.printable)
messages = open("4.txt", 'r').readlines()


for line in messages:
    message = line.rstrip().decode('hex')
    for key in range(0 ,256):
        temp = xor_mb(message, chr(key))
        temp_freq = frequency(temp)
        chi, tt = chisquare(temp_freq, expected)
        print chi, tt, temp

 def xor_mb(message, key):
        return''.join(chr(ord(m_byte)^ord(k_byte)) for m_byte,k_byte in zip(message, cycle(key)))

plain = """Burning 'em, if you ain't quick and nimble
I go crazy when I hear a cymbal"""
xor_mb(plain, "ICE").encode('hex')