from string import ascii_lowercase

from time import time

import random

class Cipher:

def __init__(self, k=None):

if k:

self.key = _normalize(k)

else:

random.seed(time())

self.key = ''.join(random.choice(ascii_lowercase)

for i in range(100))

def base_encode(self, s, shift):

xkey = self.key * (len(s) // len(self.key) + 1)

return ''.join(shift(c, k) for c, k in zip(s, xkey))

def encode(self, s):

s = _normalize(s)

shift = lambda c, k: chr(((ord(c) + ord(k) - 2 * ord('a'))

% len(ascii_lowercase)) + ord('a'))

return self.base_encode(s, shift)

def decode(self, s):

shift = lambda c, k: chr(((ord(c) - ord(k) + len(ascii_lowercase))

% len(ascii_lowercase)) + ord('a'))

return self.base_encode(s, shift)

class Caesar(Cipher):

def __init__(self):

Cipher.__init__(self, 'd')

def _normalize(s):

return ''.join([c for c in s if c.isalpha()]).lower()

if __name__ == '__main__':

print(Caesar().encode('venividivici'))

print(Caesar().encode('\'Twas the night before Christmas'))