The Vigenère cipher is a classic cipher originally developed by Italian cryptographer Giovan Battista Bellaso and published in 1553. It is named after a later French cryptographer Blaise de Vigenère, who had developed a stronger autokey cipher (a cipher that incorporates the message of the text into the key). 

The cipher is easy to understand and implement, but survived three centuries of attempts to break it, earning it the nickname "le chiffre indéchiffrable" or "the indecipherable cipher."

[From Wikipedia](https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher):

> The Vigenère cipher is a method of encrypting alphabetic text by using a series of different Caesar ciphers based on the letters of a keyword. It is a simple form of polyalphabetic substitution.
>
> . . .
>
> In a Caesar cipher, each letter of the alphabet is shifted along some number of places; for example, in a Caesar cipher of shift `3`, `A` would become `D`, `B` would become `E`, `Y` would become `B` and so on. The Vigenère cipher consists of several Caesar ciphers in sequence with different shift values.

Assume the key is repeated for the length of the text, character by character. Note that some implementations repeat the key over characters only if they are part of the alphabet -- **this is not the case here.**

The shift is derived by applying a Caesar shift to a character with the corresponding index of the key in the alphabet.

Visual representation:
Write a class that, when given a key and an alphabet, can be used to encode and decode from the cipher.

## Example
Any character not in the alphabet must be left as is. For example (following from above):

Difficulty: MEDIUM
Tags: String algorithms

Starter code:
def __init__(self, key, alphabet):
	

Solutions:
from itertools import cycle

class VigenereCipher(object):

	def __init__(self, key, alphabet):
		self.key = key.decode('utf-8')
		self.alphabet = alphabet.decode('utf-8')

	def cipher(self, mode, str):
		return ''.join((self.alphabet[(self.alphabet.index(m) + mode * self.alphabet.index(k)) % len(self.alphabet)] if m in self.alphabet else m for (m, k) in zip(str.decode('utf-8'), cycle(self.key)))).encode('utf-8')

	def encode(self, str):
		return self.cipher(1, str)

	def decode(self, str):
		return self.cipher(-1, str)


class VigenereCipher(object):

	def __init__(self, key, alphabet):
		self.key = key.decode('utf-8')
		self.alphabet = alphabet.decode('utf-8')
		self.maps = {c: self.alphabet[i:] + self.alphabet[:i] for (i, c) in enumerate(self.alphabet) if c in self.key}

	def code(self, f, s):
		return ''.join([f(self.maps[self.key[i % len(self.key)]], c) for (i, c) in enumerate(s.decode('utf-8'))]).encode('utf-8')

	def encode(self, s):
		return self.code(lambda l, c: l[self.alphabet.index(c)] if c in self.alphabet else c, s)

	def decode(self, s):
		return self.code(lambda l, c: self.alphabet[l.index(c)] if c in self.alphabet else c, s)


from itertools import cycle, islice
from unicodedata import normalize

def chunks(lst, chunk_size):
	return [lst[i:i + chunk_size] for i in range(0, len(lst), chunk_size)] if chunk_size != 1 else lst

class VigenereCipher(object):

	def __init__(self, key, alphabet):
		self.charsize = len(key) / len(key.decode('utf-8'))
		seq = chunks(list(islice(cycle(key), len(alphabet))), self.charsize)
		seq = [''.join(s) for s in seq]
		self.ab = chunks(alphabet, self.charsize)
		self.key = [self.ab.index(x) for x in seq]

	def caesar(self, c, shift):
		try:
			return self.ab[(self.ab.index(c) + shift) % len(self.ab)]
		except ValueError:
			return c

	def encode(self, str):
		seq = [self.caesar(c, self.key[index]) for (index, c) in enumerate(chunks(str, self.charsize))]
		return ''.join(seq)

	def decode(self, str):
		seq = [self.caesar(c, -self.key[index]) for (index, c) in enumerate(chunks(str, self.charsize))]
		return ''.join(seq)


class VigenereCipher(object):

	def __init__(self, key: str, alphabet: str):
		self.alphabet = list(alphabet)
		self.key = [alphabet.index(i) for i in key]

	def encode(self, text):
		return ''.join([self.alphabet[(self.alphabet.index(text[i]) + self.key[i % len(self.key)]) % len(self.alphabet)] if text[i] in self.alphabet else text[i] for i in range(len(text))])

	def decode(self, text):
		return ''.join([self.alphabet[(self.alphabet.index(text[i]) - self.key[i % len(self.key)]) % len(self.alphabet)] if text[i] in self.alphabet else text[i] for i in range(len(text))])


class VigenereCipher(object):

	def __init__(self, key, alphabet):
		self.key = key * 10
		self.alphabet = alphabet * 2

	def encode(self, text):
		encrypted = ''
		a = 0
		for i in text:
			if i in self.alphabet:
				encrypted += self.alphabet[self.alphabet.index(i) + self.alphabet.index(self.key[a])]
				a += 1
			else:
				encrypted += i
				a += 1
		return encrypted

	def decode(self, text):
		decrypted = ''
		a = 0
		for i in text:
			if i in self.alphabet:
				decrypted += self.alphabet[self.alphabet.index(i) - self.alphabet.index(self.key[a])]
				a += 1
			else:
				decrypted += i
				a += 1
		return decrypted


class VigenereCipher(object):
	cipherMap = {}
	invCipherMap = {}
	alphabet = ''
	lenAlphabet = -1
	key = ''
	lenKey = -1

	def __init__(self, key, alphabet):
		self.key = key
		self.lenKey = len(self.key)
		self.alphabet = alphabet
		self.lenAlphabet = len(self.alphabet)
		self.cipherMap = dict(list(enumerate(self.alphabet)))
		self.invCipherMap = {val: key for (key, val) in list(self.cipherMap.items())}

	def __performVigenereCipher__(self, text, performEncode):
		lenText = len(text)
		encodedText = ''
		for i in range(lenText):
			curChar = text[i]
			keyChar = self.key[i % self.lenKey]
			if curChar in self.alphabet:
				charVal = self.invCipherMap[curChar]
				keyVal = self.invCipherMap[keyChar]
				if performEncode:
					valEncoded = (charVal + keyVal) % self.lenAlphabet
				else:
					valEncoded = (charVal - keyVal) % self.lenAlphabet
				encodedChar = self.cipherMap[valEncoded]
			else:
				encodedChar = curChar
			encodedText += encodedChar
		return encodedText

	def encode(self, text):
		performEncode = True
		encodedText = self.__performVigenereCipher__(text, performEncode)
		return encodedText

	def decode(self, text):
		performEncode = False
		decodedText = self.__performVigenereCipher__(text, performEncode)
		return decodedText


class VigenereCipher(object):

	def __init__(self, key, alphabet):
		self.alphabet = alphabet
		self.key = key

	def encode(self, text):
		mx = []
		for i in range(len(text)):
			try:
				shift = self.alphabet.index(self.key[i % len(self.key)])
				start = self.alphabet.index(text[i])
				mx.append(self.alphabet[(start + shift) % len(self.alphabet)])
			except:
				mx.append(text[i])
		return ''.join(mx)

	def decode(self, text):
		mx = []
		for i in range(len(text)):
			try:
				shift = self.alphabet.index(self.key[i % len(self.key)])
				start = self.alphabet.index(text[i])
				mx.append(self.alphabet[(start - shift) % len(self.alphabet)])
			except:
				mx.append(text[i])
		return ''.join(mx)


from itertools import cycle

class VigenereCipher(object):

	def __init__(self, key: str, alphabet: str) -> None:
		self.key = key
		self.alphabet = alphabet

	def cipher(self, m: int, s: str) -> str:
		r = ''
		for (i, j) in zip(s, cycle(self.key)):
			if i in self.alphabet:
				r += self.alphabet[(self.alphabet.index(i) + m * self.alphabet.index(j)) % len(self.alphabet)]
			else:
				r += i
		return r

	def encode(self, s: str) -> str:
		return self.cipher(1, s)

	def decode(self, s: str) -> str:
		return self.cipher(-1, s)


from itertools import cycle

class VigenereCipher:

	def __init__(self, key, alphabet):
		self.key = key
		self.alphabet = alphabet

	def encode(self, text):
		return ''.join((self.caesar(ch, key_ch, 1) if ch in self.alphabet else ch for (ch, key_ch) in zip(text, cycle(self.key))))

	def decode(self, text):
		return ''.join((self.caesar(ch, key_ch, -1) if ch in self.alphabet else ch for (ch, key_ch) in zip(text, cycle(self.key))))

	def caesar(self, char, key_char, mode=1):
		(char_position, move) = (self.alphabet.find(char), self.alphabet.find(key_char))
		return self.alphabet[(char_position + mode * move) % len(self.alphabet)]


class VigenereCipher(object):

	def __init__(self, key, alphabet):
		self.alphabet = alphabet
		self.key = key

	def encode(self, text):
		clé = self.key
		while len(clé) < len(text):
			clé += clé
			clé = clé[:len(text)]
		chiffre = ''
		for (i, (v, w)) in enumerate(zip(text, clé)):
			if v in self.alphabet:
				chiffre += self.alphabet[(self.alphabet.index(v) + self.alphabet.index(w)) % len(self.alphabet)]
			else:
				chiffre += v
		return chiffre

	def decode(self, text):
		clé = self.key
		while len(clé) < len(text):
			clé += clé
			clé = clé[:len(text)]
		dechiffre = ''
		for (i, (v, w)) in enumerate(zip(text, clé)):
			if v in self.alphabet:
				dechiffre += self.alphabet[(self.alphabet.index(v) - self.alphabet.index(w)) % len(self.alphabet)]
			else:
				dechiffre += v
		return dechiffre