1.5 Problem 7

class cipher(object):
    alphabet = 'abcdefghijklmnopqrstuvwxyz'
    cipheralphabet = 'abcdefghijklmnopqrstuvwxyz'

    def __init__(self, key='', type='Null'):
        self.key = key
        self.type = type

    def __str__(self):
        return self.type +  " cipher"

    def encrypt(self, message):
        result = ''
        for ch in message:
            x = self.alphabet.find(ch)
            if x != -1:
                result += self.cipheralphabet[x]
            else:
                result += ch
        return result

    def decrypt(self, message):
        result = ''
        for ch in message:
            x = self.cipheralphabet.find(ch)
            if x != -1:
                result += self.alphabet[x]
            else:
                result += ch
        return result

class cipher (Cipher):

    def __init__(self, key=3, type="Caesar"):
        self.key = key
        self.type = type
        self.cipher_alphabet = self.alphabet[self.key:] + self.alphabet[0:self.key]

caesar = CaesarCipher(3, "Caesar")
secret = caesar.encrypt("hello this is a test")

print (secret)
#khoor wklv lv d whvw

print ( caesar.decrypt(secret))
#hello this is a test

secret = caesar.encrypt("abcdefghijklmnopqrstuvwxyz")

print (secret)

#defghijklmnopqrstuvwxyzabc

print (caesar.decrypt(secret))
#abcdefghijklmnopqrstuvwxyz