CaesarCipher2.py

#!/usr/bin/python
#CaesarCipher2.py
#Python 2.7

cipher = ''
alphabet = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']

message = raw_input ("What message would you like to encrypt? ... ").lower()
shift = int (input ("What is the shift key? ... "))
for c in message:
    if c.isalpha():
        cipher += alphabet [(alphabet.index (c) + shift) % (len (alphabet))]
    else:
        cipher += c

print cipher