ceaser_cypher.py

"""
A quick ceaser cipher; used to decrypt a message from a mysterious twitter account: https://twitter.com/cryptogram_app
"""
import string

alphabet = string.ascii_lowercase

def decrypt(encryption, key):
    """
    Decrypt a ceaser cypher encrypted message
    """
    plain_text = ''
    encryption = encryption.lower()
    for c in encryption:
        if c== ' ':
            plain_text += c
        else:
            plain_text += alphabet[(alphabet.index(c) + key) % 26]
    return plain_text

for k in range(26):
     print k, decrypt('Sdzl Hmehmhsx', k)

def encrypt(plain_text, key):
    """
    Encrypts a plain text message using a ceaser cyper
    """
    return decrypt(plain_text, -key)

print encrypt('I think I know', 1)
print decrypt(encrypt('I think I know', 1), 1)