Secret Codes

You can use this program to send secret messages to a friend who also has it, and they can use it to decode the messages so they can understand them.

To get this to work, enter a message and then a number between 0 and 7905853580625 You will then receive a secret code for that message! To decode the message, you need to put in the secret code you got out, with the same number as you put in. If you put in a different number, you will get a different answer!

ask = raw_input


def make_map(i):
    d = {}
    letters = list("abcdefghijklmnopqrstuvwxyz")
    for p in range(25,0,-2):
        k = letters.pop(0)
        i, r = divmod(i, p)
        v = d[k] = letters.pop(r)
        d[v] = k
        V, K = v.upper(), k.upper()
        d[K] = V
        d[V] = K
    return d


def encode(message, n):
    d = make_map(n)
    return ''.join(d.get(c, c) for c in message)


def main():
    message = ask('Enter your message: ')
    number = int(ask('Enter a number: '))
    code = encode(message, number)
    print('Now, you can give your friend the encoded message: %s' % code)
    print('All they need to decode it, is the number you entered above')
    print('And this program :)')


if __name__ == '__main__':
    main()