Caesar's Cipher using python, could use a little help

Question

I\'m trying to make a \"Caesar\'s Cipher\" while using python..this is what I have so far. Could anyone tell me how this is looking? Am I going in the right direction? What

Answer 1

I very simple, 3-shift solution without Umlauts and alike would be:

def caesar(inputstring):
    shifted=string.lowercase[3:]+string.lowercase[:3]
    return "".join(shifted[string.lowercase.index(letter)] for letter in inputstring)

and reverse:

def brutus(inputstring):
    shifted=string.lowercase[-3:]+string.lowercase[:-3]
    return "".join(shifted[string.lowercase.index(letter)] for letter in inputstring)

using it:

caesar("xerxes")

Answer 2

Here is a different method to show how we can handle this in a very clean way. We define an input alphabet and an output alphabet, then a translation table and use unicode.translate() to do the actual encryption.

import string
# Blatantly steal Lennart's UI design
first = unicode(raw_input("Please enter Plaintext to Cipher: "), "UTF-8")
k = int(raw_input("Please enter the shift: "))

in_alphabet = unicode(string.ascii_lowercase)
out_alphabet = in_alphabet[k:] + in_alphabet[:k]

translation_table = dict((ord(ic), oc) for ic, oc in zip(in_alphabet, out_alphabet))

print first.translate(translation_table)

It can be extended to uppercase letters as needed.