You can use unicode instead (I think, you should): Vigenère cipher, see [this](http://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher).  Then please add at the begining of the file comment `# -*- coding: utf-8 -*-`, see [this](https://docs.python.org/2/howto/unicode.html#unicode-literals-in-python-source-code).