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+Introducing Py-Enigma
+#####################
+
+:date: 2012-06-06 18:45
+:tags: Python, Py-Enigma, Enigma
+:slug: introducing-py-enigma
+:author: Brian Neal
+
+Py-Enigma
+---------
+
+For some strange reason, I don't even remember why or how, I found myself
+browsing the `Wikipedia page for the Enigma Machine
+<http://en.wikipedia.org/wiki/Enigma_machine>`_. I quickly became fascinated and
+started surfing around some more. I found several Enigma machine simulators,
+some of them even online. It suddenly occured to me that it would be a fun
+project to try and write my own in Python_. I wanted to challenge myself to see
+if I could figure it all without help, so I vowed not to look at anyone else's
+source code.
+
+In order to write an Enigma simulator, you need a really good technical
+explanation of how it worked, along with numerous details like how the rotors
+were wired. Fortunately I very quickly found Dirk Rijmenants' incredible `Cipher
+Machines and Cryptology website`_. In particular, his `Technical Details of the
+Enigma Machine`_ page was exactly what I was looking for, a real gold mine of
+information. 
+
+I had a long Memorial Day weekend, so I spent many hours in front of the
+computer, consuming every word of Dirk's explanations and trying to sort it all
+out in my head. And so a very fun marathon hacking session began. In the end I
+got it figured out, and you cannot believe how excited I was when I was able to
+decode actual Enigma messages from World War II!
+
+And so `Py-Enigma <https://bitbucket.org/bgneal/enigma>`_ was born! Py-Enigma is
+a historically accurate simulation library for war-time Enigma machines, written
+in Python 3. I also included a simple command-line application for doing
+scripting or quick commad-line experiments.
+
+Lessons learned
+---------------
+
+Since I didn't really know what I was doing at first, I wrote little classes for
+each of the components and unit tested them. I'm really glad I did this because
+not only did it find bugs, it also made me think harder about the problem and
+made me realize I didn't understand everything. When you make a mistake in
+cryptography, very often the answer you get is gibberish and there is no way to
+tell how close you are to the right answer. This was almost the case here, and I
+think I stumbled upon an Enigma weakness that the allied codebreakers must have
+seen also. I had a bug in my rotor stepping algorithm, and I got the right
+answer up until the point where the right rotor stepped the middle rotor, then
+the output went all garbage. Once I noticed this, I was able to focus on the
+stepping algorithm and find the bug. I'm sure the allied codebreakers must have
+experienced the same thing when they were guessing what rotors were being used
+for the message they were cracking.
+
+I also decided to use this little project to really learn Sphinx_. I had dabbled
+around in it before when I contributed some documentation patches to Django_. I
+think writing the documentation took almost as long as my research and coding,
+but with Sphinx at least it was fun! It is a very useful and powerful package. I
+also checked out the awesome `readthedocs.org <http://readthedocs.org>`_ and
+quickly got my documentation `hosted there
+<http://py-enigma.readthedocs.org/>`_. What a fantastic service! Now whenever I
+push changes to bitbucket my docs are automatically built on readthedocs!
+
+This was also my second project that I put up on PyPI. I'm a little bit more
+comfortable with the packaging process, but it is still a bit bewildering given
+all the choices.
+
+Conclusion
+----------
+
+I hope folks who are interested in history, cryptography, World War II, and
+Python find Py-Enigma useful and fun! You can get the code from either the
+`Py-Enigma Bitbucket page`_ or from PyPI_. And a big thank-you to Dirk
+Rijmenants!  Without his hard work and detailed explanation, Py-Enigma would
+have been considerably more difficult.
+
+.. _Python: http://www.python.org
+.. _Cipher Machines and Cryptology website: http://users.telenet.be/d.rijmenants/index.htm
+.. _Technical Details of the Enigma Machine: http://users.telenet.be/d.rijmenants/en/enigmatech.htm
+.. _Sphinx: http://sphinx.pocoo.org/
+.. _Django: http://www.djangoproject.com/
+.. _Py-Enigma Bitbucket page: https://bitbucket.org/bgneal/enigma
+.. _PyPI: http://pypi.python.org/pypi/py-enigma/