Enigma Two. Ciphers and Barbarians

 Week two.  Time to get trickier....

Enigma Lesson Two 

VLRDR  VPJBI  IYXAU

Well now, that was not a very nice thing for Julius Caesar to say about the Barbarians!  Although it was of course quite true.  Perhaps that is why he wrote it in a special letter code.  This "Julian Cipher" was one of the earliest such codes and would serve to make written messages unreadably to casual observers.  You of course are considerably smarter than a batch of 1^st century BC Barbarians, so it won’t take you long to figure this out.

 We will talk today about the easiest ways to break this kind of code, then the trickier ways it usually has to be done. 

Paper, pen, blackboard…..of course after a while people got even smarter and started to create machines to help encode and decode.  Some of these are simple and fairly well known.  Once upon a time special “Secret Agent Encoder Rings” came in boxes of cereal.  We will work with some home made versions of this device to send and receive messages to each other. 

Like everything else in the modern era these code machines kept getting trickier and more effective.  Until the code breaking machines caught up. 

Ever wonder why this course is called Enigma?  Go.

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The first cipher they worked on was the famous "Julian" or "Caesar" cipher.  It is a simple 3 space rotation cipher where V becomes Y, L becomes O.  The initial message read "YOU GUYS SMELL BAD".

This led to a brief etymologic side trip into why Caesar Salad is called that and to how what was basically a nickname evolved into a title that has been in continuous use until fairly recently.  (Czar, Kaiser, etc).

All rotational ciphers can be solved pretty simply.  I taught them the Brute Force method and they were able to easily take on another cipher called Rot-13.  This cipher is still in fairly common use.  The geocaching website uses it to encrypt hints.

A bit harder challenge next, a random cipher.  I told them I'd make it a bit easier by giving them lots to work with and breaking it down into words instead of standard five letter sets.

For this they had to look at frequency analysis, which is basically how frequent certain letters are in the English language, with considerable help from the small number of one, two and three letter words that are in common use.  The message was not that important, it said something along the lines of "I will make this easier by giving you lots to work with and breaking out the words".  Which is almost a direct quote.  But, it gave them the key to use on the next cipher which was in the same code.

The answer was:  BILBOBAGGINSLASTRIDDLE.  Shockingly none of them had read the Hobbit.  My work to repair the shortcomings of modern education is far from done.  But I allow limited use of the internet and soon they were asking me:  "What do you have in your pocket?"

The combination, obviously.  Or is it?  I was mildly disappointed that none asked in a Gollum voice, but you can't have everything.  

For those coming in late, the code unlocks a treasure chest with some better grade snacks.  The kids were able to get all this done in one hour, which I think is pretty good especially considering that this is an after school class and their brains have been numbed since about 8am.

A smart and fun group.  Next week I'll challenge them a bit more......