From msuinfo!agate!ames!waikato!auckland.ac.nz!news Tue Nov 1 12:52:21 1994 Path: msuinfo!agate!ames!waikato!auckland.ac.nz!news From: d7stfax@dtek.chalmers.se (Stefan Axelsson) Newsgroups: sci.crypt.research Subject: My Enigma hands-on (was Re: WWII German Enigma device wanted) Date: 1 Nov 1994 15:15:35 GMT Organization: Chalmers univ. of Technology Lines: 91 Sender: crypt-submission@cs.aukuni.ac.nz (sci.crypt.research co-moderator) Approved: crypt-submission@cs.aukuni.ac.nz Message-ID: <395m2n$nab@net.auckland.ac.nz> References: <38njnh$nbq@net.auckland.ac.nz> <38va8v$8ru@net.auckland.ac.nz> Reply-To: d7stfax@dtek.chalmers.se (Stefan Axelsson) NNTP-Posting-Host: cs13.cs.aukuni.ac.nz X-Newsreader: NN version 6.5.0 #7 (NOV) >Allen E. Feldman writes: >The BBC did a program which included B&W film clips of someone operating an >'enigma'. The thing looked like a small typewriter with where the paper >should be a set of lights covering the alphabet. There was no space key >and no different cases. You typed one letter then looked for corresponding >letter that lit up. The same operator pressed the keys and wrote down the >results. Well, I had my hands on an Enigma a few years back. This was a three rotor model with the switchboard plugs manufactured in 1938. It was reportedly a comercial model, but identical to early wartime models. Since it was marked with the eagle over swastica that we are all familar with my teacher hypothesized that it was meant for the government, rather than civilian use, in mobile diplomatic use for instance. The emabassys themselves used the stationary Gehimschriber, a teletype type machine which was only cracked by us. On the Enigma however, indeed its upper case only, and it has the German AZERTY keyboard. (Not the QWERTY keyboard.) It was standard practice to type Z instead of space. >If I remember rightly the operator typed left-handed, and wrote down the >encoded letters above the original letters so they knew where they got to. >The process did not look particularly fast, and the key presses were quite >deliberate - nothing like touch typing, more like using an adding machine. >A few letters a second was a good rate. It's basically a mechanical device, it uses electricity only for the rotor scrambling, and lighting of the coded/decoded message. Since turning one, two, or even all three wheels, comes from your pressing the keys, deliberate is perhaps somewhat of an understatement... ;-) This machine is *hard* on the keys. Other interessting features include, many different provisions for electrical powersupply, at different voltages. I don't remeber the strict battery maintenance instructions that were tacked to the inside of the wooded casing. Two power settings for the lights that light the letters, "hell" (bright), and "dunkel" (dim). This is probably due to the green plastic sheet that can be used to cover the letters with. This is possibly to dim emitted light in a tactical situation, but since the letters can be to faint to see properly you would set the switch to "hell." Lots of spare bulbs for the letters... ;-) And we found out that they were needed, our modern replacements were burnt out with the machine set to "hell." This was obviously a problem on the original machine as well. >Another person then sent the coded message. > >A nice easy way of modifying the code would be to send the code backwards, >so that the setting that identified the wheels came last. The 'enigma' >codes were only crackable because of the rigid transmission rules. If two >operators agreed to send reversed codes, the Bletchley crowd would probably >not have known. Yes, sending the message code (three letters identifying the settings of the three rotors) twice in the beginning of the message was in hindsight not a very good idea. But a funnier "accident" was that of the "wahlwo"rter" (elective words? (trans)) an order to the effect that in order to make it difficult for codebreakers every coded message should start with a random word to make guessed plaintext attacks more unsuccessful. So fas so good... But then the order (probably) continued "for example Sonnenschein"... You guessed it by now, the Swedes deciphering the German Gehimschriber traffic, found a *huge* percentage of messages beginning with the word "Sonnenschein" (Sunshine) a few bright young sparks of the German cipher clerks cadre managed "Mondtschein" (Moonshine). And the record was set some months later with, hold your breath, "Donaudampschiffsfahrtsgeschellschaftskapita"n" (Hmm, Donausteemshipfreightersassociationchairman... Whew!) All in all it wasn't such a bad suggestion, if they would have left out the suggestion. Somewhat like telling people how to choose a good password. (As opposed to telling them how not to choose a bad one.) If there is enough show of hands I might translate the account of how Swedish ace mathematician Arne Bo"rling lead the effort to crack the German Gehimschriber, a feat comparable to the English enigma, and US Purple cracks. -- Stefan Axelsson, Chalmers University of Technology, d7stfax@dtek.chalmers.se Sweden