Technical Details of the Enigma Machine
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Technical Details of the Enigma Machine
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Re: Technical Details of the Enigma Machine
#2All things considered, 84 bit encryption is pretty impressive, considering DES was still considered "okay" even into the late 1990's.
Re: Technical Details of the Enigma Machine
#3It really was quite a remarkable device, and if I remember correctly offered much more security than was strictly "necessary" at that stage of the crypto wars, though of course we know how all that particular story ended.
Re: Technical Details of the Enigma Machine
#4After reading to the end (very enjoyable),be sure to find out what weaknesses Bletchley Park exploited to break the encryption:
Re: Technical Details of the Enigma Machine
#5It really was quite a remarkable device, and if I remember correctly offered much more security than was strictly "necessary" at that stage of the crypto wars, though of course we know how all that particular story ended.
Yes, but on that note, the 'reflector' in the Enigma, which essentially double encrypted everything on the device was one of the features that the allies managed to use to break the device.
The reflector essentially routed the signal path back through the rotors again, which the Germans thought made the device even harder to decrypt. However, the wiring involved essentially meant that the same letter typed could NEVER be represented by itself once encrypted. (e.g. a raw 'A' could never come out encrypted as 'A' etc.).
This n-1 weakness meant that allied cryptographers could eliminate options by a large factor when running decrypting routines.
Also, the Germans would routinely ask their field operators to send long random garbage transmissions in order to soak up the time and energy of the allied decrypting teams.
However, human nature took over, and a lot of operators were simply too lazy to hit random keys on the device, but instead would repeatedly press the same key (usually the 'L' key which was the lowest key on the right of the keyboard) while chatting to their colleagues.
Thus when the allied cryptographers saw a long transmission which never contained the letter 'L', they knew it was a 'dummy lazy transmission', and they could use 'LLLLL...' as the crib which made cracking that day's Enigma code so much simpler.
An astonishing example of when a tactic to try and make things harder to crack actually made it easier to do so (with the assistance of human frailties).
Re: Technical Details of the Enigma Machine
#6Like most, I always thought that the allies were desperate to get their hands on these machines during the war.
I was lucky enough to get to play with one of these things when a lecturer from the Bletchley Park foundation toured here some years back. She gave a fascinating and riveting talk on the history of the device.
I was surprised to hear that these were actually commercially available before the war, and that the allies had quite a few of them in store already. The crucial thing they were after were the booklets with the daily rotor and plugboard settings - far more valuable than the machines themselves.
Re: Technical Details of the Enigma Machine
#7The Enigma is a neat machine. I wrote a Java iButton applet that emulated one and in doing research for that came across the rotor patent (https://www.google.com/patents/US3984922) this patent was filed in 1944 but it issued in 1976. October 12th to be precise. One month before the Data Encryption Standard (DES) came out as a FIPS standard. How Enigma worked had remained classified for decades after the war ended, that is a pretty strong endorsement for this remarkable machine.
Re: Technical Details of the Enigma Machine
#8Like most, I always thought that the allies were desperate to get their hands on these machines during the war. I was lucky enough to get to play with one of these things when a lecturer from the Bletchley Park foundation toured here some years back. She gave a fascinating and riveting talk on the history of the device. I was surprised to hear that these were actually commercially available before the war, and that t…
I thought the commercially available models did not include the pegboard, which was crucial for the higher # of possibly combinations?
Re: Technical Details of the Enigma Machine
#9Like most, I always thought that the allies were desperate to get their hands on these machines during the war. I was lucky enough to get to play with one of these things when a lecturer from the Bletchley Park foundation toured here some years back. She gave a fascinating and riveting talk on the history of the device. I was surprised to hear that these were actually commercially available before the war, and that t…
I thought the commercially available models did not include the pegboard, which was crucial for the higher # of possibly combinations?
I think you are correct. Also, the Kriegsmarine version had an extra rotor, plus they also used a secondary code book to encode keywords before encrypting on the Enigma.
Those were, from what I hear, much harder to break, thus the efforts to capture the code books and devices from the U-boats.
Re: Technical Details of the Enigma Machine
#10The number of rotors was limited by the keyboard effort. All those spring-loaded contacts between the rotors make advancing the rotors hard. Enigmas have a huge key travel, almost an inch, to provide extra leverage. You can't actually "type" on one; you push the keys down firmly, one at a time. Somebody has to write down which lamp came on, anyway, so that's not the limit on speed.
The keyboard-driven rotor machines didn't scale up well. Beyond three rotors, motor drive was usually needed, although the cute little M-209 used a wheel and lever for input, rather than a keyboard. The next step up was the Lorenz SZ-40/42, a six-rotor machine set up as a peripheral for a Teletype. That was cracked with the Colossus electronic key-tester.
The Germans built the T-52 Geheimschreiber, with 10 rotors, but that had a built-in Teletype machine and was too heavy to be portable. The Allies didn't crack that one.
That was the original limit on key length. The longer the key, the bigger and heavier the machine.