[devindotcom]

It 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.

[cyberferret]

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).