[Cryptography] Imitation Game: Can Enigma/Tunney be Fixed?

Dave Horsfall dave at horsfall.org
Sat Jan 10 01:34:08 EST 2015

On Fri, 9 Jan 2015, Ray Dillinger wrote:

[ ...]

> > Either that, or your FIGS would act on the following symbol only, 
> > which I suppose is do-able.
> The "numbers" are digits 0-9, mapped to some set of ten symbols. The 
> first character that's not part of that set signals that you're dropping 
> back to letters. If you need to type a letter that would otherwise be 
> mapped to a number, you just insert a space (well, an X since that's the 
> way they did that) first.

Ah, a sort of automatic return to LTRS, as it were.  You'd need a latching 
relay to keep the LTRS/FIGS state, and some assorted comparators to 
release it.  This means a power supply, but you already have one to drive 
the lamps (having never seen an Enigma, I'm assuming that the rest of it 
is purely mechanical), but it may need to be beefed up a bit.  Increased 
weight, but the thing was never designed to be portable, any more than a 
Teletype was (sorry, but my Amateur radio background keeps sneaking in).

The transistor had yet to be invented, and I'd go for relay logic instead 
of valves ("toobs" for you Americans), for simplicity and reliability 
(vibration can do nasty things to a filament).  Which reminds me: I assume 
the Enigma had a lamp-test button?  Be a bit embarrassing if it didn't 
light up...

> Seriously, no other comment on the redesign?  I thought that running 
> both the positive and the negative connections through the rotors via 
> different electrical paths encoding the letter by combination, and then 
> using 18 of the electrical paths through the rotors for feedback, was 
> really clever!

Ingenious!  It's ironic that the reflector, supposed to strengthen it, 
actually weakened it.

Dave Horsfall DTM (VK2KFU)  "Bliss is a MacBook with a FreeBSD server."
http://www.horsfall.org/spam.html (and check the home page whilst you're there)

More information about the cryptography mailing list