[GreenKeys] Here's a sweet one on the bay.

[Christian Gauger-Cosgrove]

On 17 May 2013 00:38, Jeffrey D Angus <jdangus at att.net> wrote:
> On 5/16/2013 10:41 PM, hwhall at compuserve.com wrote:
>
> "The US Army Signal Corp's teletype typewriter... was the US equivalent to
> the
>
> famous German enigma machine. "
Oh Lord I didn't even *SEE* that on the eBay page; I think I'm going
to die laughing at the person's sheer ignorance.


> Typical sequence was:
> 1. generate secret message in plain text.
> 2. use crypto machine to convert to secure text.
> 3. send secure text via teletype machine.
> 4. receiver secure message via teletype machine.
> 5. decode message with crypto machine.
> 6. hand secret message in plain text to the person that needed it.
>
And if you were a Nazi^H^H^H^HGerman in the Luftwaffe, you would have done it:
1. Generate (plaintext) message.
2. Turn on T-52 Geheimschreiber, and transmit enciphered message.
3. Receive decrypted mesage on the other end's T-52 Geheimschreiber.
4. Give message to Luftwaffe officer for whom it was destined.
(5. Shortly afterward in Bletchely Park, the British are reading the
exact same message.)

Because the T-52 didn't have any facility for tape operation, that's
how BP were able to get into the T-52d and T-52e versions of the
machine. Because when one operator had to rerun a message, the British
saw that was going on in that circuit... and then the operator took
some liberties in the re-run plaintext (a few more abbreviations),
which resulted in the ciphertexts/plaintexts being somewhat different.
But different in such a way that they could determine both what the
plaintext was, and the function of the T-52d.

The Lorenz SZ-4x machines on the other hand were more smartly
designed. Though BP still got into "Tunny"... in fact we can thank the
SZ-4x machines for causing the construction of one of the first
computers (COLOSSUS).


> Two examples of the machines used by "our side" (The US) during
> World War II.
> The M-209. Secure enough for most time sensitive stuff.
> <http://www.cryptomuseum.com/crypto/hagelin/m209/index.htm>
It's good for tactical uses, but still has its issues. Being that it's
really not that strong. However, it was excellent in terms of theatre
level messages (since by the time the Germans and/or Japanese would be
reading the plaintext, the Allied forces would already have
begun/finished whatever they were ordered ("Hallo Fritz? Ve have the
plaintext! The Allies vill be attacking ze Gruppe North." "VE KNOW
THAT ALREADY! VE HAVE KNOWN THAT SINCE THEY STARTED ATTACKING, THREE
HOURS AGO!" "Oh? Scheiße...")).


> And the SGIABA for stuff that needed to STAY secret.
> <http://www.cryptomuseum.com/crypto/usa/sigaba/index.htm>
>
Well, SIGABA message did *STAY* secret... until 2003, when Michael Lee
cryptanalysed it for his master's thesis at UC Santa Barbara. And then
Heather Kwong did it again at San Jose State University in 2008,
shortly after Mark Stamp and Wing On Chan did it for a Cryptologia
article in 2007...

Cheers,
Christian