[GreenKeys] Interesting cipher machine.

[John Nagle]

> The TTY in there is a TT-30/AGA-1 (aka Teletype Corp. Model 31). The box
> is a portable TTY and (SIGABA-type) encryption unit in one.? Never seen
> this version, but description enclosed.? There is a picture (enclosed)
> of the communications position of President Truman's VC-118 aircraft in
> 1947 using a similar unit.? (note the AN/ART-12 modified for RTTY on the
> shelf above.)

That's in nice condition.

It's clearly built mostly from a Teletype Model 31, but there's a wider
base, and there must be something to advance the codewheels. That
takes a lot of mechanical power with eight codewheels, so it's
probably driven off the Teletype's main shaft, rotating once
per character.

That's not quite the last of the pure mechanical crypto machines,
but it's close.

				John Nagle