SIGABA is described in US Patent #6175625, filed in 1944 but not issued until 2001.
“The Green Door” (as in, “What’s that secret you’re keepin’?”) was the “in-the-know” name for the front of the Australian Secret Intelligence Organisation’s offices when ASIO was in what is now the National Archives building in Canberra. Spying is such big business these days, ASIO has its own massive structure elsewhere in the capital. Still, it seems appropriate that the Archives should be hosting a fascinating exhibition called “Spy: Espionage in Australia”.
There are lots of unusual things to see at “Spy”, and here are just a few:
1. SIGABA electronic cypher machine Mark II (c 1940), believed to be the only unbroken World War II code, used to send Allied messages. A paper tape fed into the teletype reader on the front of the machine randomised the rotor movements. Loaned by the National Cryptologic Museum, Maryland, US. See Wikipedia's entry on this model.
2. Purple analog machine, c 1940. Used to decipher Japanese Foreign Office cipher traffic. Loaned by the National Cryptologic Museum, Maryland, US.
3. CO/B-8 Alphabet Decoder, 1970s. Used to transfer Morse code to magnetic tape.
4. Steineck ABC wristwatch camera.
5. Camera in a book.
6. Necktie camera.
7. JPS Special camera.
Below, the Fleet Radio Unit Melbourne GI Room, 1943