Syko Cipher Device

O'Brien developed a sophisticated cipher typewriter, which was complex and delicate, but then came up with the relatively simple device adopted by the military that was known the SYKO.

Although the German cryptanalysts managed to break the SYKO code, it remained in use for much of the war as a quick method for low-level encoding of radio traffic, particularly from aircraft.

Code breaking took considerable time plus a sufficient sample of messages, and for certain classes of radio traffic (such as an aircraft's position) decoded information that became available many hours later was of little value.

A few machines survive, and operating instructions issued by the Royal Australian Air Force in November 1940 have been made available on-line.

The SYKO case contains a propelling pencil with a small brass pin at the other end, which is inserted in a notch at each letter allowing the columns to be moved as required.

Encoding involves taking the special pencil and, for each column in turn, selecting the corresponding letter in the message using the pencil brass pin to draw down the moveable column so that letter is at the bottom bar thus revealing the code card underneath.

The original message is still visible along the bottom bar, so you can check the column placement hasn't moved.

Due to the pairing of characters outlined above, the decoding of messages follows the same process, with it essential that both parties are using the same coding card.

[3] Morgan O'Brien filed several patents while living in New Zealand related to burglar alarms and security on tills and shops.

[9] An Admiralty document from November 1945, formerly Top Secret, now declassified, reviews Naval codes and ciphers used during the war and also gives some insight on the usage of SYKO by the RAF.