SIGABA Machine


The SIGABA or Electric Code Machine Mark II (ECM Mark II) was developed before the start of World War 2 by US Army and US Navy personnel.

The SIGABA machine was known as the CSP-889 by the US Navy. It used rotors rather than paper tape to control the rotors that enciphered text.

The SIGABA machine contains 15 rotors. Ten of these rotors were conventional 26-conatct rotors. The other 5 rotors were smaller ones with only 10 contacts on each side.

An American, Sergeant Donald Moreland, helped to set up the IBM equipment at Ascot in Brisbane. He had earlier been in Melbourne installing the SIGABA cipher machine (ECM Mark II). The SIGABA machine was used to encipher messages from ordinary or plain text, into a secret language, which is called cipher text, under the control of a key (encipherment).

Detachment 3 of the 832nd Signal Service Company used a Sigaba Machine in the Signal Center on the 7th floor of General Douglas MacArthur's General Headquarters, South West Pacific Area (GHQ, SWPA) in the AMP Building in Queen Street Brisbane in southern Queensland. Ken Osterberg of Detachment 3 of the 832nd Signal Service Company remembers that the Sigaba system used five letter code groups. He indicated "You typed in clear and it came out five letter code groups". 

SIGABA machines were also used in the "Message Center" at Ramsay Street, Garbutt in Townsville by the 911st Signal Company, Department of Aviation, which was attached to the 4th Air Depot Group near Mount Louisa.

The SIGABA machine was the only machine system to remain completely unbroken by an enemy during World War 2. The Germans called it the "Big Machine"

Two Sigaba/ECM Mark II are being held by the U.S. Naval Security Group. One of these is exhibited on the submarine Pampanito. When Donald Moreland visited the National Cryrptologic Museum at Fort Meade October 1994, the Naval machines were not mentioned.


SIGABA - Electronic Cipher Machine (ECM) Mark II
By Rich Pekelney



I'd like to thank Donald Moreland for his assistance with this home page. 



"Top Secret Communications of World War II"
by Donald Mehl

"Big Machines"
by Stephen J. Kelley
published by Aegean Park Press, Laguna Hills, California, in 2001


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This page first produced 14 October 2001

This page last updated 03 March 2020