Secret Messages - Purple Machine

During World War 2, Japanese used many types of cipher machines one of which was known as the "Purple" machine. The machines used a series of telephone selector switches to encipher and decipher top secret messages. These messages were often intercepted by and decrypted by Allied Army and Naval Intelligence staff.

No complete "Purple" machine was ever captured during WW2. A fragment of one "Purple" machine was found in the courtyard of the Japanese Embassy in Berlin when the city was overrun by the Russians and Americans in 1945.

How the Purple Machine worked:

The Purple machine was a complicated piece of machinery not only in the 1930s, but even today.

The machine was made up of three major components.

One of them was an electric typewriter which was used for inputting information into the machine.

The second part was a “cryptographic assembly” which consisted of a plugboard, four electric coding rings, and numerous wires and switches that acted in unison with the other parts (Kahn 2).

The last part was an output unit that printed the encrypted message from the machine.

Instead of using rotors like the German Enigma machine did, the Purple machine used “electro-mechanical ‘stepping switches’” (Anon 1).

This in effect was similar to a second generation four rotor Enigma machine.

However, it was much heavier and bulkier than the Enigma machine and could not, therefore, be employed in the battlefield easily.

Further information on Purple Machine:

http://ovid.cs.depaul.edu/Classes/CS233-W04/Papers/PurpleMagic.pdf

Joe.

Suspicious Security Requests for Victorian Units

On 30 June 1943, Mr. D. B. Sison, the Director General of Security wrote a letter to The Secretary, The Department of Defence in Canberra to enquire about the role of Radio Security within Victoria's rural territories. Mr. Sison expressed the opinion that the need for the Radio Security Organization no longer existed in its present form within this area and that perhaps it should be disbanded.

Mr. Sison propose that all RAAF units return to appropriate Headquarters, but did not make any suggestions about Naval War Defense units.

Mr. Wilson went on to state:

"If it should be decided that the Radio Security Organization is to discontinue, it will still be imperative to maintain these forces for boarder line Defense; within particular observation posts".

Whilst making the recommendation he also suggested that Officer W. Leahey, be put in charge of a smaller Radio Transmission Security Unit, where his men would report any security anomalies directly to himself for immediate consideration.

The Join Planning Committee (JPC 2374) considered the above recommendations. This Joint Planning Committee meeting comprised of:-

Captain H.J. Buchanan, D.S.O., Deputy Chief of the Naval Staff
Brigadier A.W. Wardell, M.C., Representing Brigadier General Staff
Air Commodore F.M. Bladin, C.B.E., Deputy Chief of the Air Staff

The Committee agreed that the Radio Security Organisation should be disbanded forthwith. The Joint Planning Committee considered that Radio Security was clearly an integral and vital part of Intelligence work, and in fact, that it fell into place as one of the group of tasks which formed what was known as Signal Intelligence.

It was the opinion of the Joint Planning Committee that planning for Radio Security should commence at an early date to ensure that it could be quickly organised in Australia whenever circumstances required, but it considered that such planning must be part of planning for a Signal Intelligence Organisation.

The findings of the Joint Planning Committee were then considered by the Defence Committee. In a letter from H. D. Preston, Joint Secretary Defence Committee dated 30 October 1945, they endorsed the recommendation of the Joint Planning Committee that the present Radio Security Organisation should be closed down immediately. They recommended however that the question of Radio Security should receive consideration in connection with the future organisation of Joint Intelligence services which the Defence Committee understood was then under review.

At that time there were still RAAF and Navy units in operations and the termination of radio security would have jeopardized correspondence between Australian Units and Defense Forces.

Director General of Security would not have time to be investigating radio transmission anomalies himself. Why propose the disposal of a competent unit and suggest that he do this petty work himself.

Such a suggestion from the Director General of Security DOES-NOT-ADD-UP!!!!

Joe.