441 Kirby to Burton

Cablegram K3 BATAVIA, 27 November 1947, 9.13 p.m.

MOST IMMEDIATE TOP SECRET

I am very concerned about the insecurity of the Republican communications. The Dutch continually make statements showing that they have broken the Republican code [1] and although the Republicans are aware of this, they seem unable to devise a more secure version. If this lack of security continues it will put the Republic (and us) in a farcical position during the talks on board ship when their messages between Jogjakarta and the ship will be passed by wireless telegraphy.

2. I am sure that you will agree from all view points that it [is] absolutely essential that during the talks, the Republic's exchange of messages should be 100% secure. I would be pleased therefore if you would give very urgent and immediate consideration to obtaining from departmental or service sources a code which we can make available to the Republic. The code could be explained to them secretly by us and they could make any changes to suit themselves (I hope it will be possible for the code to be forwarded on plane which brings a new engine for our R.A.A.F. plane here).

3. If this suggestion is unacceptable the only other alternatives appear to be- (A) Moore suggests to them employ code based on Playfair [2];

(B) For us to try to find ways and means of improving the security of their present code and have Moore and Turner advise them (secretly, of course).

4. Your urgent comments would be appreciated, as I appreciate on this important matter that I should not take any steps without your knowledge and approval, even making Moore and Turner available to advise the Republic. [3]

1 In meetings with both the Consular Commission and the Committee of Good Offices, Dutch officials repeatedly referred to intercepted Republican communications to support claims that Republican forces were responsible for breaches of the cease-fire and more generally that the Government of the Republic was acting in bad faith. Translations of a number of intercepted communications were provided to members of the Consular Commission and the Committee of Good Offices on the understanding that the source of such information would be kept confidential.

2 A cypher conceived in the mid nineteenth century and employed as a basis for field cyphers by British military and paramilitary forces during the First and Second World Wars.

3 The Department of External Affairs replied on 28 November that urgent consideration was being given to the possibility of supplying secure communication facilities. A package of 'one time letter pads' was subsequently supplied with instructions for use by the Republican Government. On 8 December, following consultation with a Republican official, Moore reported to the Department that the Republican Government had been using a cypher involving the simple substitution of letters without change at regular or frequent intervals. By this time, however, the Republicans had prepared a new code book and recyphering system for communications between Djokjakarta and Batavia which Moore considered to be 'reasonably good'.

[AA:A1838/274, 854/10/4/2, ii]