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REF ID:A2435947 

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C SGAS 400 112 Karch 1948 

S~JECT: Combined C~pher Machine Moc~flcaticn of 

TO: Chief of Naval Commun1cat1ona 

Naval Commun~cations Annex 

Vash!ngton 25J D. C. 

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1. A Joint meeting or representatives of the Army and the 

Navy was held on 16 February 1948 to discuss the British document 

entitled, "Services Cypher Policy COBDlli~tee Paper Number 3." 

/-()f-.29 October 1947. At tbat same meet1ng·cons1derat~on was g~ven to the letter dated 30 January 1948, fro• the Chief of 

lfaval Communications on the subject of the COJBb1ned- Cipher 

Machine. The. minutes of tba.t aeeting are attached hereto as 

Inclosure 1. 

- 2. As is inC:.::..cated in the mlnutes of tae aeeting, a deciaion with r~gard to the improvement of the Combined Cipher Machin~ ~ust avait additional information, in particular: 

a. Technical data concerning the nature of the British 

'l'ypex Mark 22. . ,_. 

. b. A study with regard to feasibility of the nev idea 

presented by Navy fo~ effecting rotatable and interchangeable 

cam contours. 

3- With regard to 2& above. the British L1&1aon Officer 

bas taken atepa to obtain the necessary datl,L trca London. Vi th 

regard to 2b, the Navy repreaentat~vea have been requested to· 

provide the Army Security Agency vlth aoae of the nev rings 

and ·grooved rotors, together With a modified ECK basket so that 

studies :may be made at the Army Security Agency as to the 

reaa1b111ty of the nev idea. 

4. It 1a agreed that no further 1ntormat1on should be 

given to the British until the matters diacuaaed above have 

been clarl.fied. 

· 5. Paragraph 5 of the letter dated 30 .lanuary ·1911-B ·ri-·°'8 

the Chief or Naval COllllW11c&t1ona requeata a.~recona1derationl of 

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Declassified and approved for release by NSA on 09-20-2013 pursuantto E .0. 1352\3 

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CSGAS 

SUBJECT: 

19 March 1948 

Combined Cipher Ma~h1ne, Modlficat~on of (~ont1nued) 

the prev!nus decis!on of the Chief, Army Securit; Agency with 

rega.r ... l to the Jo~nt use of the CSP 2900. Tbe basis and reasons 

ro1• tt~e. t 14fcis1on ha.vc been fully set forth : n previous communications as well as in Joint meet~ngs and they etill appear 

to be cogent. Among them was the factor of considerable cost 

in me.king the conversion. even though the vork vould be done 

.1.n ccnjur...:t!.c,n vi.th rer:aU.lltat1cn_ef the SIGABA machines. The 

co~t Involves that of addit.!.onal p9.rts and labor. Informal 

indication· has recent.ly been given this Agency that the necel!!lsar:1 parts, as well a~ SjJccial tcol:=! and jigs l'or the conver51on, _ . could be furn:shec t;y the Nav:,~. This offer· is greatly appreciated and Wo'..11:1 result in a consic!erable relluction in the coe.t 

of con~er~:cn. llowever. a more e~g~:f1cant concern is the 

extra later in~olved, wh:ch calls for expenditure of time on 

the part cf ver'.i' sc&rce tC"chnlca 1 perecnnel ThP. Navy's own 

estimate ci' the additional time requlred, if the convers~on 11!1 p~rrormed concurrently vith rehabilitation, is two and onebalf hours per macb.lne. Since at least 2000 Army SIGABA'e are 

shortly due to be rehab111 tated thf.' total additional time 

vculd be 5000 man-hours. Such expenditure cannot be economically justified in the case of a machine whose security ls considered to be ~nt1rely satisfactory. 

. 6. It la therefore vith great regret that the Army Security Agency feels compelled to adhere to its original 

decision that it cannot accept the CSP 2900 in principle and 

ia not able to undertake the conversion of SIGABA's in connection with its own rehat11itation program. 

· 1 Incl 

Minutes of Army-Navy 

Meeting. 16 Feb 48 

HAROLD G. HAYES 

Colonel, Signal Corps Chief, Army Security Agency 

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