. " 

\ 

\ ;/ 

I 

------. ·- -~~--~- .. ,,....,-------.---·------- . ---·--------- --------= 

• 

)0 September l949 

MEMORANDUM FOR MEMBERS OF AFCIAC: 

Subject: Replacement of the present Combined O!pher 

llachine. 

The attached report of the Ad Hoc Committee, 

appointed.by AFOIAC to prepare an amended reply to the British 

R.DO/S/99 proposals, is forwarded tor your 1ntorcat1ono 

2a The Oha1rman11 .AFCIA0 11 has requested that your 

ooneurrence or oomment be oommunioated to the SECRET.ARL~T at 

the earliest practicable dateo 

• f"'1IU. 

JJ. JO~""KS· 

Seoreta~1at, AFOIAC 

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

.AFOIAC: . ·13/12 

PRNC-NCSW-3 .. 6 

TOP SECRET 

--------- - - - - -----------------

I 

' 

I 

. ; 

' 
• TIP BECHT fj-F 

ID:A243609B • 

JOINT anms O'F STA..'li"ll1 

B'PPI.A.C!D'!14'IM' oa' 'l'R! PRif;'li!)'T COl{!!I?nllD OIPiig MAOHINE 

""IE PRO'RLEM 

- l. 'l'o determiDR the United StRtee ~oa1tion toward the United Xinr:domo1 

-propollAle in RDO 5/99 (attached ae Appendix 11.&.11 ) thAtl 

Ao There be a t'ull and complete tnte:rohanp:e ~ CJ7Pto,,-aphic 

prlnatplas and polt07 on a reciprocal baaiaa 

l• If the U111tad State• Ohieta of Statf cannot ar.rea to ... abow, 

the)' authort •• the 1Uecloaure of the -prS.nctpl ea of the '!CM ( SIGAl!A) ao 

that these mq b~ incorporated in the J18V :Srttilth cipher machine (BCJ.1) 0 

1'.AQ'l'S B'AAl'"?UN ON TR! 12.ROBLEH MfJ2 DISOUSSIOlf 

2. Appendix •011 (page 3) 

CONOI tJ:iIONS 

3. .I• It ta not in the beat lntare•t ot the u. s. to ar.rae to the full 

and complete interchange or cryptoRZ"anhic principles with the Brlttah. 

Jl. 'l'he raleAae of the 'lllOM under prAt1ent -cirawnatn.nceo ia not 

warranted. 

J!• 'lh8 detatla or the 'prln.ciules at t~..e BCM nhauld be d1aclo~ed to 

the u. K. with a 'riew to lta use as .a replacement for the extat1nrCombined Oil>har Machine. In ~dd1Uon the Uo s •. ahould tu.rrdah to the 

u. it. on a continuing baais auch improYementa to the B~ &a become aTallable., 

HJiiOOM:.tmNDA'l'JOQ! 

4. It 1a :recoma:nded that• 

A• Mamoranclum aubatantiall7 aa in A.'P):l8nd1x "l3" be forwar.,ec1 to the 

British Join\ Sert'ice Miaatono 

COOBDI :VA!l'ION 

,.. Coor4!ut1an wl th Al'OL\C haa been effected a 

Declassified and approved for release by NSA on 11-19-2013 pursuant to E .0. 1352a 

TIP &EBREl 

--------·-·--- - -· --

.... -! 

·I 
, . 

------------------ -·-

ID:A243609B 

TIP &EGRET 

;lOF -

DlfISK JOim S-.dlYICES !SISSIQW . 

mmcm or WE OOMBIDD CHU.ft al S!J?AiT 

W.ASHlllVJ?Cli 

KOO 5/99 

lUiPLADBSEE m' 9IE P.REBEN!I? CCMBIJraD 

•• S!:RHll 1wuag . •• • ..... 

Puz!9M Baftttmu=· 

~ 

llDO 6/frl - 18 Mq, 1949 

• 6 Jmae, 1949 

1, !he Npl'eemdlatS.ve ot 1Jhe u. JC. Ch1eta of' Staff haw 

beer& tnatrwne4 to pm toruard. for conotdm'a1;1on by the u. s. Ch:lets 

of Statt, the afi1;ache4 mimorandum deal1116 with the 1'9Placement ~ 

the ezls\bg Combined a,:pber macb!ne. 

a. CoJmaDder Jurion-lfillo o£ the tr. Ka ~ Po11CF Board 

!a nau :In. Waa1d.ngfJcm aD4 5.11 fa1l1' 811tm:rtse4 to d1saae 1i!d.a ma1iter. 

It !a ho,pe4, therefore, that a v,,q e~ deo:laton. oa fihe afitached 

propoaa'J.a Dl9F be given •• 

/a/ R. D. COLERim:Z 

Os;pi;atn. :R.1' o 

· -TOP SECRET 

~---~-=--- -----~-- ·-· ·-

. i 

' ·---~ ... ~!' 
TOP SEBRET 

,F ID:A243609B • 

THE JOIMT COI.Il.IU?lIOAT cons EL'MOTROUIOS CO~D..IITTEE 

Tilli S.i.!:OUHITY AIID ORYPTOGRAPIIIC PA?IBL WWW 1 T • ·-·=-·~......., 

REPLl\.OEr®:N'l' Olil TiiE PRESEMT COUBIIW.'D CIPHER I.IACIIINE " tr W ,. •R -~·-·~---

(Proposed reply to the Bztitish Joint Service Mission) 

The UoSo Joint Chiefs of Staff have aarefu.11'1 considered the 

l?roposs.ls made in RDC 5/99 o:r 13 May 1949 conccnm1ng the replace .... 

ment of the e.x1st1ne; combinod cipher machineo The UoSo Joint 

Chiefs of Staff regret that they are unable to accept the proposal 

tor the full and complete intero~nge of cryptographic principles 

and polic7 on a reoiprooal basis. Full recognition, howeve~, 

is accorded the view or the UoKo Chiefs of Staff regarding the 

necessity .tor the replacement 0£ the presant COM tor high level 

Combined use~ In this reaard the u.so has developed and has in 

operation a machine (BCM} whioh is considered the best a'V8.1lable 

oqui~ment an~_entirely satisfaotor7 tor such oommunicat1onso 

The BOU 1s relatively economical te manufacture and ma7 be 

utilized in adaptor torm with the present Bl'itish'basic cipher 

equipment, thus providing an economical as well as eXped!tious 

method for improving the~ security of combined communicationso 

As an alternat1ve proposal to tho release of the ECI.1 the UoSo 

will disclose to the United Kingdo1l'.l the details and cryptographic 

principles of the BCM and will enter into d1scuss1ons eoncol:'Iling 

its adoption for Comb1r1ed use and concerning the physical 

seouztit7 necessar~ for its pl'Oteotiono These discussions can 

commence in \lashington at an7 timea 

APPENDIX. tl,Bft 

mp SECRET 

-·----·--- - -· -------

.1 
TOP SMih~~436o9a c.unca• • 

Jl'AO'l'S 'Rl!':AHING ON ,.~ j_~I.'Sf.( AND DISCl·ssro:·; 

l~ The United XirJP.dom Ohiefs of Staff have decided that they muet 

replace their main cipher machine (TYP.EX) as soon as poadb'e since they d.o 

not consider 1 t will offer adequate eecuri ty in the near futuren 

a. In Tiew of the tact that the Uoyal Na'f'Y' can carry only one machine 

in the smaller shi~a the new British machine mu.st be such that it will 

prOTide for 'British and for Combined Bri ti ah ll?ld t1o s .. communications. Thie 

also applies in the United States Navy., 

3o Although the COM• if pro~erly used, is a hir.hly secure mRchine, the 

experts of both nations agree that the cryptor;raphir. principles employed in 

the machine are not as secure as 1a considered desirable for hip.best level 

United States - United Kingdom communicationB. 

4o The United States gO'V'ernment adhere& to the general bi:i.sic princirile 

at national ao•areignty and security that the means and methoda which a 

goyernment emplo7a for the protection of its own communicetiona con•titute 

a private matter not to be ehBrP.d in toto with an)" other ROvernmAnto 

'Recause of the com~on interest ar the tr., Ko ant'! Uo s.. in world 

attaire tod8l"0 the Uo So has a vital interest in the provinion of a cryptographic system for Combined comx:mnications of assured security for hir,hest 

level uee.. On the other hand the Uo So in ita own national interest must 

reserve for itself a cipher equirment of assured security, to ~rovtde·privaccyfor its own communicationeo 

50 Because of fin.'lncial limitations it is unlikely that the 'British 

are in a position to re~l~ce their prenent ma.in cipher l"Dll.chine (T?F.fJt). 

Moreover 0 the United Stat~·a should not, u11der the -present circumstances, 

release the EOM 1f it is to adhere to the above stated policies, since the 

only equipment which might be considered to assure the necessary national 

privaC1', the asp 29000 will not be available in sufficient quantities to 

meet Uo So mobilization requirements for a conaiderable period of timeo 

6., '!'he present BOM (CSP 3800) 1s wff'icientl;y secur~ for highest level 

traffic. althoup.h not as secure as the ECMa The Navy has under deTelonment 

further modifications of the »OM which are exi:iacted to ~ive it a security 

comparable to tha:t of the l:CM without 1n.cornorat1np any of the ba.Bic ECM 

principles., Deaip.:n hau alread"y been completed for an adaptor which will 'Permit 

the conversion.of the TYPEX to a BOMo 
.,. 

• 

--------------------- - .... 

REF ID:A243609B 

e • ,Qlltl,IEl,:T;*~ 

7. · Improvement of the secui-ity of Comb:f.ned Uo S., - Uo Ko communicati.ons 

can bP. most expeditiously achieved by rRlease of the BCM to the ~r1tisha 'l'he 

provision ot th1a aevice will permit the Britieh to continue the use of their 

baaie cipher equtr.ment modified b7 a relatively chea-~ and easy to manufecture 

adaptoro The same th!llf,' hold t:rue insofar as the U., Sa is concerned si11ce an 

ada~tor can be prOT1ded ~or the EO*"CSP 2900. 

10P 8EGREJ 

!IQ> SiCl~ii' U. Su :i:US O>Jl Y