'. ,> 

REF Ii1AA243604B 

..,. 

AFSA-00/wn 

A6 . DLPArlTM.LNT OF D.GFi:.iN81!; AH~iliD FORCES S~CURITY AGDNCY 

Serial: 00040 WASHINGTON 25, D.C. 

TOP SECRET· LJ. S. ['t'[S ONLY 12 December 1949 

Y.a. h.Yiha G:WlY 

MbMOHANDUM FOR DIR.wCTOR, COMNUNICi~TIONS-ELECTrtONICS: 

SUBJ:i:!iCT: Replacement of the "Combined Cipher Machine 11 ( CCM). 

Reference: (a) JCS 2074 and 2074/1. 

1. The Director, .1-1.rmed Forces .:;ecurity J~gency is in receip:t of a copy of JCS 2074/1, and has given preliminary consideration thereto. It is understood that this matter is now 

under consideration in JC1C and will be coordinated with AF5~C. 

2. The conference with the British Cryptographic experts 

was conducted by the Director, Armed Forces 0ecurity ~gency and 

his experts. The present views of the Director, 11rmed Forces Security Agency, together with other pertinent information, are set 

forth herein for possible assistance to the ;nembers of the JCt:C 

and AFSAC in consideration of JCS 2074/1 and in preparing the required answer to the British. 

J. The -British assumption of a target date 5 years hence 

when we can and should have a new combined cipher machine seems 

valid. If necessary, in the event of an eii1ergency before the completion of a new combined cipher machine, the U.6. might furnish 

(in limited numbers) a suitable secure U.J. r;1achine to the U.K. 

for US-UK nhigh command" communications, and possibly also to certain Dominions, and perhaps to other allied countries, for the 

same type of communications. The machine suggested by the British 

·as the long-term solution { 7-rotor BCIJ::) is a current development 

project. The first model has not yet been completed. It would 

. ·:-t 

be advantageous to the u . .:.i. not to name at ttis time the specific 

machine we would make available when such an emergency arises. Today it might be a particular machine, and ten years hence a different one. However, we could -- and I think we should -- assure 

the British on t.his matter, in a general way. ,,·e agree with ths 

British that a 7-rotor BCM mould give adequate security for. hi.gh 

' command US-UK com.111unications. It will take considerable money to 

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

TOP SECRET - U. S. EYES O~tY 

_.· 
REF IDifia243604B 

:\Fb.11.-00/wn • 

Jt6 . 

..:;.erial: 00040 

l9P SEGREf 

Li, G. iiYLD O.NlsY 

1..2 December 191+9 

SUBJr.,CT: tLeplact:::insnt of the "Coi~ibined Cipher Hachine'it )( CCJ.,i:). 

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

produce it in quantity. The irnport.s.nce oi .:::ecure US-UK communications is such t;hat an adequate cryptographic machine must always 

be available. I believe that, as at present, it should be difi'erent from our own beot machine for reason;,:, stated he:ceinafter, 

and that it can be different with adequate security. 

4. fhe u.~. does not have undsr developm~nt a 7-rotor 

~cM; furthermore, there appears to be no need for undertaking such 

a development at this time1 The 0CM, especially the model ~~,·· ... ·-- - .•. _,,_~ ··--·-. ...... ~,.~ ... ····-·· . ··--~ ... 

!...(,pSP 2900)_) with certain iiioclifications··;~lis .cegarded as satisfa.c- -·-·r ·-··~r-.. ~,-- .. ~..,···-·· 

tocy and secure for highest level communications. 1

:

1

ie also have a 

limited number of another (more complex) ;,;odified .wCk (CSP :2300) 

which is also regarded as secure for hig~hest L:::vel comm uni c<::tt ions. 

However, because of its complsxity, it is not expected that there 

will be any further pcoducti.on of this machine. The GSP ~2300 and 

2900 are basically the .iorld Jar II type ~CM plus improvem8nts to 

;;;nhance security. The improvements were lo.~~ical developtuEmts applied to tho basic L,C1·~ and should not, therd.'ore 1 be considered 

to have resulted in creating new type machines. 

5. The British .state that the : .. Ci·i ( ;orld .var II version 

of the basic i~C.M) was disclosed to them in 19li-2 ..... limited nwnher of Britishers have seen it. They do not·' however, have 

enough information to bu.ild a duplicate of our ,_,Cl•i. 'i'he Jritish 

probably could construct a machine resembling our ~c~. It μrobr::.bly would take them r~1any yec:' .. rs to do ~>o, sinc:f:. our ,:,Clvi ha.::> been 

about 30 years in the making. In private convi;;rsation the 3riti.sh 

admit they do not have an ~CM blueprint. The ~cN is ntc0ssarily 

e .. cornple:x machine, and c.oe1e of t.he details co\.tld. not b8 asc~rtu.ined by merely seeing it in operation. The only irnp1~ovt::d rnachlnt: 

for oti.r own use that we can now be sure of having L3 the ti1odi.fi8J 

,_'.,CM. !"i.lthou.gh we have: 0orne prom:i.sinf; rsse::u·ch ancl d8velopment 

TC)P SECRET· U. S. EYES ONL't 
> ,-

. ·· .• ~ 

--

REF 8:A243604B 

AFSA-00/wn 

A6 • 

Serial: 00040 

TOP SECRET 

....... 

D:t;P ARTJ·1Lt~T OF DJ2;F.;..,N$G 

ARI-1mD iOt?.Cr,0 _SECUrtITY AGJ:CNCY ·.. ',iAbBINGTQN ·25_, u::c:·:· --- --

& u'.. S .. EVES ONLY 12,_December 

. :· 

U.S. rffbO mJLY 

1949 

SUBJECT: Heplaceraent of the 11 Combined Cipher i\~achine it ( CCl'vi) • T - ~. • 

--~-~--- .-,.~--

projects in the cryptographic field, it will, be several years more 

before we can expect to have a new U .s. c_rypto,'.?;raphic i;.-1acLine-'-

based on different principles, and in sufficient quantity for 

regular U.3. use. 

6. The ~ritish assumption that theoretically they could 

solve any 5-rotor machine is based on having a set of the rotors 

and a 25 letter 11 crib•'. Getting the rotors and crib might delay 

a start on such a solution indefinitely, and the result of each 

solution probably would be good for the traffic of but one day. 

Such an attack is theoretically possible, out to apply it to the 

5-rotor BCI.I would require considerable time and rnuch machinery 

(even if the roto~s and crib are available). It wou~d be an extremely difficuit and costly undertaking. A 7-rotor BCl'1~ if developed, would probably preclude such an attack. Attack on the 

basic :C:CM would be even L10re difficult than on the 5-rotor BCivi, 

but theoretically possible. It must be assumed that what men can 

make, other men should be able to take apart. Practically, the 

risk of solution is considered small in either case. 

7. I would especially invite attention to the Facts Bearing on the Problem as originally studied, and to the Discussion, 

in 1nclosure rrc;r of JCS 2074. The content of that enclosure is 

still considered to be sound. 

8. The United KingdomYs proposal to effect complete interchange of cryptographic principles on a reciprocal basis is 

still considered unacceptable. However, certain liraited interchange on the other aspects they now propose is considered desirable on a conference basis, but not necessarily on a continuing 

basis. After the first such conference, with ~isclosure of such 

currently available developments by each side as ~re previously 

TOP SECRET · U. S. EYES30NLY 

. ...: 
REF 1~436048 ...... 

AFSA-00/wn 

A6 

Serial: 00040 

DEP • .i..B.Tl'vf.t.NT OF DEFENSE 

ArilJlliD FOHCES S.t.C UR.TTY AGBNC Y 

\MSHINGTON 25, D.C. 

TOP SECRET U. S. EYES ONLY 12 December 1949 

'f'OP bnGRt,SP U, 2, A;y;e;3 QW1Y 

3UBJ.t:;CT: Heplacernent of the ·'Combined Cipher l-'~achine 11 { CCM). 

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

agreed upon, consideration could be given tci the n;atter of future 

conferences and possibly to future collaboration. 

9. We should inform the British that if they have or 

build a new cipher machine which they raight care to disclose to 

the U.S. as a possible combined cipher machine, we would be 

pleased to consider it for such use in the future -- either by 

our building an adaptor for one of our own cipher machines, or, 

if that should not be feasible, then by building or buying the 

number of machines required by the U.S. for US-UK communications. 

10. The U.S. should continue to develop a 7-rotor BCI111 and 

whenJmodel is ready (expected within a few monthsJ allow the U.K. 

to examine the principles of that machine. If both the U.J. and 

U.K. representatives agree that such a machine will be practical 

and adequately secure in use for twenty years after production, 

then agree to the adoption of the 7-rotor BCf-'i for U0-UK high command communications as the replacement for the present combined 

cipher machine. 

11. The three proposals listed in paragraph 7 of Appendix 

to JCS 2074/1 are not feasible at this time. However, concerning the present CCM, paragraph $ of Appendix to JCS 2074/1 is 

generally concurred in, since the CCM probably must be continued 

in use for several years for US-UK communications. The three 

steps proposed by the British to enhance the security of US-UK 

communications with CCM are admittedly desirable, and some or all 

of them may be practicable and in that case probably should be 

adopted. 

12. For reasons briefly set forth below, the Director, 

x\.rmed .forces 0ecurity Agency believes that it should continue to 

TOP SECRET U. S. EYES Q~':'f 
... .. 

- - ··- ·-. . . . ---.- ----

REF. r9A243604B ... ·:· ... · .. ·_:=:::• 

. . . DEP Af.t '.J.'M:i1.NT Of ®.f4:tit~:::::::;:::::,::.:_. ...... .. ~:-ARi~iED ~'.OftCES. SECUliI'rl .. ,ACf,t;;:NCY 

AFSA-00/wn 

A6 

-:-=.--·-- .·· 

Serial: 00040 >··."··:·.: :l:A..>HINGTON. 2$1· ... ·p,~·~.:~·:· '.IT>·· .. . 

TOP SECRET - l) S. EYES -O.NLY.!.:.:=:\·,;~2:::!;;.=:.·:·n· ..... · ""b · i··9·4· 9 ... : .. ~ .: ........ ····: ··.,~ · · _ecew er ··."; . .. · ... •: ·.· . 

l:J' • .&. EThS ONLY .... :·:,·:.: ... 

.. ··. . .... 

5UBJ£CT: Replace1.1erit of the "Combined_ ct1liliE:i.r .. l\~chinet' ( CCM). •. ... . .·. .. . 

- - .. - . - ...... - ... ... !'- ... - .. .;. . ·.~ . ··~ ....... -- .... ... .... .. .. ;.,. ~ -~ ... -

.· .. · . .":"" ... ··. 

be (J. s. policy ~ot ·t.o give any "f'ore;lgn '~.a:tit)n· ow;• .. most s"ec"i,lre 

cryptographic ~chine~ or the principie~·:>t:h.~:~eo.~< . ;.,uch actio"n is ... . . 

not necessary to insure. :·· secure· U.:3-UI<. ... c~riii:1l:.triib~ti~ns. : .· .. · .. · .. 

.' 

The primary 

objections are as follows: .. 

a. Twenty or thirty years fiom ·zl.Q~,,., the U .,:). nJB.y still 

be ·d,~pending upon the tC).t·rct.i.-~ ·."lnodl.fied i!.CM) for .. . . . . :.:.: .. ::· ..... :·.: ....... ·. . . 

b~ .. Prom .th~ political. vieWpo.1.~_t· :_;· . .:_·_no: one. ca,n forete;tl 

what ·~ind of Gover.niaent .W::i\i: .. b~_::· in cont.ro"i of· any 

foreign country twenty or. t~:~rty years hence,, or 

what our relations with such a·· country then l.dll 

be. Of' .course,, it is to. _be _h6pe.d and expec·ted 

that thej/.will be fz:iendly·: in, .the·· case of the U .K. .... :··. 

and the Do~inions. ·: .. ·. 

· .. :"" 

c. Giving the .t:CM to any fo~~_ign, ··~o:untry removes the 

sole riontrol and _custody_ °.f ~hat machine f'rom the 

. . ·.· 

u .. s. .... · ... . ": .··· 

( l) ~ie could not as read~lf: .. ·.a~piy· mod.i:t:icati~ns 

. which 'We might consi_de;.,_:·:·~~sential for otir own . ·... ., .. 

or for combined use-·• · .. + . 

( 2) T~ere are three i_mportint :~_physical securi tY: ·. :-: .. :· . 

(J} 

~spect.s of any 111achine·~ ·:and._. ... ·ri.one of' them. should .· . ... .. . . ·. . .· .· 

..... 

be _ignored: 

rotor.s,_ and the key 1~9~-~· .... '\'·t{'9 could not .be.· . . ...... 

sure that adequate phys·ica~ .. ··: se.cui·i ty \;iOUld be ·:·· .... ';, ... . . . 

. ·given to our ba~ic -r11achine .. :i~o prevent loss or· . . ·. ~- . . 

c~:1:~j;;u~e,. even though ·ou.r .... c~uhications :should .. -~~-· . . 

be:\a~_tjure ao lo~· as· __ the '.:)·~~_():t-s ~d key lis-~s 

ar~·. n·()_t co~promised .. ~ .. ·_;:. ," .. ::.--:.·.:>;,:,:.':··=< ... 

We. could not be sur~ tb.ttt ·d~ machine would not . . . . . . . :.:. :· ... ·· .. ,. ·· ...... 

pe used in plac;:es o.r ._i1f .. ':tyn·~:~- ·or ships QI' 

·-,,:'_":·=,.<~::r;_\ 

:: . , ... =:·.: 

.. ·.:.:.i": 

.": 

·.···: ... ":'."i 

.···· ·.:· 

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. .·. ·=·.··) 

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·.:. 

·. '· . ""·.·' 

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·'"I 

.. 

.. . 

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.·::·:; 

. ··:":. 

> 

. .· .. '··· .. .. 

TOP ~~~ ~~,!:;~:~b~:'.;~iiifr,, .. ,-•----.:·::~.::~:.?:_:~~ 
. ;. 

.. . · 

REF ·t-A2·43604B ·.·.,:-.~;·_·· . .-_··<'..:• 

AFSA-00/wn ._,_,.·... . I).i:.PAHTh1!iNT OF .. .Q.S.f.'.~.NP.~-.::,.(:·. ..... . ..... 

A6 .".:;Afh'1£D" Foac·=·s SEGtllil'ft'···:·JtG"'1'JCY · ..... 

Se~ial: 00040 '\ ' <WA~HfN~TOt{ i's ;:~f ::-~ .• ::-_ -_ - ---- -' 

TOP SECRET· -.:u -~,s-. ·EYE:S OJ~]i~:::;::~~c.:ember. 1949. 

'fQI? ot:Gah'f TM a+ ~~: Wμ • -- --- -~"-t~·B ~Y · - · · -. •• _ •_ 

SUBJJ:.CT: Repiacefu~~t. of the. rrc~mblrl~cr:·Ci~~~~·:·:1~ia~hi.riE)·it (Q.~~I) - ·- - - - - ~ .:/··- -~ ~ .:. ~ . .;; ··~· ... ~:_:_~·:::L:·:···~--~;::_~·:.j;;.~'. .. -. = ~. ~--·-~ .. ~ ·--~ ·_.·=~~ - -

. ~i":rpianes . where· we'·_:::6'\J.·~~fY.~s· -~~ld. not ... ·p~nnit ·. 

(4)--i:~::~:::;:::n~l!i:~~i::::~::~:: ··or any machine ~gr·~i~~·::_:-~r;Q~· ··to~ . comb1n0ci -:~.(>mniu.~-· .. ·. . . . ·: ... .. .. ' . . .. 

··!.cations to in.ore ·tbBj{·'.:9..d..e· .. :.·~iiied .fq_reign c.oun-

~;i"; e .• g.; to ··Cana·4.:;.:: ···itq:~ti;~ia ,_· 6·r possib~y . .. . . • .:· ':.:· .. · ~ :·: .: .. : : .. : .. :.:'ii=::.:. : . . . . .. . 

even to the. French, ·Dutch~.:_= .etc. · .. ·.:: ·.. . ·: . 

. . : .:!:.;:·: .::·.·.·.-:'.':,,:· .. 

13. With th~ ·cohsideration I liaJ·~:_:i>·e·~~-···abiu·. to ·give this. . . . . . ·' . . . . ... . ..... 

extremely important pro~lem to date, my·:·v1e~r~·=_._aa. 'to. an answer to :. ........ · .: ,:.=· 

the British are as follows: . . . · .. · : 

· .. ·:""."',· .. : .· ·:"" .... · 

a. Agr~e· ·that us·-uK conunun:i,.cati:o·n$ :must continue. (prob- . . . .. :: .. '· ···:.: ·:·::;: .......... . 

ably ro:r· .five years .if" nh~_,..em~·~gt:ll~P.Y should develop 

in· that_;. ~e~iod) to be .by=·,:~?.~;:~:~fit· .ccDr~ - bui· made. . . 

more .. secure·J ' if possiQ.l~:~. .. ~:i. ·.. rise :.of' n.e~ and. addi~ . 

tioriai .. ~oJ;~rs and ·k~y I:(~~-~-- {;(l)_d by minor mate.rfal 

::::~::!: ;:r 1:~~ a a~iltni::du:~~her r~~hine b. Propose ... that the :U .s. cortt{P,u~··:/to ·de~eiop ·a 7-rotor 

BC1'f ~~:··.a p~obabl~. re~lac:~~:~;t/'ior· th~ present. dCM ·. .. . . ·.·:·.·: ... ,_::: .. :.·· for. cdrubined ~se.. Both .u. .• $·~··: a~d.'.U ~K. experts al- .· .. · . 

re~dy ... :ha"ve. agreed that" suci{ a lii~~h"ine should ··instire 

the ne'ce.s$ary security r_6;··:·:t:~e .::.~~:xt. 2·0 yea.rs··~ .· The . . . . .·. . . ~- . ·~·. . 

cost to the. u .·s. will be · .. c'6ri·~·i4~ra.ble but ·.neces.s.ary •.. . . \· : . · .. · .. . : :.·. :·.·. :.: .::··. 

This .pl"op_os.al, if agre~d ·.#.o;~--·'.·'1.~'1ld ... ha.ve. the one Vit,a.lly .. :.·:J-falp~t-ant · advantag6>·~r···.~--~:#.;inipg the . ~CI•I 'c anti 

such .ra6d.-~f.j .. ~d. ~crvi as we ·rria:~}:(he·~~'arte~ use for .u .s. 

COLlttlunic~t-~ons) exclus:iv~i::¥:··:fo;/·:u.~~· USG, and a;:;suranc·e .· t;:t ·:··~:ol:~.· u. ~~ ·. cont~o1:'."~~~::\~·ti1·~ u~ s. ·phydicai: .. 

cus~ody •· .·-~iie· decisio·n. ~~:.6J:t;:_:tc.-d~in~d us~ ~houl~ ·be . . . . ·.,::.. . ... · 

..... ··:: ... ·· :··:;·. 

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.B,ri ti sh" irt ~J'f. cmerge.nc,Y1' ... a; ):l,:~ .. ¢1.u'e. ri;f.ph_9I" ma,cb:Lne" .. : .-: .. :~_.::>::: . . . . . l. ·.. . . . .. · .· . ; .... ·. ·.,,.,: .. ··-;:,!,:;_. . . . .: ·... . : . . . . .\ . 

. ··in.·:ti~"it~d ·riv.mbers t.o····~-~~~t~.::t~·iti~1· ·t.trg~nt .. ':o·o~~:tn~d ····.:_:.-~L>;:·-:~:l~· 

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--- : ::z::~::c:;::::s~tta,_~,_:._i: :; __ __ i_f: __ :~_i_-~.:_._.~,*~d, ba~ed - " -< .·:?4 . . . . . , .; \: _:;.:i~~~:\~\ .. : . . . . . . ,. . ... · .... :_:-::· :.· .. :_;,../ .. · .. ~: .... i'._~:_:;;\ . .-: .. ·: . . . . . ·. ·. -~ . . . . . . ."' .. ! ·:,. -:~:~:= 

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