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i -,-- - REF ID:A6035~ 

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GOVERNMENT COE-'.IDMJICATIONS DQUAR.TERS 

U. S. Liaison 0.ff ce 

GC/133/51 25 May 1951 

'fOP 5-Eeftm 

Im40RANDUM FOR DmECTORa AF'SA 

Subject: French Modii'ication of the M- 09 Converter 

Ref: (a) AFSA 041811Z ~lay 1951 (4 ) · - EO 3.3(h)(2) 

PL.86-36/50 USC 3605 

1. As instructed in the ref'erence and in company wi.th 

I examined ha modified !4,,..209 

converter in Pari.s on 21 and 22 May. W agree in the conclusion that the modification is 't:Tell ineered and thS.t 

its use is operationally feasible. 

on he a emoon of al ii'.fay called 

upon Colonel'Veyron IaCro!XJ) Etat-Majo Combine dea Forces 

Armees 11 51 Boulevard de la Tour-n&ubo11 g. · The colonel 

welcomed us and provided means of eond cting us to the office 

or Commandant Arnaud, at li!linistere de s Guerre., 231 Boulevard Saint-Germain. Here we exa.m!ned he machine and discussed it Yith Comma.Dds.nt Arnaud» -who- onceived the modi.f'icat-i.o.n. 

At his request, ~e returned to his off ce on the morning of 

22 ~for a f~ther discussion "ithC lanel LaCroix and h.tm. 

As I Jhas fluent French_, the e nvereati.ons were con-· 

duct in th& language-and I put my q estions through him. 

His report, thereforeD is the first-~ d" account of what 

was said and embodies all the inform.at on elicited by both 

of us; copies of' it l'.Yill be ava.ilmble or t"onarding to AFB.A 

possibly today. This letter is being iled et the earliest 

possi.ble moment 1n order to provide de ailed in.formation of 

the mechanical features of the modif'ic tion. Commandant Arnaud 

classif'ied as SECRET my roUgh sketches of the device. 

3. The modi.fieation consists of' placing the original 

filted-slide normal alphabet print and de.x vhe·e1s with - demountable print and index Yfheels of pproximlsl.tely the,same 

physical dimensions as the origin.mls, d t.Qat have redial 

slots in which metal type can be set s e.s to provide W:Ly desired sequence on the trheels. For c venient reference'J, 

Figure 1 deserj.bes the original Ell-209 · rint wheal assembly. 

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eclassifi ed and a roved for release b NSA on 06-17-2014 ursuantto E_Q_ 1352 "'1. 

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0COP SECRE1 

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a.. First stage of the modi.:r.·cat.ion is to remove the 

original print and index ~heels by cu ting off 'the assembly, ·flush with.the left face of the space function cam. (as indicated by vertical line in Figure l). 

b. A slot about 1/8" vide i eut through the edge of 

the space iilnction cam diametrically pposite the space pin 

and paralleling.the hori£ontal axis o · the assembly. This is 

shomi in red in Figure 2. 

c. F.tgure 2 shows general d tails of the new print 

and index wheels. The UJU.t slips on ' o the shaft against the 

space Tunction cam and is held in the correct relation to 

the space pin by the spline or projec ion (11) which engages the slot in the cam. A ving screw in the end of the shaft 

prevents_ the assembly from slipping t the left. 

d. The index wheel (4) and _he print wheel (6) each 

have 26 radial slots. A side viev of a type for the print vheel :1s shomi at {9);· it vill be ols r that tbs left end 

hooks under the coil spring ( 7) :ry in a. gro·ove i.n the c.ircumference o.f the print wheel while he rigbt end i.s secured 

by serew:ing dewn the retaining ring ( 8) • · 

e. A letter for the :index heel is shown at (loi. The 11number disc" (2) is detached fr m the index wheel (4 by 

lifting alea.f spring (not shovn) and rotating it about 15 · . with reference to the index wheel (4 so as to release the 

lock provided by the heads of three ins (3), which e.re so 

spaced that the disc ca.n be put an only the correct position. The index '!:'Theel letters (10) then ar slid into the slots from 

left to right, engaging the coil spr g (5). Replacing the 

number-disc locks the letters in pla e by prev~ting their 

movement to the left. 

f. The number-disc has s le digits in normBl order 

(2.4 decades} around its eircwnferen e; these may be used to 

encipher digits as letters. A red k ie provided on the 

rim epposite the letter Z,, ~hich is lied permanently on the 

index vhe0l (and print vheel) and is alwa s used !or s ce. 

The pins holding the number-disc on e ex 't:1 ee are so 

arranged.· that the disc cannot be t&lled in any but the 

correct position. 

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oft, after which the index wheel letter (except Z) are removed 

by sliding them to the left. The lette s are then put on in 

the nev sequence relati,ve to 'the "Z" le·t an the vhael. The 

nwilber disc is re~laced as described ab ve. Uneere-t1illg the 

retaining ring (8) frees the tj'Pe on th print. ~h&el (6) (except Z) s.rter which the ne-e" sequence is put on the pr1nt wheel, advancing 1n the opposite direot on to the index 't:Theel 

sequence. By '1iping the print 'lrheel wi h a piece of paper 

most of the ink can be removed.o so that rmming the change of' 

type)tihardly a dirtier job than changing a. typewriter ribbon~ 

l tried it myself and ~as able to take ff the old and set up the nev alphabet on both wheels 1n th1r een minutes.. Commaruient 

Arnaud said toot his test~ had shown t t after a message or 

two with a new alphabet, t.he opera.tor 1 erns it and ha.a little 

dif':ficul ty using ths nett sequence on t index wheel. 1 be13..eve 

this"' especially since the highest fre·ueney char~cter (Z for 

space) never changes • Putting on a ne alph&bet pre2ents no 

difficulty in condj_.tions of good light end 'ifforki.ng space; a 

26-letter check, lihieh Arnaud expects o ieaue with the key -lists:i should. prevent mistakes if fs.it ully executed. Changing 

the alphabets with hands stiff from co d~ or 'Uithou.t a clear · space to lay out the bits a.nd p1eces; . oll.ld be leas easy, but 

in a.ny case no more trouble than ehan.g -the peg and cage settings. 

5. No specific :installations ver. contemplated (for' NATO), 

however the French expect to convert 1 00 ot the M-209's for 

army use by the end of the year. Arna d said. ·most holders 

would be issued tvo machines, each vit three sets oi" print and index wheel letters to provide s s in ease of loss or 

breakage. He expects to change alpha ets es often a,s every other day> depending upon the traffic l~d, in.Which case 

securi.ty would api'esr to be qui.ta hi .. We asked him to 

describe vha.t he considered a suitabl indicator usage and 

were told. that this was a mere teebni al ms.tter be had not 

reached the point of formulating. Co t of the modif1.eation 

is 8.,coo francs (about $24.) per mac ; the movable-type print wheel is covered by a French pa ent concerning 'e'hieh 

he indicated there would be no di.ff'ic lty 1.f other nations ~anted to mod.if'y their ovn machines. 

6. The modification makes no p vision f'or variable 

\ ... slide, and this subjeet was not menti ed in t~ discussions. 

~~1g5~i~~~~l.Jsc36ci57~ 1 1 report will dev lop fully our other i observations during the visit. It is almost eertain ~e were 

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. in the immediate vicirllty of vha.teve French C!'YIJtanal.yt.ie 

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ef'f'.ort there i.s. Colonel I.eCro:iX di not give the impression of being s technical cryptographer o -analyst. Arnaud, on .~ the other hand, had the look and er of aw. extremely capable 

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TEO 3.3(h)(2) >1 

Pl...<86-36/50 USC 3605 

end alert person ~ho lalelr ·very well ul.W hca 't:7as. doing. on - the ~a.11 of his off:ioe,, in ttto fra.mssii ung s French military eod~ of 1760. In his bookc~se ~a& a. co lection of dictionsries ~ 

:J.nclu.ding Svedi.sh and Spa.nish11 among ot ers - also the ABC and 

Bentley\codea, a copy of 19The American leek Chamber''!} the 

Fl"encn version of Flet.cher Pratt 1 $ 11Sec et am Urgent n p etc. - bu.t no\boo?fS on mathematics. He produc d cross-section paper for sketchee,1.noluding somo <i&hich appe red to be a 30 :t 40 

transpoa.iti.o:n cage. .Pro·truding from a older on his desk 

marked "~ODRES" 'Ua.a a. sh~t -a:ith a •written hatted e.lph!:l.-

bet\ running do"'tfn\the .side. Neither he or La.CroiX; however; ask~d a.ny prying.que$tion0 except that at the start of our 

eonferenee ~rnaud mcrui;ed f'rle.ndl)l, n Vhat fields are you gentlemen e.Itperts". describes is reply 1n hi~ report~ 

Which vas to the genera e feet the.t v 1 were there only to 

report vb.at we saw.11 i'or expert eva.lua.t on. Your in:struetions 

that. the discussions viere to be crypto aphi.c in natllI'e vere 

atr1et1y obeyed.~ They\did not ask wp.e·. l ve.s stationed., and 

appeared to believe l had come from Wa hington for the meeting. I \ I 

r--"-...._ __ ___.l ... 1 ... s_s.w.er .....,io~μsly st·ud: .. :y1ng th security offered by 

J Vhen it first b came known the.t the ,__---=~m-o-=d~il~i-c_a..,..ti ..... ..... on___,.was ba.se on e. r 

Thi.a first 

L..-__,..--= ........ ==......,,,,=--7=-=-~.....,...o=-m=e=-· ~\_o~u':":I. c:"""""E=-=y~e:-::xa.=::>:!l"":::"::!'"Z. =""'1-=on=--=o"?.1"-"-z:i:::!e devJ.ee 

and the impression gained .of Com.mand t Arnaud•s technical 

competence_, and l believe\ i.t pos.sible may consider 

the maohi.ne acceptable for\ flATO use a tll1rd level.11 et least 

as an interim measure; subject to est blishment of satisfactory t"Ules t'or use, such as bisection, fre uent change of alph&bat and s~t:tin,gs_li> good indicator\.system, te. ·use of the ma.chine 

by the French should,inerease\the sec ity of their internal 

connnunica.tl ons c o:asiderably,. 

9. In addition to sending report 0 vbich 

as stated represents our combinG ex ~r e ce, I will forward 

any other information ob·ta.inable on . is· subject. The vi.si.t . to the French was a most interesting and worthvhile experience. I am very grateful for the opportun.1 y. 

EO 3.3(h)(2) 

PL 86-36/50 USC 3605 

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.J, : .... 

G iIFFIN Ch"ILES 

Co der, U.S. Navy U.S.L.O. 

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c) REF ID: A60359 () 

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ORIGINAL M-209 CONV!!:RTER "PRIN"' WHEEL A SEliBU" 

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p H ' :.-- -· ......_ - G. c;. 

R " --..... s 

T I , 

I. 1. ~. *· S. 

(Not to Scale) 

Approxi tely actua.l size. 

1. Operating knob. 

2. Index Wheel, set against mark on cover f machine. 

3. Index showing letter which is in printi/ position (reciprocal of letter~ which index wh~~l is set); 

rend against edge of machine case. 

4. Print wheel. The alphabet on this whe 1 must be the 

same sequence, but in reversed orde , ae the alphabet 

on index wheel. 

5. Space function cam. 

6. Space function pin. The position of · ls pin relative to 

the print wheel determines which ter is used for 

"Space" (Letter "Z" in 11-209). 

7. Driving gear through which kick of ing key is applied. 

(Fig. 1) 

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Not to scflle. fpproximtely t-wice actuol size • 

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FIGUFE ; • 

Fer exp le no Lion r.ee text. 

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