REF ID:A39539 

Thl• iBYeDtioa deal• wltb oryptograpblc maoh1ne17 tor automatioall7 

eno1pher1ag and deolpberiq ••MS••• The obJeot ot the inYention J.a t.be 

proyiaion ot a oryp'\ograph with a ke7board tor high-1p1ecl aanual operation, 

a bank or iDclioaU.ng deYloee or el1a\ro•-an•t• tor noting or reaordlng the 

a1pher •Jmbola of the •••181•• a1 the lattel" are belng moipher1d, and tor 

noting or reoordlllg the plaln•ted letter• aa the ••HI•• are being deoipb1red1 and ce:rtalll olpJaerln1 meohai•• lnterpoaetl bit•• the k•Jboard 

ad the bank ot 1nclioat1D1 deT1ct•• or eleotl"O••pria tor conatut.17 obanging the relatlonabip bet•• the mea•ag• oban.et.1r1 a4 the oipher 1pbol1. The inYtatloa ia pri11lar1ly ooncerned onlJ with the ciphering meohani .. re• 

te1Tecl to alleft1 which :11 of 11mple clea1gn but naYtl'tbel••• 7ield1 orypto• 

graaa ot 1reat aeours.ty. Thia olpherlng •••ha.Di• •plo71 •••• wh1oh are 

aoYel in the Ol"J'ptograpblo art. ln that lt inTOlYea operation along a tiM 

az1•, mad the eaaot orrptosraphlo re1ulta are dep1nd111t upGn a tllle taotor 

wld.oh 1• ooaatantlJ obangla& ln an irregular mamaer • 

.... The in•ent10. 1• de1or1"9d lD ooaneotioa with tour figur••• Ilg. l 

le a diqnmaU.o repre11atation of the part1 or tba meahmli• together with 

oel'taln oirault arrang .... t,. Fig. I la a dlagrmaatlo r•preamatatioll ot 

aeaa tor laparUng unlqu•••• to ••••I•• •ffll wben the latter are •• 

olphered bJ the ... keylng ••caunoe. Fig. I i• a dtaaraatie repreaenta• 

tion of the eleotrloal e1rou1ta applicable to the 11et• 1ho• :111 11.g. 2. 

Ill• 4 •bon an alternat:I.•• •oh- tor one ot ·t11• h!teio •llUllt1 of the 

meohanl• 1bo• :la n.g. 1. 

gpp1·oved for Release by NSA on 09-30-2013 pursuant to E.O. 1352¢1 
REF ID:A39539 

Ia 11g. 1 the principal element• ooa•i•\ ot a ke7boerd l, a bank 

or indicating device• 2, a rotat'- a1Jlber a--.atator hereinafter aalled • 

rotor ,, a dh:tributor 4, a cea-whHl meahard.• ' tor produo.1.ng a olpbn' ... k97, 

a perwautatiou-tranelation meobnni.BJD here1ne.tter called a t.l"aalla..., 6, and a 

s•itchboard 7. 

The turid~••ntal c17pt.ographio principle ot the pre1ent inYeDtion 

11 •• rollow1. lCe7b0Z1rd oper!ltlon 11 c7alic in character end ie performed 

•1th a cadence sim.ilr•r to t.hat in telet;rpe operation. DurinL euch O"/C'!.f' ot 

Jce1board operation, hereinHtter referred t.o aLtJl.4. oj)erating eye le, the 

aucce1a1Te alphabet• or a ooaplete eet ot 2('aiudcipher 11lph11bei1 ere 

pre1en.ted in n fixed eequence, !or iJC)tential Mpl0711ent in enclpherlllllt or 

deciphernnt. Onl.7 one or tli~ cipher al?h~bate, however, 11 selected 

during enoh operotin.g C)'Cle lln~ the aeleation ia ••ried in aucceHive operating 

C)'Clea according ~o a ~•ry lOJlt! cipher key established by means to be de1cribed. if Broadly 1pealdn&, the fOl'egolq or,yptograrphic 01>9r.atio11 1• acocmpli•bed 

pract1oall7 a! !ollo••· The operating c7ole ie ~1"1ded u~ into ?6 e~ual 

ti .. -interTala by meP.DR ot the dietribvtor 4, ~lld a letter mny be encipher~ .. ..L ~ 

(or dea1phered) within allJ one or the•e interTala bJ mer.n1 of the rotor J~~ 

th• k91board 1 :lnd bank of 1nd1aat1ng de•ice1 2.a11eeia~ecl will tla:e •••• i; "''Ho. 

A apecitic t1•e-interT!tl i~ .. 1ected within eaob opersting c7cle b7 meene ot 

the tran•lator 6 wbiah ia a•aociated with the distributor 4 cnd·'811e 1Witoh~d 

7. The tiae-inte:t'Tal that will be celected in each ca!e varies with auco•••i'f9 

operating c1ole1 aooorii::ig to a ke1 waA.ch 1-'I produoed b;r the cam-wheal cipberk•J 118chan1am 5. Each interval will yield a different result ~or the s~me letter. 

The ke1board 1, comprising 26 churactera equivalent to tb• lettera 

ot the el;>habet, has a corresponding number ot oontt.ct• ot''llbich onlJ two 

are •hon .oit, 10 and 11, aorreepolld1ng to the letters E iuid Q, reapect.lwl7. 

The baak Ot indicating devicee 2 m~J tske the.form of glow l~ap1 whioh Rre 

1lluminated when current pae~•e through the• but e preferred eabodiaent ie 

to baTe t.he 1ndlaat1ng de'Yi.C8a take the torm o:t_~olenoide trbiob operat. tlae 

k91a ot a recordina typewriter, to that a prin,.-u record of ~he enciphered 

or deciphered ...... , •• ., b• made. ~ ~~- ....... r:.. .. t;. .. .,.,, 

The rot.or 3 1& a clpher-oo.-utator wh••l ot ton now well known in 

the 0?7pt.ographic art. It 1• 110unted on a rotetable lhat\ l:>. Preu1q 

ngainat rotor 3 Are 'bro eta.tore, a lett-hand etetor 13 sad a righMaDd 

1t.Mtor 14, eaoh ~o'ri.ded with a ring ot 26 bhll-bearing ud epr1ng CODtact.1 
REF ID:A39539 

iaeulated troa o• oot.her and exerting a alight pre11ure apiut the 

firtoe of rot.or '· j, aow:r9J1 .. drawing l)Ower from so~ce 9', dl9ives tl}e Shaft 12 

and thue tbe rotor ' at • con1teat speed between the 1t.atot• ll llllld 14. 

Tile rotor 11 made ot bakelit.e or oinailt!lr in•ulating ar.terlal and con- •i•t• Of tWO ...... ,_ & left--band MM° and a Tipt-brind ~ 9flM °heaPiltl 

a ring or 26 contact aurtaoe1 '• B, c, ••• Z, equ1d1et~ntl7 spaced troa 

Olle aDOth•r circU11terenUul7.ea •II• w1'•• ,..... lneulated oolMtuctora 

pa111a1 ta..rouch tl:ae rotor -F&ot the 26 oo•taot eurtacea or the l•tt "io.c..t.. 

...-,. t.o thoee of the r1pt • in a uwr which 1& reciproc~~ palr1. 

That ia, it A cp_ !·1i• left btilt' ia conneoted to 1 op_~I:\• right , then 

J oa tbe left fliiU"''"J.1 connected to A on t.be ri&ht ifft--_~ Thu1, .,.1th lJ 

palred eontacte r.oiprooit)' 1a the enoipher1111-deciphering relatio1M1hip 

is obta1Md wit.bout. 1peaJ.al nitchiDa a:rranp1UDt1 therefor. 111 la tlle 

ea•• et ••••&• otll:N D'IJpt 0p1 .. 1 •'1•,i•1 ... u\&111 oi .. es M mat.•••••• 

The di1tr1'butor ' couieta or a ••t Qt 26 equal-area ........ or contact surtacee 15, iuulated fro• one another E:nd diatributed ciro•t•r•ntiallJ on the taoe or the 1iatributor. J. bl'Ulh arm 161 oa. ths 

aa• Datt 12 aa th• rotor ), 1w••P• over th• tEice ot the distributor 4 

at a aoutaat rate ot apeed IJ1lOhronou1 with tbP t ot the rotor 3. The 

rotor· 3 aad bruah ara 16 are keJed to th• lhatt 12 eo that t.heee two 

•l••llt• are alwa1• ill a fixed qgul.ar relat1onab1p with respect t,o the 

8b•tt. 12 and cnnnot be anpl.arl.J dlaplaced relatin to •~ch other, due 

to allppa .. on the ella.tt. A.rraq .. a.t1 .:u.7 be aade, however, t.o change 

the relative angular po1ltion1 ot the rotor and the b~ a.ra it desired. 

Brueh arm 16 tera1n11tee ...a;s bru1b 7.3 which eweepa oftr d11tributor 

eegmenta 15 aad eatabl1llhee aoaentaey cont,, ct with •~ch ot :_be latter 

1uoce•aivel.J. Diatributor ••11191'~• 15 are connected to the r1gi1t-h.tDd 

eet of tend.Zll'll 72 ot •1tchboard 7 b7 a aet ot conductore 17, or which 

olll.7 a tew are ah.own. 

The cc1m-wbeel cipher-lr:e7 Mohanie• 5 proTi.dee a long cipher lce7 

tor Ol'Jptouaphlc purpo•••· It ooneiet• of riTe or a mulUple or five 

Od-beaJ"iDI wheelt 21, 2' 1 23, 24, 25 ot -"litferent diametere. The periphe!'J 

or eaoh wheel 11 didded up iato equal aepent• to which projectinc luge 

•erTlng to act aa caa1 se7 be attached or into whioh c~m• llftJ be ineerteds 

the nWlbera ot ••am•nta on the d1fterent wheel• are ?l'•tersbl7 ?rime to ou 

enotber. Por e:Dllple, wheel 21 P1 h.1.11'8 100 aepenta, wheal 2;:! ma7 httw 99, 

wheel 23 M7 htYe 97, wheel 24 M1 h4Te 91, 11.lld whHl 25 ll'SY haft 89. ftxed 

to the• •eel1 are ratchet• 26, '1:7, 21, 291 30. The mmber or teeth ill 

each ratcbet 26 to .30 correepo•d• •1th \be mmber ot aepente 111 the oaabearinc aHl with wbioh the ratohet 1• ueociated. Pawl• 31, 321 -'-'• ;t4, 

35 on. • rHker ara 36, which 11 operated b7 •11Wt• YT, 31, drift the caabearia.1 wheel• in a •tepwi•• aenner, UDder control ot a UD.lveraal bar k97-

board conteot 39 tb.roup power aouroe 40. lacb tiM & kq is depre11ed 

roakw am .36 aad the pa•l• 31 to '' ••n• to atep •heela 21 to 25 rorward 

ou intarnl. Tb• oa•• on the per1pber1e1 or th• caa-bearing wheel• 21 to 

2' aonvol oonteat leftr11 .41, 42, 43, 44, 4' and the latter operate contacts 
REF ID:A39539 

a1eoo1at•d th•rwith, 141, 1,2, U3, 144, and U5. It will be understood 

that. the •epente on th• peripheey or each wheel 11 ~o '' ere smcoth •urtcces except where a ou 11 inserted in or attiud tO/ the sepant and ••ah 

O; wheel u7 haft •a••Jl"'t•w••iti•••.,.el~*iith11i111111Mie" Ct'm' inserted in ~.he slotted sepent1. 

Contaot leTere 41 to 45 are therefore raised and their aasociated cont~ct1 

141 to u' are closed onq when ca•• ar• pre1ented to them by th• progre1-

11 ... llOTemut of the whew 21 to 25. Furtheraon theee contact lenr1 41 

to 45 will be operated in permutntive groupingfl 10 thc;t :•ll 32 po11sible 

Bcudot-code oombination1 •1 be aet up by the contaota 141 t.o 145, for 

ke7ing purpoees. Controte 11..l to 145 are connected to co~nctore 46 to '° 

aad control magnate 51 to 55, tho function of trbich will be ~e.acribed preaently. Ifow since the Cl"m-benring wheels ~l t.o ~5 c:re or ·

1

1fferent diemeter1 

end tho1 ~-11 ste!J f'orwr>rd. one atep trir each depression or r key on the kqboard 11 it tbeee wheels are initially r;.l1gned r.t a banch llbrk EO es to ~a~ correapond to r. cipher k91, this lni tial ·nllgmaent n1111'.-."'P•etr onlJ after 

100 s 99 z 97 x 91 x 89 or 71777,lfFJ,700 letters hr.Te bean enciphered (or 

d•eiphered). Thus e. ciph1tr key ot grant length ia nn~e Hn.1lsble for c17ptograph1c purpo•••· 

The traneln tor 6 ii! 11.n inatrwaentr.ll ty well known in t.he srt or 

print.inc teleg:ra!)hy. It conei19ts ot a set or fin trenslator bors 61 to 

65 whiob are aormrlly held in position by the retractile B,:l!'!ngs 56 to 60. 

The trf'l.n1la\or baro nre alotted. according to t.~e requirements ot the Baudot 

or 5-unit prin.'1111 tel•Cl'aph oode, so th&t '2 difte!'ellt ali11Y19nte of 1lot8 

may be present'ld to a set or 32 stunt bars labeled 66. Only one stunt bar 

can drop into a 1pecitic alipaent or 1lot11 aad when this occurs a contact 

eaaociated with the selected at.lint bar is aloMd. Several or t.h•M con- ta~ts are shown at 67, it being obvious tbet there are 32 euoh contact• in 

all. These contaote &7 ere conneoted to conductors 68 which lead to the 

set ot 32 terminal• l:IJ ot ewitohbosrd 7. 

It will now become clear that the cam-wheel cipher-ke7 meohara1 .. 

' serves merel1 to select one out ot ,;2 cirou1t1 leading to the ten1nal• 

69 ot nitchboard 7 and that this selection, being quite v~riable and depending upon the auoces&ift permut;.tiona Ht up b7 the cnm-whee~tl"~t'' 

thUI! produces '- lon&, .,.,.riable ae~"""ce ot OJl,IJc circuits "'t ~ keying cha.racter1 snd !lereinntter referred to a~971ng olaapa1\•••. Po- J • vA • 

The 32 terain&.la 69 of awitchboard 7 are connected to s correepondin& number or flexible conductor• 70, 1.1nd the latter tandnate in Jaolca, 

which ma1 be i11Hrted iato plugs 71 connected to terminnle 7-; on the other 

1ide ot switchboard 7. There are but 26 such plugs 71 end each of them baa 

a pair of hole• for J"eceivinc jacks, but only six of these double-hole plug• 

will bea.Te both bolea oq=f •d b7 jacks. 87 thia arrangement the 32 ,?OHible 

reaul'&&Dt k•1ing~1ii 1et up b7 translator 6 are reduced to 26, or . whiob •lz will be •1oubla-etreot1•, that ie, in six ca1ea the same ke)'in1 ~t: · · '. 

u~a••••er aa7 be brought about b7 two ditterif'! Baudot permutations set up 

b:J the Vllllllator 6. lhloh aix ke7ing ~ N these will be de;>eDdB upoa 

the ••··7 1a which the flexible aon:iuctore 70 are cozmeoted to plugs 71 at 8111 

giftn ti.lie. It will be He.a later th1.t no ubiguit7 11 occasioned b7 the 

pre&ence of ~ ke7i121 cHl~»••* .. whioh 11 or the 1ouble-errect type. ~ ' ....... +-
REF ID:A39539 

-4-

Still reterrina to 111. l, the electrical circuit for CJ7ptograph.1o 

1'11DOtioning will llOW be de1cr1bed. It will be eeen that the circuit troa 

power aource 18 to th• kQboard 1 mu1t pe.sa through contact 19, which i• 

controlled b1 main relaJ I. s .. ce, depreaaion of &DJ key ot ke7board 1 

during the time.contact 19 r ... 1 .. open will produce ao effect since no 

power is being delivered to t.b• 1ce7lloard l and hence no circuit to the bank 

ot 1Ddlcatin& devioea 2 11 eatabllahed. Let ua aee now upon what c1rc1111-

1tance closure ot cont~ct 19 depend8J in other word•, let ua ••• when main 

relB1 8 ri.ll b• energi•ad. Let ua corusider a apecif'ic O?ercting c7cle 3 in 

the loaa aequence of operatina c1olea !!• Durin& thiE c.:e>erating CJ"Cle bruah 

al'll 16 or distributor 4 will ms.ke a complete revolution and a correeponding 

coaplete revolution ot t.h9 cipher 001111Utstor or rotor ), will take place. 

Thia operating c7cle ,& u.7 be regarded a.s be1ng divided U? into 26 equal 

tiae-int.rYala ot Ter7 short duration, each oorre1pond.1ng tc a spac1tic 

angular Position of the bruah arm 16 ~nrl ot rotor 3 in the circumference• 

through which theee two eleunta are in motion. Tbe circuit for rela7 8 

include• brush 73, bru.h ara 16. rad one ot t.he 26 H&JMllte l' or diatrlbutor 

4. lhioh ot the 26 sepenta 15 or tii11tributor 4 sill be •ali·H•, the.t ia, 

connected to power eouroe 20 during operating c7cle ~ depend• upon the wiring 

at ewitohbosrd 7 and upon the particular coD~ct ot the sat ot 32 contact• 67 

which happen1 to be oloaed during operating 07cle 3• The latter depellde upon 

the 1peoitic pe1·mut1.1tion or opertated !nd non-oper&ted tr•.a.nslstor bare 61 to 

6S of tranal.ator 6, enn thi• depende in turn upon the specific pos1Uon si..nd 

coapoa1t1on (•• :regF.rde cu•) or the cam-wheel cijJb.er-k91 meohaniu 5. Let 

us &BIWle that -Juring thie apecitic operating cycle ,& the segment deeipated 

74 in fig. 1 is the one which ia •el1ve•. A circuit is completed a& follow•& 

power cource 20, conduator 75, •ain rele7 8, conductor 76, armature 77 nd 

baok contact 78 of rela7 9, conductor 79, brulh arm 16 ::.nd brush 73 ot distributor .41 the brueh then being on aepent 74 the current continues through 

aepeat 74, couduct.or so, to ODe or t.h.e coutaota 72 of awitahboard 7, i,zad 

thence through the awitchboard along one ot the tle:zible conductora 70 to 

one of the contacts 69 011 the other side ot the awitchboard, thence ~lone 

one ot the conductor& 68 ao tbc.t one or the contact• 67 which ie closed by 

th• selected atunt. bar 66 or tranalator 6, fin:·.111 along cotuaon return conductor 81• back to power ~ource ~o. Rela7 8 is energized ~t the inst&nt 

that brush 73 11 pa1&iq O"Nr ll'Vll eepent 74, ... nd eince rotor .3 reTOlve1 

11nahronoual.J with bruah an 16, the &Dpl.er position of rotor 3 with reepect 

to 1 ts eta tors 13 aad l4 corr••ponda to tho angulhr ;:iosi tion of bru.eh arm 16 

at tha't. inetant. The c1pher re•ultant produced by depre1&ing a key on ke7-

board l will be det.ermi.Ded b7 the b~~r poe1tion ot rotor 3. Tbe re&son for 

tbie 1• t.hat 11.nce rotor 3 baa 26 ciphering poli.Uons each yieldi°" a coaplet•l.J' 

different aet ot cipher re1ultA11ts for th• 26 character 1ce71 or ke7b08rd 1, th• 

epeoific c1pber reaultant tor a apecific ka7bo~i.rd character enciphered 1fith1n 

a epeoitic operating c1ole A depends upon the apecific Pegment of distrib~tor 

4 which ia alln during that c7cle. 

The circuit through the ke7board 1, the rotor 3 an~ the bank or 

indicating deTices 2 will now be dr.acribed. Wtien ;~ key 10 corre1ponding to 

the letter •E• le depreaaed harin& operating cycle ~ nothiq happen11 until 

brush 73 reacbe1 Hpaa.t 74 ot distributor 4. tor the k:eJboar::! re!llB.ina "dead•-., 
REF ID:A39539 

- 5 -

until that aoaent. The inatBnt thlit relay 8 ir. energi.z~d, current iB 

delivered from power pource 18 through closed contact 19 and arN1ture ~2 

ot r.la7 a, Bloq aollductor 8' to the contacts or ke)'board l. Since contact 10 ie cloeed, the current continue• along conductor 8-' to a contact 

on etator 13, thence through the rotor '• wbiob is. ttt that instant in P.n 

u11ular poasition oorreeponding to tbllt of brwUi arm 16, to a contact 86 on 

right •tator l.J., thence alona conductor 87 to indicating device or solenoid 

88, which corre1pom!1 (111 t.hia tieure) to letter •Q• 1 thence tilong conductor 

90 through slow acting rel.41.7 9, tine.117 along conductor 91 back to p01l'er 

source 18. Solenoid e~ 1a aotu.ted (or 1r bmt>B nre used fl l~mp if' lighted) 

to indic~te the cipher reeultaat •Q• tor pl~in-text letter rt•. 

lhen olow-act1ng rela7 9 is energized the circuit tor main relay P 

is brokGn i..t 78 •en armeture 71 le withdrawn. A mechanically controlled 

trip 92 enc;agea leY11r 77 and holde it awaj from cont~ct 78 until +he uni-n.real 

bar on keJb0&rd 1 retura1 to normal when the key 1e released, whereupon lenr 

77 is .'.'.:llowed to tell baok nnd clore cont•. c1. '?S. The pur?Qee or I.ts 111rrr.nge11ent is to innure thr..t ae~ •010 *4.ne lett.er •ill be imic? tef! or printed 

per o;pej:ating CJ"Ole, that ia, per depression of a key OD the keyboard~ 

lben the UDiYerPl bar on the keyboard 1 reaches the end or lta 

downward stroke it oloee1 contact 39, which controle the circuit to magnets 

'J7 ~·nd ~8. Rocker an 36 1a operated, causing pawls 31 t.o 35 to engage 

ratchets 26 to 30 alld adnnoing c......_dag wheels 21 to 25 one nap forward 

to the next position, aetting up a n .. Baudot permutation or contact-leTer• . ~ 

41 to 45, associated oontact1 141 to 14,, and magnets 51 to ''· A new keying ~ 

cMa.apaet.er is thu1 ••tabllahed b7 traulator 6 and the a1et•11 11 now ready for 

the next operating 07ole. Inn 1t the eame ke;y is depreeeed on the k411boar4 

the equ1V3lent pr~ the bank or indicating deYicee will be different, 

unless the keying ~r happen• acoidentall.J to be 1.he ea• ae before. 

Continued depre•eion ot the .... ke1 will produce a "817ing sequence ot 

equiv:rjlenta correaponc!ln1 in length with the length of the ke7ing 1equenoe 

produced by the cam-wheel •oba.niem 5. Thie latter sequence is ot great 

length, as baa ."lready b .. n explained, being the re•ultant or the interaction 

ot five wheels ot ~ifferent clicmeter1 with different number• ot teeth, theae 

numbers beini prime to one another. 

Since the oonnect1ons within the rotor ) are reciprocal in ?nir•, 

a1 explainlld, the deoipb.el"lleDt of a 2essage takee place by resetting the 

wheel• or aaa-nnl aechaaiaa ~ to t.he irdttal ke7 position ::nd operating ... the k91board 1 to correspond with the cipher letters, whereupon the plr:in-. 

text eqllivalente will be produced P.t t~a bank or indicating device• 2 • ... 
REF ID:A39539 

The meohmliem. ahown in Ilg. l and described 1n the roregoing term1 

is euoh1 honYar, that it eeTeral mea1&ge• are enciphered b)' the ...,. 

keying HqUtnOe they will be 1a the same aeries ot ciz:·har alpha.'ltete and 

in thle oaee there exists a poaaibility ot a eolutlon by ol")'pla.na.l,tlo 

prooedun. To explain wtat l1 •ant 11J these lriat•en.te it ta n•aaaRl"f 

to oall at tent loa to tbe tact that the cipher comutator 3 proridea a en 

ot 26 cipher alphabet• and that ba1icallJ the Ol"Jptosraphlc prinoiple ot 

the ayat• ae deMl'iMcl l• one in which the S.adi•idual alphabete Of thia ••'l of 28 oipher alphabet• are 'brought into plaJ la ea Jl"der cletera111ecl 

by the teylng ••cauenoe ••t up by the nm••hael1. hr e.uaple, etappo1e 

we aon1lder th1• k97111g 1eq111Do• to be eueh tbat tor a g1Yen k•J as •et 

up on tbe o......_el1 the tirat 20 alphaMt1 to be bl'ought into pl\lJ are 

Aphabet a•ber1 11, 4, 19, 21, 15, 3, 119 al, 129 1, 11 18, 22, 'I, 13, 

lft 2&, 2, 18, Me How it eeYeral •••••I•• nart with the ._. initial 

cam•wbeel eetttng, t)l!_ l\leaesalw letter• ot all theH meeugea will bl 

ia the •- eequa••nti.plser alpbablta, ud thel"efore the ••nral •••P• 

•1 be 1uperilapoMd, :rleldl.ag 00111111• of' letter-1 which are monoalpha betlo 

la ooapoalt1on. ot, •Yen it the aeaHge1 do not start at exactl7 tbe 

••• polat in the ke7ln1 ••ctuenoe, bu.t pol"tioae ot theee ••••Ill•• oftrlap 

one mother with reaped to the k•Jlng ••quenae, thm the onrlapping 

porUoaa which are in the ••• alpha11eta1 •7 be auper11lpoaed. ror 

u•ple, aalng the •1111 1equenee of alphabet awa'ber11 mat1oaed aboTe, 

aupPOH a tlrat ••••P beP,na with alphabet auaber 18 1 a ••••d aeau.ge, 

wlth alphabet 4 9 a third one, with alphabet 11, and ao •• :lt l• •••11 

aeo••Hl"J to lhlft the •eeond •••••1• •• letter to t.h• right ot the 

first, 1hlft the tbil'd -••age one letter to the right ot tbe 1eooad, ad 

thm all three rrieeeagea wUl be pl"Operl1 auperimpo•ed with "•P••t to the 

k9)"1ng 1equenee1 the letter• ill oolU11D1 are aow la th• RID• olpher alpha• 

bet•• ad 'lh• ••••aa•• are eueoeptible ot eolutloa by 111onoalphabette prinoipl••• The proper pointa tor auparilllpoaltioa aan 'be a1aertaine4 

nm without a knowledge ot the particular key •ettinga tor the•• three 

me11age1, from a detailed etudy ot the repetition• bet••tll ••••as••• It 

ie neo••••l"Jt therefore, in order to o1rcWl'fent this poHib11S:t7 ot 

euperimpo•ing mea1&1•• or san1 thereof ao that they will hi la the •-

keying .. quenoe, to impart a Ol"Jptographlc uaiquan••• to the ••••&•• 

eo ae to denro:r, maat• or auppreae repet itione sought about 'bJ the 

abanae enc1pherment of idmtiaal worda 'bJ idmtic:al. 1aquenoe1 ot alpha• 

beta. 

Ueohanilm tor aocoapl1ehing thia ia 1hown in Fig. a. iiere the Iha.ft 

121 carries aeTeral cipher oot111utators or rotor1, 3&1 3b, 3c, 3d, aad 3e. 

The .. rotors are separated fl"Gll one uother 'bJ stator• 122, 1231 lMr, 12s, 

eaah oai·l"Jing rings of aontaot1 oa llotb taaaa, to prod.cl• tor oontinuit.7 

of oll"O\l:lt from oae rotor into the ne... The ooatact• ill th••• •tator•• 

a• are thoH in atatora 13 and 14, alreadJ d••orilNMI, are 'bell•bearlng 

1prln1 oontacte and tboy pre11 again•t the ntor1 ao a1 to bold each 

rotor 1n plaoe, ud kMp 1t troa rotating on the abaft 12, euept wlaa 

rotato17 aot.S.on la lapan94 to it bJ meant to 'be 4•••1"1be4. Th• per:lph•l'J' 

of eaoh rotor 3a to 3• 'bear• a collar 115 1n which 21 gear teetb Mft 

. ~-
REF ID:A39539 

be• cnat 80 11.e to engage with gear wheel• 113 and 114 whiah are mo111lte4 

on that\ 12 9 the l•tter now 1orr11ponding to sbatt, 12 of rlg. 1, Gear 

whetl1 113 and 114 can be Independently llid lidewhe along the than 12 

end keyed 111to podtlon oa the 1batt 1 b)" m1an1/ not 1bown, 90 as to agag1 

the toothed aollar1 of 11111 two of the ftn rotor• 3a to 3•t at the will of 

tile opel'lltOl'• Gear whffll 111 ad 114 haYI ZS teeth and their pUoh 11 

the .... •• tho•• on t!ae oollar1 ot rotor• Sa and i•t 10 that the motioa 

iapartecl to a l"Otor )J wheel 113 or •hffl U4 11 a 111 dri••· Tba 1haft 

11 18 rotaied by motor 93, a1 tn ftg. 11 the distributor 4 or rig. I 11 tbe 

cli1t'tl1'utor a1ailarl7 ••'bered in Fig. 1, with the brtlsb !!ra 11 and llrulh 

f3. Thai, instead 1·r clrf.Ting one roto,. 3, aa 111 Jig. 1, the J10tor tJ and .-n 12 •111 drive an.7 tw ot the ft-re dlttereat ntor1 3& to 31. Thi 

tunotion et tbe d11trlbutor t and llru1h arm 161 la •o• the .... aa d111ribe4 

Sa ommeetion wt.th ftg. 1, IRat tbe rator that will be a11oein.ted with th•H 

element• 1• now eutcr•ptlble of' nrt.a'bllH7. 

The rotora 3a to 3e are to bt •et ta a t•11 by aligning the letter1 on 

their perlpheri•• at a .benlh •rah. Sill•• there are 2S incli Ticlual rotatol'J 

podtion1 ot each l"'Otor on the ehaft, there are 1t5 different initial 1ettin1• 

ot the•• rotore, .._oh nell eett.lng proTlding a d1tf'erat tri ot 28 patba 

tor the pa1•ge of' elenrlo ourrent.a troa the teylloal'd 1 to the bank ot 

eleetro-mapete 2. The olrntte from the keylloard 1 'through the aet ot 

rotora Ir.I to th• bank of aolenoid1 2 are ebom d:lag ...... tloall7 ln .r.t.g. 

3. In tbl • ftpra 1tator1 13 and 141 and rotor1 3! to SJ 9G1Te1pond to the 

1lallarl7 de1lpatecl stator1 •d rotore ot J'lg. 2~ Th• internal w1rlng1 ot 

rotor• 3.11 3}1 I.It Sid 3j are aot reaiprooal ill pair1, •• le the ca•• with 

the eln&l• rotor 8 of 1'11•. 11 but are all l"allciOll aoaneetion1. The rotor 

I.I la, haw1Y1r, dlttennt ln it• conatruotlon traa 'he other rotora, in that 

lt Isa• a rb1 ot oontaota oa onl1 one face and tu1e oontaot1 are lnter-

. oonneoted 111 paira. Tbu1 rotor 3.1 ••r••• a1 a •••• tor reYeraiDg a eul"l'•t c0'"1.:v1 T~ flJt!.,, Ht ot roto:re troa a oontaot la 1tator 13, pa111ng tbrougb rotors 31, 3}, , 3.1, Jj, and amd!ag 1 t baok through rotors 3j, 3,11 l.!?t JA to another ooatut 

in stator 13. stator 14 now ••rYe• no •l•atr1oal tunotlon but ••rely •• a 

aeohanloal bearing against wbioh rotor 3,1 ~r•••••~ R•l&J 81 eontaat lt, 

,Krmature 821 and 'ba:tt•l"J' 18 oorrespoad to 1tmilarl7 de11pated. •l•ent1 or 

/ftl• 1. Tb• key• ot the k•Jboard l now ••"• a double tunetioa lnete&d ot 

a llngl• tuaat1on a• iD rig. 1. lath k•J operate• a l•Yer whioh opena a eoa• 

taot _. olona another. l'or ln1tan1e, wh• tu I k91 l• depre11ed ooataet 

leTer 10 l• wlthdra• fro• •tan 111 and make• ooatad at. 111. Whea nla7 

a l• energised a current nowe trom battel"J 181 aloag IOlldvetor 83, aontaot 

112, iner 101 aonduotor M to a coataot 115 in 1tator 131 t.huoe tbrollsh the 

Ntf r'5-«'ld baok to uotblr aoata•t 115 in etator 13 th••• along oondurior 

85, l.evor 1111 ecmtacrt 113, eoluold "Q•, beet to batt•l'J 181 Solu.old "Q" 

l• anuated ud th• oipber re1ultaat of I la Q• Ill deelpherin11 aa.-tag 

t•t th• rotors are 1n the ld.entloal potitlon th., were ill when enoipher:ba1(the 

oiphar ter being the 1useO, on depre1el.llg the ~ k91 of the 1'e7boanl it wlll 

be ••• tbat the tallowing reolproeal deciphering oirou.it te eatabli1hed& 

·1 · 
.., 

j 

I 

REF ID:A39539 

Batte17 11, eoad•l'tor 11, ooataot U4, l•••r u, ooacluotor 85, oontan 111 

la atator 13, through end baok through the rotor1 to oontut W, ooacluotor 

M, lner 10, oontaat 111, 101•0111 ".&", baok to batt•l"J• Tl:na•, the plala• 

ten re•ultant of Q 11 .1. In thll 11UU11r a reclprooal •oiphering-dM1plattr1ng relationUip i• readlly enablbhecle 

We will now con1id•r the 117ptograpbio operatio11 of the 1yn• after 

th• iatroduotioa ot tb• foregoing teaturea. The ke1 tor a -•••P will now 

aoa11n of the tollowin1 •l••nt•t \ 

(1) The ooapoaition ot the •• whael1, (tbllt 11, the poaition• 

or tbe .... on the wh•l•)·ad their initial 1etting or alipmeat at 

a beoh •rt1 the aonae~at IWitohboarcl '• 

(2) The ooapoeUloa or the rotore~ tat is their internal wt.rings; 

the relati•• order of rotor• 15, 1}1 SJ ad 3j oa the 8haft, ancl the 

initial •tttng or alipaent of all the rotor• at a •ota •rt• 

(3) Tile l"Otora whloh are ••lene« tor en11.1••nt with gear wheel• 

113 and 114. 

. ........ 

It 'be0011•• obYlou1 that. tftn it two/are idantioal, letter tor letter, 

•• it thq Mela at esa.stl1 the ... , poi.at ln the te7lng 1equen1• produoed llJ' th• ••wheel .... n,, and •••n lt gear wheel 111 la engaged with tb• 

-• rotor, ao long a1 the aet'U.ng ot th• J'Ohl'a 3.1 to 3,1 on abaft 121 ia 

41ffer•t by at least one letter for th••• two u1-.ge1, or 110 lone •• elthar 

ot par wbMle 113 and 114 la 1et to d1"1Ye clifferent rotora, the oiphel" text1 

1'111 be clltterea.t and eztel'llallJ there will 1le no 11.p ot the internal 

ldatlt1 of the two tent. l'urtbermore, thel"e im nothi~_g ~o pl'eYent there 

'tllta1 thl"M gear wh11l1 1Jailar to US lnated of onlr two, •• 1bom la r1c. 1, la which oa•• thrff of the fiTe rotor1 au be drlnn. And, c.r ooune, 

it there were aay 10 rotore lt woald be poHl'l• to ha•• •1 n•'ber l.cp to 

I of euoh drlnng * .... whMla, thaw attordiq a ••l'J ride nage tor keying 

pvpo•••• In othtr word•, 11 now fully deTelope41 the 11.t• pro•iclea for 

a multiplia1.t1 ot key11 IUOh that a uniqu•••• •1 be S.•parted to Matas•• 

••• 1n the .... - wheel ke7ing ••tt•••!Jw1th a oorraepoa.dlngl7 bigh 

d.egl'•• or aeyptographia aeour.tt1. 

,,.,.... 

The trLllGl::. ter mcch:u:iis.'f! 6 i ,.. . of 1nterc~.cnectcd cent:· ct-l n Fi,:• l m· y be re:)U: cec b ,, ,. ' schematic~lly in Fig <» Iev;~s 196, ~na asr.cci~tf>d Jai"e~ cont~Yct~ ~~stem •· d t.!h . • .,. n W!e ll.tter fi • • · ·- r. euown 

en e osgnei;s 51 t.o SS are b gure, the contflct levers 1 \ 

leverE: {·n:.; ag:cets of Fig. l ~~=~~ous ··:1t!i eimi~rly :.!esignrted c!nt:~t .(S 

of Fig. 4 are ho:nolot;oWJ wit:::. e.i:ni1- vt, t:e ~~me functionJ the b~rs 61 to 6S 

.r Gtl.gD9.ted. b£..r~ of Fig. l :_nd serve 

-

·, 
REF ID:A39539 

-6-

&D tMtuiYaleDt tunction, via, i.o Ht up, by perautative arrug ... nta o~ 

aatuat.ed and DOD-actuated bars, permutative arrange .. nta of contact-leTera 

operat.1.D1 IWitchae to ••t~bl11h one ot )2 dittereat circuits to the 

ter11iul• ot nitchboard 7. It will be aeen thf.t permut.t.tiw arraag ... nts 

of th• contact-lever• a1 ~o the lett or right poa1t1ona will reault in 

1elect.1ng one of 32 path• tor a current tlowina trom power 110urce 20 to 

the switchboard 7. '?be 11&1JMt• 51 to 55 and their aaeociated bar1 61 to 

65 •1 be replaced by aultiple .. contact rel.-71 well kDown in the a.rt.