REF ID:A41616Mii 

.._,. 

Brief Descri;>tion of ·<'- Cry.;tofrt>;>hic Sy'stem and Mschine b.lploying a 

Single, Aperiod!citlly-Displaoed Cipher Cowou.tator. 

1. Thia inTention de11ls with a cr.r;;itograph1e iae.chine in which the 

oxyptographlo ,t>rinci;>le :!,.e basicuJ.fy a.IS f ollowe: 

Power ia delivered to the keyboard 11.t, the ~ncipher1ng }>Oeition at a sp .... 

clfic instant in a period of Z6 l)oa$iblo insu.nta, tho c1phor resultant 

of a given plain-text letter de;,;.iend1nt therefore Uilon the specific ioatant 

the kcybcnrd is ~de •alive"', einoe for •a.oh 0£ tbe 26 d.if£ertfnt instnnts 

a dit£orent :;rd;Led ci?her al;h9.'bet is :>ros~"lted for encipberment. The oi~er of _,rQ;1entation ot cipher nlvhabet11 is regular but the exact 1nst~nt 

of the selection of. o e1Jeoifie cipher alphA'bet 11'3 ver1 irregular and depends ui>on a keying f aotor. 

2. The mJlchine consists 00.aical.ly of tl si~le, conat·mtl.¥ rotstine1 

::!6 segmont, 26 ohsro;icter cipher COTJ!E!Uto:t.or, l· beled l in l"igure /}l, controllod by n kefi.ng syste:i includiXJS a ~at of roU:itabla, ditfe~ential ca• 

wheels or cm equi vGlent electrical 0~1.111 arrangement. This control syatem 

. oomprioes 5 or Q multiple of ' oa~ wheels •hich o)e~te cont,.,ct levors, shown 

at 2. The int~-action of the S cont!.ict levera results in eotting up at 

the 5 rel.ayo, 3, 4, 5, 6• 71 a per:autation 1n the Baudot code. Correo?onding 

to tbia permutation there is set up a permutati~n of 5 trAnslatar bars, 

la.belcd S, 9, 10, ll, 12. the~m a.re slotted mwabera and when e. specific . pemut~tion 13 80t u~, ono of 32 ~tttnt bars f<>llo into plt.lCe and cloal?:! a 

contr1ct. 3everal of the~o contsote are 3hown in the sketch at lJ. These 

o1rcu1 tis le.;.d to a swi tcbboard 1.4, on ona $ide ot which there a.re 32 poaitions and on the other sido of which tber3 a.re only 26 positions~ Z4&!'err1ng 

to the c.nm wheels these fl.I'fl of dif.f'ercnt dinmEtter and of different nuabers 

of intel'Yals, pr~:ferably all priJlle to one another. They are individu•illy · rot&tf.l.blc in atep-a'ise &nner, under control of th.a l.:eyboard, The potential 

cipher key which reaults frora such rm '1.I"l'R.ngement 1e in length the i)roduct 

of tbs individual. int~ muabera or the several o~m whEtela. Yor e.xt..tmple, 

if tllere are 5 o.a.'l wheelas the ;f'irat of 100 lntervtla; the aecon<.l Qr 99, the 

third of 971 the .fourth ot 91 and the titth of 89 intervals, the total 

lerigth or the c1pha key tiiould 'be 7tr17,469,700. This mor~ly meuns that 

the oi_pher ke.r would conoist of t.:.n unintelligible et1:uence of ciphering kq 

clm;r;;'.cter:s o:f' corrGG)onding length. 

J. Tb.E; 32 poasible l"a3ultant Dn.udot permutations which are led to 

ni tchbb!ll'd 14 are tor the purposes of this invention reduced to 26 by 

consolidating 6 of th6 3~ oirC\lits into th( oth•:r 26, so tbet there wwill 

be .only Z6 diftarent raault:ant·etfeots tor ceyptocra.-Jhic keying ~urpQses. 

In th.ls invention thi;$ ;Le nccomplif'.hed quite 3iul.;ly 'tr/ t1.tld.ng vbn.t are 

umially kno"ln 4RI the 6 extrG functions and ~owing them in W"i th 6 or the 

other 26 lette~-representing Baudot penautstion6. Which 6 ~111 be selected 

to be *'double-represent!.ltions" c11n be deterltliracd nnd varied at will at 

the Pitclll>aerd l4• 

filpproved for Release bv NSA on 12-11-2014 pursuant to E.O. 1352\3 · 
REF ID:A4161~ ..... 

4. In this invention tho Z6 specific effect• thus rendered 9ossible by 

crun action .merely detendnt: vhich on~ of 26 segments will be nm.de "alive" (that 

ia, will be connected to n polfer source) on ~ set of 26 s~ents in the dis. 

tributor head lS, over ~hich brush 16 swe~~s ~n synchronie~ \'ti.th conimutator 

wheel Ill. As shown in the figure, thia ~ction merely menns that at a given 

lnatnnt rel~ 17 is energised, the instnnt of cnergir..ation being controlled 

by the cam. c.rrangC11ent and will be d1£fercnt·rar cncll key opention at the 

keybosrd. 

s. Vihen a. Bt>ecific segment of tbe distributor 15. is made "nllve" by 

beii:ig aonnected to "1 power source,· and •hen the brush 16 reaches this l1V$ 

3agmentt the keyboard of the CJ'Yi?togrnph is made "ill•e"' at tMt instant 

by the completion ot the eircu.tt fro~ power source lB st cont~ct 19. If a 

key is depressed during that cycle, the letter corresponding to that key · will be enci~hered in the specific cipher alphabet determined by the specific 

al'Jglllar position of the cipher conmutator lat the instant that the.brush 16 

reoch&s the live eagment on distributor 15. In other words, the keyboa:-d is 

made •alive" at 1 of 26d1fferent 1nstanta in tho cycle pr.i.a3cd thr~1gh by the 

commutator wheel; each or these ~nstants eorresponds to a different mixed 

alphabet of which there ie n total ot 26. It ia to be understood that the 

onm wheel assembly is set at an initinl kqing position by pre-orrengcmant 

and that the eams advance one step or intorvlll. per depreesion of the: keybo~rd 

and no more. 

6. Th& cipher com~tator·fla1' b6 made a r&Ciprocal.cipher commutntor; or by 

duitable awitching arrangements a nonreciprocal enoit>hering.dec1Jheri!'lf relationship may be provided for., 1.f desired. 

7. 'l'he keyboard 20 iB connected to the lefthllnd stator 21, 8nd the circuit; ·Pfi.IS froa 21 through cipher comutator 1 to the rightlumd st.Ator 22 

and thence to th& bank ·or indicatln~ devices 23, back to power source 18. 

8. Means find circuits must. be provided to prevent the crykJtoeraph !'.rom r~cording or indic~ting e. resultrtnt more than onae for the ar:.nie set up of 

keys, so that there may be one a.nd only one cipher &'!luiv~lent :Jer koying 

operation. 

9• Instead of a aet of 6 trnnslater ba.rs and 32 stunt ~r~ an srr~ngement 

of 1PUltiplu contact relay.a a.e shown in Figure 2 et ~ may be pl"Q'Vided if decl'.!led 

more pra.ctiCS:ble than translater bli.r.s. 

10. For decipherment~ hnving ~ reciprocal ciphm'ing aommutator the key 

setting ot the cmn wheels being tho ~mse na the initi~l settiJlf, ~t the enci:r>herin.g 

en.d the se4;uence of· keying char1~aters would be identical at the deciphering end 

end tho reo1proo1ty between plain-ta.~t and cipher chsrcoters is established 

through the cipher co=nutator and tho deci:oherment is effected in !'!. simple 

•auner, tMt is, if ~t enoipher:ment e.t n given 1net8nt A e;uHls K then U1 

deci;hcraent at tha.t homologou3 inat~nt (with respect to the cipher key) X 

would be deciphered us A.