REF ID:A39559 

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.. PreHmi.nary description of a s1ngle-collllUtator cr,yptog:raph 

suitable for War Department 11reatricted11 or 

11 confidentialn comnmnications. 

1. Thi• invention deals with a cryptograph in which the cryptographic 

principle is ba.sicallJ this: power is delivered to the key'board at a specific 

instant in a period of' 26 instants, the cipher resultant ot depressing a. 

given ke.r depending then upon.the specific instant the keyboard is made 

"alive", since for each of' the 26 dif'f'erent instants a different mixed 

alphabet is presented. The order of presentation of alphabets is regular 

but the exact instant ot selection is irregular. 

2. Th& cr,yptograph consists or a single, constantl.1' rotating, 26-

sepent, 26-character COJJlllllltator wheel of the Hebern type, controlled 

b,y a ccintrol s,rstem including a set ot rotatable, dif'terential cam wheels. 

This control qstem consists or five or a multiple of five cam. wheels 

which operate make or break contact levers and their '1ction (by causing 

suitable interaction 'between sets ot five cam wheels in case 10, 15, ••• 

cam wheels are used in sets ot fives) results in setting up five-unit 

code, Baudot resultants. The cam wheels are of different diameters, 

individual.l.J' rotatable in stepwise manner, under control of the kqboard, 

the D11mbera of' positions on the various cam wheels being preteranq prime 

to one another so as to J"ield a resultant enoipheriJJg k8,Y ot Baudot permutations, there being a total ot 32 such permutations. 

3. The 32 resultant Baudot permutations are carried, by means of' a 

Baudot translator, or by means of a set of relqs, into a 11translation 

stage11 where a "Specif'ic permutation will set up a specific effect. Normall7 

there would be .32 such specific effects, but f'or purposes or this invention 

Approved for Release by NSA on 09-30-2013 pursuant to E.O. 

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REF ID:A39559 

six of the .32 effects :must be consolidated into the other 26, so that 

there will be only 26 diff'erent resultant ettects tor cryptographic purposes. In this invention this is accomplished V&rT aim.pq, b,y tald.Dg the 

six extra functions (• - + - - -•, • - - f - -•, • - - - + -•,•~ ~ + + +•, 

" "' + - f .p, and " - - - - -") and throwing them in with six or the other 

26 letter-representing Baudot pennrtations. Which six will be selected to 

be •double representations" can be determined and varied at will b,y a 

suitable plug and jack arrangement. 

4. In this invention the 26 specific etf ects thus rendered possible 

by cam action merely determine which of 26 segments will be made 9 allve11 

(that is, will be connected to a power-source) on a set of 26 s.egmenta in 

a circle over which a brush sweeps in synchronism with the commutator wheel. 

S. When a specific segment of' the element that is S1Jllchronized in i "?s 

rotation with the commutator (the distributor) is made 9 alive" b,y being 

cmmected to a power source, and •hen the brush reaches this 11live11 segment, 

the kqboard of the cryptograph is made wallve" at that instant. If a ke;r 

is depressed during that instant, the letter corresponding to that key will 

be enciphered in the specii'ic mixed alphabet determined by the specific 

position of the cipher cmmnutator at that instant. Thus, in other words, 

the kSTboard is Ede alive at 8JJ7 one o£ 26 different instants in the cycl~ 

passed through by the commutator; each of these instants corresponds to a 

different mixed alphabet, of which there is a total of bot 26. It is' to be 

understood that the cam wheel assem~ advances one step per depression of a 

ke;r of the keyboard, and no more. 

6. The commutator wheel can be made a reciprocal enciphering commutator; 

or b,y BUitable switching arra~ements, a nonreciprocal, enciphering-deciphering 

relationship can be provided for, if desired. 

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REF ID:A39559 

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7. leans and circuits would be provided to prevent the crn>tograph 

from recording Qr indicating a r~sultant more than once tor the same setup ot key, so that there would be one and onl7 one equivalent per keying 

operation. 

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