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- 1924 ~JUN 4 REF ID: Al osoi~..:.~· /_1 

l'M 4 • . .. . ... 

OFFJOE 

CHIEF SIGNAL OFF'CER ... 1. r1Gt. 

Clll~ t' r)i'~}t.'\l Of f·CfH 

PROPOS.AL FOlt !CODIFYnrn TELETYPE APPARATUS FOR 

CIPHER PUHPOSES. 

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

The following sketch and accompanying explanation were conceived 

and drawn up by ~a this 4th day of June, 1924, for modifying Teletype 

Apparatus for oryptographic purposes. 

The principal new appare.tus required is a t~po transmitter of the 

usual type but so modified as to permit of the five contacts being established in sequence and in phase with the five keyboard transmitter contacts of 

the teletype. transmittin~ keyboard. In the accompanying sketches A desi&nates 

the five keyboard oontaot.s which are establisheCI. in sequence; B designates 

the five tape transmitter contacts \lmich are. e.lso established in sequence, 

contact l of A being operated si:mul te.neously with oontaot 1 of B; contact 2 

of A being operated simultaneously with contact 2 of B, and so on. The five 

leads from A are connected in parallel to one end of the winding of the teletype me.gnat C;· the five leads frora B are connected in parallel to the other 

end of the winding of the teletype magnet c. Bus bars 6 and 61 are connected 

to the positive pole of battery,, bus bars 7 and 7 1 are connected to the n':lr;e.-

tive pole of battery. 

The operation is as follows: Suppose the letter X, cod.a cot:!.bination 

*-~~~, is set up on the keyboard, and the letter Z, code combination ~---:+, 

is set up on the tape transmitter. Contacts are so arranged that eft .-or the 

code combination roeans an actual contact to -t- battery 1 a - of the code col'l.-

bination means an act11d contact to - battery by means of the contacts 

vibre.tin~ between the two bus bers 61 7 e.nd 6 1 , 7 1 • Hence, for X_,contact 

1 of A is making contact to -t!' battery when it is operated, and simultaneously 

for z contact 1 1 of Bis making contact to *battery. Consequently no circuit 

is established through c. When contacts 2 and 2 1 e.re operated,, irmnediately 

following 1 and 1 1 ,, 2 is making contact to - battery,, 21 is making contact 

also to - battery, hence no circuit is established through c. ~:hen contacts 

3 and 3 1 are operated,, 3 is at~ 31 is at -; hence a circuit is established 

and C is energized. Vihen contacts 4 and 4 1 are operated, 4 is at -:t', 4 1 is at -; 

hence a circuit is established and C is ener~ized. When contacts 5 e.nd 51 are 

operated,, 5 is at+.-,, 5 1 is also at +; hence C is not enerp.;ized. The entire 

result is the combination --t!t-, which is the code for the letter Ne 

In deciphering, the operations are sil'lilar in nature, the letter Z 

on the tape and the letter N set up on the keyboard contacts yield X, the 

original keyboard letter. This is shown in Fii;ure 2. 

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@'pp roved for Release by NSA on 09-12-2013 pursuantto E .0. 1352a U 
• REF ID:A105021. 

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-;k. = +--t-+1- ~ 

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N-=--++-~ 

N-= --++- ~ 

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