• REF ID:A41489. 

:w"'" 

Two key-t~es are required in regular op51ration.. These are knoMJ. respeotively as the "A" and "B" t?_Pes. The "A" tape should have one less character than the ,-'B".~ For example, the "A" tape may have 799 oharaoters and th~ ~- 11B1

' tape BOO oharao ters. Two t~es of these lengths are sufficient for handling a. total of a.bout 100 9 000 words, after which new and different tapes roust 

be used. As the seoreoy of t'he system depends on the proper halldling of these 

ta.pas, the following instructions, should be caref'u._lly fb>llowed: 

PREPARATION OF KEY TAPES. 

Kay-tapes should be prepared as follows, using the special tape provided 

for the purpo se: 

1 •. Pun.oh a tape on the keyboard perfora.tor. The first four 

characters of this tape should be "letterstt signaJ.s and the remaining characters should be selected AT RANDOM, using aJ.l of 

the thirty-two characters of the printer code. This tape shoUld 

be at least 804 characters long including the 1·our "letters" 

characters at the beginning. 

2. Mark every tenth character by drm<nng a line a.cross the tape 

This operation can be conveniently performed by lockin·g down the 

selooting pins of a tape transmitter ·~using the "start-stop11 lever) 

and drawing the tape through tilis transmitter. Lines may be drawn 

on the transmitter cover one :inch a.pa.rt to indicate the length of 

tape corresponding to ten c.P..aracters. The first mark on the tape 

should Be drawn through the center of the 1Jbaracter immediately 

FOIJ..OWING the four "letters" cmracters. 

@'pp roved for Release by NSA on 11-19-2014 pursuantto E .0. 1352a 
REV ID:A414B. 

3. Number the marks on the tape. The line across th~ character 

F6LLOWING the four "letters" characters should be marked 11011 , the 

next one 11 10", etc. 

4. Cut off the tape immediately after the 799th character if it 

is to be an "A" tape or the 800th character if it is to be a "B" 

tape. 

5. Using the jig provided for this purpose, glue· the ends of the 

tape together so as to form an endless loop, lapping ·the first 

two 11 letters 11 characters at the beginning over the last two characters on the tape. I~ gluing, see that the feed holes and edges 

of the tape line up properly. Use only a small amount of glue as 

otherwise the splice may be too thick to pass readily through the 

special ciphering transmitters. 

6. Use this first loop as a master ta.pa for preparing other 

similar tapes by running it through one of the special ciphering 

transmitters and perforating a tape with the machine perforator. 

Before performing this operation, turn the left hand switch on the 

r 

edge of the shelf to the position marked "ON" and the right hand 

switch on, the edge of' the shelf to the position marked 11TAPE", i . 

and turn the levers on the other ciphering transmitter and on the 

message transmitter to the pos.i tion marked "STOP". If' a large number of' tapes are to be prepared, the printer may be removed from the 

table and a spare machine perforator substituted for it by attaching 

to the base of the machine perforator the extension plates provided 

for this purpose. In this case, the right hand switch on the edge 

-.. of the shelf should be turned to _the position marked "BOTH". 
7. 

tt -lIBF ID:A414BfaB 

In preparing duplicate tapes, run the master tape continuously untii a sufficient number of duplicate tapes have been perforated. These duplicate tapes will have two "letters"· chara:cters at. 

the beginning of each in addition to the regular 799 or 800 charact.era. These tapes should be cut apart between the last character 

of one tape and the first "letters" characters at the beginning of 

the next tape. 

a. Glue each of the tapes to form a loop, lapping the two "letters" 

characters at t.he beginning over 'the last two characters, using 'the 

jig. The tape loops should now be just 799 or 800 characte~s long 

(depending on whether the tape is an "A" or a "B" tape). 

9. Compa~ the duplicate tapes to see that they are exactly alike, 

by running them through the ciphering transmitters with the lever onthe message transmitter turned to position marked "STOf,". Any difference in the tapes will be indicated by an operation of the printer. 

10. Each tape should be given a designating mark such as "A-1", "B-2", 

eto. This mark should appear on the tape near the splio~. All similar tapes should be marked alike. 

DELIVERrNG KEY-TAPES. 

The original tapes should be prepa~d at one point and delivered to the 

various stations by courier. A sufficient number of tapes should be prepared 

so that three of each -kind may be furnished to each station. Each station will 

then have two exactly sWlar spare tapes :for each "A" and each "B" tape for 

use in case the original tapes wear out or are accidentally destroyed. If neeessary extra tapes may also be prepared locally at each station. All k~y-tapes 

should be prepared on the special paper provided for this purpose. 
' ' 

USE OF KEY-TAPES. 

REF ID:A414.B 

-4-

The particular ta.pea to be used on any day should be decided on by 

agreement between the stations. After being used on one day, the key tapes 

at each station as well as all similar spare tapes must be caref'ully dest.royed. 

The numbers on the key-tapes are used to designate the positions at 

which they are to be set to encipher or decipher each message. Six numbers 

are used to designate the settings 0£ the two ("A" and "B") tapes. Letters 

representing these numbers are perforated as the first characters of the 

enciphered message, as described'in the "Operating Instructions £or Local 

Operating Sets". The £irst three numbers always designate the setting of 

the "A" tape and"'the next three numbers designate the setting of the "B" 

tapee For example, 124379 would mean that the "Au tape should be set at 

124 a~d the "B" tape at 379. 

A certain range of numbers should be assigned to ea.oh station, and 

these should be so chosen that the tapes at one station will never combine 

in such a way as to produce the same key combinations as are used at some 

other station. If' there are only two stations using the same tapes,, an 

initial setting ot 000000 should be used at one station~ and an initial 

setting of 400000 at the other station. Under these conditions the 11A 11 

tape at the second station will be given such a lead that it will be half 

a revolution ahead of the "B11 tape and the tapes at the first station can 

only reach this position after they have completed 400 revolutions. 
• 

If nnre than two stations use the same key tapes, the "A" tape should 

be divided into as rmny parts as there are sta. tions and i:ni t:ial t?-pe settings 

assigned accordingly. These parts need not be equal and preferably should 

be in approximate proportion to the amount of outgoing traffic handled at 

eaoh stationo