The work of transmitting a message in cipher by means of the cipher 

printing telegraph equipment may be divided into six steps a.s follows: 

1- Preliminary operations including ti~ng 9 numbering, and counting words, 

2- Perforating 

3- Enciphering 

4- Deciphering and checking at Sending Station 

5- Tra.nsmi tting enciphered ~ssage over line 

6- Deciphering and checking at Receiving Stationo 

Under norrm.l conditions tliese operations overlap 9 i .. e. dii'ferent messages 

.or parts of messages are simulta.neoμsly passing through these various stepso 

The apparatus is so arranged that each message may be deciphered as a check 

before it it transmitted over the line _(step f4}. It is thought however, 

that if the work of counting words 9 perforating and enciphering are carefully 

and accurately perfo~med step :/f4 may beeliminated with a resULting saving 

in labor and apparatus. 

The ne thod of performing these siX operations is described in detail in 

the "Operating Instructions" for local and line operating sets. The six 

steps are also explained in general terms belowo 

1= PRELIMINARY OPERATIONSo 

Each message stlould be timed on its arrival at t~e Cipher Bureau as a 

check on any subsequent delays in handling. This is done au to ma tically 

with a time stallJ>• The words in each message should also be counted in 

accordance with ordinary telegraph practice'! Each message should be stamped 

with a ·serial number before perforating. 

This work ma.y be performed by the perf'ora ting or enciphering operator, 

or ·if' desired9 all except the numbering of the message mey be performed by a 

reoei ving cl erke The message nurnber. 9 time and v.ord count are to be ti· an snitted as pa.rt of the message_... · 

2- PERFORATING. 

In performing th.is operation a 11per:iioratoru having a keyboard similar 

to tba t on a typewriter is used and by this means a perforated paper rape 

is prepared on which each cba.racter of the message is represented. by a 

transverse row of lloleso These holes are perforated according to a. standard 

printing- te:i..egraph alphaoet of 32 characterso As this sane code is used 

in connection with the regruar nmUl tiplex.11 and "start~stop" print mg telegraph 

systems, it need not be explained here o 

In addition to the characters of the message proper, the message serial 

nurnber 9 filing time, and word count are aJ.~o-perforated in this tape as well 

as certain characters represented the settings of the 1!k:ey rape~' as will be 

explained 1.atero 

@'pp roved for Release by NSA on 11-19-2014 pursuantto E .0. 1352a 
3.io ENO IPHER Ullo 0 RE'f°ID:A414894~ 

This operation produces an "enciphered message tapet1 o The holes punched 

in this tape represent characters formed by combining the characters of ·the 

original message tape with the cmrac ters of two "key tapes" The key tapes 

produce wl:at is in effect an extremely long "running key" and if the tapes 

are properly handled, this key Vli!.11 never repeato The key t~es are known 

as the "A" and "B" tapes anl should be made and used as directed in the 

instructions on· "Key Tapes" e 

The enciphering operation after being perperly started is automatic 

and may proceed vrhile the original message tape is being perforatedo 

A switch is provided by means of which the action of the key tapes may 

be stoppedo By using this switch, a certain number of characters at the 

beginning and end of the message tape a~e reproduced without being encipheredo 

Included with these characters are the letters designating tre settings of 

the key t~es, the' message serial number, and a series of characters w.bioh 

indicate to the reoe1 ving line operator the beginning and end o:r the enciphered message. 

4- · DEC Il'HERilifG AND CHECKING AT SENDING STATIONe 

This operation produces from the enciphered n:e·ssa.ge tape, a printed 

copy of the original message including the message number 0 check etc. 

Eltcept for possible errors in transmission. this oopy is exactly the same as 

the one which will be produced at the recei:ving station when the message 

is deciphered there. 

The tape is deciphered by first setti11g the key ti;p es a.s indicated by 

the first six characters 01" the enciphered mess age tape, and then running 

the enciphered message tape through the machine so that its characters combine 

with thOse of the key tapes to produce the characters of the original message. 

The-message characters are printed out automati~lly in pige fO:tme 

The deciphered copy ani the original message should be care1·ui1y 

compared and the v.ords in the deciphered copy counted and compared with the 

"check" printed at the top of the sheet. 

5- TRANSMITTING. 

The enciphered message tapes :ma.y be transmi. tted over any printing 

telegraph circuit using either 11mu.:J.tiplex" or nstart-stop" apiratus, i:f 

suitable reoeiVing eqUipnent isadded. The enciphered messages are reaeived 

in the form of peri"orated ta.pas and there1·ore .a perf'orati:ng mec.bani:mn or 

"maohine peri·orator" must be added to the receiving eqUipment. 

A machine perforator my be added to any printing telegraph set by 

removing the printer unit and substituteng the :na.chine perforator for it, 

but if this is done.it will not be possible to print service messages or 

other messages which are sent in plain Engli sho For this reason, ~ sbelf 

which may be attached to any "start-stopn_ table f'or mounting the ma.chine 

perforator, and a small table which may be attached to any "mul tiple:m'° 

table for the same purpose have been designed. When this shelf or table ~ 
0 ~ ID:A4148944\) 

is used, incoming messages may be printed or received an t~ e or both at 

the will 01· the receiving operator .. 

In order to identify the message, Indicate its destination9 and inform 

the receiving line operator thatt.ltle message is in cipher tand there1·ore 

must be received on t~e) a s.bort preanible is transmitted with each message. 

T.bis preamble is transmitted by the line operator at the sending station 

in the usm.J. way a.nd is received on the printer at the receiving atationo 

After receiving such a preamble, the line opera,tor at the receiving station 

, switches on the· ma.chine perforator and switched off the printer so tta.t the 

enciphered message will be received as a per:foJ·ated tape simi.J.ar to the 

"encipnered message tapett at the sending station •.. 

6- DIDIPHERUG AND CHECKING AT RECEIVING STA.1.HONo 

Thetape whioh is received over the line is deciphered at the receiving 

station by tr.e i'ollowing the same procedure as outlined above for deciphering at the sending station (step :fl-4). This produces at the receiving station a printed copy of the original message incluiing serial number and check. 

The words in this message should be counted and co~ared with the number 

given in the 11check" and the message shou!l:d be examined :t'or errors. In 

correcting errors etc, the same procedure my be 1·01lowed as 1·or handling 

ordinary telegraph traffic.