HISTORY OF CONVERTER M-134-C 

eclassified and approved for release by NSA on 11-08-2013 

o----- ursuant to E. 0. 13526 
REF ID:A522328-

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DBTAIIED TABI.E OF CONTENTS 

fOR 

VOLUME l 

INTRQDUCTION •.••••••• , •••••••••••••••••••••••••••• 

PAGE 

l 

A. General....................................... l 

B. Cryptografhio Fwtctioning of Converter 

M-.l,34.--0. • ••••• , • •• • ~. • •. o • ••• ~ • ...... • ••••• • • • 3 - · 

II THE BEGINNING OF mE ELECTRICAL MA.CHINE AGE 

J:N . A.RMI' CRYPTOGRAPHY ••• · ••••••••• " • " ~ ~ , • • • • • • • • • • 13 

III EfEBERM CONV&R'.lER (and Related Patents):~ •••••••••• 17 

At Gen~al~n''''H''''"'HHHH•HH•u•••• .... 17 B, · CryptanaJ¥ti9 +~~t~ 9~ Hebern.CQnverters •••••• 19 

C, Cryptographic Functioning., ............ .-••••••• 22 

D. Evaluation •••••••• ~··••••••••••••••••••••••••• 23 

IV CONVER'lER M-134-Tl •••••• : • • • • , • • • ••••• • • • • ~ •• " •• ~ • 26 

A. General ......................................... 26 

B. Invention ••••••••••••••••••••• •·•••••••••••••· 26 

c. Building and Prel.iminar1 Testing of 

First. Model ••••• " ••••• , ••• , • , • • ... , , • ~ ••. • • • • • 27 

D • Service. Test ••.•••• , ••••••••••••• ·• • .. • • • • • • • • • • • 32 

E., Oeyptographic Functioning ••• -'• ••••• ,.......... 36 

F. Cryptographic Securitq •••••••••••••••••••••••• 39 

G. Pa.tent •• ••••••••••••••••••••••••••• .. •••••••••• 42 

H. Conclusions •••• ~··•••••••••••••••••••••••···~· 42 

v QONVERTEa M-134-?2................................. 45 

A. General•••••••••••••••••••~••••••••••••••••••• 45 

B. Cryptographic Functioiling •••••••••••••••••••••. 46 

C. Building of First Models and Two 

Prelimina.ry Tests•·••••••••••••••••••••••••• ;1 

D. Serviee Test.•••••••••••••••••••••••••••••••••• 55 

E. Pa\ent.•••••••••••••••••••·····•·••••••••~••••• 56 
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REF ID:A52232B 

LIST OF TABS IN VOLUME l 

Photograph - Converter M-134-0 

Photograph - Converter M-134-C 

Photograph - Oonverter M-1,34-C (sh~ especie.J.ly the 

.i.nct~, control, and cipher rotors) ~.morandum to the Chief' of Staff,, Subject: "The develop- . •nt of an ind•cipherabl.e printing telegraph cipher 

for military purposes•, Sept. ll, 1918 

.Patent No. 11 510,W 

.Patent No. l,68.3,072 

Photograph - fiebern glectric Code Machine .. Photograph - Converter M-134-'fl 

Photograph - Oonverter·~134..:.n; rear view 

.Photograph ... Converter u ... 134 ... Tl.J cover removed 

.~otoeraph - Converter ~l34~Tl; top view, cover ranoved 

i:botograph .. Convert;er ~134-Tl, part]Q dismntled, top view . PhQtograph - Converter M-134-Tl, right side view, cover removed 

Photograph - Convert.er U-l.34-Tl; under side 

PhQtogra.ph - Convert.er M-134-Tl; lef't. side view, cover removed 

.Three Drawings of Converter M.;.1.34-Tl 

fatent No. 2102.81772 (covers Converter M·l.34-Tl) 

PhotQgraph ... Converter M.-134-1'2 and Electric Typewriter Photograph - Converter »-1:34-T2; front view 

Photograph .,.. Converter M-l.34-T2; rear view, tape trans-. 

mitter removed · Photograph - Converter M-1J4-T2; rear view, covers removed 

Photograph - Converter J4-l34 ... T2; plan view 

Photograph - Converter il-l34-T2; plan view, covers removed 

Photograph - Convert.er M-l34-T2J plan view, 2 cipher discs 

removed 

Photograph - Convert.er M-lJ4•T2; bottom view, covers rooioved 

P'.notograph - Convert.er lf.;.l)4-T2; disc stepping me·ehanism 

.Photograph - Converter M-l34-T2J tape transmitter, featuring 

contact combination 

Photograph - Associated Electrical Typewriter of Converter hi-134•1'2 

Photograph - Converter Ji;...l)4•T2, Associated Electrical. Type- · 

writer {showing solenoids) 

Converter M .... 134 ... 'f2 Schedmatic Diagram 

Converter M-134-1'2* Theory ot Reversing Switch 

CQnverter Li-134-'1'2., Wiring of Tape Tr$11.Smit t.er 

Converter Y-l34-T2, Cross Wiririg ot Individual Discs 

Wiring Diagram of Converter M-l34-T2 · Patent Application No .. 6821096 (covers Converters M--l34-T2, 

M-134, :M.-134-A) 
REF ID,:A52232_6 

CHAPTER X, INTRODUCTION 

For photographs ot Convti-ter M-134-0, s,e Tabs A, B and C. For additional photographe, see Vol. __, Tabs --'· _.. __, _, __, _, _, _, _, _, _, _, _, _, _, _, _, -~ 

_, _, _,_ .. A. General 

(SW111la17) 

Converter M-134-C is an electromechanical, transportable, cipher 

ma.chine usecl in permanent and mobile message centers for the purpose 

of autome.tically enciphering and deciphering messages, both tactical 

and administrative, with speed, accuracy, and security. It was introduced into the m.Uitary service ehortly after the entrance of the 

United States in World Vlar II~ Because of its e:~tremely high degree 

0£ cryptographic security coupled with its tra~rtability and its 

adequate speed of 25 to.50 words per minute, it became the "backbone" 

ot Army and Na'Vy' joint and individual cryptographic communications. 

Navy nomenclature designated the machine as ECM Mark II (short. title: 

CSP 888/889) and J.rIDT nomenclature designated it as Converter M-134-C 

(short titles SIGABA). Ae~~ding t.o the new Army nomenclature plan, 

its designation has been changed to ASAM l. Since it was known in 

the Army as Converter M-1.34-C during the most impOrtant phase of its 

existence, World W~r II, it is refer.red to in this ~istory by its 

~arlier Armv nomenclature. 

'nle history of Converter M-134-C necessitates following two 

important cryptographic principles through a rather intricate developl 
: .... . ·-.:-;_: .. 

···: .... 

- .· .. · 

";_::, 

.. ~~ . . ; ,._ .. .. ·.:.. . .. . . . . ' . . : .· . ' . . . . ,.:.· .. ; . . ·- , . 

th•'basio··omtogra)ilio ph~0n of Conwrt.r'U..134-C, are- given :~· . - ·- - . . . : I ~I ·. . ~·· JlhTaiOai embQdSm&nt ·bf mj~s or 15· -~t~ra contained.in a· removable . ·. ASA 1"[ .) .A 

.. cipher basket(' (short title a SIGIVI). 'l'hese 15 rotors are arranged in 

.. ~~re~:;~t~~-;~~-(~e~ ph~·~~~,' T~~ O·,) ,· 5 ot these ro~ors are the 

enciphering rotors (.inarked. 19, Tab C)j which convert a plain-text letter 

into a cipher-text letter by means of an electric current passing 

through this 5-~tor cipher maze. The remaining 10 rotors. are composed. 

ot two g:roupsi a group ot five rotors, called control rotors (marked 181 

Tab C), which step in metered fashion, and a group of .five small 

stationary rotors, called index rotors (marked 17, Tab C). Electric 

currents pass through the control and ~>rotors (marked 18 and 17, , ,,, .... ~ :" 

Tab O), successively, in order to produce simulated random stepping 

of the five rotors (marked 19, Tab C) which accomplish the enciphering. . . . 

, Brieti.,-, the.tY.10 concepts to be traced are 

... ·· . (1) .. ·Em~phe~~J)1::meana . ot. :~elec_t;~~~::¢~rent . through a rotor . . . . . .. ~ ... ~ .' .... · · .. : ;·.. ·. . . 

' ~ .. ~~:,. ·anc1 ... : ·:. ·, . . ·-·>,··-: 

, . . ~ ;:· . .. '" . • ... · 

( 2) ran~ step_p~: ot tne -enoiJ)hering .rotors. . .... 

·.·:. (These two·~Gp~p~c concepts~~-turther-~lained in section B i ,_ . • ~ ,. • •• : .. . .. . 

. ·: ~~~·~., .. 

· I:. For an. ~labat~~~ ~-the cryptogr~p~g hn~tiioning··~r a rotori 

·see .. ·. page .. . . .. . . ... ,_) '. •' 

.. ··: .... ...... '~ · .. 

• • • ~ < 
REF ID:A52232B 

The two important cryptographic principles listed just above 

were not suddenly conceived, and once they were conceived, .mechanical 

and electrical applications of them were made separately and inadequately on early models long before they finall,y evolvsd.into the cryptographic, electrical, and mechanical perfection or Converter M-1)4-C.-

The experimental and adopted models in the direct llne of cryptographic 

development which culminated in Converter M-134...C are as followsz 

Hebern Cryptograph (first Hebern device presented to Chief Signal 

Officer in 1923); Converter M-134-Tl (conceived about 1926 and built 

between 1930 and 1933), Conver.tar M-l34-T2 (conceived about 19.33 and 

built. in the same year); Converter U-134.(the adopted form of Converter :M-l34-'f2J; Converter M-1.34-A (first built in December 1939 J, 

and Keying Unit ~229 (propdsed in 1941 a.s new means of stepping the 

~ rotors ot Converter Mr-1..34, M.-1.:34-A). The exact manner in which each 

ol theser experimental and adopted models :ls in the direct line of 

. ' 

cryptographic development which culminated in Converter M-134-C can be . ' 

seen only by understanding the details of each. Such details are given - . . 

in the. separate chapters"which concern each mod.el. (To locate the 

chapter concerning any particular model, see index.) 

B. Cryptographic Functioning ot Converter M-134-C 

In order that the reader ma, have a better widerstanding of the 

cryptographic concepts to be traced, it.is necessary to present here a 

brief description of the manner in. which Cc:>nverter M-134-C converts a 

plain-text letter into a cipher-text letter. Ph.;ysical.ly, the electro-
REF ID:A52232B 

mechanical Converter M-134-C coneis'ts of the following main component . . 

parts: a keyboard, a printer unit {8, Tab A; 9 and 10, Tab S), a. controller (3, Tab A), and a cipher unit (2, Tab A; 17, 18, and 19, Tab C). 

The functions of the keyboard and printer unit are obvious: When a 

key of the keyboard is depressed, it causes the printer unit (101 Tab B) 

to print on thEi tape either the same plain-text le~ter or a.n encipherment of that let.~r according to the position o_f the controller (J, Tab A). 

the controller is a switch (J, Tab A), -the main function of 'Which is to 

' 

switch the current. through the cipher unit so that encipherment ("E" 

position) or decipherment ("D" po~ition} will occur, or to switch the 

current directly to the printer unit so that plain.:..textletters will 

~·printed exactl\Y as typed ("P" position).1 The cipher unit (short 

\ 

ti.tle: SIGIVI) co1'6iats of six rigidly mounted bakelite separators 

~ which form a support for the three rotor shafts (17, 18, 19, Tac C). 

The purpose ·of the unit is tO support t.he index (17, Tab.C), contl'()l 

'(18,, Tab C), and cipher rotors (191 Tab C) in wuch relative positions / S 

that electrical circuits are formed through each row of rotors. The 

five small rotor.s in the front row (17, "Ta~ C) are called index rotors. . . 

The index rotors can be moved manually only. The five rotors in the 

middle row are kno\'lll as control l'.<)tors (18, Tab C). The three middle 

control rotors step in metered fashion (see footnote ,i, page 2) and 

l •. 'l'he only other position of the controller besides the Off (ttpii 

position) is the Reset position ( "R"). When the controller is in 

the "R" p0sition and the Zeroize-operate key at "Zeroize," the 

effect is automatic advancement of the rotors until they all 

present the letter "O" at the bench mark. 
REF ID:A52232B 

the two end control,. rotors remain stationary during eneipherment and 

decipherment. The five rotors in the rear row are known as the cipher . . 

or alphabet ·rotol"$. All five cipher rotors step in an irregular 

manner during encipherment and decipherment. 

To properly encipher a message, the three sets or rotors must be 

arranged and aligried in such a way that the arrangements and alignments 

can be reproduced by the deciphering operator. The· means by which 

these arrangements and alignments of rotors are selected by .the enciphering operator and transmitted to the deciphering Qperator in disgu,ised 

form constitute a rather complicated set Qf ,keying instructions. These 

instructions are discussed in Chapter • Here,- we are concerned only 

with the fact that in order to decipher a message the arrangement and 

alignment .of the rotors·must be tbe same as those used to encipher the 

f"'"', . message •. · 

In order that the reader may under.stand. the two cryptographic prin-

;:;... 

eiples mentioned above (page ~, it is necessary to understand the I ;.l.. 

.cryptographic function of .the SIGAB.A rotor. '.rhe SIG.A.BA rotors are 

merely switching commutators whic,h carry ~n electric current across 

the rotor maze in a circuit.ous path determined: by the wiring of the 

rotors and the alignment of the rotors relative to one, another. The 

rotors of SIGABA Qonsist of two types; 5 small rotors with ten contact 

points on each side face and 10 large _1'9tors with 26 contact points ' . . 

on each side face. Each of the 10 contact points on the .left;, side 

face of each index rotor are wired at random to one of the 10 contact 
,, 

' 

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REF ID:A52232B 

point;s on the right side 

T~? face of each sm~H index rotor. Each of the 26 

contact points on the left side face 0£ each control and cipher rotor 

are wired at random to one of the 26 contact points on the right side 

£ace of each control and cipher rotor.1 The five small rotors (index 

rotors) fit only into.the .front rotor bank. The 10 large rotors (control rotors or cipher rotors) fit into either the rear or center rotor 

bank. 

The actual encipherment of a letter is performed by the five 

irregularly turning rotors of the rear rotor bank. The center rotor 

bank (control rotors) and the front rotor bank (index rot.ors) perform 

the function 0£ controlling the stepping of the five rear rotors in 

such a way that simulated random stepping of the rear rotors is the 

effect. 

The five irregularly stepping rear rotors perform their ,function 

of encipherment of a letter as follows; The path of the electric · 

current·is from the contact of the key depressed to the contact. to 

which it is wired in the right end plate, to the touching contact on 

the right £ace of the .first ~otore, to the contact to w?ieh it is wired 

on the right side of the first rotor: .. , and on through the cipher maze 

1n this manner lsee diagram below) to the touching contact on the left 

\ end plate, to the magnet which effects a certain letter of the type 

wheel (10, Tab B), thus causing that letter ~the cipher letter) to 

be printed on the tape. 

. l. this wiring is accomplished according to e. cha.rt (composed by 

random selection) so that sets of the 15 rotors can be wired 

exactly alike for intereomm\lllication between SIGABA holders.-

6 

/" ' 

' \" :,~. 

:· .. 
REF ID:A52232B 

Illustration ot Path of Electric Current 

throw#! AlJ?h4bet Rotor lle.ze 

With each encipherment_of a plain-text letter one or more ot 

the five cipher {alphabet) rotors advance one $tep. \Vhich £!. !!!.! 

~cipher (alphabet) rot.ors stee ~rum many 1! determined J?l ]h! 

pa.ths £!_. ~· electrical circuits through the control rot.or ~ !!!S 

the index rotor ~. The paths of these four circuits . a.re va.riad 

• by the ·change which occurs-in the relative positions of the control 

7 
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REF ID:A522328 - - ------ ------- ---

1 

l~P ~Hi~H rotors with ea.ch encipherment of a letter. The index rotors remain 

stationa.17,2 The paths of the tour electrical circuits, (which select 

the ci}iler (alphabet) rotors to step with each encipherment of a letter) 

e.re determined in the manner described in the paragraphs which immediately 

follow (pages $ - ll) • The diagram on the £ollowing page (page 9) illus-: 

tra.tes the efteat of the four circuits through the two (control an~ 

cipher) rotor mazes. The description in the paragraphs which immediat.el3' 

follow-refer to this dia~am. 

On the right end stator or right contact face, four contact.points 

- are energized or become "alive" with each depression of a. kejr. The four 

"live" contact. points remain the same for each enoipherment. In the 

diagram (page 9), the "live' contacts _of the right. end stator are shown 

at points designated b7 the letters E, J, o, and Q • .3 The four circuit$ 

~, which begin at these tour "live" contact points are indicated by a red, 

blue, oJ,"ange, and green arrow. The paths of the four circuits through 

both the alphabet and index maze can easily be traced by following the 

red, blue, orange, and green arrows •. The paths across the control maze 

is of course determined by the wiring of the rotors and the relative 

positions of the rotors for this part;icular encipherment. 

1. The control rotors advance in metered tashion: The control rotor in 

position no. 3 is the fast-stepping control rotor; it steps once for 

ea.ch depression of a key of the keyboard. The control rotor in. 

position no. 4 is the medium-ta.st-stepping rotor; it steps once each 

time the te:st-stepping rotor has made one complete revolution (or has 

stepped 26 times). The control rotor in position no. 2 is the slowstepping rotor; it steps once each time the medium-stepping rotor no. 

4 has ma.de one complete revolution (or has stepped 26 t.imea). Rotors 

l and 5 remain stati0Ilal'7~ · 2. The index rotors remain stationary throughout one day. They are 

realigned manually at the beginning of each new dl;\Y. 

,3. The "liven contact points here designated are not the actual contact 

points of the right end stator which are· "live." This is an 

illustration only. 

..x IS 
REF--ID :A52232B 

FIGURE .. ·~ 

PIAGIW& OF THE PATHS OF FOUR EIECTRIGAL CIRCUITS 

'lHROUGH 

mE CONTROL AND INDEX RO'IDR MAZES 

(ca.using certain rotors of the cipher or -alphabet maze to step) : 

• 

9 
REF ID:A52232B 

the 26 contact points of the lett end stator (left contact face). 

The 26 contact points of the left end stator are wired together in 9 

groups or bands~ These 9 bands lead to 9 of the 10 contact points 

on the left end stator of the index maze, The 9 bands or groups in 

the wiring of the left end stator o.£ ~he ~ontrol ~ze is made Up as 

follows; Sli t>! the contact points ··of the left arid · stator a.re wired . . . 

together and lead to one contact 0£ the left end stator ot the index 

maze. The six-wire band, ot the left end stator of the control rotor ' . . ' ' ." ' " . . ' ' .• . 

mtl.~e is designs.~ ~· ~e di~gram by the orange lines which connect 

. the contact po~ts designated by the letters C ,,,. D, F, H ,. J, R • .l, In 

' . ) 2 the diagram, this 6~point band leads to the contact point of the left 

stator of the index maze designated by the number, o.3 The significance 

of .this banding is that if one (or more) of the'f'o~ circuits established 

leaves the control maze at any one of these 6 contact points, it will 

be directed by means of this banding to the same cootact point of the 

left stator or the index maze, {in the illustration, contact 0). _The 

other bands can easil.y be noted. on the diagram. There is a 5-point band 

(indicated. in the diagram by the green lines leading from the le.ft end 

stator ot th~ qontrol maze to contact 7 of the left end stator of the 

. .index maze); there are two 3-point bands (indicated on the diagram by 

l. The contact points here indicated are D,g! the actual points banded 

together in the right end stator. This is an illustration on.l7. 

2. The number of contact points banded together are accuratel.J' given throughout this text. Which points they are is a matter of illustration only and are not the actual points concerned. 

3. This right-end st.a.tor band does ~ actually lea.cl to the cont.a.et 

point of the right end stator of the index maze indicated on the 

diagram or if it does it is merely a coincidence. This ia an 

illustration only. 
REF ID:A52232B 

·two groups or blue lines leading from the r end stator); there is 

one 4-point band (red lines); there is one 2-point band (purpl.e. ·lines); 

there are 8sing:cy wired contact points (black line_s) • These bands . Th l"e'e' 

include all 26 contact points of the left-end stator 0£ the control maze. 

There are 9 0£ these bands leading to 9 of the 10 contact points of the 

left-end stator of the index maze; this leaves one "deadn or inactive 

contact point on the left-end stator of the index maze. In the illustration. on page 9, the "dead" or inac.tive contact point, on the leftend stator of the index maze, is cont.act point 2. 

Fr<>lrl the left end stator of the index maze, the four circuits 

follow the path established by the wiring and relative positions of the 

index rotors. The ten contact points of the right end stator of the 

index maze are banded together .in pair.SJ each pair Of wires is COlUleCted 

~ to a magnet, which when energized, will step one of the five cipher rotors. 

(On the diagam, page 9, these contact points of the right end stator of 

the index maze a.re banded in pa.irs as follows: 0 and 4 are banded together, indicated by blue lines; 2 and 8 {orange lines), etc .• ) 

Following, by means of the diagram on page 9, the circuits designated 

by the red and green arrows £rom the original contact points all the way 

through the control and index mazes, it will be noted that these two 

circuits eventuall;y lead throμgh the same band of the paired contacts 

of the rig.ht. end stator of the index maze; thus both circuits influence ~ ck~-.~~ ~-~w~ 

the same ro~or. In the example, the"red and green'~ both move 

rotor no. 3. The circuit ,designated by the blue arro~1s moves cipher 

ll 
REF ID:A52232B 

rotor no. 4. The circuit. designated by the orange arrows move cipher 5 ,_ 

rotor no. _,,J:'. Therefore, the example shows that with this i:articular/ .S 

encipherment ot a· letter, three ciph~r rot()rs (l,-31·-tt) advance one /-~. 'T, .5 -

step, With the next enciphermen t of a letter., the change in the 

relative posit.ions of the control ;t"otQrs will direct. the four circuits 

through different. paths. 

12 
REF ID:A52232B 

CHAPTER II. THE BEGINNING OF THE ElECTlUCAL MACHINE AGE 

IN ARMY CRYPTOGRAPHY 

Eaeh of th~ successive mOdelsl.mentioned in the preceding chapter, 

and mich a.re di~cussed in detail in the succeeding chaptez•s, were 

attempts to pl"'Qduce a t>apid electrical cipher machine having an extremely 

high degree of cryptographic security. 'I'he necessity for 'both security 

and speed lvere made apparent. by the lessons leamed during World Wa.r I. 

Code_s and a few manual cipner systems-but mostly codes-were the m.ea.ns 

of enciphering classified COJ:m'D.unieations during the first great war. 

The military operations ot World Wa.r I were conducted on such an ex.ten• 

aive scale that t.he use or codes snd manual cipher systems became "a 

serious menace to the prompt transaction of military businessn.2 

Because of the delay a.nd irritations inevitable in manual and pencil 

>- and pad procedures, .field co:J.t:lrulders in the heat of battle disregarded 

cryptographic precautions or negleeted the decipherment of pertinent 

messages. 

These inadequacies became apparent before the end of World War I 

a.nd a serious attempt was made to produce a rapid and secure ma~hine. 

In the last phases of VJorld War I·, the Oti'ice of the Chief Signal 

Officer-' placed the problem of evolv-lng an Yndecipherable Uprinting1. Converters M-1.34-fi, M-134 ... t2, M-134, M-l.34-A, M-lJ4-C1 Keying 

Unit M-229. 

2. Memorandum £or the Chief of Staff, from the Chief Signal Oi'ficer, 

Subject: "The development of an indecipherable printing telegraph 

cipher for military purposes", Sept. ll, 1918. See Tab D. 

3. The cryptographic activities Of the u.s. Anny during and immediatel.¥ s~bsequant to World War I were the joint responsibility of the Chief 

Signal Officer and the Director of Military Intelligence. The responsibility of the Chief Signal 0t£iaer placed emphasis on the establishment and development of enciphering and deciphering methods and procedures. · 
REF ID:A52232B 

telegraph cipher" be.t'o o the American Telegraph and Telephone Company. Al.l pertinent cipher knowledge possessed 

by the Signal Corps was pla.eed at its disposal and it was also given 

all the assistance it needed from the cipher experts of tho llilitary 

Intelligence Branch1 of the General Staff. The work was vigorously 

undertaken and two months be.fore the end of World Wa.r I, the.development of a "printing-telegraph aipher"2 for use with the telegraphic 

apparatus ms completed. {See Tab D)3 Plans f'or ext.ensive field use 

of the 8 cipher• were suspended td.tb the cessation of hostilities. 

l. See footnote 3, page 1.3. 

2. The printing-tel,~gaph cipher ma.de use of the well.:..krlown features 

of the print.i.l'lg telegraph art, such 3e ta~, the keyboard' perf orator., the transmit r, and Baudot code. A set o! electrical 

impulses released iy a. t~pe perforated in the telegraph Baudot 

code as the plain ext. were combined with a set of impulses releaeed. 

by a tape, perfora. ed with random 13audot characters, as the principle· 

of selection, to s· t up a· third set of impulses controlling the 

perf'oration of a ti i.rd tap!) as the cipher text. This cipher text 

tape was then tran itted by telegraphic facilities. In reverse 

manner, impulses r leased by a. duplicate of the random perforated 

tape used in the e cipherment of a given message were combined with 

impulses released the perforated cryptote.xt tape of the message 

to produce a perto ated plain text in the telegraph code. This 

information is fro 11Cipher Printing Telegraph Systems, Address 

presented by G. s. VERNAN, AT&: T Co., a.t the lidwinter Convention 

of the American In titute of ElectricaJ. Engineers, New York, S-ll 

February 1926." C py filed: Office of Director of Oonmunications 

Research, ASA, Fil : AT & T Printing Telegraph Machine. This 

description of the printing telegraph cipher shows that this early 

device was s1fii.l.ar to the secure one-time tape system~ in current 

use. However, the keying tapes of the printing-telegraph cipher 

were not "one-time but were re-used. For a detailed exposition of the developnent of the printing-telegraph cipher, see the "History 

of the Convert.or .M 228 ... 3. Tab D is ''MEMORAitfD tor the Chief of Sta.f'f', from the Chief Signal 

Officer, S~bject: 'The development of an indecipherable printingtelegraph cipher", Sept. 11, 1918". 

l4 
' ~ \ 

REF ID:A52232B 

Considering the vi r ot this beeJ.nning1 it seems logical that 

the development of elect ical cipher equipnent would have continued 

at a rapid p:ice. But su h \'l&a not the case. The cessation of hostil• 

ities, which curtailed t e inmediate need for sueh equipment,. seems 

to have negated the inte st of the top policy makers~ Thus the development of electrical cip er machines tell into an almost complete lull 

for the next ten years. Since the new peaeei'ul era created little 

. need for E.ieQrE!ti Q~o tions,, there was no impetus to produce 

cryptographic apparatus and even i.f there had been, no funds • . However, this sit tion did not prevent those most int.erest~d in 

cryptography from th' · 5 about such devices. In 19211 Mr. William ,_.---

F. Friedman joined the taf.f' of the Office of the Chief Sigti..al Officer. 

He had had extensive c to~aphic experience before joining the 

staff of the Office of he Chief Si~a.l Officer and had for a. long 

ti.me been preoccupied th the idea that hand-operated systems were 

not oonsonant with the chine age. Therefore, he, from time to t.ime, 

drew up eketches1 of hi own new cryptographic ideas or improvements 

of already existing sys ems. He worked out some oi.' these ideas in 

1. Some of ti.le now id.e s set dom in sketches were improvements of 

the· Printing-Tele~ ph cipher. These icprovements will n2!· be 

discussed in this n·story becuuse they a.re more pertinent t;.o the 

development of Con: rter lf .... 228. Those improvements, whien were 

designed i'or use in conjunction with telegraph or teletype equipment, are diacussed in the "History of Converter M-228". 

15 

",; 
.. . .. ._ 

.. .. " .. . ... -~· 

'• . . 

·.# ...... ' ... iJ'. .· . - . 

,_-

... ... . . . -~ ~. 

oonJ~o~iOrrld.th.o , eii&tn~re _ot-·t.he ··~t ... ~13, 11r. Lou1a 

.. ·t·-,~-~-~-: :orp ~ .. ~,~.J.'~~-·t ot.ih8s.~,-earli .sketQhei 

. ··.·..·, ~'Wt6~~~~ ···<· .,~~t~8i~.:Jjf t~:b8. 

. : . 

· ~~~- imp()~t- -lationehip to Oon1'8ner·M-~ Clevel()JXllellt, - .·:::···~-··.···.~·"~--~~~"-_ .. ··.··~··"--~ .... ~~;:- ~-:.~·,:;.;~~.;~·:,~· '- ·.····~:::~··) :::-:·.· .. ••·. -··--:. :.:::~~ -~;,._: ·,· ~:· ,,,-, . -~ :.:.-· .·;.·~.r .. ··:··.· .. ::.:·:.-~-1 ....... _..·.., .. ; · · -- .:Thirt'eketoh,.~c0noe1: ed '&rid 'dra.Wll ·in abQut 1926; possibl.T 1925, by 

Mr. Friedman, was a aketcli-.for what later became Converter K-1.34-Tl. (Se~:-~~~~~~ IV.-) • ;_·:-:_,:.;-·_ .. ·- :-:_ . . ·. ·• ,_, .. 

. _. ·''.' . ·. 

, ... _. ·. ·.:. ..... ·. 

. ~-~ . 

. . . ·. 

·. ·::.: . 

l6 :-- :'.· ·- .· .... 

. ': · .. ··· .. · ...... - .... _ 

s: 
REF ID:A52232B 

lO~ CHAPJER ~EC~H llI 

BEBERN CONVERTER 

(and related patents) 

For photograph of original Hebern Converter, see Tab G. 

A. General 

As emphasized int.he first chapter, the two concepts.to be traced --

from their beginnings to their culmination in the rapid and secure 

Converter M-134-C are (1) enciphement by means ot an electric current 

throue,h a rotor maze and ( 2) random stepping or the enciphering rotors. 

Although the second all-important principle was developed by the 

cryptographic experts of the Signal Intelligence Service of the Office 

of t:'le Chiet Signal 0£.ticer, t.he £irst principle was not. Since 1 in 

. the l920's,, the office 0£ the. Chief Signal Officer devoted very little 

money or energy to the development of cryptographic equipment,, it is 

easily understandable that the first steps in th.is direction were taken 

by inventors associated with commercial houses vmich manufactured 

cryptographic equipment. tor sale on any available market. · Just how 

many inventors were working in this direction during the ·early 19201s 

. is, for our purpose, indeterminable. However, it is known that 

several in\"Slltions for varying the paths of energy es~ablished in an 

en.ciphering mechanism between a pl.a.in-text letter and the resulting 

cipher-text letter were patented dl.lring the early l9201s and be!ore. 

Four examples of patents which can easily be recognized a.s development work which points in the direction.o! the first principle are 

17 
1. From Koch, British Pe.tent 163,357 (1920): . "· •• I declare that 

what I claim is: 

(1) A ciphering and deciphering machine of the type hereinbetore 

reterred to having an intermediate seplrate pa.th carrier or 

valve which is capable of being be>dily and freely adjusted 

between a stationary transmitter and .receiver element and 

which is formed with a number of pat.hs in which at. any moment 

tor any desired transmission of energy the whole number of 

auch paths in .the intermediate path carrier or valve is 

available and the intermediate path carrier moves in the 

direction of an imaginary line joining the successive ends of 

the receiver paths, the arrangement being such that each 

intermediate path has only two orifices of contacts, one on 

each side of the intermediate path carrier so that the total 

nU!Jber of contacts on the intermediate path carrier is equal 

to twice the number of pa.the in the intermediate path carrier. 

(2) A ciphering and deciphering machine as claimed in Claim l 

in which a plurality or intermediate path carriers or valves 

are disposed between the ends of the transmitter paths and 

the ends of the receiver paths. 

(3) A ciphering and deciphering machine as claimed in Claim l or 2, 

in which the movement of the int.ermedi.a.te psth carrier or 

carriers is effected automi:ltica.14' on any key 0£ the transmitter 

bein8 depreosed. 

(4) A cipherine and deciphering machine according to Claim'3 in 

which the .movement of one or more of the intermediate path carriers 

is effeQted irregularl.3'••• etc., etc •. 

2. From Wahnoe1 u.s, Patent l,4721775 (1923): 

"The present 3.nvention relates to an automatic cryptograph which in 

consequence of its nature ma:s- be used for a numbor of various purposes. The distinguishing feature o! the present oryptograph is one or 

more sets of double drums-in the f ollQwi.ng ref erred to as duplex 

alternators-being ea.ch in similar manner as the commutator of an 

ordinary eleetromotor fitted with a number of se~nts, the said se~ents being electrically interconnected from drwa to drum and fran 

one duplex alternator to the other one in any suitable manner, the 

said duplex alternators 't':ith tt1eir interconnections being inserted 

as electrical. intermediate meml;>ers between the keys on a letter 

keyboard and moving mechanisms !or a system of type levers, the said 

keys when operated in ordinary manner actuating the type levers by 

eleotrics.l means and at the' same time, causing the interposed duplex 

alteniators to alter their mutual position, so as to effect a constantly .varied 'lill.ltual transposition of the letters of the alphabet, 

numerals and sign:a. 
... ~·. ~ :··: 

.... -·., 

··- ···. 

:;·.-.:... 

.\ . 

· · · 1~~3,0,,2,· llbiCh includes 'description of" Hebem .l'Otor) J the second 

'(.·~~~~'.-~~b :F:·:;o; cow'-~f"~Pat~t No. i~683 ~2·) ~~~s~ {~-~desc~~~s a ' • • r ' . • ' • 

machine which was ph3'81call,y rebuilt t.o produce the Converter M-134-T2 .. ,. \._ ' ~ ' '. .. --- -·· \. (tol"' ;p Oo")t.'\~-.::!:l·"'· ;,,..>& ;:;-._p "'" ! 

(see Chapter V). This particular Hebern model was a 5-rot.or non- ' 

I\ 

printing machine. The improvements made so that it became Converter 

M-134;..'1'2 e)imfoated;the basic weakness of the origin:U device by sub- .. 

stituting a means ot producing random instead of metered stepping of .. · ;: ··:-•·; I , •. • , • , . 

. · 1~s enciphEiring rotors. . This improvement was not developed and. applied . . . 

to the Hebem mac¥he · ilntil tm years alter the Hebem machine had been 

subndtted to the 0.ftice .of .the Chief Signal Officer. 

~· · · Cr.zptanal,,y\1.c Tests ot Hebern Converters· . · 

_·._ ··The tHebem E1ectric Code Machine~, (tor Pboto~ph~ .. see Tab G) as 

~. · :. ; -: >:-:·.:· .~~ >·. r~:.:> ·: ·,-;~~.~~·~~~\~~- ~~:: t·.::!: -:~,:·>·· · .~, .·.: .... ~::; :~ ·)~~·!:..:·:~.-~~.;.-;;:~.' .. :~. · ~.~·:7 .: ·• \-..;:.~ ._.:·;>" :::'.:~·: .. ·~:-<·:·: -~> :"; ~ -~~-~·._'~1\::;:.-~. ·. -~~.~~· :.·-~: !~-:. . ~· ·· -: · · ..... ·· 

· :.__·: -~·:·:-·-~T~t)r~~:ea.11~,-~~j••~t~ _to-·the Chiet.Sigri~~-Of'.ti.C_e~,in the latter .. : ·- :<"· : ... /· ··:·;_. ~- ·-~\~I-j:~~~~·~\St::i~~~:~~~ :> ·.-~. ~~~~!.f./P~:·-~:.-~.:~:·~~:j~-~~~~~~~~~:~:(~:~!:~·~::. ·,, '. <;·\~~~~·-:~~~2:..:?:~~:~.'f<:· :·:·~_.·-~ ·~:·~·.~ ~<-:;.·~~-~ i:~;:~>. _' :~·:.~: f ·.~:.·~t?(· ·.. ~ . . '., · _- .- . · · -·.,:'':~-~';.of, 19~ .·tor. ~ndriatiqn and ·cQiisideratJ.on relatlve tO ·its suitabllit1 

. ··; . ':~,··;·t~£t~·'~'~e -~~i~&l~••· ~T~ ~l&i•• f of-~.aipte.,.billt3 - .. '' .we,r.i)De.de ·tor. :tnie)•·ch~ •.. Since. a- clirsory examiriation~·o.r the :machine ·,';~·._,. .':::·~.~~~\:: • • '' • J' ~~~·>; .. · :,.,:·~~·,~ .:.' 1: ,· • ' •: • f • ~ .. j i. J• •. • • ~ • : ... •~I:· ' • • . . , . ·,.: ·sl:i°'*1 it , t.e>: be '1rorthy. or._ the oloses_t.: st~;; ·a-.-detailed .·~eypt~ic ., ! ·-... :•' • '•, .... ~~:.o,.' ;'" ' ·.I • < •"' .... ~ ' • .: ,' • • • --~ • ' •' • :. ,- i : • ·~ ...... .. : . .. · .. . . . . · .... · . ~:· ... ~: -' 

. , . . '•· . : . . . ..... _ ... 

.... 

'.•' . 

.. • -. ,, . 

. . ·.· .. . .. ,.::...- :' ... ~ 

. ; 

\ ·~· .:.-.. ' ·. ~::. ... ' . "t-' 

, ....... . 

. ... 

' . 

. " . ;;~. ·> \ . . -. : .... 

_,,·.·.·: .. ~ .. ~~!_;._._,·.,.:~~- -;~~-~~~:t~';i::·.~_::_.:,;;~-.~-:..,_~~~~·-~ .. ::. . ~ ' .· \. .. · . .' ... 

. . : ~. - _: 
REF ID:A52232B 

test was undertaken by Signal Intellig~ce Section, OCSigO.. The 

cursory examination showed that the degree of secrecy which it afforded 

seemed to be considerably higher than that afforded by any other machine 

so far exa..iincd except the Printine Telegraph Ma~hine (see Chapter II). 

T'ne Printing Telegraph Machine was much bulkier and not at all suitable 

for use in a theater of war below Army Headquarters whereas the Hebern 

machine was small, compact, and rugged, making it the most suitable 

device. for field use which had been developed and presented to OCSigO 

by 1923. The detailed .. c.i;rptanalyt.ic investigation of the machine proved 

that although the cryptograms which it produced were by no oeans 

"absolutely indecipherable" or even "praeticall.y indecipherable", the 

degree of security was fa.irlJ' high,, and the machine ottered possibilities . . 1 

tor modification with a view to augmenting the degree of security. 

~ This prediction of its possibilities made by William F. Friedman in 1924 

was realized in 193.3 i·.·hen its secrecy was ~endousl.y aumented pz ~ 

im2rovements which made it Converter :M-134-T2. 

A step-by-step description of results of the detailed cryptanalytic 

s'tudy ot Hebern' s machine was written by Mr. William F. Friedman of SIS, 

OCSigO in early 1924. However, this technical paper was not published 

until 1934 along with a second paper

2 

on a cryptanalytic test of a 

·1. Friednian, .William F., klaiisis of a Meehanieo-Electrieal d?ij)to- ai:aph, Technical Pap:tr, Part I. written in earJ...v 1924, published 

in 1934. 

2. Friedman, op. cit., Part II, published in 1934 along with Pa.rt I. 

20 
-REF ID :A52232B 

---- .· 

llgence Section in 1932 at the request {in April, 1932) of the Code 

and Signal Section, Office of Naval Communications·, Navy Department. 

Both of these papers have for years proved particularly valuable as 

training literature .for students preparing to cryptanalyze the later 

and more secure Army machines. The importance of these two technical 

papers to the Navy is expressed in the !lfa:vy "History of Invention and 

Devel.opnent ot the Mark II ECM" in a chapter eaLled 11The Contribution 

of the Signal Corps" as follows: 

••• These solutions were very importa.~t, in three ways, 

namely": -

. a. They showed t.he weaknesses of the meter action ot 

the 1923 HCM and of 6 of the 30 optional steppins actions of 

the 1930 BCM. 

b. The 1924 solution was the basis of further analysis 

by .the Navy which disclosed stepping actions that would block 

analJ'tical solutions or short-cut solutions based on possession 

of t£1e code wheels. Friecbl.an arrived at si,mila.r conclusions, 

independentl.¥. Otnersise,, we would have had to abandon the 

Electric Cipher Machine as being deficient in inherent security. 

c. In recent yea.rs, the principles and tee.hniques of· 

these solutions were instrumental in the solution of certain 

systems whioh are still using a modified meter action. 

i. See next page for cryptographic di.t'f erences between the .t'irst 

and second Hebern devices herein referred to. 

2. The test was conducted 'by Mr. F. B. Rowlett, Dr. s. Kullback, 

and Dr. A. Sinkov under the supervision of Mr. w. ·p. Friedman> 

Chief ,of Signal Intelligence Section. 

21 
REF ID:A52232B 

The second Hebern device ( reterred to above, Pac- 21) which waa 

cey-ptanalyzed in 19:32 for the Navy, differed from the earlier mod.el 

in that the stepping arrangement was no loneer me~erlike .• l Anz 1!2 

of the five rotors {depending upop. ~ action selected) moves forward 

continuously, a third rotor moves forward one step per 26 depressions 

of the keybo11rd~ and the two remaining rotors l<tove one step after 650 

depressions on the ~eyboard. 

C. Cryptographic Functioning 

'?he .original Hebern device (see Tab G tor photograph), presented 

to the Office of the Chief Signal Officer in 1923, consists of the 

t'ollowing component parts necessary to understand the machine cr,yptographically: a keyboard, a bank of 26 let.tar lichts, 6 bakelit.e 

separators, two aluminum wheels, and 8.1."'1 encipher-decipher switch. 

A pla.in.:.text letter is enciphered by depressing a key of the key-

· board, which action opens an electric circuit ti'lrough the rotor maze 

to a lamp of the lampbank. The lamp wilich :l.s llgilt.ed irly this action 

indicates the cipher letter. The r.:,>tor maze provides a circuitous pa~"l 

t.or: the travel t>f the cm~rent. The path of the cw~rent is as .t'ollowa: 

From t.he ct.mt.act of the key depressed to the cuni;,act. to which it is 

wired in the lert2 end plate,.:3 to the touching contact on the lert face 

l. For a detailed explanation of the mechanical stepping of these 

rotors, see Friedm.an, \'JilliQ.m. F., Analysis of a Mechanico-Electrical 

Crypt.ograph, Part II, published 19.34, pages 2-a. File CSGAS-8;3, 

Analysis Section. 

2. The keyboard is wired to the left-end plate and t.he lamps to the 

right-end plate when.the enei,her-decipher switch is a.t "Direct". 

T'ne lamps are wired to the lef't-end plate and the keyboard to the 

right end~plate when the encipher-decipher switch is at "Reverse~" 

3. The le!t-eud plate is wired to the letters ot the keyboard according 

to a random-mixed but necessarily fixed sequence. 

. 22 
of the first rotor, to t!1e contact to which it is wired on the right 

side 0£ the firat rotor, to the touching contac~ on the left face of 

the bakelite separator, directly through the separator to the opposite I 

contact on the right face ot th~ separator, to the touching contact 

on the left face of the second rotor •• ,and on through the rotor maze 

in this manner to a lamp which lights. For a graphic explanation of 

this principle, see the diagram of the current going through a rotor 

maze, page 7. 

Three of the five rot.ors step mechanically in .metered fashion by 

means of a. universal bar and rocker sha.i't., two aluminum wheels, and 

associated levers and rotor stepping dogs. The effect of this. mechanical 

l . 

action is a.a follows: The f'i.fth or extreme right-hand rotor steps 

forward continuously once per depression of the keyboard; the first 

rotor-steps forward once per 26 depressions1 and the middle rotor steps 

forward once per 650 depressions. Rotors 2 and 4 are displaceable only 

by hand. 

D. Evaluation 

Kr. Hebem.is currently bringing suit against the government for 

infringement of his patonts. This tact makes an eva.lua.tion of his 

contribution difficult. Ho1'Gver1 /if it were not !or this suit, the 

legal aspects of Hebern•s claim to distinction would. never have come 

to the fore. All of the other cryptographic machines in this history 

l. For a detailed. explanation of the mechanical stepping of these 

rotor.s 1 see Fried.man, William F. 1 AnaM}ttis of a Mechanico-Electrical 

CrZPtogra3h, Part. I, published 19341 pages 6=8. File CSGAS-83, 

Analysis ection. 

2.3 
REF ID:A52232B 

are evaluated without regard to the intricacies or legal claims. Therefore, the same criterion is applied in the evaluation presented in the 

following paragraphs. 

Edward H. Hebem invented the tqpe ot rotor which is used in many. 

rapid, electrical, rot.or oryptograJil$ ot the Arrq and ?~a.Vy. Use of 

such rotors in cascade (or enciphement by means of electric current 

going through a. r<>tor maze) is,,. as ha.a been pointed out previously,, one 

of the two ha.sic principles of Converter Jl .. 134....c·. This principle was 

reduced t.o practical means by Edward H, Hebern. Whether an7one else 

independentlJ' conceived and patented the sarae practical .r.ooans lnamely,, 

that. which has become known as the Hebern-type rotor) tor use ot this 

principle is :for the courts· to deci4e. Regardless of their decision,, 

however,, it. was Rebern * s machine which first brought the pl\vsical 

~" embodiment of this principle to the attention of the Arrrw and Navy 1n 

a form so practical that it has never been abandoned. 

T'ne :t'ollow.i.ng evaluation of Hebern • s contribution is most int.er- . 

eating. It is presented by Capt.a.in L. F. Safford, u.s.u. in· his Hist.ory 

of Invention and Devel.opm.ent of the Mark Il EGMi 

Hebern has never received adequa. te recompense for his part 

in the development of the Electric Cipher Machine. He is the 

oric!nal' ~ventor. He brot4ght his machine to tba attention of 

the Havy Department, built numerous mod.els, and b1 his perseverance developed it to the point where it almost became a practical 

machine. liebern organized three or four different companies, 

which 11Snt ba.nkru.pt. in turn. He lived in poverty, and during 

much of this period was supported by his wife vdlo ran a boardinc !louse. Hebem was put in jail by irate.stockholders and 

would have been much better off personal.]3 if he had not 

invented the ECM or ha.d not had any dealings with the ?~avy 
REF ID:A52232B 

Department. However, Hebern has no legal claim on the Government because in the opinion rendered in J.A.G. Con£ .. Ltr 

0-S67/68 (8-2S-W9) of 30 Sept. 19)2: -

'Hebern has contributed substantial improvements in the 

ciphering art and while his claims ~ limited and are believed 

not to be infringed, yet. th.ere are several points 0£ fact and 

law that may be urged. Taking the decisions of the courts as 

a guide, however, it is believed that en1 decision on the patents involved herein (Hebern Hl,5101441, #l,683,072 and #l,861,857) 

would be in favor ot the Governroont.' 

For additional evaluation, in the light of improvements made on 

the Hebern convert,er 1 see Chapter V 1 page U. 

25 
REF ID:A52232B 

CHAPTER 

lDP~~mE lV. CONVER'!ER M-134-Tl 

for p:iotographs ot Converter M-1J4-Tl,· aee Tabs a, I, J, K. L, M, N, o, P. 

A. General 

The actual construction of models of automatic cryptographic machines, 

for the Arrrq begins with Convert.er ll-l,34-Tl. Converter M-l.34-Tl is a 

highly portable unit (9" x ll" x 12"1 weighti 22 lbs. without batteries) 

which constitutes the following principle parts• a keyboo.rd (marked 4, 

Tab K), a bank or 26 letter lamps (marked ; , Tab K} 1 a. single rotatable 

cipher wheel or rotor (marked 2, Tabs J and .K), a key tape transmitter · . 

(marked 1, Tab J ), certain assoeitited solenoids and relays, and a small 

electric motor. Encipher.cent ot a plain-text letter is aecOlilplished by 

depressing the plai..n-text letter of a massage on the keyboard, which 

action causes a lamp of the lamp bank to light, designating the cipher 

letter. The cipher letter mu.st then be copied by hand. Converter 

M.-134-Tl•s single rotor ser'V'es to vary the·connection3 between the contacts of the keyboard_ letters and the lamps. The manner in whloh this 

sineJ.e rotor accomplishes its function is ·explained in Section C. of 

this chapter. 

B. Invention 

Converter M-134-Tl was coricei wd in 1926 or possibl,y 1925, _by 

William F • Friedman,, Ur. Friedman revealed his original conception 

for this machine to George A., Graham (then Chief Engineer of the Wire 

. . Section at Signal Corps Development Laboratories), who contributed 

26 
REF ID :A52232B. 

I~~ ~EC~R auttioient det&ll to the original idea to be considered co-inwntor. 

· naw c:.onc:.4t1·ori.S 

In the l920•e however ~H• tor oeyptographic devices remained in the 

form ot ideas or sketches. Onl,y a few individuals were vitall.y interested. and t}lese were.not, at the t.ima, in a position to bring pressure 

to bear in favor ot either actual construction or allotment 0£ sutticient 

tunds tor adequate research. 

C. Building and Prellminary Testing 

of the First Model 

Finally, on l July 1930, after ConverterM-134-Tl had remained in 

the form of a sketch !or four years, the comparatively insignificant 

sum of $1,500 was made available to Research and Engineering Division, 

OCSi,gO, for building a cryptographic machine. 1 As a matter ot routine, 

this project was given to Si811al Corps Laboratories, specii'icall3 the 

Wire Section, for the working out of details. Since Mr. George Graham, 

Chief Engineer of said Wire Section, was oo-inventorof the machine, 

it was convenient that he was at the Laboratories to personally supervise the building of the mod.el. However, even with Mr. Friedman's 

constant urging, through channels, to get t.he construction started and 

the understandable interest or Mr. Graham, in addition to the f'act that 

the.small sum ot $11 500 had f'inall.y been allotted for the construction, 

it. was st.ill very difficult to get it started. The reason was that 

1. iLlliO~&ndm tor il&Jor Crawford, trom William P, Friedman, Signal 

Intelligence Section, 5.Aug. 1930. "• •• on l Jul,119.)0 there became 

availe.ble to the Research and Engineering Division the sum ot $1,500 

tor the developnsn t ot cifher mac~ey •••• n Source or funds is · 

not indicated in available correspondence. 
REF ID:A52232B 

'priorities" were •1tablished for the various projects in the laboratories and "cryptographic developnent work was at tbe.bottan of the 

list, or nearly so. The emphasis was on the development of radio 

equipment and the absurdity or spending mllllons of dollars on producing 

radio comtnunications appu-atus without spending at. lea.st a tew thousands 

on producing ap~atus to protect these conmunications should· have certainly been as clear as it was eompletei, disregarded. by those in charge 

of policy in such matters."1 This almost universal attitude that 

development. of cryptographic apparatus was comparatively unimportant 

resulted in undue delays. First of all, unnecessary time. was spent in 

an attempt to decide w'aether the developmental 1V0rk should be done by 

a. comercial manufacturer. (Ironically, a commercial manufacturer was 

' considered not 1n order to produce a better machine but so that the 

·/""' development work would not interfen9 ut.h other projects at the laboratories.) However, all tine spent on such a consideration was wasted, 

£or "no commercial firm would have dreamt of und.ertaldng c:tJ:¥ suoh 

. 2 

development £or the very small amount of money available." 

fina.J.4r,- on 28 November 1930, the Laboratories received .from the 

Chief Signal Officer the directive to proceed. Almost a year later 

{July l9.3l), the Laboratory reports showed such slow progre~s that the 

following important memorandum, which registered. a definite change 1n 

l.. Fried.man, Will1am F., &Draft. of Brief History of the Development 

of Cryptographic Apparatus in the Army 11 , filed Headquarters 

Building, Historical Unit. 

2. Friedman, op. cit. 

2S 
REF ID:A52232B 

attitude toward development of cryptographic apparatus, was written 

by the Officer in Charge ot Training DivisiQn.1 

l&EJ!ORANDUM TO: Executive Officer \TH.RU ·aesea.rch and Developnent. 

Division) 

l. According to the last progress report of tbe laborat.ories 

a.t Ft. Monmouth, the development of the cipher mahine, .funds tor 

which became available on July 11 19.30, was but 20 per cent complete4 by April .30, 1931 .. 

2. This Division regarda the c1evelopment of th1s cipher . 

apparatus as of prime importance not only to the Signal Corps but 

to the whole Army, as well ae to the various larger administrative 

offices of the military establishment. It believes that this 

development should be prosecuted much more vigorous:cy- t.'lan has 

thus far. been the oa.se. · 

3. The recent visit of the Assistant Chief ot Staff, G-2, to 

this office, during which over an hour•s conterence was devoted to , a discussion 0£ oipher ma.chines and their developn.e.nt, leads t:.his 

Division to believe that the General. Staff is vitally interested in 

such a project a.s is now being carried on in this connection, and 

that the Sta.ft deems the completion, as soon as possible, 0£ the 

development of a cipher machine as highly advisable. 

4. During the recent conference betwe'en Mr, Gra.1-ia.m and Mr. 

Friedman, on the occasion of Mr, Graham's visit to this office 

last week, it was reiterated. by tile former that this development 

can be persued onl;y as vieorously as the low priority accorded 

this project permits, it now being near the tail end of all wire 

projects assigned to the laboratories. 

5, For the foregoing reasons it is urgently recommendea. 

that the priority now accorded this project be.changed, and 

that the project be granted as high a priority as is consistent 

with the development of other projects of aimilar import.a.nee. 

J)., M. Crawford, 

Major, Signal Corps 

l. Memorandum·. to: liecutl'.ve Officer (fiiiiU Research and Development 

Division), f'rom D. M, Crawford, Major, Signal Corps, July 24, 1931. 

Filed in Folder "Converter .M-l.34-n, SISDE-5", Office of Director · of Communiootions llesea.rch. · · 
,-~, 

In response to this memorandum, the priority assiened the 

cryptographic developnent project was finally, on 12 Septf.nber 1931, 

"tentatively raised from Number 19 to 6 in the Wire Section of the 

Lab0ra.tor1es1tl and the Laboratories were "instructed to expedite the 

4evelopn.ent."2 

Seven months lat.er, in March 19321 when the first model was at 

last ready for inspect1on3 at the Sienal Corps Laboratories, Mr. 

Friedman ma.de a trip from Washington to Ft. Monmouth, ti. J. 1n order 

to eee and use the model and to discuss this and other ~atters with 

Mr. Graha.i"7i. MI·. Friedman spent the better part of four days at the 

Laboratories-from Mondq art.emoon, Marcil 211 through Thursday 

afternoon, March 24. Monday attemoon and Tuesday were devoted to 

another matter.4 On Wednesday, March 23, the final touches were put 

on the new Converte.r u ... 134-Tl by Mr. Graha..-n's assistants, thereby 

placing it in com.pl~ readiness for its preliminary test on Thursday 

l. rfotation o.f in.formal routing sheet toi Wa.r Plans and TraLiing 

Division, from Research and Develoμnent Division of OCSigO, 

12 Sept. 1931. Folder "Converter K-l.34-Tl", op. cit. 

2. Friedman, op, cit . .3. All info:nna tion 1n this end the following paragraph eonceming 

t:1is March 1932 inspection trip was taken from. the cited memorandum unless otherwise indicated: MEMORANDUM TO: Executive 

Of'ticer (THIW O.I4C. War Plans and Trai11in3 Division and O,I.C. 

Research and Developnent. Division), ilaroh 291 19.)2. Filed in 

Folder "Converter M-l34-T2, SISDE-5", Office of Director of 

Communications Research. 

4. ilEUORANDUY TOs Executive Officer (TliRU 0.1.c. War Pla11s and Trainine Di Vision and 0.1.c. Research and De.velopment Division), from 

Willi.am F. F:riedm.an; Marc.11 29, 19)2. "Immediately after arrival, 

Monday aftemoon, a.n<i after :rep0rting at headquarters 1 . Fort Monmouth, l had a conference with Mr. Graham in regard to the cipher 

facsimile system ot t.he German inventor, Dr. Wrede, for the pU.rpoae 

ol discussing the outlines of the conference to be held with· tlle 

inventor the next da.,y, Tuesday •••• " 

' . 
. '• .• . . \ 1.· 

.. 

•.. ~ ; -- .... 

m0rning~ Mr.·.Pri~-~rto~ ~-teat hinisol.t.by·personall,y 

-~~1?i1,~il:>:~- .. a p~~t. >mea&Jage • ot; SOO. le tt,ere. · Thu process re- .· .... 

: q~.e.C(~ fD:i.li~te~~ ... -~-:~~~.~-ma.ch~·· perto~ . fJa,t~at•atoril.r, 

.it,i_~· r~~-:~~( ~~~~ • ~p~intment. •. It .~k·20·dJlut,.s to . . . . ' ' . . . . -~ . . 

--~cipher_.theae 50Q i~~~n 1 or 1n other 110r~ the r~te- ot speed was 

oPiT 25_ 'lett.era per ~e. _ Thia ·J.c:M ~t,e o! ~ ;lf&s .:caused by 

t.wo f a·ctors a . . 

(l) :th$manual.p~o~aea'irlv0ived ~-!ii-st selecting the proper . . letter on t.he keyboard, noting the cipher letter on the · light. bank, e.nd writing down the cipher letter. 

(2) the slowness of one or the control relays. 

It was thought by those present at the scene of the test tjat 

practioe.on the part oft.he operator would considerably improve the 

slow speed caused by the manual processes involved. However, improving 

the speed of the manual processes was contingent upon effecting a 

greatly increased mechanical speed. Therefore, the possibility of 

- 1 providing the converter with an adapt.er !or this purpose was discussed. 

In its ultimate form this adapter was t.o make it possible "Without any 

intermediate steps~ to encipher, transmit, receive, decipher, and print - . . . . 

orn>to~ _a_t. a high .. ;ra~e ot ape~~-~,< (sic)_ NQ dou~t,J0-.3~-~;ve-letter 

.. ~.#.~'ms~~ .. po~iiii~~. ~i''i~ wa.· ••. u..a~ ~~t ss,'CXlO would 

· be ~uired 1.Q-:_ordo_r,_, '.t<?)~d such -an adapter. since much developmant,aJ. . . ' . . . . ' ... ·~.. . . .· .. . ~ 

.·. · .. _ . 

le Acs\uail,- -t6e. :*pt;~. cns•ea :coUld not have ~c~ the desired inQ~ue- ~.if s~cr~~iiioe its function was Solal.,r-·tor prOduotion of in$tant.a.n~u8 'priri~iiig •.. The e.xpl.anation_.of tbie.· statement, is 

. given 1n the text_ ·on -_pagee~.S &Qd.Jf. .· · ·_ · · · · _ -. : · 

31 · .-

•• ~ I' 

........ 
,---.,,. 

/""'"'-... .. . ' 

REF ID:A52232B 

mP ~m~H work remained to be done. Of course, ttit was absurd to expect the 

money would be forthcoming and it was not. nl 

However, minor moditicat.ions were made in the existent model 1n 

an attempt to improve it and increase its speed of operation, These 

changes took 9 months and in January 193.3 the revamped model was 

delivered to Washington for test. 

D. Service Test 

During January 1933 t.t'lis revamped model of Converter M-l.34-Tl 

was service tested.2 The.most important fact proved by' this service 

test was that the mechanical speed ot the .machine, determined by 

i. Friedman, op. cit, 

2. Br wl:w.t agency the Convert.er M .. l.34-Tl was service tested is unknown. 

The final report of the service test, dated 28 March 1933, presents, 

the following in£onnation conceming speed' and reliability of the 

converter; 

n •••• A test of' the cipher machine disclosed the following: 

a. s

0

ed. 

- _ (l The maximum mechanical speed or the ma.chine, determined 

bf depressing the same key repeatedly and aa rapidl.3' as possible, is 

)3 depressions per minute. · (2) The maximum speed ot ancipherment or decipherment by an 

operator ~orking as rapidl,y as possible for a short length of time, 

approximately five minutes, is .30 letters per minute. . (.3) The average speed of encipherment or decipherment by an 

opera.tor working in a methodical nvmner for a fairly long period, approximately 30 minutes, is 25 letters per minute. This average is 

based upon the actual enoipherment and decipherment of 1066 fiveletter groups, equivalent to appro.xima.telg 6000 letters. . (4) Comparative speed tests or Cipher Device M-94 and. 

with the Division Field Code, using portions of the sane test as 

above, showed that the cipher machine is appro.xiJootely twice as 

fast as the M-94, but no faster than the Division Field Code. 

· B• Rellat>illt,.y. - In general it may be said that. t.he machine 

is quite reliable in operation, but the following mechanical failures were noted during the test.: 

For continuation, see footnote on .following page. 

32 
REF ID:A522328 

TO? smRH 

the same key rej>eatedly and as rapicU.y as possible, was 33 depressions 

· per minute. Since the necessary min.1murn was 60 characters per minute 

and· tk1e desirable optimum was 200 to 250 characters per minute, the 

speed of the model was pitiably slow by comparison. 'fne limitation on 

its speed was imp0sed by the tact that the cipher wheel had to be displaced throuzh angular distances and brought to rest at a precise spot. 

~ven the addition of a pJ,":l.nting mechanism, which was again considered 

afte~ this second test, would not have added to the speed 0£ the converter to any are.at extent because most of the time lost in operation 

was due to the necessity for waiting (a variable length of time in each 

case) until the cipher wheel had stepped to the ·proper position. This 

delay would have intervened even 1f the entire operation from depression 

Continuation of .footnote 2 from preceding page: 

{ l) When the keyboard keys are allowed to come up slow4' 

after depressing, the cipher wheel oooasione.J.ly fails to rotate and 

orient itsel.t' to its next correct position. Thia failure seems to 

/ 

be caus$d by faulty action of the tape-stepping mechanism, and renders 

all subsequent text incorrect. In normal operation of the keyboard, 

however, this failure does not. appear. · . (2) Occasionally, the cipher wheel is brought to a stop 

in a position slightl.¥ oft that required to bring the contacts on 

the wheel in juxtaposition with those on the fix$d discs ~et.ween 

which it revolves. Wnen this happens the lamps will tail to light. 

and the cipher li1eel must be given a slight push by hand in order 

to establish contact for lamp indication. · . (3) Unless the perforations in the keytape are accurately 

placed with respect to the pins of the ke;rta.pe transmitter, there 

will be occasions when the transmitter pins will be set up for a 

penn.uta.tion either not represented on the cipher v.heel, or not 

correct wit.h respect to the tape. When t.ltls happens the cipher 

wheel; in the first ca.se, will not stop revolving, and in the second 

case, will stop at an incorrect position. W'a.ile the first ease happened many time a during t.."le test., the second ei tiler did not happen 

or it it did, reir.nined unnoticed, as it involves only a single-letter 

error. 

33 
REF ID :A52.Z3~8 

of a key to printing of the character had been automatic because it 

was an inherent feature of the co~verter. 1 This inherent difficulty 

recognized, in writing, in both the preliminary (l February 1933) and 

.final l2S.March 1933) reports or the eervica test, led· to the logic~ 

conclusion t.hat Converter M-134-Tl be at lea.st temporarily set. aside 

in favor of a new type desien which would accomplish the necessary 

increase in speed. Stimulated by the disadvantages of the Converter 

M-134-'l'l.t its co-inventor William F. Friedman, conceived a. new type 

converter, the idea !or which he presented in d.etail on 28 March 1933 

as an attachment to the tinal service-teat report on Converter k-1.34-Tl. 

The description contained in this attachment was entitled "The Proposed 

New Crypt.ograph11 • 

The result .was that Converter M-134-Tl was abandoned and work on 

~ the "Proposed Mew Cryptographn 1 which eventua.lly became Converter 

M-l.34-T21 was begun. · (See Chapter V.) In the development of the new 

r-.. 

converter, one feature of the old was retained, namely, use or the 

random key tape, al.though, in the new machine, it was used to step 

several rotors individually rather than, as in Converter M-134-Tl, 

to ~.J;? a single rotor. 

l. tiils sentence and the one preceding are a paraphrase of paragraph 

2a, "Preliminary Report on Signal Corps Converter, Type M-l.34u, 

dat.ed l Feb. 193.3· 
/~• 

/ ' 

REF ID:A52232B 

E. Crutog£aphic.Pu.nct.ionins 

For photographs and di~ams, see Tabs B, I, J, K,. L, M, N, O, P. 

Converter 11-134-Tl (Tabs H $0.d l) (9" x 11" x 12•1 Vleightt. 22 lbs) 

consists or the following principle partss a ke7board (marked 4, Tab.I), 

a bank of 26 small letter lamps (marked 51 Tab K), a. rotatable cipher 

wheel {ma.rked 2, Tabs J and K), a key tape transmitter (marked l, Tab J), 

certain associated solenoid.a and relays, and a small electric motor. 

This cryptographic machine has only_one rotor (ma.J:"'ked 2, Tabs J and K) 

which revolves between two fixed end plates. Tlle 26 keyboard contacts 

are wired, individual.ly1 to the 26 contacts of the left end plate. The 

26 lamps of the lo.mp bank are wired individual.11 to the 26 contacts of 

the right end plate. The large rotor between the two fixed end plates 

has 52 brush type contacts, 26 on one side face and 26 on the other.side 

.face (these contacts, unmarked, can be seen in picture of rotor, marked 

3, 'l'ab·L). The contacts are equidistant .from one another. The rotor is 

wired crisscross, from the 26 contacts on one side of the rotor to the 

26 contacts on the opposite side, as shown in the wiring diagram on 

the opposite page. The contacts are wired in pairs, meaning that if 

contact l on the left side face (key side) is wired to contact 1$ on . 

the right side face \la.mp sideJ then contact 18 on the left side face 

is wired to contact l on the right side face. {See diagram opposite.) 

Since the current goes throuc;h the rotor Onl¥ f'ran left to right, it 

is necessary that the rotor be wired 1n this manner in order to produce 
~,. 

REF ID:A52232B 

reciprocity; in other words, so that if plain-text Q equals ciphertext W in enciphering, t.hen cipher-text. W will equal plain-text Q in 

deciphering. 

The path of the electric current in encipherment 'ot a letter is 

aa follows: From the contact of the ke7 depressed to the contact to 

which it is wired in the left end plate, to the touching contact on the 

left face o! the rot.or, to the contact to which it is wired on. the 

right aide of the rot.or, to the touching cont.act on the right end plate, 

to the lamp to which it is wired. 

The manner in Which the contact on the le.ft. £ace ot the rotor is 

selected during the enciphering process is as followa: When any 

partic\ll.ar letter ot the k$7board is depressed, the same contact. of 

the left end plate is always selected by tha.t action. For example, it 

Q of the keyboard is wired to contact 3 ot the left end pl.ate, ·then 

·contact 3 of the left end p~te will be activated ever<J time the kq Q 

is depreseed., The variation in the cipher letter substituted for the 

plain-text lett.er Q u produced by tne rotation of the :ro·tor. Rotaticm 

of the rotor causes different eon~ta of the 26 left face contacts 

of the rotor to be prssented to contact J on the left end plate. 

Converter M-l.34's only rotor revolves step-by-step !?,y! continuaJ±,v: 

until it, is stopped by cert~in unusual factors. A key or the keyboard 

c~ be depressed only when the rotor is stationary w~U.ch .is the same as 

saying that a letter can be enciphered only when the rotor.is stationary. 

A smail electric motor turns the rotor, step-by-step, until a certain 

37 
,1::'-''·" 

REF ID:A52232B 

coincidence occurs 11hich is described in the paragraph tollowing. 

On the wide periphery ot the rotor are 13() pins arranged in 26 

rou of 5 pins each (see rot.or pin, marked 3, Tabs J and K). 'lhese 

pins can be elevated ·into operative positions or ler~ remaining in 

in.operative positions. T'ne reason tor these pins is to allow simulation of the Baudot .code. For example, according to the Daudot. code, 

the permutation of elements for the letter A is represented thus 12.345 • 

..,.....__ 

The SilJl + indicates tha.t a pin is to be elevated into its operative 

position; the - sign, U-iat it is to be left in its inoperative. position. 

All the pins can be arranged in operative o:r inoperative positions to 

correspond with any sequence of signals of the Baudot code. This 

sequence may" be varied at will. The function of the pins on the periphery 

of the rotor is to control the set of 5 contact-levers (marked l,·Tab K) 

just behind the rotor in such a way, that when a pin is in it.s operative 

position and therefore presents itself to the contact lever, it presse$ 

against the latter and causes it to make contact. Pins in the inopera-. 

tive position do not act upon these contact levers. The function of 

the rotor pins a.rid contact levers are further explained in the paragraph 

following. 

The key tape transmitter .functions jointly with the rotor .Pins 

(see pin, marked 31 Tabs J and K) and cont.act levers (marl'..ed 1, Tab K). 

A random Bauqot code tape, containing per.mutations tor the 26 letters of 

the alphabet, is started through the tape transmitter (marked 11 'lab J) I 

at t.he right rear of the converter. Whan the first character 0£ the · 
~. 

I ' 

REF ID:A52232B 

key tape.is over the esensing pins, the motor driven rotor will continue to revolve, step..b,y-step, until a. Ba.udot code rotor-pin set up 

(on the periphery of the rotor) exactly equivalent· to the Ba.udot character 

over t.he sensing p1ns in the tape transmitter is contacting tho cont.a.ct 

levere. This coincidence opens two relays vt1ich !3top the rotor. At 

the moment when the rotor is thus stationary, the key m.ay- be depressed 

and ti.le current will go f'rdQ the ke1 contact to the contact to 'Which itl 

is wired in the left end plate, through the rotor by means ot the 

· contacts selected by this ,simulated random stopping o! the rotor, to· 

the appropriate contact of the right_ end plate, to a lamp which lights 

:.' '.';~~,\~ .. ·.t.> . a.nd thus designates the oipher ··!!e:;t,t.,er, This process is rep;.ta.ted for 

' 

each cipher letter~ the most ini.portant feature of each encipherment being . ,'. 

this simul.atecl ~and,om $topping of the rotor ·whioh effects a random 

selection of the lett-face rotor contact used for encifherment of each 

letter. 

· F. Ca;ptor.ra.@ie Securit::£ 

The following security evaluation o~ Convert.er ll-134-Tl :was made 

by Analysis Section, Methode Branch, Security Division.1 The basic 

weaknesses were presented as toll.owsi 

Since Converter M-134-'ll., in effect, produces a total of 26 enciphering alphabets from which one is selected by means of a random key to.pe 

i. 'f.ne evaluation given here was made especially tor this history by 

Josephine Waggoner, Analysis Section, Methods Branch, Security 

Division. · 

39 
REF ID:A52232B 

tor any one encipherment, the system. resembles a one-time pad system. 

Consequently, if the disc and end plates are known, two mesSa.ges in· 

depth can be read. If the disc and end plates a.re unknown, multiple 

depths can be read fairly easil.Y since columns representing enciphements 

wlt.h the sar.1e monoalphabet can be combined. However, since the sq.\w.re 

of the one-time pa.dis replaced by a. one rotordeviee, this machine has 

some additional weaknesses not inherent in the one-time pad system. / 

These are ·as follows: 

1. I!' the fixed endplatea are \'lired identically, the plaincipher text will be reciprocal~ Thi~ reciprocal nature of ·the text aids 

in crib-setting since a let.ter cannot enciphel .. itself. It al.so aids in 

depth reading, since there a.re only 13 reciprocal plain-cipher pairs 

possible at any one setting of the dis<S'!' 

2. If the fixed end.plates are wiretj. differently, crib setting is 

possible even though the text is not reeiproeal. Any twenty-six point 

rotor must have at least one parallel wire. If' it is ra.ndo.mly wired, 

it wili probably have several parallel wires. (As many a.s 18 have been 

found on a randomly wired rotor.) Any one plain-text letter can thore~ 

fore have only 25 or less cipher equivalents. This fa.cl;. can be used in 

crib setting, since the missing cipher letters for high-frequency plain 

letters such as E, T, o, etc. can be readils. determined. 

The following two specific problems were evaluated by the crypta.na.lyatl as follows: 

i. See footnote 1, preceding page. 
REF ID:A52232B 

First problem: 

l. Given: a. Knowledge of the operation ot the ma.chine. 

b. Wiring ot disc and end plates. 

c. Two LJ.essages in d.epth. 

2. Conclusions; a. T'ae two ·messages can be read. 

b. Relative at.a,ping key can be recovered. 

3+ Solutions A deciphering table of the 26 possible alphabets 

is .made up. Messages can then be read in same 

man.'1er as two in depth on a one-time tape system. 

Key recovered would be a relative stepping key. 

Second .e_roblemi 

l. Given: a.. Knowledge of the operation of the machine. 

b. Stepping tape. · 

c, 500 or more letters of matched plain and cipher. 

2. Conclusions: a. Steppine tape can be matched. 

b. THi:riug of the end plates &'1d disc can be 

recovered. 

). Solut.ion; Stepping tape is mat:ched to plain-eiphor text b7 

using repeats, that is, occurrenees of encipherment. 

or same plain letter at; same setting of disc. Once 

stepping key is set, twenty-six partial alphabets 

third problen: 

a.re available tor 3tudy. These alpha.bets m-e used to 

recover Friedman t3ble for the disc" from vhich a. 

relative wiring ot' both end plates and diac can be 

obtained. If end plates are !r.i.10wn, ?"ecovery of disc 

is straight-forward. 

1. Given: a. Knowledge of operation of the machine. 

b. 4 rnessazes a.nd plain-text of one if text is reciprocal.; · 5 messages and plain text ot one if not reciprocal .2£ 

8 or more messages in depth if text is reciprocal; 

10 or LU.Ore if not reciprocal. 

2. Conclusions: a. Messages can be read. 

b. Wiring of disc and end plates and relative 

stepping key can be recovered. 

3. Solution; Partial alphabets obtained from depth reading are 

used to recover Friedman Sq.uare of disc as in Problem 2. 

41 
-

' ' . 

~.: Patent1 

' ;, ·'Colmrter Jl-134 ... Tl 11 .OoVereci b,. a Oi,ngl.~ pat,eDt, number •:. .. . . . 

-·2,028,n2 Ceee Tawr.) iiauea 28 J~ i936 'to w1uiam F. Friedman - ' . ' . 

. . . &ild George A. Grabaia. . The ap~catioil •s fll~d·: 23 JanUa.17 1932 . . 

· When· »r. · Frie~ . wu · a M11ber ot th. ·Signal. · XntelJ.1senc~ Section ot ; • ' • -, ~ I : '•: ,· .._ "• ' ~· • 

·t1ie Ottioe ot ·the Chiet Sign.al Officer and Kr. Gr,μiam was an electrical. . .. 

enginGer with the -~f9la:l. ~COrps _J.aborat.ories at Fort Monmouth, New . . . . . . _- ;:«:- :.~--;- - - . . -. . . - . 

·Jersey. As filed, the. ·application cant.a.ins fitt1 claims, forty ot 

these being directed to the apparatus and ten to the method by which 

encipherment was accomplished. The result or prosecution was the 

allowance of nearly aμ o.f t,he apparatus claims and the final rejection of all method cUrliriS •. ·The all.owed claims represent excellent 

patent ~overage or the invention. Title to the patent \2,028/772) 

now rests jointli. with the inventors, the GO\remment having retained 

the customary ro7alt1-f;ree, nonexclusive license to practice the 

· invention. 

. .;· 

H. Conclusions 

In evaluating ~he.im.J>Ol:"tance 9t Convert.er M-134-Tl, it should ·'.:.:·:..:':~<·":··<;:.·,:>:~.: .•. . .'. : ':~".,:-.::..L-. .. :, .. :'°.•i •• .". ~···_.· .• ·.• ~ ~ ';;. .. 

: <. ·.·:~b8Jl~ed as n.pr~~;~iig-_~~--Wt.JJ4~ qexperime~tal_phasel! of a 

.·:,, "'.. ··};:~Je;t to pro<tu~ a,~ti ~~M>~tic, rapid cryptograph .~ _It was • • • .l • . .· • .--·<""~-:;. . . 

. t·':· i~ fils liiformat~ ... _'lrned ·'by•Denrr B. Stauffer, Chlet) · , Patents Sect.ioti•-·-:.;·_:u. · · 2. fri~, op. ·cit~·:_':·:·:· · 

42 

.·· ·. '• 

(. 

' : : ~-. 

.;.· 
. ···· . . ' .. · .. :· ~· .. ·. 

_,_;. :· -· .. : . . . . . : .. :; , ..... ' .. 

....... .. . ·.•. 

r<EE: ID:A522328 

.... : ·.·. . .... '"· 

• ··~ 1 

.VY DEPARTMENT 

JM OF CALL I 

-------~q__!!._~1- 1 ~ <7 ' \k-1-'-

__ Q_{~~-~--~ 

_____________ .., _______ - ------

. .: ~ ..... 

. •.' ., . 

~: . . 

·.: "',"· :· '·.' . . ··:· . : . . 

·.: ~.~ ·-·.< .· .... ' ._"_.-._· .< · . 

'.- -... .";. ··-: ~ .. ~ ·. . .. : ...... ·' 
REF ID:A52232B 

l~? ~HD~H produced during a period when many unsuccessful attempts to produce 

a rapid cipher machine had been ma.de by commercial manufacturers. So 

far as is l-..novm, no auto.ma.tic cipher machines were~ at that time, in 

actual service either in commercial or governmental ofi'iceo anywhere. 

Comrerter M:-l.34-'i'l was the result of prellminary experiments which 

pointed in the direction of limitless possibilities at the same time 

that they demonstrated the limitations of one particu4r design. 

The most important new idea of Converter M-134-Tl is the concept 

of the rc.ndom Ba.udot eode keying tape atowin~! rotor. The idea of 

. a rand.om keying tape had been used before, but ~ conceEt ~ .!?!_ 

watched ~ ~ g! l"<U1dom characters (i>,I random selection .!?z electrical 

:impulses) ~ &>.£ ~ pa.rticp!az: PurnOse !}! producing .!. random stepping 

£!. rotors.. In Converter M-134-Tl, this concept of random characters 

/"' (or random sc;;;lection by electrical impulses) influencing the movement 

of, in this case, !?m rotor became so important in the inventor's mind 

that consideration 0£ needed secondary alphabets was neglected. HoVlever, the concept itself (underscored above) is tremendously important. 

In Converter u ... i34-n, the rand.om keying tape ~ used to !i-<'~ a.' rot.or. 

Only a short step of imagination is needed to see how this concept 

became that. of using a. random keying tape to step the rotors of Converter M-l34-T2. Looking many years ahead to the Converter M-134-C 

itself,, it is found that the keying tape is dropped as the specific 

means of producing the random characters (or random selection ~Y 

electrical impulses) which serve to step rotors in.a random. fashion. 

43 
REF ID:A522328 

But the p1•inciple of random characters (or random selection of 

electrical impulees) stepping rotor~ in random tashion is never 

.. dropped, but. inst..ecd is kept to be the most significant single factor 

in the security of Convert.t;r ll-134-C. 

,. 
REF ID:A52232B 

For detailed descript.ion and photographs of Converter M-1J4-T2, see 

Tabs R, S, T, U, V, W, X, Y1 z, AA, BB, CC, DD, EE, FF, GG, HH, II. 

A. General 

The developnent of Converter M-134•1'2 began in Karch 1933 inmediateiy a1'ter the senice test of Converter M-134-Tl. The Tl model Wa.s 

not only too slow but it was believed th~t the desired optimum of 200 

to 250 characters per minute could never be attained by a. machine operating upon its basic principle; that of an irregularly displaced ·cipher 

wheel. There.tore, the report on the senice ·test ot the Tl model 

reconmended a. change in the basic design c.t the machine and, attached 

to the report, was a practical proposal for building a new model which 

would operate on a different ·principle• The new proposal offered a 

.~ particularly great advantage from a practical point ot view in t.ha. t a 

commercial c!Pl;ler machine, already in p,ossession of the Oi'fice of the 

Chief Signal Otfioer, could be modified to produce the cryptographic 

. l 

technique which it outlined. The machine to be modified was the 

5-rotor Hebern DeVice, covered by Pat,ent No. l,6831072 (see Chapter III), 

which had been cryptana.1¥zed by OCSigCl in 1924· (See Chapter III, 

Sect.ion B. ) 

'Ihe new proposal, t.he speaif'ic ~bodiment of which was to become 

Converter M-l)4 ... T2, eliminatc;ed the basic 11eakness of the Hebern ma.chine, 

l. &This oi'fice (WP&T of OCSigO) can furnish a machine which will, it 

is .believed, readily lend itself to modification for the purposes 

in mind. ti Service· Teat Report on Converter Jl-l.34-Tl, 28 March 1933· 
REF ID:A52232B 

which wa• "the fixed characte:r of the successive rol#atory movements 

. l 

ot the cipher wheels,.. This invariability of motion in the Hebern 

device produced predictable relationships between the plain-text 

characters and cipher character& tor any given initial arrangement 

of the cipher wheels. The proposed new system eliminated this basic 

weakness by substitution of a variable mechanism !or displacing the 

cipher wheels for the fixed mechanism of the Hebern rJ&Chine. , This 

variable mechanism was a. random Baudot-code tape (Tab U) running 

through a tape tran~mitter (.Tab U). It caused to progress in variable 

rela.tio!1ship the .five rotors (Tab U) which acted as switching commutators to establish a resultant for each and every keyboard operation. 

The manner in which· the Baudot-code tape effected. random stepping of 

the rotors is ·explained in greater detail below. 

B. Omto,a:am±c Functionin_g 

'l'he following parts (arranged in two groups, (a) and (b), according to their !unction) of Converter M-l.34-T2 must be explained in order 

to underst':U'ld the converter cryptographically; (a) a keyboard. (Tab V), . five rotors (Tabs V and W) which act as switch:ing commutators between 

· two end plates, and a lamp strip consisting or 26 small letter lamps 

(Tab V); (b) tape transmitter {Tab ·V), plug and jack strip (Tab V), 

and associated magnets and relays. The elements ju.st mentioned are 

arranged. in two groups because they belpng to di.f 1'erent !unctions or 

1. Service Test. Report on Converter M-134-!1,, 28 March 1933. 
REF ID:A52232B 

the converter. The elements in g~up (a) provide tor enciphe~nt of 

the. plain-text letters. The elements in group (b) provide the means 

ot stepping the rot<>rs. 

The encipherment of a letter by means of the elements in group (a) 

ia accomplished cryptographicaJ.l¥ in the same fashion in which it is 

accomplished cqptoeya.@ieaitt with the Hebern converter: The pa.th of 

the electric current in encipherment of a letter is as foll0v1s: From 

th• contact of the key depressed to the cont.act to which it is wired 

in the left end plate, to the touehine contact on the let't race of the 

first roto~, to the contact to which it is wired on the right side or 

the first rotor, and on throu&i the cipiler maze in this manner (see 

diagram, page 7) ••• to tbe touching contact on the right en(! plate to 

t.he lampl to which. it is wired. 

The above-described process ot encipherment {as regards the path 

of the ctirrent througn the cipher maae) is that used in the Hebem 

converter as well as in Converter M-l34-T2. The difference-the all- - - import.ant di££etence between the Hebern converter &nd Converte~ 

M-134-'f2- lies in the introduction of the second group of elements, 

group (b), above; the tape transmitter (Tab V), plug and jack strip 

(Tab V), and associated relays and magnet.a. These elements of Converter Jl-134-1'2 control the steppinc 0£ the rotors (Tabs V and W) in 

random, and therefore unpredictable, fashion lsee paragraphs immedia.tel.J' 

l. Tnis process causes the lamp to be illuminated i1' only the cryptograph is in useJ if the Cl'J'Ptograph is connected. to the electric 

typewriter, designed tor use with it, the designated letter is 

printed on the page copy. 

47 
REF ID:A52232B 

below for det.ailed explanation) whereas the mechanical, metered 

stepping of the rotors of the Hebem converter l see page r:~ S) is its 

c:ryptogl"aphic weakness. 

The fwiction of the tape tra.nsmitter {Tab V) in Converter M-l34-T2 

• 

is to step forward. the cipher discs (Tabs V and. W) in accordance with . 

tthe Be.udot-code key ta.pa (Tab V). The tape operates the rotors as · 

foll~: T'ae five sensing pins of the tape transmitter are individuallg 

wired to .five magnets whl.cp, when energized, cause the associated rotors 

to step. {For a detailed description of the "Cipher Disc Step Forward 

Mechanimnu, see Tab z.) the fir et sepsing pin1 of the tape transmitter 

influences the first rotor;1 the second pin intluenc<Ss the second rotor;l 

' 

etc. mien a tape is put through the tape transmitter, ~'le first rotor 

will step if a perforation is directly over the first sensing pin; the 

first rot.or will not step ii' a ''non-hole" position is over the first 

sensing pin. The same ie t.rue of t.he saeond sensing pin and second 

rotor, etc. For example, if the character of' a Ba.udot-code tape placed 

over tao sensing pins is + - - - +, then rotors l and 5 trl.11 move forward . . . 

one step while rotors 2 1 J,. and 4 will re...."lB.in stationary. 

A pl1J8 and jack strip ~Tab U), consisting of 5 plug~ and 5 jacks, 

is provided for the purpose o! changing the eoa~ections between the 

sensing pins of the tape transmitter and t.he rotor-stepping magnets. 

l. this relationship is accwate only it' plug l of tile plug and jaok 

strip is in jack l, plug 2 in ja.ek 21 etc. For explanation of 

the variable fact.or which tbe plug and ja.ck strip otf ers, see 

para.graph beginning "A plug and jack etrip •• ,n on this page and 

page 49. · 
REF ID:A52232B 

(See also description of plug and jack strip1 Tab R.) It is explained 

above that sens~e pin no., l controls the stepping or rotor no. l.; 

sensing pin no. 2 controls the steppine of rot.or no. 2, etc. In order 

to V'ary this relationship·., the plug and jack strip is installed in 

the 5 connections between the tap~ transriitter contaeta and the rotor 

magnets. By means of it., sensing pin no. 1 can be made to control . 

rot.or· no. 5 simply by placing plug no, l in jack no. 5 or it can be 

m.ad.e to control any of.' t.he other rotors by placing plug no. 1 in the 

jack which is connected to the eorrespondine rotor magnet. By ehanzing 

the order in which the plugs are inserted in the jacks, the tape transm!tter can :Je made to control the :rotor-stepping magnets· in different 

order to a total oi 120 ditte:rant arran~em.ents. 

Tbe clia.gram oolow shows the plugs and jacks arranged so that sensing pin 1 controls rotor no. 2; sensing pin 2 controls rotor no •. 4; 

sensinz pin 3 controls rot.or no. l; sensing pin 4 controls r~tor 3; and 

sensing pin 5 conbrols rotor 5. 

49 
REF ID:A52232tr 

At the time that. the proposal tor Converter M-134-T2 was offered 

in March 19.3.3, specific keying instructions were not provided. ('l'he 

keying instructions were first. published in· September' l9.3S. For keying instructions by which Converter M•l34 was operated by WJine personnel, see page .) H~er, e.l.l the elem.en.ts which provided its 

inherent security were offered in the first proposal attached to the · 

service test report. lt·was not a gradual development as far as its 

inherent cryptQgrapn'-c security was conc~rned.. C<.>mparatively, only a. 

. . . 1 . very little developmental engineering work was needed in order to 

provide the specific embodiment of these ideas in the machine called 

Converter M-134-'1'2. 

1. An example of the type of developmental work to be done on Converter f.1-l.34-T2 is evidenceq by the followine co:..TOspondenae: 

The service test report on Converter M-134-Tl, which document 

contained· the proposal for Converter M-134-T2, contains the following quote: 

This office can .i'urnish a. machine which will., it is believed, 

readily lend itself' to modification for the purposes inm!nd. 

All that would be necessary would be to add to it tha present 

key-tape transmitter, five magnete,, and. associated wheelstepping mechanisr.as·consistirig of simple levers acting directly 

upon the present cipher· wheels. The modification suggested 

might be accomplished in this manner within . .!! short .Y:!!!. !!'!.!! 

without difticultz. ~ter,, while SC Labs was iD. the process of building the model 

proposed, there ca.me a second suggestion, Sept. 21 1933: , The following alternative to the use of magnets for stepping 

the cipher wheels is sug3ested for consideration. Suppose a 

motor is provided for continuously driving a shaft upon llhich 

five ca.ms ~re mounted in a line above the rea:nective cipher 

wheels; the function of' the ta~ transmitter i;; t:1en merely to 

actuate five small mae;nets which, by interposing or withholding 

small bars between the cams and their followers, control the 

stepping of the cipher wheels by direct action of the shaft 

drive. By such an arrar.1gem.ent 1'1i may be possible to provide 

For continuation, see footnote on .following page. 

;o 
-REF ID:A52232B 

C. Building or First Models 

and TWO Prel3Jiiiiim feat.a 

On 12 April l93J, the Office of the Chief Signal Officer directed 

Signal Corps Laboratories to proceed with the development of Converter 

M-l.34-T2, by convertix\g .t;he'·~ebem machine as proposed in the a.ttaol1-

ment. t.o the :Jervice. test report. on Converter M-l.34-Tl.1 (At the ,ame 

'· 

1 'dont.inuation 0£ i'ootnote l from preceding page: .. 

speed, accuracy, and certainty ot cipher wheel displaeemaots 

a.ud at. the se.r.;.e ti.me eliminate certain or the disadvantages 

of direct ciagnetic action of the cipher wheels,, which action 

might be too severe for smooth, lone-continued functioning of 

the assembly. Your oo.mments on t.his suggestion are invited. 

The answer received by OCSigO from SC Labs, lS Nov 1933, was as 

f'oUows: 

••• 3. In your·lst Ind.of Sept 2, 1933··· the suggestion is 

made that a motor perform the actual. "WOrk or stepping the discs 

rorward ~Y cam action under the selection of the magnets. 

T'.nis suggestion is well within the realms of practical application a..1d is certainly not new in any respect, being the basic 

consideration of most. printing telegraph machines and electrical 

typeW?'H.ers. However, the application of the motor, the 

magnets, the selecting ba.fS; the cam shaft, and the clearing 

features (restoring of the selected bars to norma.1} requires 

a c.ombination of electrical. and mechanical details which woul.d 

necessitate considerably more time to construct than the 

relatively simple direct magnet. aet.ion, assuning that the 

direct. r.:iagnet action can .be .made entirely practical and positive 

in performance. Obviously, then the logical procedure is to 

.first thorough.13r expl:. it. the simpler consideration,, and to hold 

in reserve other considerations, in "Which case the motor drive 

is one possibility~ 

1. Letter, Subject; "Converter ll-134-Tl", To: Officer in Charge, S,C, 

Laboratories; fr()m; Hugh Mitchell, Maj. s.c., Signed "By order of 

the Chier Siena.1 Officer".; 12 April 19.:n. 

l. There ia attached a. copy of the report of -service 

test of Converter, type M-134-Tl which indicates that this 

model is not satisfactory due to its inability to operate 

,at the speedde8.i.i'ed~ The service-testing agency has recommended that a, new .model of a CoJr"verter, type ll-l.34 be constructed by converting a commercial cipher machine as recommended in the attached proposed cryptographic ma.chine. 

For continuation, see footnote 'on following page. 

51 

lG? ~ECIH 
time HJnilit.ary cha.re.ct.eristics" of a cipher ma.chine for use in 

message centers of divisions and higher headquarters, describing 

the basic features of the Converter M-134 development were drawn up. )

1 

In accordance with the directive, an instrument maker at Si~al 

Corps Laboratories devoted his tu.ll attention t.o convereion of the 

Hebem device into Converter M-l34-T2. In .Maroh 1934,, the revamped 

Convert.er was pronounced by the Laboratories as ready for service test 

and between then a.nd 14 July 1934.., it. was given a. preliminary test in 

the Office of the Chief' Signal Officer. The report (14·.~~ 19:34) on 

this preliminary test stated that the machine had proved to be "very 

satisfactory as regards. its cryptographic funotioningn. It was 

·aontinuation of footnote 1 from preceding page. 

2. l;t is desired that your Laboratories proceed with 

this development by converting the cryptogra;hic machine 

which was delivered.to 1our Laboratories by Lieut. Elder 

on March )0th, in accordance with the attached proposal. 

,3. '?his office should be kept advised of the status 

of this project, and anr comments or recommendations relative to the attached report or proposed new cryptograpiic 

machine should be suomit,ted to this ottice with the least. 

practical delay. 

l, nThese characteristics have not. been submitted to t.he Signal Corps Technical Conmittee, inasmuch as it is for sple use by 

the Si&J.al Corps, and 1n vew or the fact that the project is 

considered a.s confidential. However, these characteristics 

have been approved by this office and should govern you in 

th1s development,n CONFIDENTIAL ttr, WO OCSigO-)ll,;-(M-1;34), 

Subject: Converter M-l.34, l2 April 19.33. :. • .., .. ., 

52 
REF ID:A52232B 

retumed to the Laboratories with a list of suggested changea,1 

In Jlatch 1935, the process report of the Laboratories stated that 

the Converter M-134-T2 was again read¥ for i:est. Due to the fa.ct 

that the Laboratories were then in ·the prmtess of moving from one 

location to a.nother, the test was postponed until early May. On 

15 U8if 1935, the War Plans and Training Division of OCSigO completed 

its study of the converted Hebern model and concluded t~1a t the device 

was then "in satisfactory shape to warrant the purchase of at lea.st 

six additiono.l mo4ela for service test".2 Also, additional suggestions 

I. Letter, To; R&D bivision, Prom: Henry L, P, King, Capt. s.c .. , 14 July 19,34. Folder No, 21 M-1341 M-134-A, SJ2!cifications. 

'lhis letter direeted. that the following list of changes be submit tad to Sigila.l Corps Laboratories: 

a. Remove 11Start-stop11 switch lever on the key tape 

transmitter. '.t11s 1s unneceS'5ar'y' and its rem.Oval will 

lessen the possibilltie$ for improper .functioning of the ~--.... machine, 

b. Remove "On-off" switch lever on t.he key-tape transmitter,, for the sarne reason as under a. 

c. Remove one set or connection-changjng plugs and 

jacks at the rear of the cryptograp~. Only one set is 

necessary to accomplish the purpose for which these a.J:"e intended. The plugs should be numbered trom. 1-5. 

d. Provide means. for rote.tint; the cipher wheels back-. 

ward or torwa.rd by hand, for ease in eettinc up a keyword. 

e. Add a letter counting device, which ean be reset 

to zero at will by a. siinple hand operation, so t..11a.t the 

number of let.tars cryptogra.phed can easily be checked. 

t. Insulate key bars ot keyboard from the frame. 

2, -Memorandum, Fors Maj. Cotton, B&D Division, Fran: s. B. Akin, 

Majpr, s.c., 15 May 1935. Folder M-134, Specifications. 

53 
REF ID:A52232B 

m~rn ~~~H l in the line of engineering development were made. 

l. !'he foll.ow1ng auggeations •re made by WP&T, ocs1go. (Uemo, l'or; 

Maj. Cotton, R&O Division,. From: s. B. Akin.t Maj. s.c., 15 May 19.35. 

Folder M-134, M-134-A, Sp!cifioations): . a. ·The key-board o£ the cr.yptograph should be made standard and 

the space between t.he keys should be ma.de. approximately equa.l to 

t.hat on a standard type'W1"iter keyboard. b. For greater surety ot electrical continuity ·across the five 

cipher 'Wheels, the latter should be modified in whatever respect 

necessary to accomplish the purpose. 

c. Means should be incorporated .in the apparatus, so as to prevent the typewriter from operating more than once per depression ot 

a. key of ti1e keyboard of the cryptograph; This means that some sort 

ot a. lockina· circuit or a locking mechanism will have to be provided. 

d. Means should be incorporated to prevent t.he typewriter from 

printing a. character unless the tape transmitter is also actuated, 

'!'his may be aceompllshed in any manner which will insure that no 

printing will occur until the key that is being depressed on the 

cryptograph keyboard. has reached the limit. of its travel. At present t~1e printing impulse occurs at the time when the depressed key has 

progressed only about l/3 of the full distance of its travel~ On 

hearing the striking of tne type bar, if the operator releases the 

ke7 and proceeds to the next depression, the tape has not stepped 

forward nor have the cipher wheels been moved as they should have 

been moved. As a consequence the encipllerine operator, by incom-

,,---..... plate depression of the keys, may cause the printing or cipher 

characters without acco.rnp&Il¥ing stepping forward of the key tape 

and cipher wheels; the deoipherine operator, however, not having 

any ym.y of knowing when encipherment occurred without Sll1' tape and 

cipher wheel step-forward operation' at the enciphering station, will 

not be able to decipher the message. Ot course, instructions for 

operating the apparatus may emphasize the·necessity for completely 

depressing all keys to the full limit of their travel; but it is 

through best to provide an aut.omatie means of obviating this 

difficulty it possible. · 

••• After these service test models have been procured the next 

steps in the development of t.his project should con.sist of studies 

regarding: 

a. Methods £or the production of the ke7 ta.pee. 

b. Improvement of the tape t.:ranemitter. · The trans.mitter now_ 

in use was designed for use in a. start-stop printme tele8l"aph 

SY"stem and presents the art as it existed twenty years a.go. No 

doubt. a better transmitter, more suitable for the purpose !or which 

it is intended in Converter Type M-134""7'?2, is now available on the 

J!Jarket or can be more or less easi.4' designed, the latter to use 

the brush-sensing principle employed in modem tabulating machinery. 

For continuation, see footnote on £ollowine page. 

54 
·REF ID~A52232BAl.t~1ough the first report recommended the purchase of "at least 

6 additional machines", 1 this number was later modi.tied to two models, 

to be built by Signal Corps Laboratories.. The two new models were 

completed and available for service test by Juno 15, 1936. 

D. Service Test 

When the two new models were completed in June 1936 (see Section 

C above), plans v:ere made during the next few months for testing of 

Converter M-134-T2 by using the two machines for exchange of messages I 

i between two distant points. To a.coomplish this type of test, Mr. . I . 

William F. Friedman took one of thfj ms.chines to Panama b.V ship, leaving New York Cit;..y on October 301 1936. The othsr mode1 v:as placed in 

the message center of the Office of the Chief' Signal Of'i'ic~r. All 

preliminary arrangements for this test were completed by early November 

and from 7 until 2.) ~Jovember, inclusive, many cr,yptograms were exchanged 

between Panama and Washington. This service test demonstrated, that the 

new cipner machine was operable at the rate of 30-:-35 words per ·minute 

and that it. a.ttorded "the highest degrae of cryptographic security".2 

continuation of !ootnot.e ~ from preceding page. 

In partic~, it is desirable that. the tape transmitter mechanism be 

such as to cause as little wear and tear on the tape as possible. 

It this can be aocomplished1 the life of the ta.FGs will be very 

much axtended and will by that much make the system more successful. 

Possibly a tape stepping mechanism s1milar to that used in motion 

P.ieture projectors offers good opPortunities for application. 

1. Ibid. 

2. Notes on Preliminary Service Test on Convert.er M-l34-T2, tiled in 

Folder .3, Converter M-1341 M-134-A, Procurement ( t11ru 19~0), . CSGAS-80. 

.5S 
REF ID:A52232B 

Only minor d.i!ticulties manifested thel!lSelves during the Pana.maWashington test conducted between 7 and 23 No'Vanber 1936 (see Section 

D above). As a result of this test, the Converter M-131+ we.a reeom1 mended for adoption as standard. with a number of modifioa.tions and 

~dditions.. One of the two models used for the test \vas :returned to 

Signal Corps Laboratories where the suggested modifications and 

additions were incorporated, Based upon this model, specifications 

for quantity production were drawn up. At about this time the designation 

of the test model, M-lJ4 ... T2, was dropped and the machine was henceforth 

called Oonverter. . .. M~iJ4. . ' ~ . .. . . . 

E. Patent2 

Appl,.i.cation for Paten~ Serial Num'oer 682,096 (see Tab JJ), of William 

F. Friedman covers Qonw.-ter M-134-T ... 2, Converter M-1341 and Converter M-l,34-A. 

The appliQ&tion was filed relatively earl;v. 2; July 1933, and contains proba.b~ t.he first disclosure ot a rotor n. \.Wline cont.rolled by an 

extemally genEJrated key.. . SI-'Scifioally, the spplleation discloses a 

five-wheel machine in '-mi~ the wheels are stepped depending upon the 

presence or absence of per.tore).tions 1n a. tape, the tape beine provided 

with a. succession of Baudot code groups. More broadly, the inventiC?n 

oontempla.tea means assuring substantially aperiodic stepwise displacements of the several rotors. 

Although numerous claims have.been allowed1 the application is considered classified and is under a Patent Office secrecy order. 

T!lere is no likelihood o:f the early issue of t.he pa.tent. 

HENRY B. S'fAUFiER 

Chief, Patents Section 

CSGAS-71 

l. For details concerning adoption as standard, see~Chapt~r VI, 

Section J, page$~ Vo&-t,:1u/~ 

2. T'nis paragraph -tnis writ.ten by Henry B, Stauffer, Chief, Pa.tents 

Section, CSGAS-71. 

56 

TIJJ? ~R~H .+ 
REF ID :A52232B · 

TAB A 
SECRET 

REF ID:A52232B 

4 

FIG. I 

1. Tape chute 5. Side tape chute 

2. Cover lid 6. Stroke counter 

3. Controller 7. Name plate with register number 

4. Tape retaining arm 8. Print hammer 

SECRET 
REF ID:A52232B 

TAB B 

Converter M-134.-0 
REF ID:A52232B SECRET 

FIG. 2 

9. Ribbon shift lever 11. Tape feed roller 

10. Type wheel 12. Zeroize-operate key 

SE6RET 
.. ~ 

REF ID:A522328 

TAB 0 

Photograph ot Converter M-134-C 

( showing espe cial.l_v the index, 

control, ond cipher rotors) 
REF ID:A52232B S:ECRET 

;;'t---+-----ra 

FIG. 4 

17. Index rotors 

18. Control rotors 

19. Cipher rotors 

SECR8T 
REF ID:A52232B 

TAB D 

Uemo.randwn to Chief ot Staff 

Subject.: The development ot an indecipherable printing telegraph. cipher 

for millta.ry purposes. 

From: 'l'he Ohiet Sign.cl. Officer · 

September 111 1918 
REF ID:A52232B 

SECRET 

September ll, 1918 

MEMORANDUM for The Chief of Staf t: 

Subject: The developnent of an indecipherable printingtelegra.ph cipher tof.' military purposes. 

1. For many J"&at-s expert.a in dif terent countries have been at 

work .more or less continuous]¥ 1 on the developoon t. of sor.i.e form of 

secret teleeraph cipher which could not 'be.deciphered by outside 

agencies and which would, therefore, make possible the transmission 

by telegrapll of the moot· secret messages involved in military opera- tions, without ati3' ohance of these messages being interpreted. 

2. A satisfactory solution of th.e problem presupposes a syst«ll involving t.ho transmission of electrical impulses over the line 

w21ich carmot be deciphered even when intercepted. 

3. Modem military operations bave reached such a. sea.le and 

extend to such an enormous terrain that, in the absence of a suitable 

cipher, a very large volume of telegraphic business must. be conducted 

in some form. of code• The use of this necessary code has reached such 

e. Stage at preGent., in the different departments of war, O.S to involve 

a tremendous am.cunt of expert. labor in coding and decoding these mef!-

aages. T'ne delay in tllis necessary operation is a. serious menace to 

the pror:ipt transa.ctio.i."l of military business. So far as is knolm, all 

previous efforts to obtain a.n a.bsoluteJ.¥ indecipherable cipher I.lave 

failed even in the hands of 1 the most expert cryptographers. In the 

conduct of a conflict like the present war, the large volume of daily 

business has to be coded and decoded da.14' between two continents, 

involving great eltpense and the services of a. large personnel, Wot. . only ia this a serious burden to the strictly cilit.ary departments, 

but exactly simHar conditions obtain in diplomacy, propaganda work, 

Department of Justice investigations, oarket reports, and 08.111 other 

activities of a confidential nature required 1n the conduct of the war. 

4. Some months o.go the Chief' Sigμal Officer placed thl.s particular 

problem of evolving an indecipherable printing-telegraph cipher betore 

some of the best telegraph engineers ot this country and the Engineering Department of the Chief Signal Officer's office under the charge of 

Lieutenant. Colonel J. o. Mauoorene, was given direct oha.rge of the 

development with inotructions to cooperate, criticize, and to place at 

the disposal of these telegra.p:ii enginGers all the cipher knowledge 

at the disposal of these telegraph engineers all the cipher knowledge 

tho Siaial Corps possessed. T'ais work was undertaken vigorously b.r 

the engin.eerine staff of the SitJlal Corps and the enzi.neering staff 

of the American Telegraph. and Telephone Company, with the a.dded 

COPY SECRET 
c. 

REF ID:A52232B 

Sf CHEY 

assistance ot tho cipher experts of the Military Intelligence Branch 

of the General Staff, who have cooperated tlwoughout this developrrient. 

5~ The result of these ei'i'orts has been the development of swh 

a system of cipher printing-telegraphy, and this system ha.a now been 

installed for official teats between the Signal Corps laboratory 

1710 Pennsylvania Avenue, Washington, D. c., and 463 West Street, 

New York City, waere trained personnel, consistina of Signal Cori:e 

enlisted men, are now operating this apparatus with entire success. 

6. The printing-telegrap.lil, without ciphe:r attachm.ont, is now 

al.reads installed in France extensively &"id io used in t..1-io c:onduet of 

official business bet.ween Headquarters A. E. F .. end·Headq,uarters 

s. o.s. in France, and al.so between London and Headquarters s. o. s. 

direct over a cable laid a.cross the English Channel by t~1e Sif;l,al Corps. 

General Pershing ha.a reeent.13 asked for additional equipoent for 

thirty.oore stations to be installed in the m.lit.ary telegraph system 

oi our oversea forces, 

7. The cipher apparatus already referred to bas been designed~ 

therefore, as an a.ddit.ion t;o the e.r.isting printi.."lg-telagraph system 

now in operation, and if a.dopted and approved by the Chief' 0£ Staff, cipher printinr;-telegraph units can be shipped and iru:lt.clled. at. any station 

where the printing-teleeraph is now used.. 

(). This cipher apparatus, ha.mg been developed in the United 

States, is not known to our forces overseas.11 and the first line has 

been inst.ailed for. ~h~.purpoae o.f dotem.ining whet.her or n.ot this cipher 

is t.horou,o)lly prf.$qt;,~~~l"and adequate for military service, to supersede the present ~b,0,f.ions and slow methods using code. 

9, It is reaoomended. tha.t this oodel installation now in operation 

be immecUa:tel.a' examined by a: committee of the General Sta££, r-1ith a 

view to deter"mininCP at the earliest practicable moment, whether or 

not this appara.tua s~1ould be purchased and inetall.ed where necessary 1 

both in this country and overseas. · 

Major General, 

Chief Si01a.1 Oi'ficer of the Army. 

l Incl. 

~OPY. SECRET 
REF ID:A52232B 

TABB 

Patent No, 11 5101441 

Hebern1 filed: March .)l, 1921 

issued: Septenber 30, 1921+ 

Includes description of Hebem Rotor 
REF ID:A52232B 

Patent tJo. l,683)072 

Hebern, filed: Hovemher 20,, 1923 

issued.t September 4, 1928 
REF ID:A52232B 

fAB G 

Hebern Eleetrie i:.:ode lib.Chine 

(presented to Aw'.q in 1923) 

/ 
REF ID:A52232B 
------- --

REF ID:A52232B ...----------- - - --
·-

~ I 

II,, 

CONVERT6R N•JS4·TJ. 

• 

WT. Z..2. LB. 
REF ID:A52232B 

TAB l 

Photograph of Converter M-134-fl 

P.car View 
REF ID:AS2232a 

• 

• 

C'ONVGRrF I? f1 .. 1S4-TJ. 

R£A11 view 
REF ID:A522328 

TAB J 

Photograph 0£ Converter 1'-134-'ll 
REF ID:A52232B 

2. Rotor 

3.. Rotor pin · 

• - .j. 

- --1> ~" 

) ) 

f, .-'.C..:',j; L~.~=, . -: _::;_iJ 

f~;~-~~J "" 

) 
CONVERTE~ 11-J.34-TJ. 

HEAR VIEW 

COVE/? RE/1DVED 
REF ID:A52232B 

TAB K 

Photograph of Gonvorter U-134-Tl 

?op view, cowr ~ved. 
REF ID:A52232B 

l. Contaet.·levers 

2 .• Rotor 

3. Rot.or •Jin t . 

1 • 

4. Keyboard 

5. Lamp bru1k 

·, 

Lt·"-= ~,;~.~-~~-: 11 ; 

( ( ( 
3 ---------~ 

CONVEHrER M·Z34·TI. 

TOP VIEW 

t.OV6H llEMOVED 

1:~~l: 1':1~t 1 : II )1~·1 :: /:~'....!'i)~:?~.~'.~;~~!~l~~fi ---------

s 
REF ID:A52232B 

TAB L 

. ' 

Phowgrc.;;ih of Converter fil-l.3L}-'1'l 

Partl,v diw.<?.:ntled; top view 

~-. 
•7 

......_ -..... <:;--

) 

-:):I 

-;J 

'il _; :: .. J 

ft ... 'J .:;_·. 

•' 

---·--,; 

REF ID:A52232B 

l. U Clip 

2. U Clip 

3. Roto.r removed from convo1"ter 

) 

'l 

) 
• 

COllV6RT£1' H·l3• ·T1 

~RTLY DIMl/ANTl.ED 

Toto V16W 

• 
REF_JD:A52232B 

TA.13 U . 

- ------ ---~======:::::====~~iiiiiiiiiiiiiiiii 
REF ID:A522328 

1 •. Tape stepping contacts 

} 

< ) 

-- ~~~j 

1t~~-;;~p~ 

) 

I 

J 

' \ 

11 I 

I 
CONV£HTE R M-1.Stf.•Tt 

HI ti HT $/1'£ V16 W 

COVGR ft6ftf0V£D 

\ 
---- ---~·-~- - ------------ -------· - ---- ~ - -~-- -

t'l:n.der std.e 

,,--

----~ ----~---------------==----

~---------------·--
) 

REF ID:A52232B 

l. Individual keyboard key contact 

2. Keyboard loJking magnet 

4. Universal b~r 

~ j 

I 

fi-2> • ;;._<, '· 

r::.:- . :i 

1_'. -~. ~ :.i 

~.- ~;._~:~-::~·~~ 

"' 

) / 
CONVSRTEH M-l~4 ·TJ 

f/N0£1' SI oe 

l 

• 
---- -------

REF ID:A52232B 

TAB 0 

Photogro.ph of Converter M-134-Tl 

Left side 7imv, co7Gr renoved . 
REF ID:A52232B \ 

---- ./l 

~: 

',". - ' - ~! . ·-. - ·' 

l. Clutch disengaging magnet (atop magnet) 

2. Armature of _stop maz.;1ot 

·-"{\-+, 

~-....~/~} 

4. Slide bar 

5.. .l.tat.chet wheel attached to rotor she.rt 

6. Driving side of positive cluteh ,. 

c:.:...,~· .. . ' 

'. 

'-' 

) ) ) 
• 

3 

z. 

CONVERTEH M·J.34-TJ. 

LEF"T ~/DE VIEW 

COVER REMOVFJJ 
TAB P 

Three Drawings of Converter M-1)4-Tl 

Figure l - Wiring Diagram 

Figure 2 - Plan of Wheel Stepping Pawl 

Figure 3 - Side Elev. ot Cipher Wheel (Rotor) 
< l':t I 

'i 

; 

! . 

I i I, 

I 

8 8 8 t ., . >-'"01· . • I 

~ ::s 

0 (; " c . 0 ·. .• ,, b li1. . . ~ '·· .;i) 

I'). 

I"!> 

QQGQQQQQ 

QQQQQQQQQ ' . . . I 

- . l 

II ::._·r1 Q Q Q Q Q @.Cl\) • . ' i;..'_-1< . eer;&u -- d • 
REF.ID:A52232B 

TAB Q 

Patent No. 2,0281712 

(covers Converter M-lJ4-Tl) 

Issued Jan. 28, 1936 

to 

WilliAm F, P'riedman 

and 

George A, Graham 
• 

REF ID:A522328 

· Oonyerter M-l.34·'f2 

and 

Electrical Ttpt~iter 
REF ID:A52232B 

Detailed Descri tion of Converter M-l -'f2 and Associated Electrical writer. - Convert.er IL-l.,34.-T2 

{Utt wide, " long, 9 high; weight. 35 lbs. in conjunction with the properl,y modified electrical typewriter (15" wide, 17" .long, ll" high; weight 43 lbs.) constitutes an electromechanical machine by means o.f 

which messages may be enciphered or deciphered automatically up to speeds of about 40 words per minute. 

Convert.er M.-134-'?2 may be used to encipher or decipher· messages without. the electrical typewrit.er. In 

this qase instead of the crypto0ra.pi:1ic resultant of the convert.er keyboard operation being printed by the 

electrical. typn11riter, eo.ch resultant character is indicated by lamp illumination on an alphabetica.lly 

de ignated lamp strip. 

Briefly, the cryptographic security of the converter is effected by the following features: 

co. ~ •• JL.~ A celluloid tape, ~uth pin holes punched in the five-unit code controlling a tape transmitter o 

:p · ere·11s in variable relationship 11!! cipher discs (£!: rotors) as switching commutators to establi~μ .... ~-·: 1 

. . tilt.ant £or each a.nd every keyboard operation. Each resultant therefore depends upon the initia~"po-_ ..:. ,,; 

U . ,or the key tape in the tape tra.nami.tter, upon the initial setting of the cipher di.scs and upo~~ ·.::c.t ., . .. ~nt positions of each. . . . . . ~>.:.( ·. -J 

{,.. .. ~~~ ~ plug and Jack strip which comprise~ a switching means for establishing various connectidf::lJ:~- · -~ 

~.. ~\: tae tape transmitter and the cipher discs. th,=.o.. " 1 Zf":. _ .. 'fh.e power facilities required for operation of the Converter M.-l34-T2 and the electrical tY'pe~iJi :·fj 

aft ll.C)' volts d.c. with a capacity of at least 250 watts. . . tr£.-;;~:.. ;-::«-. . )11.~". '"?'J 

. C:otverter M-l,J4-T2. - Reference tabs Q to I inclusive. The conve~r com.prises a base frame, 1tif' ,• -· !(l, -'-~ eyboard operation eounter, keyboard universal bar contact combination, f'lve rotatable cipher d c~ 

~ t.ipr; between stator elements, encipher and decipher. reversing ~dtch, i'ive cipher disc step-f~i - ·- -.l 

mag te~ tape transmitter, plug and jack strip, lamp st:rip, lamp reSJ.Stanee unit, one slow-release ere ,:;~ 

mul i~act terminal strip for connection to the electrical typewriter, power switch and lamp swit.Ch;. ~ ·; 

pow r plug and cord, power fuse and incidental wiring. C~.;.~:.' ,, ;; 

Base Frame. - The base frame comprises a. modification of t.he Remington noiseless typewriter as m _-..r 

!a.c ured by the Remington Noiseless Typewriter Works, Middletown, Conn. All el$L1ents of the converter 

&re untied on this frame in orde~ to ~ploy a commercial..13' available structure insofar as practicable. 

P1ug and Jack Strip .. - Reference Tabs Rand DD. Five plugs, cords and jacks are provided which are ins~alled in th~r five connections betweoo the tape-transmitter contacts and the cipher-disc magnets. The 

plugs a.re connected to the tape-transmitter contacts and ue numbered accordingly from 1 to 5 ~cl.usive, 

The jacks a.re connected to the cipher-disc magnets and are a:J.so numbered respectively from l to 5 inclusive. 

Accordingly, these connections mar be patched across as desired and changed. at will as a variable feature 

tending to further extend the cryptographic seeurit1 of the machine. i\.11 stations must. agree in this ~~~. -

For continuation, sea Tab s. 

) ) ) 

• 
SECRET 

Fig. l - Converter M-l34-T2 and Electrical 'J)'peviter 
REF ID:A52232B 

TABS 

Converter M-l34-T2 

Front View 

. ' 
REF ID:A52232B 

Continued from Tab R .. 

Lamp St.rip. - Reference Tab R.. The lamp st.rip may be used for the indica.t.ion of resultants w'aen the 

electrical typewriter is not used. The lamps are mounted beneath a bakelite strip which is pr<>vided with 

lettered opalescent inserts. One spare insert is also mounted on the stri:p to preserve the symmetry ot 

tt combination. The lamps are ratod as 2.2 volts, .25 ampere Tung-Sol nashligi'lt bulbs, non-focusing, as . utactured by the Tung-Sol Lamp r:orks, Inc., News.rd, New Jersey, or oquel... A 400-ohm resibtance unit is 

c r.iected in the la.mp cort1lllon. 

Keyboard. - The standard typewriter keyboard is used, so that the operator will not be required to 

_ l !f!;\a special keyboard.. All key~ other ~ the ?6 letters o~ the alphabet and two blanks are omitted 

:".:f'n · tilo blank keys are blocked up moperat,l. ve and are vrovided l.ll order to nake the plan view of the .· ~x , --c, .-r::\ 

.-~.~ ~rd symmotriea.l as well as providing guide keys for t!Je no:mo.l. position of the operator's hands.~,,--~ ·1; ~~-~ -er:;words the keyboard is ·restricted to the 26 letters of the alphabet. Each key bar is provided. tf.t.th:1' -~ 

.:a~ oe~ae~ extension whiC~l opera~s into :ontaet jaws. Electrically ill key bars a.re cormected in CO~lt: -~-jJ) 

',~ tp on~ side of the circuit and tne individual contact jams are connected to the studs of the stat.iOJ.ll\z:'~ - ~ 

i-P te?-of the enciphering-deciphering r:>versins switch. The individual cirouit.s are connected tnroubh'· .::,:j 1:_ ,- tef.1 and then through ti1e cipher disc cow.bination to the electrical ty?writer solenoids or the lanJ~'. <-~j 

'.\;~ th" case may be. The key contact jaws are of ti1e wiping type ancl should give a .minimum of trouble..;'f""-< , _-.:;, 

Kezboard Universal Bar. - 'l'ne keyboard is equipped with a universal bar mounted transversely and-·;:;;; ·~~ 

.. c~;ly beneath the key bars and it is actuated by the depression of any of tlle keys. The depression ,:~of! a -~ey serves to rot.ate this universal ba.r on its axis, the movement. being used tea" two purposes; t.e;i '~~-~r · 1

·:-to ope,ra.te through a yoke coupllne the operation count.er; and also by ncans of a. lever extension it ::-~ .. _-_ ~ 

--~l .~a-&;\ two contact. .combinations. · '·- -·· _ ··-·~ , - -- ltizboa.rd Ox>t!ration Counter. - 'fbis counter is provided to record the number of keyboard operation~ -: -, .. ~ 

as check ac;a.inst. the number of characters printed; the number of step-fol"V'iard positions of the key · ta : . and the number of characters in tlle message or the cryptograin as the case way be. The counter may 

be esto:red to zero at any time by manwil operation of the reset lever. 

Keyboard Universal Bar Contact Combination. - 1'hese contacts are in "make" l"elationship with the 

universal bar in such a mnnner that the depression of a key causes these contacts to close before the 

individual key contacts are closed. lt is important that this :relationship be preserved for proper 

operation of the machine. Upon permitting the key to rise ~return to no1"lMtl) the universal eonta.ct.s 

open aft.er the individual key conta.cts open. The function of the universal. contacts in the circuit is 

shown in Tab DD. 

For additional deseript.ion of parts, see Tabs R, U, w, Y, z, AA, BB. 

) 
REF 

SECRET 

Fig. 2 - Converter M-134-T2, Front View 
REF ID:A52232B 

TAB T 

Converter M-134-'1'2 

l . . 

Rear view, tape transmitter rmioved 
) 

REF ID:A522328 

For detailed deseription of Converter M-l34-T2 

see Tabs R,, S .. U,' W, I, Z, AA,, BB 

) 
SECRET 

SECRET 

Fig. 3 - Converter M-l.34-T2, Rear View, Tape Transmitter Removed 
REF ID:A522328 

TAB·U 

Converter U-1:34-'l'2 

Rear View 

Covers Removed 
) 

REF ID:A52232B 

Slow Release Rel&! - Reference Tabs T,, X,, and PD. '?he i'tmct.ion of 

this relay is to energize the cipher-disc stepping mag.nets for sufficient 

time to insure a complate core travel and to subsequently clear the circuit 

to the normal or open state. This relay is of l.300 ohms resist.once and is 

equipped. with a copper slug for slow rel.ease. The contacts are an a.ppllcation of J;.he Burgess inelosed type microswit.ch. These contacts have proved 

very dependable in service and should require no attention. 

For addit.ional detailed description or Converter M-134-T2, see 

Tabs R, s, W, Y, z, AA, BB. 

) ) 
REF ID:A52232B 

S'SIPET 

SECRET 

rig. 4 - CcmYmoter 14-134-T2, Rear View, Covers Removed 
~- REF ID :A52232B 

· ·TAB V . · . 

· Converter ll-l34-T2 

. . Plan View . 
REF ID:A52232B 

~I j ~ I ·' 

~ ' ·, '::·· : -~ ;/ . ~ 

For detailed description of Converter M-134-'1'2 

see Tabs R, S, U, W, Y, Z, AA, BB 

,. f ,--.: 

·.' 

' -

(t~;·\· . ' 

, r~ 

" 

'/~ 
REF ID:A52232B 

SECRET 

Fig. 6 • 0 U tier a-.J.34-!2, Pla ftw, Covers Removed 
I 

REF ID:A52232B 

. TAB W 

Converter 11-l34-T2 

Plan View 

Covers Rer..10Ved 
REF ID:A52232B 

tL''.'.:: ;

1

; :·, 

~j ~l:· ), :J 

Clifer Discs. - Reference Tabs V, w and oo. The convert.er is 

equippe with f'ive cipher discs positioned to rotate between six 

stator heads as distributors or commutators. Four of these stator heads 

separate the cipher discs and Ere provided with distributor faQes against each cipher disc. Two end stator heads are provided. with distri~ut.or 

faces internally contacting the end. cipher discs and externally by means 

of stud terminals are connected to the key contacts ood the Ei.ectrica.1 

typewriter solenoids or the lamps through the encipher-decipher reversing switch. Each cipher diec presents 26 segments on each face rihich are in 

contact with 26 spring and ball co,.11tacts on each stator head. The connections throuzl1 the stator head are direct. 'i'he segraents on one face at 

ea.eh individual cipher disc are wired in randora fashion to the segments 

on the ppposite face ot the disc. The particular wiring i.'or each disc 

and for ti1e co.o.bina.tion is shown in Tab GG. The exposed periphery or 

band of e~ch disc is designated in 25 positions alphabetieolly f'rom A to 

Y, the 26th or Z position being designated by a numeral. '1'he numerals 

serve to identify the disc in addition to indicating tha ~6th position. Each disc is readily removable and interc!'langeable with any other disc. 

No throue.~ shaft. is used, each disc being rot.at.able upon a spring 

tensioned be.11 in the center of the stator heads, and i."1 removal any 

pa.rt.icular disc 1$ aim.ply withdrawn from between the stator heads. In 

addition to the desi[Jla.tion band each disc presents a scalloped edee 

for two purposes; 1.e .. , to facilitate setr.ine of the discs by hand, and 

also a.-cting as p0sitioni."lg centers 1..-.,, conjunction with the step-forward ~ 

mechanism. In sett~ the discs to an initial position they roo;y be 

turned in either direction by de:,ressing an.d holding back the button 

extensions of the step-forward. pawls-loes.ted directly behind ea.ch disc 

position. As regurde electrical continuity through the coobination of 

disc and stator heads there are 26 wires connected to e'.lCh end stat.or head 

and 26 circuits through the discs no matt.or in which position the discs 

happen to stop. It will be seen that 26 through circuits are provided at 

all times even though the relationship ot all circuits is alt~red by a.ny 

disc movement. One particular ci!·cuit is traced through tho combination 

in Tab 00. 

For additional detailed description of Converter.M-1J4-t2 

see Tabe R, s, U, W, Y, Z, AA, BB. 
REF ID:A52232B 

SECRET 

Fig. 6 - Gi I W '8r K-134-1'21 PlllD ftft 1 0oYers Blmoved 
REF ID:A52232B 

Conw1 .. \ier M-134-'.1.'2 

Plan View, 2 Cipher discs removed. 
REF ID:A52232B 

For detailed description of Oomrerter M-l34-T2 

see Tabs R, s, U, W, Y, Z, AA, BB 

~\ 
REF ID:A52232B 

SECRET 

ftg. 7 - CClaftrter M-ll4-f", Plan View, 2 Cipher Dian 91moved 
REF ID:A52232B 

TAB Y 

Converter M-134-T2 

Bottom View, Covers Re.moved 
REF ID:A52232B 

Encipher-Deciph,er RE,\versing Switch. - Reference Tabs X and EE. 

This switch is mounted beneath the keyboard f"Jld is operated through 

a rack and pi.nio'l drive, the pinion being extended to a kn<>b in 

front of the keye~ The switch acts as a con:bi.nation of 26 doublepole., d.ouble-tilrow switches in t.he 26 circuits f'rom the key contact jaws 

through the cipher-disc combination to the typewriter solenoids or 

lamps as the case may be., and it .functiorw to reverse the cipher-disc 

contbination in these circuits. This feo.ture is necees~J in order to 

oa.intain the reciprocal relationship between the resulta..11t obtained 

in encipherm.en t with ·respect to the reau.ltant. required in decipherment. 

As an cl:arnple and as shown in Tab EE, with the swit.eh in encipher 

position and striking the A key results in the printirig of a G, Then 

with discs in the same position and switch thrown to decipher position, 

the striking of the G key reaults in the printing ot an A. 

For additional detailed deseription see Taha R, S, U, W, Y, 

z., AA, BB. 
REF ID:A52232B 

SEGMET 

SECRET 

Fig. 8 - Converter M-l34-T2, Bottom View, Covers Removed 
REY-ID: A5223-ZS- - -

I -

Converte~.M-l34-T2 

- Disk Stepping Mechanism_ 
_. ............................... --------------------~~~~~~ 

REF ID:A52232B 

Cipher Disc Step Forward Mechanism. - Each of the five cipher discs are equipped with individual 

stepping mechanisms comprising a. filagnet solenoid, tension spring, step-forward pawl, and location 

roller. The individual. magnets a.re operated by the tape transmitter. Upon the circuit being closed 

through a given magnet, this magnet draws down the core building up tension in a spring and near 

the end of the stroko a step-forward pawl is drawn into engagemont with a ratchet tooth on the 

pertinent cipher dis.c. Upon d.eenergization of the magnet the power stored in the spring is delivered. 

.. ·':.. ~to step forward the cipher disc through the step-£ori1ard pawl after v'.ilich the step-forward pawl is ~-· · .:. ·>i · .. :: .. :;iisenga.ged.. A location roller and arm is properly conjunetioned 'With this .action to definitely ~·- , _ti . -·-.. --~establish the stop position of the cipher disc. 'l'his roller is beneath the cipher disc and £alls ~~- ·;,;.:_~~-~ 

.. :...J.nto the scalloped edge on the periphery or t.he disc. T'n.e step-forward pawl arms are extended throu~-~;:::.;.3 

.. ~~-~he cover or the converter into buttons to permit the ma.nual disongageraent of the pawls from tile _;; .-·~"-~ 

... ·- --- ~-pipher discs in order to facilitate the rotation of th~e discs by hal1d. The buttons should be "'=' -t' -;f~iiepressed and moved to the rear when disengagement is desired. · .:::.~i 

~~.-/ ·~::};~t _, ~;-~3 

For additional detailed description., see Tabs Ji" S, U, W, Y; Z, AA, BB. 

) 
SECRET 
REF ID:AS2232B 

TAB AA 

Convert.er li""l.34-T2 

Tape Transmitter 

Featuring Contact Combination 
REF ID:A52232B 

Ta.~ Transmitter. - Ref. Tabs Z and FI!,. 

(l) T'nis unit is a ·modified VJestern Electric Co. multiplex transmitter 1-B as used commerc1ally 

in multiplex printing telegraphy. This transmitter operates on the :five-uni~ code from a perforated· 

tape to establish five contact combinations in marking or spacing positions depend«it upon the arrangement of the eode perforations in groups transv0rsely disposed on the tape. There are .32 different 

permu.tative possibilities in the f'lve-unit code. 1.'he tape is pi"OVided also with a continuous series ot 

perforations in line lonait.udinally·, tl.ie spacing being identical with the spacing between code eroupa 

to permit progressing tl19 tape eonsecutively i'rora one code group t.o ti1e next. The tape transmitter'".~ ~, .. ,_,-~'. 

'~-;:; ~~pped with a tape $7~ove and guide; a latched di• t.o permit. insert.inc the tape at any desired c e -"--~~~~ 

lfl gr®p; a ster>-f'orv:ard star wheel engaging the step-fol'\-va.rd holes of the tape; five code pins conjun . D;-.iil ;::~-, ~ ~he codt),-group hole ·positions of the tape ~d operat~ve upori five contact levers. in marking ... s ''_ ,'!;3;~ 

--~· .,1"l-t1ons; and a magnet a~ting to depress all five code plllS from. tape engagement and to step forw .. ·.· ..;.;;.-;:-.;;::-' .c.'~:i~ t1~ tape by ratchet movement on the star wheel to the: next code group, after -r:hich the code pins &J'i.='" .... -~J ·~-:'!:'!' tlhased to assume their tape dictated positions. When a code pin is held down by the eircumstanceilo ~ja 

,:i·~'::-:; ~- ~~ole in the tape, at that time the associated contact lever is held against tile spacing-contact ....... ~~ 

-=~ OJr;.-f.he other hand, when a code pin is permitted to r.i:se tlu'ough a hole in the tape, the contact lev0r ~# 

.;;,:.~ &:·-moved over to ·tt1e i;iarkint!-contact bus. · 

(2) The modification of the tape transmitter couprises the addition of a con~aet com..bination .. , ,.".!.".:::~, 

. 1< ·~"'ii)-ated by the magnet ar.nat.ure and u wiring rearra.."l.gement to o.da.pt the unit for its proper function· ~"::.:;:;· 1 

..-::·=_:-_ ... ..:..:..1' .... . ·-.-........"\_ :-' '""~"the conve_.-..,er.. . · ."" -.,... '. ~~~ _ ;3J (J) The function. ot the tape transmitter in th~ converter is to step forward the cipher diseli ~- ~~-~~. 

;;'-'~;_-= ~d'ordance with the key tape. The key to.pe is made of celluloid r.;:;ther t.i1an paper in order to permit: - - :J 

) 

origer repetitive use. Each code group of the key tape establishesl' through the code pins and eontac 

evers of th.e tape transmitter, ~ircuits energizing the pertinent ciphei-disc magnets selected which 

act to step forwllrd the pert.inont discs one position, le~ving the non-selected .magnets in norm.al posit.ion. 

'1'he circuits from the disa magnets to t..he tape-transmitter contacts nre eonneoted in series-parallel nith 

respect cd) the contact. combination of the ta.pe-transrait.ter mo.gnet, in order that. the disc magnets be not 

energized until after tho tape has been stepped forward and &11 pins and contact levers ~re in position. 

The necessity for this tape-trruwmitte1.,, ma.gnet-contc.et combination depends upon whet.her or not the 

comm.on connection from power is connected to the marking of spaeing bus.of the transmitter. If th& 

) ) 
REF ID:AS22328 

SECRET-
REF ID:A52232B 

\ 

Tab AA continued. 

common is connected to the marking bus 2 the magnet contacts can be eliminated, but if the common is 

connected to the spa.cine L>us t.he ii'lclusion of the magnet contacts is imperative.. The common is normally connected to the m&rking bus but may very readily be changed to ti1e spacing bus. Access to 

ti1ese busses may be had by removing t.he cover plate of the tape transmitter. The advantage ot the 

use of the .!illll'ldng bus in thett a tape hole means step forward of the pertinent cipher disc and is 

consistent with the tel.egraphic viewpoint of markine si.gnuls. On the other hw1d, the advantages of 

the use of ti1e spacing bus are twofold; first, the transmitter contacts are somewhat more positive 

than in .marking position due to spring tensions, and second, being inconsistent with the telegraphic 

viewpoint.., offer possibilities in e:ryptoeraphic security because the tape no-hole positions normully 

knovm as spacina ti:len actually become rua:rld.ng insoftu• as the cipher-disc maepets ere- concerned. In 

either event it will be noted by reference _to Tab DD that the eipher-diac, tape-transmitter circuit 

is closed through the cmitacts of a al.ow-release relay ~-1;1ich in subsequently openin& ele3.rs the 

circuits for sprin5 step forward of t~te cipher discs leaving t:.ie circuit norea.ll.y' open. ~: All 

intereollilluntcating stations must be in agreement with regard to th0 use of the mrking or the spacing 

bus for dire: step forward. 

For additional detailed description, see Tabs R~ s, u, U, Y, Z, AA, BBa 
.. 

REF ID:A52232B 

TAB BB 

Associat.edElectrical·Typewrit.er· 

of 

Converter M-l.34-T2 

Plan view 
REF ID:A52232B 

Electrical Tmntiter. - Re.t. Tabs AA1 BB, :ca and DD. 

This typewriter comprises a modification ot the Inteniational 

Business Ma.chines Corporation electromatic typewriter. The 

modification consists oti the incorporation of 26 solenoid 

magnets with drag links arranged to operate 'the 26 latter key 

bars; the addition of a universal bar opera.tine a contact 

combination upon the depression of any key bar; and the incorporation of an auto.ma.tic five-character space contact and 

solenoid magnet operating upon the apace bar,;. and an automatic carriage-return contact with solenoid mag.net operating 

upon the carriage-return key bar and including a warning bt\'ll 

signal. T'ne spacing contact is operated by every sixth detent 

of the tabulating rack. The carriage-return contact is operated by a stud at the end of the tabula.ting rack. ·The wiring is terminated in a plug strip on the base front of the 

typewrit.er proper for engagement 1dth a jack strip a.t the rear 

of the convert.er. A plue and cord a.re provided. for connection 

to power for 'the operation of the driving motor. 

For additional detailed de$cription, see Tabs a, s, u, 

W, Y, Z, AA, BB. 

~ .--· r.-..,., :.::-:.·.~~~ r~ r1P.r:~1,1;~ .. : I i'.l ~ .. . 1, .. ,1 I j ' 1d 11; I.·, ~, ·.1 t J < ., I l \ :.~ ft ' I ·11 '\' . ; ' I ~' ! ': :/\_ t :";.\@ ' ~ ~ j/ ~', 
REF ID:A52232B 

SECRET 

SECRET 

Fig.11 - Electrical Typewrit.er, Plan View 
REF ID:A522328 

Converter 11-l.34-T2 

Associated Electrical T,ypewr.i.ter 

(showing solenoids) 
:~~) 

----- ..::--~!~ 

c~:~Z] 

) 

REF ID:A52232B 

For detailed description ot· Electrical Typewriter, 

see Tab BB.. · 

For other detailed ·description, see Tabs a, s, u, 

W, Y, z, .AA, BB. 

) ) 
• 

SECRET· ---

Fig .• 12 - 11.eotri.cal Typewriter, Showing Solenoids 
~-,:. 

REF ID:A522328 

TAB DD 

.. " · Cf>nverte:r ll.l.34·T2 

Sonematic Diagram 
REF ID:A52232B 

For detailed desoript.ion of Converto~M-134-T2 

see Tabs R, Si U, W, Y,_z, AA, BB 

;:7::- < 

'• • j 

!·, i 

,' 

,,/ I " 

-, -·-· i 

,'-~, 
~__.....,SPACE 

...._......._ ...... SOLENOID 

...---~ ......... CAIZ21AGE .......__ ...... IZ£TUR.N 

SOLENOID 

TO OTHER. 

SOLENOIDS . 

~ 

RACK CONTACT 

CA~'21AGE 

S?ETVeN CONTACT 

DISK MAGNETS 

I Z 3 4 S 

0 I S ~ S 

~EVE£SING SWITCH 

'' 

TYPEWfZITER' 

VNIVE.~SAL 

- -JJ - -_-:__-::-\· 

... __ ===uN1vE"isAL BAR> 

SAE 

TAPE T~ANSMITTEI<.~ - - I 

.sw~. ----:~~ lj I j ~ .3AMP. 

D TAPE TRANSMITTER TERMINALS 

',--:--0 • l.:; CONVE~iEIC rEr<?MJNA .... s 

t=-..i TYPEWRITE~ TE~MINALS 

FIG. 14 

SCHEMATIC DIAGRAM 

llC V D.C. 

SEC.:ZET 
REF ID:A52232B- , 

• 

TAB EE 

Converter M-l34-T2 

Theor;y of revorsinz sw:i.t.cn 
.REF ID :A52232B 

',, 

I~ ·,11 

• 

·For detailed description of Converter M-134-1'2 

see Tabs R, s, U1 W, Y, z, AA, BB 

·t\ i I 4 

'11 .,·;-:'.; _';! 
ENCIPHER 

OECIPHE~ 

. REF ID :A52232B 

G 

\;' 

A I! 

A 

/ / 

...... .... 

/ 

/ 

...... ... 

G 

_ _._.A o--.---n---1+ I \ --------- .......__. ......... 

SECRET 

F\G. t5 

I 

I\: 

II 

" 

I 

I ' 

) 

THEORY OF REVE~S\NG SW\TCH 

'' 

I 
REF ID:A522328 

Converter U-134-'!2 

Wiring of tape transmitter 

• 
• 

REF ID:A52232B 

~1~n:--, , I • , , " 

t··1 ,,, 

I 

For detailed description of Converter M-134-T2 

see Tab$ a, s, U1 W, Y, Z, AA, BB 

:·J //.:.;. !H ·; 1J/ .. 'l 

I t ' ' ~ ' : I ' ' f 

~· 'I '\ ... '::-:)~;•'-~' 
--

REF ID:A52232B 

,_____ _______ --- -------- ---- -

c 

+ 

z 

5 

-~ur-----

SECRET" 

Fl G. 16 

Wl RlNG OF TAPE: TRANSMITTER 
REF ID:A52232B 

Converter M-l.34-T2 

Cross wiring of .. incU.viduaJ. discs 
~~.: _--~.;2! 

;i; ' '.fl ~.t~-~··2 ~~~ ·. ~ ~ 

··-.. ij'~ 

::~tj 

) 

REF ID:A52232B 

For detailed description of Converter M-1.34-'1'2 

see Tabs R, S, U, W, Y,,_ Z, AA, BB 

) 
-1· .... "~·-·,.,.· -~ 

ACTUAL DISK DESIGNATIONS 

AND STUD POSITIONS 

Z6 c Y-J Y-D Y-V Y-X Y-W F Z<D 

l F x-o x-c x-s x-v X-G K ' z p w-o w-z w-u W-H W-Q N l 

.3 T V-E V-L V-G V-G V-T z .3 

4 Q U-R u-e il)-K\ U-N u_;_ P 8 4 

5 w T-W T-Y I T-P \ T-0 T-X v 5 

'° u S-K S-N I 5-.J \ 5-1 S-5 x '° 7 L R-A R-P I ~-N \ ~-e, ~-H H 7 I \ 

8 z Q-T Q-F I Q.-G Q-J Q-6 E a 

9 I P-M P-1 I P-X P-4 I P-0 G !3 

10 INDEX x 0-1 0-H I 0-F 0-K \ 0-J iZ 10 \ 11 WINDOWS -l -u I -Y -F \ -Y T I I 

If B M L M T I M I M U \ K D 12 I~ H ~c -G I -e -~ \ -c 1W -----13 

14------ G K-H K-Q/ ' K-3 K-E \K-U I p I 14 

IS 5 J-F \ J-~ I .J-A J-C v-L c lS 

16 N \-6 \ 

\ 1-!S 1-C 1-P 1-5 I 16 

17 E. H-Y H-V H-0 H-A H-N y l7 

18 A G-V G-A. G-B G-W G--:- A L 18 

19 R F-X F-W F-L F-0 F-M 5 19 20 J E-N E-.J E-M E-T E-D M ZO z,. M o-u D-M D- D-M D-E A· zr 

22 v C-P c-x c-o c-~ C-1 u zz 23 0 6-G &-K 8-R. 6-L e-~ J Z!) 24 D A-G A-0 A-H A-Q A-F 0 Z4 ZS y 1-5 2-E ~-T 4-V s-v Q ZS ~IGHT LEFT f 

~ 

~TATOle CROSS WIRING OF STATOR. 

INDIVIDUAL DISKS 

IPH.ER Dl5K 
REF ID:A52232B 

TAB HH· 

Wiring Dia.gram o! CoQ.Yer\er M-134•'1'2 · 

. ,, . 
/ 

REF ID:A52232B 

For detailed descrip~ion of Converter ll-1)4-T2 

see Tabs R, S,, U, W, Y, Z, AA, BB 

) 
h'P1C.-L.COJITA.CT 

ON TtbtNAL .:5Ti'IP 

' .I. l+ 

•I I .. ,. ·;: 

- -------· ---,;N~-~-t-Z--U--------- ------·1 ,---------

; .•. ~_,-.... ,,_' 

• N " 

. . 

' 

CONNlCT I·" IO·JI> 15·t. Z·P 11·1( tO·.J 

,J·T Lt·9 .ll·tl 

4·Q !l·M :t·'I S·W ,. G U 0 

4i·U 15·' Z4 D 7·L 1• N l5·T 

e·z. 11-e: l.-< e-1 16·A 

Z·N 9·& 1<.· 1 Z.!·J 

,.z 10-r 11-v Z4·o 4·& ll·T 1&·L Z5·Q 

a·v •t·O 1e-.5 z•·P' , e·X 1)·'# ZO· .. 

7-H 14-P ll-4 

' '/ -

'" L 

' ..I 

"., 

. ID 

'f-

~-' ·> -·IL 

1111----<~4 .'Cit: 

·W 

·U 

.'o 

i 

' . ,, "

~~ 

L 

I I 

Ii 

I 

I 

.ii • 

0 

e 

- -· ---·- -- ~ 

v1r:w ... Oo .... LN(,i AT &oTTOU OF l.".f.VflSIMO 5MTCt4 

FIG.18 

CONVEIHE~ M-134-TZ 

WllZING DIAGRAM 
REF ID ~A-52---2 3-2·8 · ~ 

TAB ll 

Patent Applica.t.ion ~o. 682,096 

(covers Converters M-l.34-T2~ M-1.34, M-134-A) 

Filed by William F •. Friedman. 

J~ 25, 1933 

Not issued: Under Patent Office Secrecy Order