·, 

REF ID:A4111i577 .... Patented Dec. 13, 1938 2,139,676 

UNITED STATES PATENT OFFICE 

2,139,676 

CRYPTOGRAPmC APPARATUS 

William F. Friedman, Washington, D; C. 

Application August 4, 1937, Serial No. 157,383 

18 Claims. (Cl. 35--4) 

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0, G. 757) 

The invention described herein may be manufactured and used by or for the Government for 

governmental purposes, without the payment to 

me of any royalty thereon. 

,5· This invention relates to cryptographic· apparatus for automatically enciphering and deciphering messages. 

An object of the' invention is the provision of 

a cryptograph with a keyboard for high-speed 

10 manual operation, a bank of indicating devices 

or electro-magnets for noting or recording the 

cipher symbols of the messages as the latter are 

being enciphered, and for noting or recording 

the plain-text letters as the mess?.ges are being 

UI deciphered; and certain ciphering mechanisms 

interposed between the keyboard and the bank 

of indicating devices or electro-magnets for constantly changing the relationship between the 

message charactel's and the cipher symbols. The 

20 invention is primarily concerned only with the ciphering mechanism referred to above, which is of 

simple design but nevertheless yields cryptograms 

of great security. This ciphering mechanism em- ploys means which are novel in the cryptographic 

25 art in that it involves operation along a time 

axis, and the exact cryptographic results are dependent upon a time factor which is constantly 

changing in an irregular manner. 

The invention is described in connection with 

30 the accompanying drawings, in which: 

Fig. 1 is a diagrammatic representation of the 

parts of the mechanism together with certain 

circuit arrangements; 

Fig. 2 is a diagrammatic representation of 

35 means for imparting uniqueness to messages even when the latter are enciphered by the same keying sequence;· 

Fig. 3 is a diagrammatic representation of the 

electrical circuits applicable to the system shown 

40 in Fig. 2; and 

Fig. 4 shows an alternative scheme for one of 

the basic elements of the mechanism shown In 

Fig. 1. 

Referring to Fig. 1; the principal elements con45 sist of a keyboard I, a bank of indicating devices 2, a rotating cipher commutator hereinafter called a rotor 3, a distributor 4, a camwheel mechanism 5 for producing a cipher key, 

a permutation-translation mechanism hereinaft50 er called a translator 6, and a switchboard l. 

According to the present invention, means are 

provided whereby the individual alphabets of a 

set of twenty-six or more mixed cipher alphabets 

are caused to present themselves for ciphering 

55. purposes in a fixed sequence and this. sequence 

is regularly repeated. When a key on the keyboard is depressed only one of these cipher alphabets, however, is selected during one complete presentation of the sequence of alphabets 

and the cipher resultant obtained depends upan ,5 

the cipher alphabet that has been selected. This 

selection is varied according to a very long cipher 

key. 

Broadly speaking, the foregoing cryptographic 

operation is accomplished in practicing the in- 10 

vention in the following manner:-

The rotor 3 serves as switching means for 

changing the whole set of twenty-six connections 

between the keyboard I and the bank of indicating devices 2. The rotor is caused to rotate with 16 

a constant angular velocity by the motor 93, and 

the time required for the rotor to make one complete revolution will hereinafter be referred to as 

the operating cycle. Assuming a system employing twenty-six elements Cto correspond with the 20 

twenty-six letters of the English alphabet) rotor 

3, in making a complete revolution will pass 

through twenty-six angular positions, each con-. 

suming ~1w of the time required 'for the rotor 

to complete one operating cycle. The operating 25 

cycle may therefore be regarded as being subdivided into twenty-six equal time-intervals during which a letter may be enciphered by the cryptograph. To each of these time-intervals or an- 30 gular positions of the rotor, there corresponds a 

cipher alphabet, that is, a set of connections between the keyboard and t.he bank of indicating 

devices. Coordinated with the rotor is the distributor 4, whose brush arm 16 causes brush 73 35 

to sweep over the twenty-six equal segments of 

the face of the distributor synchronously with 

the rotation of the rotor. The distributor cooperates with the keying mechanism to determine 

which of the cipher alphabets will be selected, 40 

that is, ·which of the twenty-six angular positions of the rotor, or which of the twenty-six 

time-intervals, wi!I be the one selected during a 

specific operating cycle for enciphering Cor deciphering) a letter. This selection in each case 45 

varies with the successive operating cycles according to a cipher key which is produced by 

the cam-wheel cipher-key mechanism 5. Each 

different one of the twenty-six time-intervals will 

yield a different resultant for the same letter: 50 

therefore there are twenty-six different resultants possible for each letter. Within the operating cycle, when a key of the keyboard is depressed, the letter corresponding to this key is 

enciphered (or deciphered) by that one of the 55. 
REF ID:A41615ill .... 2 2,139,676 

cipher alphabets which was selected in the aforesaid manner. Arrangements are made for locking up the keyboard so that when a key is depressed not only will the associated keyboard 

5 contact be closed but also it will remain closed 

for one whole operating cycle and no other key 

can be depressed during that same cycle. Thus, 

keyboard operation may be regarded as being 

rhythmic in character and ·may be performed 

10 with a cadence similar to that in teletype operation. The operation of the keyboard results 

in the action of the responsive·· indicating devices 2, which may print the characters produced 

by the ciphering operation in a rhythmic man15 ner. But it is obvious that this cadence does not 

have to be reproduced identically by the operator who is to decipher messages for the cadence 

is not at all an essential part .of the functioning 

of the apparatus. In fact, if a clutch mechanism 

20 were provided whereby the rotor and the distributor would only be started consequent upon 

the depression of any key of the keyboard, and 

would be ·stopped automatically at the end of 

the operating cycle;·. then for each depression of 

25 the . key the rotor and the distributor brush arm would start, would make one complete revolution, the .letter would be enciphered (or deciphered) and upon completion of the revolution 

both the rotor and the distributor brush arm 

30 would stop. Thus, no cadence in keyboard operation would be required; and operating speed 

would. only be limited by practical considerations. 

The •foregoing apparatus and its operation will 

now . ·be described in detail. 

35 The · keyboard I, comprising 26 characters 

eqillvalent to the letters of the alphabet, has a 

corresponding number of contacts of which only 

two are shown as at 10 and 11, corresponding to 

the letters E and Q, respectively. The bank of 

40 indicating devices 2 may take the form of glow 

lamps which are illuminated when current passes 

through them but a preferred embodiment is to 

have the indicating devices take th,e form of 'electro~magnets or solenoids which operate the 

-· keys of a recording typewriter, so that a printed 4" record of the enciphered or deCiphered message 

ms,y be made. . 

The rotor 3 is a cipher-commutator wheel of 

form now well known in· the cryptographic art. 

It is mounted on a rotatable shaft 12. Pressing 50 against rotor 3 are two stators, a left-hand stator 13 and a right-hand stator 14, each provided with a ring of 26 ball-bearing and spring 

contacts insulated from one another and exert-

-· ing a slight pressure against the face of rotor 50· 3. A motor 93, drawing power from source 94, 

drives the shaft 12 and thus the rotor 3 at a constant speed between the stator 13 and 14. 

The rotor is made of' Bakelite or similar insulat60 ing material and consists of two faces, a lefthand face and a right-hand face each face bearing a ring of 26 contact surfaces A, B, C, ... Z, 

equidistantly spaced from one another circumferentially on the outer face. Insulated conduc65 tors . passing through the . rotor connect the 26 

contact surfaces. of the left face to those of the 

right face, in a manner which is reciprocal in 

pairs. That is, if A on the left face is connected 

to ?s:: on the right face, then X on the left face 

10· is connected to A on the right face. Thus, with 

13 paired contacts reciprocity in the·encipheringdeciphering relationship is obtained without special switching arrangements therefor. 

The distributor 4 consists of a set of 26 equal75 area segments or contact surfaces 15, insulated 

from one another and distributed circumferentially on the face of the distributor. A brush 

arm 16, on the same shaft 12 as the rotor 3, 

sweeps over the face of the distributor 4 at a 

constant rate of speed synchronous with that 5 

of the rotor 3. The rotor 3 and brush arm 16 

are keyed to the shaft 12 so that these two elements are always in a fixed angular relationship with respect to the shaft 12 and cannot 

be. angularly displaced relative to each other, 10 

due to slippage on the shaft. Arrangements 

may be made, however, to change the relative 

angular positions of the rotor and the brush arm if desired. Brush arm 16 terminates in a 

brush 13 which sweeps over distributor segments 15 

15 and establishes momentary contact with each 

of the latter successively. Distributor segments 

15 are connected to the right-hand set of terminals 72 of switchboard 7 by a set of conductors 

17, of which only a few are shown. 20 

The cam-wheel cipher-key mechanism 5 provides a long cipher key for cryptographic purposes. It consists of five or a multiple of five 

cam-bearing wheels 21, 22, 23, 24, 25 of different 

diameters. The periphery of each wheel is di- 25 

vided up into. equal segments to which projecting lugs serving to act as cams may be attached 

or into which cams may be inserted; the num- bers of segments on the different wheels are prefably prime to one another. For example, wheel 30 

21 may have 100 segments, wheel 22 may have 

99, wheel 23 may have 97, wheel 24 may have 91, 

and wheel 25 may have 89. Fixed to.these wheels are ratchets 26, 27, 28, 29, 30. T'n.e number of 

teeth in each ratchet 26 to 30 corresponds with 36 

the number of segments in the cam-bearing wheel 

with which the ratchet is associated. Pawls 31, 

32, 33, 34, 35 on a rocker arm 36, which is operated by magnets 37, 38, drive the cam-bearing 

wheels in a stepwise manner, under control of a 4o 

universal bar key-board contact 39 through pow- er source 40. Each time a key is depressed 

rocker arm 36 and the pawls 31 to 35 serve to 

step wheels 21 to 25 forward one interval. The 

cams on the peripheries of the cam-bearing 45 wheels 21 to 25 control contact levers 41, 42,-43, 

44, 45 and the latter operate contacts associated 

therewith, 141, 142, 143, 144, and 145. It will be 

understood that the segments on the periphery 

of each wheel 21 to 25 are smooth surfaces ex- 50. 

cept where a cam is inserted in or affixed to the 

segment and each wheel may have a cam inserted 

in any number of the slotted segments. Contact · levers 41 to 45 are therefore raised and their 

associated contacts 141 to 145 are closed only 55 when cams are presented to them by the progressive movement of the wheels 21 to 25. Furthermore these contact levers 41 to 45 will be 

operated in permutative groupings so that all 

32 possible Baudot-code combinations may be set 60 

up by the contacts 141 to 145, for keying purposes. Contacts 141 to 145 are connected to con-. 

ductcirs 46 to 50 and control magnets 51 to 55; 

the function of which will be described presently. 

Now. since the cam-bearing wheels 21 to 25 are 6·5 

of different diameters and they all step forward 

one step for each depression of a key on the 

key~board I, if these wheels are initially aligned 

at a bench mark so as to correspond to a cipher 

key, this initial alignment will recur ·only after 70 

lOOx99x97x9lx89 or 7,777,469,700 letters have 

been enciphered (or deciphered) . Thus a cipher 

key of great length is made available for cryptographic purposes. 

The translator 6 is an instrumentality· well 75 
REF ID:A41M577 

"119" 

2,139,676 3 

known· in the art of printing telegraphy. It con- sists· of. a· set of five translator bars 61 to 65 which 

are ·normally held in position by the retractile 

springs 56 to 60. The translator bars are slotted 

5 according to the requirements of the Baudot or 5"~iinit printing telegraph code, so that 32 dif-. 

. ferent alignments of slots may be presented to a set .of. 32 stunt bars labeled 66. Orily one stunt 

bar, can drop into a specific alignment of slots 

10 and when this occurs a contact associated with 

the selected stunt bar is. closed. Several of these 

contacts "are shown at 61, it being obvious that 

there .are .32 ·such contacts in all. These contacts 67 are ·connected to conductors 68 which. 

rn lead ·to the set of 32 teTminals 69 of switch-

' board l. : . It will ,now become clear that the cam-wheel 

cipher-key mechanism 5 serves merely· to select 

one out .of 32 circuits· leading to the terminals 69 

20 of switchboard l and that this selection, being 

quite va:riable and depending upon the successive 

permutations set up by the cam-wheel mechanism 

5, .thus produces a long,:variable sequence of keying,.:circu~ts corresponding to keying characters 

25. and' hereinafter referred to as the keying sequence:· ; : .. -:The: 32. terminals .-69 .of switchboard l are con- nected· to·a corresponding number of flexible conductors 70, and the latter terminate Jn jacks, 

30: which,:·may be inserted into plugs l I connected to 

terminals 72 on the other side of switch l. There 

are·b.lJ.t.26 sl,lch plugs ll and each of them has a pair 

of. holes for receiving jacks, but only six of these 

double-hole plugs will have both holes occupied 

35 by ja(!ks. By this arrangement the 32 possible 

resultant keying circuits set up by translator 6 are 

reduced. to. 26, of which six will be "double-effects", that is, in six cases the same keying character may be brought about by two different 

40. Baudot permutations set up by the translator 6. 

Which six keying circuits these will be depends 

upon the way in which the flexible conductors 70 a:re connected to plugs 71 at any given time. It 

wfo be seen later that no ambiguity is occasioned 

4'"· by the presepce of a keying circuit which is of the 0 double~effect type. : , . • .Still .referring .to Fig. 1,. the electric:;tl circuit 

for'., c1;y.ptographtc fmictioning will now be described. it will be seen that the circuit from , power .source 18 to the keyboard I !!lust pass 50· through contact 19, which is controlled by main 

relay ,8. Hence, depression of any key. of keyboard I during the time contact 19 remains .open 

will produce no effect since no power is being de-

. livered to the key board I and hence no circuit to 55' the bank of indicating devices 2 is established. 

Let'us see now upon· what circumstance closure of 

cou'tiict 19 depends; . in other words, let us see when. inain relay 8 will .be energized. Let us con601 sider ;a specific operating cycle x in the long se- quence of operating.cycles n. During this operating.cycle brush arm 16 of distributor 4 wm make 

a complete revolution and a corresponding complete revolution of the cipher commutator or 

651 rpto.r 3, will take place. This operating cycle x may be regarded as being divided up into 26 equa'l 

time-intervals of very short duration, each corresponding 'to a specific angular position of the 

brush arm 16 and of rotor 3 in the circumferences 

7o: through which these two elements are in motion. 

The circuit for relay 8 includes brush 73, brush 

arm 16, and one of the 26 segments 15 of distributor 4. Which of the 26 segments 15 of distributor 

4 · will be "alive", that is, connected to power 

75.' S()ur.ce .20 during operating cycle :i; c;lepe11ds μpon 

the wiring·at switchboard l and·upon the particular .contact of the set of 32 contacts 6 l which happens to. be closed during operating cycle x. The 

latter depends l1POn the specific permutation of 

operated. and non-operated translator bars 61 tQ 5 

65 of translator 6, and this depends in turn upon 

the specific position and composition (as regards 

cams) of the cam~wheel cipher-key mechanism 5. 

Let us. assume that during this specific operating 

cycle x the segment designated 74 in Fig. 1 is the 10 

one ·which is. "alive". A circuit is completed as follows: power source 20, conductor 15, main relay 

8, conductor 16, armature 11 and back contact 

18 of relay 9, conductor 79, brush arm 16 and 

~rush 73 of distributor 4; the brush then being 15 

on segment. 74 the current continues through 

segment 74, conductor 80, to one of the contacts 

l2 of ·switchboard l, and thence through the 

switchboard· along one of the flexible conductors 

10 to ,one of the· contacts 69. on the other side of 20 

the switchboard, thence along one of the conductors 68· . .to that one of the contacts 67 which 

is closed by the selected stunt bar 66 of translator 

6, finally along common ·return conductor 81, 

back to power source 20. Relay 8 is energized at 211 

the instant .that brush 73 is passing over live segment .74, and since rotor 3 revolves synchronously 

with brush arm 16, the angular position of rotor 

3 with respect to its stators 13 and 14 corresponds 

to· the angular position of brush arm 16 at that· 80 

instant... The cipher resultant prbdur:ed · by depressing .a key qn key.,board I will be determined 

by the angular position of rotor 3: The reason for 

this is that since rotor 3 has 26 Ciphering positions each yielding a· completely different set of 35 

cipher resultants for the 26 character keys.of keyboard J, the specific cipher resultant for a specific 

keyboard character enciphered within a specific 

operating cycle x depends upon the specific segment of distributor 4 which is alive during .that 40 

cycle .. 

The circuit thro11gh the keyboard I, the rotor 

3 and the bank of indicating devices 2 will now be 

described. When a· key I 0 corresponding to the 

letter ·"E" is depressed during operating cycle x, '5 

nothing happens until brush 73 reaches segment 

14 of distributor 4, for the keyboard remains 

"dead" until that moment. The instant that re- lay 8 is energized, current is delivered from power 

source 18 through closed contact 1.9 and armature· 50 8~ of relay 8, a}ong conductor 83 to the contacts 

of keyboard I. Since contact I 0 is closed, the 

current continues along conductor 84 to a contact on st;:itor J3, thence through the rotor 3, which is 

;i.t that instant 1n an angular position correspond- 55 

ing to that .of brush arm 16, to a contact 86 on 

right.stator 14, thence along conductor 87 to indicating device or solenoid 88, which corresponds 

<in this fjgure) to letter "Q" thence along conductor 90 · torough slow acting relay 9, finally 60 

along conductor 9 I back to power source 18. 

So!en9id 88 is .actuated <or if lamps are used a 

I.a.mp Js lighted). to indicate the cipher resultant 

".Q" for p}aip.-text letter "E". . · 

When s}9w.,acting relay 9 is energized the cir- 65 

cuit for main rel11,y 8 is broken at 78 when armature 11 ·is witlicirnwn. A mechanically controlled 

trip 92 engages lever 11 and holds it away from 

contact 78 until tbe universal bar on keyboard I 

returQ!> to normal when the key is released, 70 

w.he.reupop )ever 11 is allowed to fall back and 

close 18, The purpose of this arrangement is to 

i.nsure :tnat npt more than one letter will be in .. 

dicated .or printed per operating cycle, that is, 

per depression of a key on the ·keyboard. 'l5. 
REF ID:A41615i1l 

4 

When the universal · bar on .. the ·keyboard I 

reaches the end of its downward stroke it:·c1oses 

contact 39, which controls the' circuit to· magnets 

37 and 38. Rocker arm 36 is operated, causing 

ii pawls 3 I to 35 to engage· ratchets 26• to' 30 and 

advancing cam-bearing· wheels 21·.to 25 one step 

forward to tne .next position, setting·.up ·a new Baudot permutation of contact~levers 41 . to, 45, associated contacts 14 I to I 45, and magnets 51 to 55; 

10 A new keying character is thus··established by 

translater 6 and the system is now ready for the 

next operating cycle. Even if the same.·key is de-' 

pressed on the keyboard the equivalent produced 

at the bank of indicating devices will be different, 

15 unless the keying character happens accidentally 

to be the same as before. Continued :depression 

of the same key will produce a varying sequence 

of equivalents corresponding in lerigth with·the 

length of the keying sequence. prodticed"'by the 

20 cam-wheel mechanism 5. This latter sequence is 

of great length, as· has already 'been··explained, 

being the resultant of the interaction of· five 

wheels of different·diameters with different mim'-. 

bers of .teeth, these numbers being· prime. to one 25 another. . , . . . : . r. · 

Since the connections within 'the' rot01:'··3 are 

reciprocal in pairs, as explained, the-· dedpherment of a message takes place by resetting· the 

wheels of cam-wheel ·mechanism. 5 to the initial 

30 key position; and· operating the keyboard - I' tO' 

correspond with the cipher letters, whereupon 

the plain-text equivalents will be produced at the 

bank of indicating devices 2. · 

The mechanism shown in Fig. l' and described 

.35 in the foregoing terms is such, however, that if 

several messages are enciphered by the same keying sequence they will be in the same series of 

'cipher alphabets, and in this case there exists a possibility of a solution by cryptanalytic· proce40 dure. To explain what is meant by· these statements it is necessary to call attention to the ·fact 

that the cipher commutator 3 provides· a set of 26 

cipher alphabets and that basically the cryptographic principle of the systein as describ'ed is one. 

45 in which the individual alphabets of this set of 26 

cipher alphabets are brought into play in an order . 

determined by the keying sequence .set up by the 

cam-wheels. For example, suppose we consider· 

this keying sequence to be such that for a given 

50 key as set up on the cam~wheels .the first 20 alphabets to be brought into play are alphabet 

numbers 16, 4, 19, 26, 15, 3, 18, 21, 12,6, I, 18, 22; 

1, 13, 17, 26, 2, 18, 24. Now.if several:messages· 

start with the same initial cam-'wheel setting, the 

55 successive letters of all these messages will be in 

the same sequence of cipher alphabets, arid therefore the several messages may be superimposed, 

yielding columns of letters which are monoalphabetic in composition. Or, even if the messages do 

60 not start at exactly the same point. in the keying 

sequence, but portions of these messages overlap 

one another with respect to the keying sequence,· 

then the overlapping portions which ·are in the 

same alphabets, may be superimposed. For exarii65 pie, using the same sequence of alphabet numbers 

mentioned above,. suppose ·a first message begins 

with alphabet number 16, a second message, with 

alphabet II, a third· one, with alphabet 19, and so 

on, it is merely necessary to shift the s·econd mes70 sage oi1e letter to the right of the first, shift the 

third message one letter to the right of the second; 

and then all three messages will be properly superimposed with respect" to the keying sequence; the 

letters in columns are now in the same cipher al75 phabets, and tl~e messages are susceptible of solu-

'191" 

tion, by monoalphabetic principles. The proper 

points fO-r·superimposition can be ascertained even 

without a knowledge of the particular key settings 

for these three messages, from a detailed study of 

the .repetitions between messages. It is necessary, 5 

therefore, .in order to circumvent. this possibility 

of superimposing messages or parts thereof so that 

they will be in the same keying sequence, to impart 

a cryptographic uniqueness to the messages so as 

to destroy, mask, or. suppress repetitions brought 10 

about by the chance encipherment of identical 

words by. identical sequences of alphabets. 

-. Mechanism for accomplishing this is shown in 

Fig: :2! Here the shaft I 21 carries several cipher 

commutators 'or rotors, 3a, 3b, 3c, 3d, and 3e. 15 ' 

These rotors are separated from one another by 

stators 122, 123, 124, 125, each carrying rings of 

contacts on both faces, to provide for continuity of 

Circuit from one rotor into the next. The contacts 

in these stators, as are those in stators I 3 and 14, 20 

already described, are ball-bearing spring contacts· and ·they press· against the rotors so as to· 

hold1 each rotor -in place, and keep "it from rotating. on the· shaft I 2. except· when rotatory motion 

is imparted to it by means· to be described .. · The" 25 

periphery of each rotor 3a to 3e bears a collar 215 

in·which 26fgear. teeth have been cut so as to engage vHth gear wheels 213 and 2 I 4 which are mounted ·on shaft I 2, the latter now correspond:. 

·ingtoshaft 12ofFig.1. Gearwheels213and214 30 

can l:ie independently slid sidewise along the shaft· 

!:! and keyed into pos\tion on the shaft; by means: not shown, so as to engage the toothed collars of 

any two of the five rotors 3a to 3e, at the will of 

the operator. Gear wheels 2 I 3 and 2 I 4 have 26 35 

teeth and their pitch is the same as· those on the 

collars:of rotors 3<i and 3e, so that the motion imparted to' a· rotor by wheel 2 I 3 or wheel 214 is a 

1 :·1 drive. The shaft I 2 is rotated by motor 93, as 

in Fig. 1; the distributor 4 of Fig. 2 is the distribu- 40 

tor simUarly numbered in Fig. 1, with the bri.tsh 

arm 16 and brush 13. Thlis, instead of driving one rotor 3, as in Fig. 1, the motor 93 and shaft 12 may 

drive any two of' the five different rotors 3a to 3e. 

The function of the ·distributor 4 and brush arm 45 

I 6, is now the same as described in connectiOn 

. with Fig. 1, but the rotor that will be associated 

with these elements is now slisceptible of variability. 

The,;rotors 3a to 3e are to be set to a key, by· 50 

alignif!.g the letters on their . peripheries at a 

bench· mark. Since there are 26 individual rota~ofy'positions of each rotor on the shaft, there are 265 . different_ ii;iitial settings of these ·rotors, 

each s:uch ·s'etting providing a different set of 26 55 

paths· for the passage of electric currents from 

the"ke:Yboard I to the bank o'f electro-magnets 2. 

The ·drcuits from tlie keyboard I through the 

set. of rotors 3a-e to the bank of solenoids 2 :are 

shown diagrammatically in Ffg. 3. In this figure 60 

stators -13 'and." ,14. and rotors 3a to 3e correspond 

to the similarly designated stators and rotors of 

Fig. 2. The internal wirings of rotors 3a, 3b, 3c; 

arid· 3d are. not reciprocal in pairs, as is the case 

with the single rotor 3 of Fig. 1, but are all ran- 65. 

dom' connections. The rotor 3e is, however, different in its construction from the· other rotors, 

in that it has a ring of contacts on only one face· 

and these contacts are interconnected in pairs. 

Thus rotor 3e serves as a means for reversing a 70 

current coming into the set of rotors from a con- tact in stator I 3, passing through rotors 3a, 3b, 

3c, 3d, and sending it back through rotors 3d, 3c, 

3b, 3a to another contact in sta.tor I 3. Stator 

14 now serves no 'electrical function but merely 75' 
REF ID:A41ii577 

.._, 

2,i39,676 5 

as a .tnechanical bearing against which rotor 3e 

presses. ·Relay 8, contact 19, armature 82, and 

battery 18 correspond to similarly designated elements of Fig. 1. The keys of the keyboard I now 

5 serve a double function instead of a single function· as in Fig. 1. Each key operates a lever 

which opens one contact and closes another. For 

instance, when the E key is depressed contact le-: ver I 0 is withdrawn from contact 111 and makes' 

IO contact at 112. When relay 8 is energized a cur-. 

rent flows from battery 18, along conductor 83;. 

contact 112, lever 10, conductor 85 to a contact; 

115 in stator 13, thence through the rotors and 

back to another contact 116 in stator 13 thence~ 

15 along conductor 84, lever 11-, contact I 13, solenoid· 

"Q", back to battery 18. Solenoid "Q" is actu-• 

ated and the cipher resultant of E is Q. In .deciphering, assuming that the rotors are in the 

identical position they were in when enciphering 

20 (the cipher key being the same), on depressing 

the Q key of the keyboard it will be seen that 

the following reciprocal deciphering circuit is es-, 

tablished: Battery 18, conductor 83, contact 114, 

lever 1.1, conductor 84, contact 116 in stator 13, 

25· through and back through the rotors to contact 

115, conductor 85, lever I 0, contact 111, solenoid 

'.'E", back to battery. Thus, the pla.in-text resultant of Q is E. In this manner a reciprocal 

enciphering-deciphering relationship is readily 

30 established. · We will now consider the cryptographic operation of the system after the introduction of the 

foregoing features. The ·key for a message will 

now co.nsist of the following elements: 

35, (1) The composition of the cam wheels, (that 

is, the positions of the cams on the wheels) and 

their initial setting or alignment at a bench 

mark; the connections at switchboard l. 

(2) The composition of the rotors, that is their 

40 internal wiring; the relative order of rotors 3a, 

3b; 3c and 3d on the shaft, and the initial setting 

or alignment of all the rotors at a bench mark. · (3) The rotors which are selected for engagement with gear wheels 213 and 214. 

It becomes obvious that even if two messages 45 are identical, letter for letter, even if they begin 

at exactly the same point in the keying sequence 

produced by the cam wheel assembly, and even if 

gear wheel 213 is engaged with th~ same rotor, so long as the setting of the rotors '3a to 3e on 50. shaft 121 is different by at least one letter for 

'these two messages, or so long as either of gear 

wheels 213. and 214 is set to drive different rotors, 

the cipher texts will be different and externally 

there will be no sign of the internal identity of 55· the two texts. Furthermore, there is nothing to 

prevent there being three gear wheels similar to 

213 instead of only two, as shown in Fig. 2, in 

which case three of the five rotors can be dliven. . And, of course, if there were say 10 rotors it would 60 ·be possible to have any number up to 9 of such 

driving· gear wheels, thus affording a very wide 

range for keying purposes. In other words, as 

now. fully developed, the system provides for a 

. multiplicity of keys, such t.hat a uniqueness may 

65• be imparted to messages even in the same cam 

wheel keying sequence, with a correspondingly 

high degree of cryptographic security. 

·The translator mechanism 6 in Fig. 1 may be 

replaced by a system of interconnected contact70, levers 96, and associated paired contacts shown 

schematically in Fig. 4. In the latter figure, the 

contact levers 41· to 45 and the magnets 51 to 55 

are homologous with similarly designated contact 

levers and magnets of Fig. 1 and ser-ve the same 

7r,;· function; the bars 61 to 65 of Fig. 4 are homologous with similarly designated bars of Fig. 1 and 

serve an equivalent function, viz., to set up, by 

permuative arrangements of actuated and non- actuated bars, permutative arrangements of contact-levers operating switches to establish .. one of 5 

32 different circuits to the terminals of switchboard l. · It will be seen that permutative arrangements of the. contact-levers as to the left or right positions will result in selecting one of 32 

paths for a current flowing from power source 20 to 

to the switchboard l. The magnets 51 to 55 and 

their associated bars 61 to 65 may-be replaced· 

by multiple-contact . relays well known in the 

art. 

Changes, modifications and equivalen~ · ar- 15 

rangements are contemplated within the ~c_ope 

of the invention as defined by the appei;ided 

claims. 

I claim: 

1. In a cryptograph, a keyboard comprising a 20 

set of character elements, and a corresponding 

set of signaling elements in operative electrical 

connection; means including a cipher rotor 

mechanism for varying the connections between 

the character elements and the signaling ele~ 25 

ments, said mechanism having a multiplicity of 

potential ciphering positions and being . driven 

sequentially and repetitively at a uniform angular 

velocity through all said _positions, each complete revolution of said rotor mechanism consti- ao 

tuting a ciphering cycle and each said ciphering 

cycle corresponding to: the time during which a key of the keyboard is depressed; and means for 

selecting one of said potential ciphering positions to become the operative ciphering position 35 

within a ciphering cycle. . 

2. In a cryptogJ.'.aph, a keyboard comprising a 

-. set of character elements, and a corresponding 

set of signaling elements in operative electrical 

connection; a cipher rotor mechanism for vary~ 4Q 

ing the connections between the . character ele-. 

merits and the signaling elements, said rotor 

mechanism having a multiplicity of potential 

ciphering positions and being driven sequentially 

and repetitively at a uniform angular velocity 45. through all said positions, each complete revolution of said rotor mechanism constituting a ciphering cycle and each said ciphering cycle 

corresponding to the time during which a key 

of the keyboard is depressed; means for select- 50: 

ing one of said potential ciphering positions· to 

become the operating ciphering position within a ciphering cycle; and means for ·varying the 

selection with successive ciphering .cycles, the 

latter corresponding to successive depressions 55; 

of the keys of the keyboard. 

3. In a cryptograph, a keyboard comprising a 

set of character elements and corresponding. 

contacts electrically associated therewith; .an 

indicating mechanism comprising a set of signal- 60, 

ing ·elements corresponding in number with the 

number of character elements and in circuit relation therewith; means for establishing and 

varying the electrical connections between thecharacter elements. and the signaling elements, 65, 

said means including a cipher rotor having therein a set of insulated conductors, said rotor being 

capable of assuming a multiplicity of potential 

ciphering positions; means for driVing said rotor 

sequentially and repetitively at a uniform. angu- '1'01 

lar velocity through all said ciphering positions; 

each complete revolution of said rotor constituting a ciphering cycle and each said ciphering 

cycle corresponding to the time a key of the keyboard is depressed; means for selecting one· of ?5; 
REF ID:A4161581 .... 

6 2,139,6.76 

said potential ciphering positions to become the 

operative ciphering position ·within a· ciphering 

cycle, said means comprising a distributor mechanism· and a brush timed to revolve about the 

5 face of said distributor synchronously with said 

rotor; a circuit including a relay, which when 

actuated connects the keyboard for operation, 

said relay being controlled through said circuit 

in which is included the brush of said distributor 

10 :mechanism; a translator, . and contacts closed 

by said translator; a set of cam wheels for controlling said ·translator; ·and means .for angularly displacing the respective cam wheels of 

said set with successive depressions of the keys 

15 of the keyboard. ' 

4. In a cryptogi·aph, a keyboard ·comprising a 

set bf character elements; an indicating mechanism comprising a set of signaling elements, 

both sets of elements being in circuit relation; a 

20 cipher rotor for establishing a multiplicity of 

connections between the character elements and 

the signaling elements; means for driving said 

rotor sequentially and repetitively through the 

entire series of such connections, the time re25 quired for the rotor to pass through said series 

of connections corresponding to an operating 

cycle; a distributor the face of which is divided 

up into insulated segments· corresponding in 

number with the number of character elements, 

30 and having a brush sweeping said segments synchronously with the rotor;· a cam wheel mechanism for establishing a cipher key;· a translator 

mechanism for combining the effects of said cam 

wheel mechanism; a switchboard for reducing 

35 the said effects to a number corresponding with 

the number. of character elements;· a source of 

potential; and a relay controlled by the cam 

wheel mechanism through the intermediacy of 

said translator mechanism and distributor for 

40 the purpose of connecting the keyboard to said 

source at a selected instant within the operating 

cycle. 

5. In a cryptograph, a keyboard comprising 

character elements, an indicating mechanism 

45 comprising signaling elements, and a cipher rotor 

for establishing and automatically, rhythmically, 

and sequentially varying the connections between the character elements and· the signaling· 

elements; means for selecting one of a set of 

50 said connections during the time a key of the 

keyboard is depressed; and means for varying 

the selection with successive depressions of the 

keys of the keyboard. 

6. In a cryptograph, a cam-wheel mechanism 

55 for establishing a cipher key sequence consisting 

of permutations of a plural-uriit code; and 

means for translating the permutations set up in 

·said code by said cam-wheel mechanism into a 

limited number of single-unit keying characters.· 

60 7. In a cryptograph, a cam-wheel mechanism 

for establishing a cipher key sequence consisting· 

of permutations of a plural-unit code; ·means 

for translating the permutations set up· in said 

code by said cam-wheel mechanism into a lim65 ited number of single-unit keying characters; 

and a switchboard for reducing said· keying characters to a smaller number. · 

8. In a cryptogr.aph which employs a translator· 

assembly having permutation bars and·stunt bars 

10: in operative electrical connection; means for 

producing a relatively long cipher key sequence· 

composed of single-unit keying characters said. 

means including a. cam-wheel mechanis~ for 

controlling said permutation bars; a set of con75 ·tacts coq.troll~d by said stunt bars; al)d .a. di_s.:-~ 

tributor provided with segments which are in 

electrical connection with said contacts. '; 

9. In a cryptograph, which employs a translator 

assembly having permutation bars and stunt bars 

in operative electrical connection; means. :for 5 

producing a relatively long cipher key· sequence 

composed of single-unit keying. characters, ·said 

means including a ·cam-wheel mechanism 'for 

controlling the permutation bars of said translator; a set of contacts cori.trolled by the stunt '10 

bars of said translator; a circuit including· a 

switch board; and a .distributor, the segments 

of which are connected to said contacts through 

said ·switchboard for reducing the number of 

effects obtainable from the.translator-to the num- rn 

ber of segments on the distributor. 

10. In a cryptograph which employs a translator assembly including permutation bars and 

stunt bars in operative circuit arrangement; · 

means for producing a relatively long cipher key 20 

sequence, said means comprising a cam wheel 

mechanism for. controlling. said permutation·· 

bars;· a set of contacts controlled by said stunt 

bars; a switchboard;· and a distributor 'having 

segments in electrical connection with ·said con- 25 

tacts through said switchboard adapted·to reduce 

the number of effects obtainable from said trans.:.· 

· la tor to the number of segments on. the· distrib'-· 

utor; and to· vary the connections between th·e 

contacts of the translator and the segments· of 30 

the distributor. · ' ':· 

11. In a cryptograph, a keyboard compriSing a 

sef of character elements; a· corresponding set of 

signaling elements, both sets of denients' being 

in operative electrical connection; a set of ro- 35 

tatable ·ciphering comm·utators for. varying ·the 

. connections between the character elements and 

the signaling elements, each of said commutators 

having ·a multiplicity ·af potential Ciphering positions; mearis for selecting one or· more of said' 40 

commutators . to function . as . rotors;. means for· 

driving ·said selected rotor or rotors sequentially 

and repetitively at a uniform· angular velocity 

through all of their potential ciphering positions;· 

each complete revolution of said selected rotor or 45. 

rotors constituting a ciphering cycle/ and each 

said ciphering cycle corresponding to ·the time 

during which a key of the keyboard iS depressed; 

and . means for seleCting one· of said potential 

ciphering positions to become the operative 50 ciphering position in said ciphering cycle. 

12. In a cryptograph, a keyboai·d. comprising a 

set of character elements; a corresponding set of 

sfgnaling elements, both sets of elements' oeing 

in operative electrical connection; a set ·of ro-· 55. 

tatable ciphering commutators for· varying the 

connections between the character elements and· 

the signaling elements, each o(said commutatcn:s'. 

having a multiplicity of potential ciphering positions; means for selectively operating one or. 60, 

more of said commutators as· rotors, inCluding 

means for driving the' .same sequentially and> 

repetitively at a uniform angular.velocity through 

all of their potential. ciphering positions each: 

complete revolution ·of sai9. sele,cte4 .· roto,r: br. 65l 

rotors constituting a ciphering· cycle .and each 

said ciphering cycle corresponding ·i;o the .. time. 

during which a key of the keyboard is depressed; 

means for seiecting one of said pot~ntial cipherfog. 

positions to become the operative ciphering posi7. 7:0;' 

tion in said ciphering cycle; and means for vary;'" 

ing the sel~ction of said potential· ciphering posi:-

tion with successive ciphering cycles ... : . · . · 

13. In a cryptograph, a keyboard comprising. a'. 

Set 9f cJ;lantcter elements and a co.rre§pOndJ~~· s~t· 7fl~ 
,\ 

,, 

' 

REF ID:A41il\577 

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2,189,676 7 

of contacts electrically associated therewith; an indicating mechanism associated with the keyboard and comprising a set of signaling elements 

corresponding in number with the number of 

5 character elements of the keyboard; a circuit system including said sets. of elements and a source of potential; means for automatically, rhythmically, and sequentially establishing a multiplicity 

of sets of different paths for the passage of elec10 tric currents from the contacts of the keyboard 

to the signaling elements of the indicating mechanism; means for momentarily selecting one of 

said sets of paths and simultaneously connecting 

the common terminal of the set of contacts ·of 

15 the keyboard to said source so that an electric 

current initiated by depressing one of the keys 

of the keyboard will flow along one of the paths 

in said selected set of paths to one of the signaling 

elements of the indicating mechanism; and 

20 means for varying said momentary selection of a set of said paths with successive depressions of 

the keys of the keyboard. 

14. In a cryptograph, a keyboard comprising a set of character elements and a correspondfog 

25 set of contacts electrically associated with the 

character elements; an indicating mechariism 

associated with said keyboard and comprising a corresponding set of signaling elements; multiple 

sets of electric conductors, and means for rhyth30 mically and sequentially interposing said con- ductors between said keyboard and said indicating mechanism; means for selecting one of said 

sets of conductors and establishing operative 

electrical connections between the contacts of 

35 said keyboard and the signaling elements of said 

indicating mechanism; and means for varying 

said selection irregularly and .with successive 

depressions of the keys of said keyboard. 

15. In a cryptograph, a keyboara comprising 

40 ·character elements; a corresponding set of signaling elements in a potentially operative electrical connection with the keyboard; means com- prising a rotatable commutator for varying the 

connections between the keyboard elements and 

45 the signaling elements; a motor to rotate the 

commutator at a constant speed, each complete 

revolution of the commutator comprising one operating cycle during which the keyboard may 

be operated in enciphering or deciphering; a . 50 cam-wheel mechanism comprising a set of cam- bearing rotatable members; means for angularly 

displacing the cam-bearing members upon operation of the keyboard; a set of contact levers and 

associated contacts controlled by the cam-wheel 

55 mechanism; a translator mechanism controlled 

by the cam-wheel mechanism for combining the 

effects of the cam-controlled contacts and caus- ing the selection of one of a plurality of cipherkeying circuits; a switchboard for reducing the 

60 plurality of cipher-keying circuits to a number 

of circuits corresponding with the number of 

character elements of the keyboard; a· distributor 

comprising a plurality of insulated segments 

corresponding in number with the number of 

character elements of the keyboard and con- nected to one side of the switchboard; a brush arm carrying a brush which sweeps over the 

segments of the distributor, the brush arm being 5 

keyed to the same shaft on. which the commu- tator is rotated so that the commutator and the 

brush on the distributor face rotate synchronously; and a relay controlled by said distributor 

for connecting the keyboard to a power source · IO 

for a specific instant in the operating cycle, said 

instant being determined by the cipher-key com- bination established by the cam-wheel mechanism. 

16. In a cryptograph, a keyboard comprising a 15 

set of character elements with associated con- tacts; an indicating mechanism electrically as- sociated with the keyboard and comprising a corresponding set of signaling elements; means for connecting the contacts with the signaling 20 

elements and for varying said connections se- quentially and rhythmically in a multiplicity of · ways, said means comprising stators and including ciphering rotors which are interposed between pairs of said stators and which have a 25 

multiplicity of potentially-operative ciphering 

positions with respect to said stators; a shaft 

carrying said rotors; means for rotating one or more of said rotors at a constant angular ve- locity; means for momentarily connecting the 30 common terminal of the contacts of the keyboard 

in circuit relation when said selected rotors have 

reached a selected ciphering position, thus caus- ing the selected ciphering position of the rotors 

to act as the operative ciphering position; and 35 means for varying the selection of the driven ro- tors and of their operative ciphering position 

with successive depressions of the keys of the 

keyboard. 

17. In a cryptograph including a keyboard 40 comprising a set of character elements and a corresponding set of signaling elements; a circuit system including a source of potential: means for connecting the keyboard to said source for the purpose of establishing operative elec- 45 trical connection between the keyboard and the 

signaling elements, said means being actuated 

only during a specific time-interval within a set 

of equal time-intervals into which each cycle of 

keyboard operation is divisible. 50 18. In a cryptograph including a keyboard 

comprising a set of character elements and a corresponding set of signaling elements; a circuit 

system including a source of potential; means for connecting the keyboard to said source for 55 the purpose of establishing operative electrical 

connection between the keyboard and the signaling elements, said means being actuated only 

during a specific time-interval within a set of 

equal time-intervals into which each cycle of 60 

keyboard operation is diVisible; and means for 

changing the successive actuating time-intervals. 

wn,L!AM F, FRIEDMAN. 
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REF ID:A4161~ 

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W. F. FRIEDMAN 

CRYPTOGRAPHIC APPARATUS 

Filed Aug. 4, 1937 

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REF ID:A4161577 

Patented July 18, 1939 :·· ~ ,- ' 

2,1~~,137 

·.'· .fj 

U.NITED ST ATES PATENT OFFICE 

2,166,137 

. l.· 

.. · I ' . .: ~-;,.. -: i: 

ELECTRICAL SWITCHING MECHANISM 

William F. Friedman, Washington, D. C., and 

·Frank B. Rowlett, East Falls Church, Va. 

·• : r :.J; ~ . ') ' • j i• I l • f . .- ' Application August 19, 1935, Serial No. 36,868 

10 Claims. (Cl. 200-17) ; ... (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. _G. 757) 

r·' The inventicin described herein may be manu-

· :factured and used by or for the Government for 

. ·governmental _purposes, without the payment to 

'us of·any royalty thereon. 

15 · '·_Th.ls invention relates to a switching mecha-

· fosni· and proposes a mechanism of this character 

for automatically establishing and/or varying circuit connections in a random order. 

As. distlnguished from the idea of performing 

· 10 · switching operations in an orderly sequence, the 

present invention contemplates an opposite func-

• tiOn arid provides means to vary the circuit con- ·nections -in an Irregular, aperiodic or fortuitous 

manner. The inve.ntion contemplates an opera15 ti6n which affords opportunity for the" laws of · probability to function in establishing the variation in circuit connections, rather than an opera-

. tion controlled by the usual laws of direct cause and effect. . - An object of this invention is to 

· 20 :Provide a· means of selecting from a plUrality of 

. available electrical circuits a single circuit at 

random, which electrical circuit will- be o'perative . :for a period 'oi time, the length of which ;depends 

.upon one or several variable factors. · 25' : · ;Another object of this invention is to provide 

- apparatus for varying the speed of rotating bodies 

by means of a friction drive mechanism working 

in conjunction with cam wheels of irregular outline and operatively coordinated with a differ30 ential gearing system for the purpose_ of opening 

and closing eleCtrical circuits for varying periods 

of time. 

A further object of the invention is to provide a de-vice- in the nature of a fortuitously-operated 

-35 device for selecting from a large assortment of 

punched cards, a randoni sample. . 

· A further object of the invention is to provide a . devic-e ·in the nature· of a scrambling device for 

_-'3:rrapgln\i in ~ purely random sequence, a large 

40 number _of punched cards originally arranged according to a definite sequence, such as an alphabetical or numerical sequence. For example, in 

the well-known'_ card-s-orting machines employed 

in' accounting or statistical work, the function of 

. 45 -the machine is to arrange a large number of 

punched cards in a· sequential order, such as al-

. pfiitbeticai or numerical. In certain types of op-

. eratiOns with punched cards it is often necessary 

to disarrange the cards so as to destroy the origi-

·. 50 nal sequential order and bring the cards into a 

purely random order. However, once a large 

number of cards· has been sequentially arranged, 

any attempts to destroy the arrangement by 

shuffling the cards would be extremely tedious and 

55 many cards would be damaged. In the present 

· invention, . the device if operated in connection 

with an, ordinary card-sorting machine, would 

permit of placing a sequentially-ordered batch of 

cards iri the machine and taking out of it a purely 

fortuitously-ordered batch of cards. • 5 

In order that the invention anci. its mode of 

application may be readily understood, there is 

disclosed in the accompanying drawing and in 

the detailed following description thereof, one form or 'embodiment of the invention. · 1110 

In the drawing, the single figure shows in schematic form an apparatus for carrying out the 

invention.'- . 

Referring to the drawing, I is a gear, driven 

by any pri_:μie mover such as a motor M; gear I :·15 

meshes with the two gears 2 and 2', having different numbers of teeth. Gear 2 is fixed to shaft 3 

and drives the worm gear 4, which in turn, 

through the train of gears 5, 6, 1, drives shaft 8, 

on which is mounted cam 9 of irregular outline. •-20 · Roller I 0 rides on the periphery of cam 9 and 

serves to move lever 11, through a succession of 

angles which are determined by t.he depressions 

and ·elevations of cam 9. The free end of lever 

11 is connected by a piri _ 12 to a collar 13 which '-25 

is free to slide up and down on shaft 3 but is 

independent of the latter in its rotation. The 

upper end of collar 13 presses against disk 14, 

which is also mounted on shaft 3 but, by_ a slot 

and bar arrangement, is driven by shaft 3. ·'30 

Spring 15 serves to keen the assembly 12, 13, and . 

14 in place ori the shaft 3 and also to cause the 

roller I 0 to follow the. outline of cam 9. Disk 

14, by frictional effect, drives.wheel 16, keyed to 

shaft I l so that as shaft· 3 turns disk · i 4 turns ~35 

and slides up and down against the face of wheel 

. 16, causing shaft 17 to rotate at continuously 

varying speeds as the roller I 0 rides on the periphery of cam 9. inherent in the mechanism 

here disclosed and as the result of such a friction r.«w · drive a slipping action is produced, which action 

- is aided by the sliding movement of disks 13 and. 

13' on the face of wheels 16 and 16', respectively. 

The cams 9·and 9' as well as the system of gearing 

previously described, contribute an important .-.4f:i 

part to this slipping action and consequent lost 

motion whereby the switching operation is performed in an- irregular, aperiodic or fortuitous 

'manner. This· constitutes_ an important _object 

of the invention all as fully set forth in the speci- · 50 

fication and shown !nthe drawing. On the shaft 

11 is mounted the commutator generally designated as 18 and a contact wheel 19, provided 

with a plurality of contacts 20, connected in a 

random manner to the commutator rings 21, 22, 55 
REF ID.:A4161577 

·2 2,166,137 ".·· 

23, 24, 25. Resting against the commutator rings irregular contours individually operable with 

are collectors 26, which are connected to con- said units. 

ductors 27 leading to individual circuits, which 4. A combination according , to claim 2, in 

circuits may include any conventional means or which the last named means includes cams of 

5 instrumentalities suggested, schematically as at different irregular contours. 5 

33 for utilizing the randomizing function of the 5. A switching mechanism comprising in compresent invention. bination, a rotatable commutator. provided with 

The action of the members 2 to I l inclusive contact elements and a rotatable conductor opis the same as that of the members 2' to 11'. erable with said elements for establishing a plu10 Shaft 11' rotates switch arm 30, carrying brush:· rality of circuit connections; independently vari- 10 

31 which sweeps over the contacts 20 as it rotates. able friction drives for operating said commuThe commutator assembly which essentially com- tator and said conductor respectively; and means prises commutator 18 and its associated parts, in- including differential gearing, and cams of ircluding contact wheel 19, may be· regarded as regular contours- operatively coordinated with 

15 one · component of a switching . device, while said gearing and individually with each of said 15 switch arm 30 carrying brush 31 maybe regarded drives-to vary the circuit connections aperiodias the other component of said switching device. cally. 

Brush 31 is connected to the common return 6. A randomizing switching mechanism of the 

conductor 32 for the circuits Ri, R2,' RJ, R4, R5 to character described; ·comprising a rotatable com20 which conductors 21 lead. Since wheel 19 and· mutator provided with a plurality of contact ele- 20 brush arm 30-rotate in- different .. directions .and ments and a rotatable conductor· operable -with 

at constantly varying speeds, the circuits Rr, R2, .. said ·elements for -establishing a plurality of .CirRJ, R4 and R5 are selected in the order ,of., the cuit connections;. and. means for. continuously 

contacts 20 on wheel 19, but 'each circuit' is op- and irregularly chan"ging, the .relati\\e.-speed of 

25 erative for a different interval of time. · said commutator .::md .said ,conduc~or" to .vary .

25 In the· drawing, specific mechanical principles . the .circuit connections aperiodically:, said means ' 

are shown for effecting the movements of the including a friction drive-operative with the'.conivarious parts of. the apparatus. ·However, these mutator and conductor individually, cams'..qf 

are shown only for the purpose of demonstration irregular contours operatively_ coordinated with 

30 of the principies incorporated in this invention, each drive, and gearing .for actuating. the cams! 30 and it·is pointed out that any other mechanical differentially. . .. 

means for varying the .angular velocity of ·the 7'. A. mechanism for controlling .the operation 

commutator 18 rotating with contact disk :19 and of an electrical system, .comprising relatively rothe contact arm· 30, either .separateiy .or con- tatable switchin,g. deV'ices ·provided with cooper-

~35 . jointly, will ·effect the result desired. It is also ating contact elements .for establishing a _plu- -35 

pointed out that, while five commutator'rings are rality of circuit connections; and means for .con-' 

depicted in the drawing,.any number may be, used, tinuously .and aperiodically varying the relattve 

and that the number of contacts on the face of speed of rotation of said switching devices, said 

the disk 19 may be equal to .the number of con- means comprising 9hange speed drives cindiVid40 tact rings or greater by .any practicable number. ually operative with .. said switching .devices,. in- (

40 It will also be noted that cams 9 and 9' are in- terchangeable -cams of different_ irregular -con- ' 

tended to be detachable and interchangeable, tours operative .with said drives, and a.differential means being shown in the drawing to .facilitate gearing system for.operating the cams 'and drives 

removal for that .purpose, or to pern1it. substitu- in opposing relation. . " 

45 tion of other cams of different shape. · - · 8. A mechanism of the character desc'riped, "

45 Changes, modifications .. and equivalent " ar- comprising switching components movable .tela- ·· rangements.are contemplated.within .the scope of .tive to each other and provided with .contacts 

the invention as defined by the appended claims. for establishing a plurality of circuit. connec- We claim: tions; and means including .continuously slipping 

50 1. .In a mechanism of the character .described, drive elements .and cams of irregular contours ,

50 · a pair of rotating bodies associated for operative operative. with each component for continuously · 

movement relative to one .another; friction drives and irregularly varying the timing of the. con- having a slipping action and arranged to actuate tacts in .a random manner .. 

said bodies in a discrete time· relation; and means 9. A switching device comprising .. components 

55 including a system .of differential gearing. and provided with .electrical. contacts, .said compo- -r.5 cams of irregular contours operatively coordi- nents being rotatable with respect. to each other "' 

nated with said gearing and with each of said .for establishing a plurality of circuit connections; 

drives individually to aid the slipping action arid a friction drive mechanism for each of said comto effect aperiodic movement of said bodies ,rela- · ponents, and including means for separately .and 

60 tive to .one another. · · . diffe~e~tially .oper~tin~ said me~hani_sms t.6 "vary 060 2. A mechanism of the character described for _the t1mmg of the c1rcmt connect10ns m a random· · contr.olling the ·operation of an electrical system, manner. 

comprising a rotatable commutator provided with 10. A switching mechanism, compnsmg relacontact elements .and a rotatable switching device tively movable components provided with con65 operable with said elements for establishing a . tacts for establishing a plurality of different . 

plurality of circuit .connections;. and.means to circuit.connections; means for varying the circuit"'65 

effect a random .operation .of said system .c.om- connections, comprising. frictional drive rriechprising variable driving units for operating· said . anisms operable variably with said .components; 

commutator and said switching. device asynchro- and means for changing t.he rate of movement 

70 nously, and means .for differentially controlling of said mechanisms to .assist in randomizing. the , the operation of.the ·Units. circuit controlling operation of the.contacts. 70 

.3. A combination according to claim 2, in WILLIAM F. FRIEDMAN. 

which the -last named means- includes cams of FRANK .B. ROWLETI'. 

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July 18, 1939. 

REF ID:A4161577 

W. F. FRIEDMAN ET AL 

ELECTRICAL SWITCHING MECHANISM 

Filed Aug. 19, 1935 

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2,166,137 

ATTORNISYS -

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REF ID:A4161577 

Patented Jan. 28, 1936 2 028 772 ' ' 

UNITED STATES PATENT OFFICE i 

2,028,772 

CRYPTOGRAPHIC SYSTEM 

William F. Friedman, Washington, D. C., and 

George A. Graham, Fort Monmouth, Oceanport, N . .J. 

Application .January 23, 1932, Serial No. 588,344 

34 Claims. (Cl. 35-4) 

(Granted under the act of March 3, 1883, as 

amended April 30, 1928; 370 O. G. 757) 

, . The invention described herein may be manu-1 

{ factured and used by or for the Government for 

' governmental purposes, without the payment to 1 us of any royalty thereon. .

5' This invention relates to cryptographic systems 

and an object of the invention is to provide a cryptograph for enciphering and deciphering 

messages automatically, rapidly and by a method 

which, being absolutely aperiodic, renders ·the 

10 cryptograms unsolvable without the key. 

A further object of this invention is the provision of a cryptograph controlled by means co- ordinated with a cipher-key transmitter through 

which is passed a key tape which serves as the 

15 keying element in the encipherment or decipherment of messages. 

A further object of this invention is the provision of a cryptograph, which, although em- ploying for its keying element a plural-unit-code 

2'.l of the Baudot type (a code of thirty-two permutations), nevertheless produces cryptograms the 

characters of which are restricted to the twenty- .1 six letters of the alphabet. In this respect the 

cryptograph excludes the usual six extra Baudot 2.~ characters, the transmission of which occasions 

much diffi.culty in ordinary telegraphy by the 

Morse alphabet. The way in which these six 

extra· characters are eliminated constitutes one · of the unique and important features of our in-

:lf> vention. 

A further object of this invention is to provide a cryptograph adapted to function either inde~ 

pendently as a self-contained cryptographic unit, or in conjunction with an independent typewriter ~-' having a standard. typewriter keyboard. In the 

first case, the cryptograph makes no permanent 

record of the message, but merely produces visual 

signals; in the second case, the cryptograph 

makes possible the production of a written record 

4G of the message. 

A further object of this invention is the provision of a cryptograph functioning at the transmitting end of a communication system as a 

means for directly controlling a telegraph trans-

.;.) mitter keyboard, so that the intelligence to be 

transmitted is automatically enciphered before 

transmission; and similarly, at the receiving end, a corresponding cryptograph functions as a 

means for indirectly controlling an ordinary 

~J typewriter so that the intelligence received in 

cryptographic form is deciphered before being 

typed by the typewriter. 

By way of an introductory statement to our 

invention, it may be said that in practically all 

05 the portable mechanical, electrical, or mechanico-electrical cryptographic devices or systems 

heretofore devised, the cryptographing and decryptographing of messages is entirely controlled 

by elements all embodied within the mechanism 

itself; that is, the basic or invariable elements 5 concerned in the cryptographic ·treatment, as well as the keying, or variable elements for controlling 

and cryptographic treatment are integral parts of 

the device or apparatus. In contradistinction to 

this situation, in our invention, only the basic, 10. 

or invariable elements concerned in the cryptographic treatment are integral parts of the mechanism, the keying, or variable elements being 

·wholly independent of .the mechanism itself, and 

consist of an extraneous factor which when prop- 15 

erly associated with the mechanism controls the · basic or invariable elements of the mechanism in 

cryptographing and decryptographing messages. 

In the accompanying drawings: 

Fig. 1 is a diagrammatic illustration of a mech- 20 

anism embodying the invention; 

Fig. 2 is a view in side elevation showing part 

of the commutator or connection changing device; 

Fig. 3. shows that part of the commutator 21S 

which carries the ratchet ·mechanism and also 

includes an illustration of the wheel stepping 

magnet and pawl; 

Fig. 4 shows a section of the commutator car- rying an arrangement of pins on its rim; 30 

Fig. 5 is a view in side elevation showing a 

detail of .the commutator drive and tensioning 

motor; and 

Fig. 6 is a plan view partly in section . of the 

commutator drive and automatic control therefor. 35 · It is believed that an explanation of the schematic representation of our invention will form 

the best basis for its understanding, and therefore reference will be made more particularly to 

Figure 1. In this figure, I represents the key- 40 

board of the cryptograph, the arrangement of the 

twenty-six keys thereof being that of the standard 

typewriter lrnyboard except that only twentysix keys corresponding to the twenty-six letters 

of the· alphabet are included. Each· key of the 45 

keyboard operates an electrical contact, as shown 

schematically for the Q and W keys. In addition, our keyboard is provided with a universal 

bar which is actua.ted with each depression of any 

key. Keyboards of this type are well known in 50 

the art and require no further description. 

The cipher wheel or commutator is shown at 

2 in Figure 1. It may be made of bakelite or 

similar material, and serves as a commutator or connection changing device for carrying fifty- 51S 
REF ID:A4161577 

2 2,028,772 

two brush-type contacts arranged in two rings or sets of twenty-six each, one set being placed on the obverse face 3, of the wheel 2, the other set. 

being similarly placed on the reverse face 5, of 

5 the wheel. The twenty-six contacts on each face are arranged equidistantly from one another in a circle adjacent to the periphery of the face, the 

contacts on the obverse face being connected to 

those on the reverse face by means of flexible, 

10 insulated conductors which pass through the interior of the wheel, as shown schematically and 

by way of example in Figure 1, for two pairs of 

contacts. The cipher wheel or commutator is 

fixed upon the shaft l, which serves as an axis 

15 about which the wheel may rotate. The contacts 

of the obverse face 3, of the cipher wheel press 

against ball-bearing type contacts arranged on. the fi.xed plate 4; the contacts of the reverse face 

5, of the cipher wheel press against ball-bearing 

20 type contacts arranged on the fixed plate 6. The 

fixed plates 4 and 6 each contain twenty-six con- tacts arranged equidistantly in a circle. The cipher wheel rotates between these fixed plates 4 

and 6 so that each contact on the obverse face 

2? 3, of the cipher wheel presents itself in turn to 

each contact on plate 4, and each contact on the reverse face 5, of the cipher wheel presents itself 

in turn to each contact on plate 6, as the said 

wheel rotates. The contacts of plate 6 are re- 30 spectively connected by conductors to the con- tacts of the ·keyboard I ; the contacts of plate 4 are respectively connected by conductors to a bank 

of twenty-six electrical elements which may be 

small lamps, relays, or solenoids, only two of -

~o. which are shown as at Ill. For the sake of simplicity of explanation, it will be assumed that 

the electrical elements in this bank are lamps. 

As shown in Figure 1, when the key Q is depressed, assuming the cipher wheel to be in the 

40 position indicated in the figure, a circuit is estab- . lished as follows: From positive pole of battery 

11 through conductor 12, closed contact at the 

Q key, conductor 13, contact 14 on fixed plate 6, 

contact 15 on cipher wheel 2, conductor 16, cont5. tact 11 of cipher wheel 2, contact 18 of plate 4, 

conductor 19, through. lamp 20, conductor 21 to 

negative of battery I I. Lamp 20 has a translucent glass window before it, on which a letter is 

painted, say the letter W. Hence,·depression of 

50. the key Q on the keyboard gives the cipher re- sultant W, under the conditions specified. 

Suppose that the key W of the keyboard is depressed, instead of Q. By following the path set 

up for the electrical current, it will be seen that 

55 the Q lamp will be lighted. Thus, reciprocity is · established between the keys on the keyboard and 

the lamps so that if, for example, Q=W, in en- ciphering, W=Q in deciphering. The same re- ciprocal relationship can be established throughIJO. out the alphabet by connecting the flexible con- ductors in the interior of the cipher wheel in an appropriate manner to paired contacts on the ob- verse and reverse faces of the cipher wheel. 

If the cipher wheel were stationary, the rela65. tionship between the key depressed and the lamp 

illuminated, that is, the equivalence between 

plain-text and cipher letters, would be fixed for 

each wiring of the interior of the cipher wheel. 

But the cipher wheel is rotatable and hence this 

70 relationship is subject to variation. As thus far · described our cipher wheel is by no means novel 

in the art, similar wheels being well known in 

other cryptographs. Our cipher wheel is, however, novel in respect to certain features con75. nected with the way in which the relationship be-

. tween plain-text and cipher letters ls varied and 

controlled, and these features will now be presented. 

The rim or tire of our cipher wheel 2, is provided with 130 pins arranged in five superimposed ii 

bands each band consisting of 26 equidistantlyspaced pins. These pins, which are operable independently, are preferably arranged in groups 

of fives transversely of the rim face, and are positioned for permutative operation in accordance 10 

with the permutations of a plural unit code such as the 5-unit or Baudot code. To explain what 

is meant, we may say that according to the Baudot code, the permutation of elements for the letter A, for example, is represented _thus: 15 

1 2 3 4 5 

++---· 

For our purposes we will let the + sign indicate 

that a pin is to be posit.ioned for positive operation, the - sign, that it is to be left in its inop- 20 

erative or inactive position. In Figure 2 there 

is shown a view in side elevation of a. section o! 

the rim o! the cipher wheel or commutator, with 

the pins now being described. The pins indicated 

by dotted lines in Fig. 4 represent pins which 25 

have been left depressed in their inactive positions; the pins indicated by whole lines represent 

pins which have been elevated into their active 

positions. The permutations represented in Fig--

ure 4 correspond to the Baudot signals for the 30 

letters Y, Z and A. The order of the letters in 

Figure 4, is, o'f course, only illustrative, since all 

the pins can be arranged in active o·r inactive 

positions to correspond with any sequence of signals of the Baudot code, and hence this sequence 35· 

may be varied at will. 

The function or the pins on the rim of the cipher wheel is to control the commutator transmitter shown within the dotted line block desig.-

nated as at 22 in Figure 1, which consists es- sentially of a set of 5 contact-levers movable between ·pa,ired left and right contacts. Formally, 

these contact-levers are held against the left con- tact, by the action of respective retractile springs, 15. but when a pin on the rim of the cipher wheel is 

in its active or operative position, as in the case of pin 48 in Fig. l, and cap. therefore pr:esent 

itself to the contact-lever with which it is asso- ciated, it presses against the contact-lever and causes it to make contact at the right; Pins in 50 

their inactive positions do riot, of course. act upon 

these contact-levers, allowing the latter to remain 

against their respective left-hand contacts. The 

function of the paired contacts controlled by the 

respective contact-levers of the commutator 55 

transmitter will be explained presently. 

A portion of the cipher wheel near the edge 

of the reverse face 5, is formed to carry a ratchet 

wheel, shown in Figure 3. This ratchet wheel 

contains twenty-six equidistantly-spaced teeth, GO 

only five of which are shown in Figure 3, one 

tooth being designated as 23. It is likewise designated 23 in Figure 1. Assocl.ated with the 

ratchet wheel is the pawl shown at 24, Figures 1 

and 3. The ratchet wheel and pawl, together 

with electro-magnet 25 and its armature~ I, Figures 1 and 3, determine the stop position of the 

cipher wheel in its rotation on the shaft 7, under 

the drive of coiled spring II, which is wound or· 

maintained under a desired tension by a motor M. 

G5 

70 

Referring to Fig. 5, the spring 8 may be conveniently housed in a barrel 117, fixed on the shaft 

1 '.for integral movement therewith and with said 

cipher wheel, which is also keyed or otherwise 75 

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REF ID:A4161577 

2,028,772 3 

secured to the shaft l. A worm wheel 48 having a hollow hub 49 is journaled for rotation on shaft 

l and functions through associated instrumentalities to actuate tensioning spring 8, one end of 

,,_ said spring being secured to the worm wheel at 

50 (see Fig. 6) and the other end of the spring 

being fixed to the shaft at 51. As before stated 

spring 8 is maintained under tension by motor 

M (see Fig. 6), which is coupled to drive the worm 

1 o wheel by means of worm gear 52. 

As will be seen by reference to Fig. 6, the circuit 

for the motor, which keeps coiled spring 8 under 

tension, is closed or opened according to the degree of tension which it is. desired to maintain 

J .:; upon the said spring; that is, after the spring 

is sufficiently tensioned, the circuit is interrupted 

to stop the motor and is only started again by 

closing the circuit when the tension has been decreased below a predetermined minimum. For 

;:0 the purpose of controlling this action, the circuit 

arrangement in operative connection with the 

motor, comprises leads 53 and 54, including a 

voltage source 55. The motor shaft is operatively 

coupled to the worm gear 52 by means of a slid3 

~:;; coupling comprising components 56 and 57. When 

the motor operates to put tension upon the spring 

8, component 51 of the slide coupling is gradually 

moved away from its component member 56 due 

to the resistance of said spring 8. Thus the worm 

:OJ wheel 48 tends to move the worm gear as indicated by the arrow and progresses the entfre 

shaft 58 from the slide coupling to the right (see 

Fig. 6) against the action of spring 59. Sleeve 

50 which is rigidly secured to shaft 58; is opera-

~:; tive through the adjustable L-shaped arm 61 with 

spring contact member 62, said member being 

adapted to ride on insulated block 63, conveniently mounted on bearing !34,.in which shaft 58 

is journaled. Block 63 is provided with a notch 

·10 or groove 65, into which the projection 66 of 

spring contact member 62 will drop and bre::i.k 

the contact at 61 to open the circuit and stop the 

motor M. During this period of operation, it 

should be noted that the drive shaft l is held 

r; from rotation, normally, by the armature 41 of 

magnet 25. 

While a spring motor driving mechanism for 

the cipher wheel is here disclosed by way of example, it is understood that other methods are 

. ,;') contemplated such as motor and clutch, or a stepping magnet arrangement, or other suitable means that will impart movement to the cipher 

wheel in accordance with the principles o'f the 

invention. 

'"·' The movement of the cipher wheel is preferably step-by-step, or at intervals which will be 

explained subsequently in discussing the way in 

which the whole system functions. 

The cipher.-key transmitter 26, Figure 1, is a {i\l slightly modified Baudot code transmitter such 

as is employed with printing telegraph equipment 

of kriown commercial types. Its general features need not be explained, similar transmitters 

being well known in the art. It is sufficient to 

G.) say here that a tape containing perforations permuted iE accordance with the Baudot code is 

passed. through this transmitter, setting up a series of five contacts inside the transmitter in accordance with the Baudot code. The transmitter 

TO is, of. course, also provided with a tape-stepping 

magnet 21, the fvnction of which is to step the 

ta.'pe forward at proper intervals. The principal 

difference between the transmitter as used in 

standard printing telegraph equipment and as 

7.r. used in our inv,ention consists in the way in which 

the left and right paired contacts of the nornial 

Baudot tape transmitter are interconnected. In 

the normally-wired transmitter the five contactlevers and their ten associated, paired contacts 

are members of a set of five separate or independ.: 5 

ent circuits; in the transmitter a-:S modified for 

our purposes the five contact-levers and their ten 

associated paired contacts are conductivity-determining members of a series circuit, as explained 

in the next paragraph. 10 

The cipher-key transmitter 2G, is associated 

and functions jointly with the commutator transmitter 22, to control the angular displacements 

of the cipher whe0l or commutator in the following manner. Note relay 23, which is energized 15 

by current from battery 2!l, through a path which 

begins at conductor 8(1 and indudes only ten of 

the twenty contacts and all the contact-levers of 

commutator transmitter 22, and key-tape transmitter 26, and is completed along conductor 31. 20 

Note also the illustrative set-up of contacts and 

contact-levers at 22 and 26 in F'igure l, in which 

a specific case is presented. It is assumed there 

that the arrangement of operative pins on the 

c;pher wheel which are at that moment present- 25 

ing themselves to the contact-levers of the cipherwheel transmitter 22, corresponds to the Baudot 

permutation for letter Z. At the same moment 

the character on the key tape and the permutation 

of contacts set-up within the cipher-key trans- so 

mitter 25, also corresponds to the letter Z. Note 

that in view of the manner in which the .twenty 

cpntacts and the ten contact-levers of 22 and 26 

are interconnected, the circuit from battery 29 

through relay 28 is completed only when the 35 

whole set of electricai connections established at 

the cipher-key transmitter 26, coincides with the 

whole set of connections established at the com- mutator transmitter 22, Hence, if Z is set up 'in 

cipher-k:ey transmitter 26, relay 28 will operate 4o 

only when Z is set up in the commutator transmitter 22. Similarly if any other letter, say X, 

is set up in the cipher-key transmitter 25, relay 28 

will operate only when X is set up in the commutator transmitter 22. The complete path of 4'5 

the current when such coincidence 'of connec'-

tions in transmitters 22 and 2G is established is 

as follows: 

From positive of battery 29 along conductor 30, 

through all the contact-levers and the ten asso- 50 

ciated closed contacts of transmitters 26 and 22, 

conductor 31 to back contact 32, of armature 33, 

winding of relay 28, conductor 34, to negative of 

battery 23. It is obvious that since the armature 

33 and bs,ck contact 32 of reiay 28 form parts of 55 

the circuit for energizing relay 28, as soon as the 

relay has received an impulse and armature 33 is 

attracted, the circuit for energizing relay 28 is 

brol{en at contact 32. Slnce armature 33 is under 

tension of a retractile spring, if not prevented 60 

from being pulled back into its normal position 

on ;·elease of relay 28, armature 33 would reestablish contact at 32 and would set up a chattering. 

But the mechanical arra.>igements are such that 

when armature 33 is first drawn up by relay 28 it 05 

passes by and is immediately engaged by lever 35 

and held from returning to its retracted position 

where it can reestablish contact at 32, until lever 

35 is displaced by mechanical ac.tion to be described later. Armature 33 of relay 28 also con- 70 

trols the magnet 25, already referred to, which, 

in turn, controls the rotation of the· cipher wheel 

2, in the following manner: 

The motor-tensioned coiled spring 8, tends to 

rotate the cipher wheel in the direction indicated 76 
REF ID:A4161577 

4 2,028,772 

by the arrow, say to the right. The circuit for 

the motor which keeps coiled spring 8 under tension is closed or opened depending upon the tension of the spring; that is, after the spring has 

5 sufficient tension, the motor is stopped and is only 

started again after this tension has decreased below a certain minimum. The rotation of the 

cipher wheel is step-by-step, controlled by the 

magnet 25, and the ratchet referred to above. Asl o sume the contact-levers in transmitters 22 and 

26 set up to different permutations so that relay 

28 is not energized and hence contact 36 is closed. 

A current starts from positive of battery 31 

through conductor 38, closed contact 36, conduc15 tor 39, back contact 40, armature 41, conductor 42, 

winding of magnet 25, conductor 43, to negative of 

battery 31. A momentary impulse passes through 

magnet 25 and causes armature 41 to be attracted, 

breaking the circuit at back contact 40, where- ~ o upon armature 41, under action of its spring, re- turns and again closes the circuit at 40. However, the· mechanical arrangement is such that the 

momentary attraction of armature 41 releases 

the pawl 24, associated with the ratchet on the 

9 5 cipher wheel and thus allows the cipher wheel, 

driven by coiled spring 8, to advance one step. 

Thus, the cipher wheel continues to .move, one step at a time, so long as back contact 36 of relay 

28 remains closed. When, however, the permuta3 !) tion of contacts set up in the commutator transmitter becomes the same as that set up in the 

ciphe!'-key transmitter, thus causing the completion of the circuit through relay 28 as already 

described, and thus, when contact 36 is opened, 

35 under the action of relay 28, and is held open by 

lever 35 as described above, magnet 25 cannot 

operate to withdraw armature 41; hence the 

pawl 24 cannot be released, whereupon the cipher 

wheel cannot advance any further. As stated be40 fore, t.he first impulse through relay 28 causes armature 33 to be attracted, to pass by lever 35, 

which then engages the armature. Thus contact 

36 remains open as long as lever 35 engages and 

holds it. It is only within this period, when the 

i5 cipher wheel is stationary, that the keyboard I, can be manipulated, the mechanical arrangement 

being such that the keys of the keyboard are locked except when the cipher wheel is stationary. 

Suppose now a key is depressed. The cipher 

50 resultant ,will be determined by the position of 

the cipher wheel at this time, because the circuit 

established through the cipher wheel depends 

upon the exact relative position of this wheel with 

respect to fixed plates 4 and 6. When a key is 

55 depressed, the cipher resultant is shown by the 

illuminated lamp; the latter continues to be illuminated so long as the key is held down. 

We return now to relay 28 and its other arma- ture 46. The latter controls the operation of the 

60 tape-stepping magnet 27 of the cipher-key transmitter 26, in the following manner: The tapestepping magnet 27 is actuated by battery 44, 

but the circuit is normally open at contact 45. 

When relay 28 is energized, however, armature 46 

65 is attracted and contact 45 is momentarily closed, 

allowing tape-stepping magnet 21 to function. 

This causes the key tape to step forward to the 

next position. It will remain in that position 

until the next time relay 28 is energized. 

70 There now remains to be described only how 

lever 35 is controlled: The keyboard is provided 

with a universal bar, operable by every key. 

When a key is depressed and then released, the 

universal bar, near the close of its upward swing 

75 on return to normal position, actuates the lever 

35, and causes it to be withdrawn from its en- gagement with armature 33. The latter immediately returns to its normal, retracted position, 

allowing contacts to be reestablished at 32 and 36. 

In the meantime the tape-stepping magnet hav- 5 

ing been actuated as described above; one of two 

things can happen as regards the set-up of con- nections in cipher-key transmitter 26: either a new set of connections between contact-levers 

and paired contacts has been established, or, by 10 

chance, if two similar characters occur in se- quence on the tape, the same set of connections 

as before has been established. These two cases are described in turn: 

Cl) If a new set of connections in cipher-key 15 

transmitter 26 has been· established, say a set 

corresponding to the Baudot signal for X, the 

set of connections no longer· matches that set-up 

in the commutator transmitter 22, which, as we have seen, corresponded in the preceding case 20 

to the letter Z. Consequently, immediately upon 

closing of contact at 36 under action of the universal bar, the circuit for energizing magnet 25 

is closed, allowing the cipher wheel to step :forward. It will continue to do so until that set-up 2/5 

of pins on the rim o:f ·the cipher wheel corre- sponding to letter X presents itself to the con- .tact-levers of the commutator transmitter 22, 

whereupon relay 28 is energized, contact at 36 

is broken, magnet 25 deenergized, and the cycle ao has been completed. 

(2) If, by chance, the next character on the 

key tape is the same as before <Z again), relay 

28 is immediately energized, since the commu- tator transmitter is still set up for permutation Z. 35 

Magnet 25 does not function and the cipher wheel 

is held in place. Two letters are therefore,.,,enciphered at the same position of the cipher wheel. 

Of course, if the key tape now consists of a series 

of Z's, the cipher wheel will remain in fixed posi- 40 

tion during the encipherment of a corresponding 

number of letters. 

It is obvious that the permutations of perforations on the key tape as well as the permutations 

of operative pins on the rim of the cipher wheel 4,3 

must be restricted to two sets of 26 similar permutations, otherwise there would be times when 

the cipher wheel would continue to revolve indefinitely and no encipherment or decipherment 

could take place. This is true for the reason that 50 

in order to bring the cipher wheel to rest 1t is 

essential that a permutation of pins on its rim 

exactly coincide with that permutation which 

happens to be set up at the cipher-key transmitter at that moment. This restriction to two sets 55 

of similar permutations does not, however, re- duce the cryptographic security of the system in 

any degree whatsoever. 

Ill addition, attention is especially called to 

the way in which a serious disadvantage of other 60 

cryptographs employing the Baudot code for 

cryptographic purposes Is obviated in our system. 

In order to explain what is meant it is necessary 

to enter into a brief discussion of Baudot transmission from the practical, economic point of 65 

view. For this purpose reference is made to 

U. S. Patent No. ~.416,765, issued May 23, 1922, 

to G. S. Vernam, lines 12 to 81 of the specification. 

In the patent to which reference has just been 

made, a special mechanism was devised to sup- 70 

press the six extra characters which cause all 

these difficulties; and while accomplishing the 

object intended, the mechanism is quite complicated and has in addition the further disadvantage that the method selected to accomplish the 715 

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suppression of the six extra characters results in 

increasing thernumber'of characters to be transmitted by. as much-as 10 to 30 per ce:nt; _In our invention; -both these disadvantages have been 

5 eliminated in the simplest manner-possible,. viz~. 

by arrarigements which necessitate only 26 of the 

32 Baudot permutations for cryptographic· puri;>oSes. ·so .far as ·cryptographic technique is con- cerned, basically our arrangements for 0 eliminat-

•lO ing- the six extra characters ordinarily introduced 

by the use -of the Baudot code for cryptographic 

purposes differ from· those described in' the ·patent referred to above· in the following respect: 

In the cryptographic system underlying -the 

'15 latter 'method the cipher resultants in the cryptographic process are tlle resultants of electrical 

interaction between· a set of ·signaling elements 

in the Baudot· code set up_ by: a message character and a set of signaling elements in the same 120 code'set up by a key character; these resultants ·can not be restricted to but 26 <if the 32 possible 

Baudot permutations because of this interaction. 

In our cryptographic system : the. cipher ·result:. 

·ants in.the crYI>tograpbic process ii.re not at all 

·25 the resultants of 'electncal··interaction between 

!two sets of: signaling elements in the Baudot code; 

,the signaling :element representing the message 

·character is' not ·at -all .·in 'the ·Baudot code and 

-does not' interact directly with the signaling ele130 -ments.:representirig.the key character, nor·is the 

cipher 'resultant· represented by signaling elements in the Baudot code. The· role the Baudot 

code plays in our ·system is,' so far as signaling 

'elements are concerned, oi:J.ly an indirect one, and 

i35 . that is why in our systei:n the restriction of cipher -characters to a -set of only 26 is rendered easy' 

without any apparatus specifically introduced to 

suppress the' six extra characters. . . ·" ·tt is'obvious that··instead cif having the crypto140 ·graph]f\lhction to produce viSu.al ·signals of the 

tYi>e indicated in-;the foregoing deseription, it is 

possible to" provide 'at I 0, Figure 1, a set of -26 . electro-magnets' instead -of a set of 26 lamps, 

which magnets' would act 'through proper. plung-

:45 ers or armatures· directly· upon the keyboard. of a typewrlter. with which--they~, are associated, so as to cause the typewriter to print' the letters of 

the 'cipher message, in the case of enciphering, 

and the letters of the plain~text message,. in the 

'50 case of deeiphering. Again,· these magnets; instead of being asso- ciated with the keyboard of ·an ordinary type-

·writer might he associated with the keyboard of 

an au'.tomatic .· telegraph transmitter keyboard, 

-55 and thu8; in the case"of- enciphering, bring about 

the trarumission·'of signals ·corregponding to·en• : ciphered· letters, .- At -the· receiving end of this 

system, the' receiyed signals would_ act directly 

. upon the keyboard of the cryptograph, and the 60 "latter' -would cause the received cryptographed 

Sigrialsc to ;be deciphered -anc:t if. the cryptograph 

at 'the receiving end is ;associated with a typewriter 

as described tn the preceding paragraph, the 

65 cryp'tograph would cause a written record to be 

made of the deciphered message. 

It is also obvious that the mechanism which 

we have provided permits of variations in cryptographic resultants other .than those introduced 

70 .by challging -the .key tape. - One of these .sources 

.of_ variations lie~ in .. .the' pqssibility of changing 

the permutations ·of . ·operatfare . and inoperative 

.pins on the rim of the cipher wheel. -Another source lies in the changing.of ,connections-between 

,

75 .the:key~oaz:d contac~s and ti,i~.contacts of plate 6, 

5 

Figure:l; or between the co~tacts1of plate; 4 a,tld 

_the signaling elements in bank IJO. Another source lies in constructiilg the_ cipher w]J_ee} in 

two seetions; ·an upper andlower, s0 that the two 

sections: can be PoSitioned or juxtaposed at any 6 

one of twenty-six· different points of coincidence with respect to each other., thus; varying 

the cipher resultants. Another source lies in the 

changing. of connections between· the -contacts ·on the- obverse· and reyerse faces of th,e cipher 110 

wheel. F'inally, 3n· important source of varia- - tion lies in the changing of the -connections between the homologous contacts of the cipherkey· transmitter 26, and the commutator -trans.,. 

mitter 22. All these sources of variation exist- J5 

ing within the mechanism- itself are subsidiary, 

however, to the principal source inherent in con'-

stant change of key tapes, and it may be said 

that so long as a given key tape is .coextensive· in I 

number of characters with that of the_· intelli- 20 

gence to·be enciphered, so that no two messages. are ever enciphered by the saQ'.le key tape or portion thereof, and so long as these key tapes 

consist of unintelligible, entirely randomized se- quences ·of characters, -the messages enciphered .25 

according to such a system are ·absolutely inde-1 

cipherable without actual possession of the trey 

?apes employed in thetr encipherment or a knowledge of the sequence of -the characters on such 

key tapes. · 30 

We claim: 

· 1. In a cryptographic system adapted for use with a plural unit code transmitter; means com- prising electrically operable elements for ·coordi.,, na~ing the transmitter with said system; ~nd-cir- 35 

cwt means for interconnecting said elements for . ..£!'.Y.Pl.Qgrl!-nhi~.,,p~s. said means comprising 

contact levers and paired, contact points peri:putatively positioned and operative in series relation. · 2. In -a cryptogr11.ph, a keyboard c9mprisillg 40: 

character elements in operative electrical connec- · tion with corresponding signaj.ing elements; means comprising a commutator for vacying the 

connections between the keyboard- elements and 

said signaling elements;- a.commutator transmit- 41 

ter; ~_c:iP..b_e_r..:;.k_ey...J,___x:_a,n,§mit_~/::; and means Coor- - din~ted with said transmitters for effecting progressive operation of the commutatar. 

3. In a cryptograph, _a keyboarci c9mprising 

chai:acter elements in operative electrical connec- 50 

tion . with- c_orresponding signaling -elements; means comprising. a commutator for varYing the 

connections between the character elements and 

_said signaling- elements;~ ciJ;l;Q~:-~eY_transmit,;oo. 

._ter d_mecpa~~"' and means coordinating said 55 

mechanism with the commutat()r for effecting· its 

progressive operation. 

4. In a cryptograph, a keyboard c"Qmpplilng 

character elements in operative electrical .con- nection with corresponding signaling elements; 60 means comprising a commutator for varying the 

connections .between the character elements and 

said signaling elements; a .cipher-key transrllitter. 

mechanis-m: ... ~nd means comprtSillga ~Ilimiitator transmitter coordinating said mechanism with 65 

-the .commutator-for effectk:ig its progressive operation. 

5. In .a- .cry;ptograph, a keyboard comprising 

character- elements in operative electrical con- nection with a corresponding number of signal- 70 

.ing elements; means -comprising a commutator . .for :varying -the .connections between the key-

·board elements and ,said signaling -elements; a commutator transmitter; a ciQher-keY. -transmit-

;ter; and ,circμit :mtl8J1S ·".COO'rcllilateci"With" siid'. 7 5 · 
REF ID:A4161577 

.tran8mftters· for. effecting· progressive operation 

of the" commutator~ . . . 

. 6·. rri a cnri:>togiaph;· ·a keyboard ccimprising 

charaete:r elements in ·operative electrical ~con~ 

I nection. with corresponding·•. signaling elements; 

means compriSirig a corri:rriutator for ·varying the 

coi:mections between the keyboard. elements· and 

said signaling elements; a commutator .transmitter_; _a cipher-key.....ll:!1rismit~.r,; and circuit means 10 coordinating both of said. transmitters for jointly 

effecting progressive operation of the· commu- tator.· · ':· :r · 7. In a cwtograph,. a keyboard· comprising 

character elements in operative electrical con- llS nection with corresponding signaling elements; means comprising a commutator for varying the 

·conneCtions oetween the keyboard elements. and 

said signaling" elements; .. a commutator transmitter; a CiP.her-keY- ttarismittei:; and means ·co- 20 ordinating said coriunutator and cipher-key 

transmitter through the commutator transxrutter 

for effecting progressive oi)eratiori of the ·commu- tator. · · · · · · 

8. Iri a cryptograph, a.· keyboard . comprising 

25 characte:r elements in opera.tive electrical· con- ·nection with corresponding signaling elements; 

means' comprising a commutator for vacying. the 

connections· between 'the keyboard elements and 

said signaling elements; · a commutator· traris30 mitter; a cipher-ke~ transmitter mech~iSI!)..°;. 

and means coordinated with both of"said transmitters for effecting progressive operation of the 

commutator, said cipher-key tiansinitter mechanism being controlled' by a keyirig element which 

35 is independent of the cryptograph. . 9. In· a · czyptograph, a keyboard compriSing 

·character elements· in operative electrical con-

·nection with corresponding signaung elements; means comprising a comm.utator for· varying· the i ;{o connections. between the- keyboard. elements. and 

·said signaling elements; a commutator transmitter; a cipher-keY- · tr!μlsmiJ;t~r_mec.ha:Qislil; and means coordinatedWlthboth'ofsafo-transmitters 

for effecting progressive operation of the commu- <:f5 tator, said cipher-key tran8mitter mechaniSm being controlled by a tape bearing perforations per-

·muted in accordance With a plural unit code. . 10. A cryptograph, comprising· an electrical 

circuit and including a current source; a relay in 

:;o said circuit; a· set of contact levers anci paired 

contact points, permutatively positioned.and operative therewith in said circuit;· a second set of 

contact levers and contact points associated in 

similarly operative relation with said circuit; and 

:;;5 means for completing said circuit and energizing 

-srud· relay only at such times as the" entire series 

of connections established within the first set of 

contact levers and their associated contact Points 

is identical with the entire series of connections 

60 established within the second set of contact levers 

and their associated contact point-8. 

11. A cryptograph, comprising ·an electrical 

'circuit and including a current source; a relay in 

·said circuit; a set of contact levers· and paired 

fi5 contact points, permutatively positioned and operative therewith in said circuit; a second set of 

contact levers and contact points associated in 

similarly operative relation with said circuit; ·and ·means for permutatively varying as a set each of 

iO the said sets· of contact levers, · · 

12. A cryptograph, comprising an electrical circuit and including a current source; a relay in 

said circuit; a set of. contact levers and paired 

c_ontact points, permutatively positioned and op76 erative therewith in said circuit; a second set of 

contact. levers. and contact pairit.S assoCiated in I 

·similarly .operative i'efation with said circuit·; 

·and. means for permtitatively varying as· a set 

each of the said sets of contact levers; the permu'-

tative ·variations being in· accordan·ce with the 5 

same plural unit code for both sets of contact 

-levers.· 

13. A ccyptograph; comprising an electrical 

circuit and including a current source; a relay 

in said circuit; a set of contact levers and paired 10 

contact points, Permutatively positioned and op~ 

erative therewith in· said circuit; a second set of 

contact levers and contact points: associated .in 

siinilarly · operative relation with' said circuit; means for completing said. circuit .and energiZing ·15 

said relay only at such times as the entire series 

cif connections e8tablished within tlie first set .of 

contact levers and their a.ssociated contact points 

is identical With the entire series of connections 

established within the second set of contact levers ·20 

arid their a.sSociated 'contact points; and means .for perniutatively varying: as a set each of the 

·two sets of contact levers, the permutative varia~ 

tioris being in accordance with the same plural 

unit code fcii' both sets of contact levers. · 21S ·. ·14: A- cryptograph, comprising an: electrical · 

circuit and including a current source; a relay in 

said Circuit; a set of contact levers ·and _paired 

contact"points, permutatively positioned and operative therewith in said circuit; a second set of so 

co·ntact .. leve'rs arid- contact points associated in 

Siinilarly operative relation with said circuit; an_q, ·means for permutatively varying as a set each of 

:the said sets· of contact levers, the permutative 

·variations for one of said sets of levers being in ·35 

accordance with one plural-unit code, those of 

·the oilier of the· two sets of levers being in ac- cordance with a different plural-unit code. · · 15. A· cryptograph, comprising an electrical 

·circuit and inCluding a current source; a ·relay {40 

fu said circuit;·a set of contact levers and paired 

"contact points, permutatively_ positioned and op-

. erative therewith in said circuit; a second set of 

contact levers and contact points associated in 

similarly · operative rela.tion with said circuit; ~45 

means for completing said circuit and energizing . said relay only at such times as the entire series 

of · conriectiohs established within the first. set 

of contact levers and their associated contact 

points is identical with the entire series of con- •50 

nections· established within the ·second set of 

·contact levers and their associated contact 

paints; ·and means for permutatively varying as a set ·each of the two sets of con tact levers, the 

·pelinutative variations for one of said sets of ~l):J 

levers being ·in accordance with one plural-unit 

code; those of the other of the two sets of levers 

being in accordance with a different plural-unit 

code.· 

· 16. In a cryptograph, a connection changing 100 

·vice comprising a rotatable drum, bearing a se,. 

ries of pins arranged in groups about its rim, .the 

groups comprising each a plurality of units positioned transversely of said rim and. corresponding in number of groups to a predetermined se- :65 

lection of characters; means for positioning the 

pins for independent operation. in groups in. ac- cordance with the permutations of a plural-uni·t 

code; said drum also bearing on its obverse and reverse faces respectively a series .of equidi.Staritly 70 

·spaced contact elements arranged' in a ring adjacent to the periphery; and means for estab-

'lishing fortuitous electrical connections between 

the contact elements of said faces. . . 17. In a cryptograph, a connection changing ,75 

\. 

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REF ID:A4161577 

, 

2,028,77.2 

device comprising a rotatable drum, bearing a se- ries of pins arranged in spaced groups about 

its rim, the groups comprising each a plurality 

of units positioned transversely of said rim and 

5 corresponding in number of groups to a predetermined selection of characters; means for positioning the pins for independent operation in 

groups in accordance with the permutations of a plural-unit code; said drum also bearing on 

10 its obverse and reverse faces respectively a series 

of equidistantly spaced contact elements arranged 

in a ring adjacent to the periphery; and means 

for establishing fortuitous electrical connections 

reciprocally in pairs between the oppositely dis15 posed contact elements of said faces. , 18. A cryptograph, comprising an operatively 

associated electrical circuit and including a cur- rent source; a rotatable 'commutator bearing: a series of pins arranged in groups about its rim 

20 and positioned for independent operation in accordance with the permutations of a plural-unit 

code, the groups comprising each a plurality' of 

..,..,_ \ pins and said groups corresponding in number! to ~,.~-~predetermined selection of characters; a traiis-

- /25 m1ttercur!t;~·0ned by said pins, said transmitter 

'-:" comprising a set of contact points and contact 

1 ' levers operative therewith in series circuit' rela- 1 ·uon~ i 

/ 19. A cryptograph, comprising an operatively 

-' 30 associated electrical circuit and including a cur- rent source; a rotatable commutator bearing a series of pins arranged in groups about its i:im 

and positioned for independent operation in ac- cordance with the permutations of a plural-unit 

·•" code, the groups comprising each a plurality of 

pins and said groups corresponding in number 

to a predetermined selection of -characters'; a transmitter controlled by said pins, said transmitter comprising a set of contact points and cion40 tact levers operative therewith in series circuit 

relation; and means also controlled by said pins 

and permutatively operable with said transmitter 

to set up progressive steps in the continuity of 

45 

said series circuit. · 20. A cryptograph, comprising an operatively 

associated series electrical circuit and including a current source; a relay in said circuit; a rotatable commutator carrying a series of pins positioned in groups about its rim for independent 

r;o operation in accordance. with the permutations 

of a plural-unit code, the groups comprising each a plurality of pins and said groups corresponding 

in number to a predetermined selection of characters; a commutator transmitter controlled by 

,;;; said pins, said transmitter comprising a set of 

contact points and contact levers operative therewith in series circuit relation; means consisting 

of a cipher-key transmitter, said transmitter 

comprising a set of contact points and ·contact 

GO levers operative therewith in the same series circuit relation; and means jointly controlled by 

both of said transmitters for setting up progressive steps in the continuity of said series circuit 

Q:j 

for operating said relay. 

21. In a mechanism of the character described, 

the combination of a commutator transmitter; a 

cipher-key transmitter; and a rotatable commutator bearing on its rim a series of pins arranged 

in sets, the sets corresponding in number to a 

70 predetermined selection of characters, said pins 

being positioned permutatively in groups of five 

in accordance with a selected 'set of permutations 

of a five-unit .code. 

22. In a mechanism of the character described, 

75 the combination of a commutator transmitter; a 

( 

~ 

\ 

I 

cipher-'j{ey transmitter; and a rotatable commu- tator bearing on its rim a series of pins arranged 

in sets, the sets corresponding in number to a predetermined selection of characters, said pins 

being positioned permutatively in groups of five n 

in accordance with a selected set of permutations 

of a five-unit code to effect control of said com- mutator transmitter. 

23. In a mechanism of the. character described, 

the combination of a commutator transmitter; a 10 

cipher-key transmitter; and a rotatable commutator bearing on its rim a series of pins arranged 

in sets, the sets corresponding in number to a predetermined selection of characters, said pins· 

being positioned permutatively in groups of five 15 

in accordance with a selected set of permutations 

of a five-unit code to effect control of said com,. 

mutator transmitter; and means operative with 

said commutator transmitter for jointly con- trolling the progressive displacements of the 20 

commutator. 

24. In a mechanism of the character described, 

the combination of a commutator transmitter; a cipher-key transmitter; and a rotatable commu,. 

tator bearing on its rim a series of pins arranged 2,~ 

in sets, the sets corresponding in number to a predetermined selection of characters, said pins 

being positioned permutatively in groups of five 

in accordance with a selected set of permutations 

of a five-unit code to effect control of said com.,. 30 

mutator transmitter; and means coordinated 

with a cipher-key transmitter mechanism and 

operative with said commutator transmitter for 

jointly controlling the progressive displacements 

of the commutator. 35 

25. In a mechanism of the character described, 

the combil}ation of a commutator transmitter; a cipher-key transmitter; and a rotatable.commutator bearing on its rim a series of pins arranged in sets, the sets corresponding in number 'o 

to a predetermined selection of characters, said 

pins being positioned permutativ:ely in groups 01' 

five in accordance with a selected order of permutations of a five-unit code, and to the exclusion of undesired permutations of the sa.id code. 46 

26. In a mechanism of the character described, 

the combination of a commutator transmitter; a cipher-key transmitter; and a rotatable com- mutator bearing on its rim a series of pins ar- ranged in sets, the sets corresponding in number 60 

to a predetermined selection of characters, said 

pins being positioned permutatively in groups.of 

five in accordance with a selected order of permutations of a five-unit code, and to the exclusion of undesired permutations of the said code 65 

to effect control of said commutator transmitter;· 

and means coordinated with said cipher-key 

transmitter mechanism and operable with said 

commutator transmitter for jointly controlling 

progressive displacements of the commutator. 60. 

27. In a mechanism of the character described, 

the combination of a commutator transmitter; a cipher-key transmitter; a rotatable commutator bearing on its rim a series of pins arranged 

in sets, the sets corresponding in number to a C5 

predetermined selection of characters, said pins 

being· positioned permutatively in groups of five 

in accordance with a selected order of permutations of a five-unit code, and to the exclusion 

of. undesired permutations of the said code to 7'0 

effect control of said commutator transmitter; means coordinated with said cipher-key transmitter and operable with said commutator·transmitter for jointly controlling progressive displacements of the commutator; and circuit 16 

1.1' 

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REF rn:A4161577 

8' ·2;028,772 

means. including an electro-magnetic relay for 

controlling said displacements. 

28. In a mechanism of the character described, 

the combination of a commutator transmitter; 

5 a cipher-key transmitter; a rotatable commutator bearing on its rim a series of pins arranged 

in sets, the· sets corresponding in number to a predetermined selection of characters, said pins 

being positioned permutatively in groups of five 

10 in accordance with a selected order of permutations Of a five-unit Code, and to the exclusion 

of undesired permutations of the said code to 

effect ~control of said commutator transmitter; means coordinated with said cipher-key trans15 ,mitter and operable with said commutator trans-

.mitter for jointly controlling progressive displacements of the commutator; and circuit means including an electro-magnetic relay for 

controlling said displacements, the circuit means 

20 being under the joint control of both of said 

transmitters. 

series of pins positioned for perrriutative opera:. 

tion in groups comprising each a set of five pins 

and said groups corresponding in number to a predetermined selection of characters; ·a cipherkey transmitter; a commutator transmitter con- 5 

trolled by said pins, said transmitter comprising 

a first set of contact levers and paired .contact 

points electrically operative therewith, said levers 

being actuated by .the permutatively positioned 

pins of said commutator, when electrically oper- 10 

ated through said levers and fivff of said contact 

points, to set up a first set of five progressive steps 

in the continuity. of an electrical path for the 

displacement of the commutator; means coordinated with said commutator transmitter for joint- 15 

ly controlling progressive displacements of the 

commutator, said. means being controlled by said 

cipher-key transmitter; a second set of contact 

levers and paired contact points electrically operable therewith, said levers being actuated by said ::o cipher-key transmitter, when: cfrcuits are com- pleted through the contact levers of said cipheri .. 1'. 

29 .. A mechanism ·of the character described, 

comprising a set of elements constituting a keyboard and a set pf elements constituting a sigkey transmitter and five of the contact points, to . _ _,,,... 

set up a second set of five progressive steoJ>Jll.the-....._,..."'-

25 naling bank, said sets of elements being electrically interrelated; a switching device for varying the electrical relation between the two sets 

of elements; means for angularly displacing the 

switching device in an aperiodic manner, the 

30 angular· displacements being unequal. 

30. A mechanism of the character described, 

comprising a set of elements constituting a keyboard, a· set of elements constituting a signaling 

bank, and including electrical connections be35 tween said sets of elements;. a switching device 

for varying the connections between the two sets 

·of elements;·· means for angularly displacing the 

'switchin1Ldevice· ·in an aperiodic manner,· the. 

angular dispiacemerits being unequal, the in~ 

40 equality in angular displa,cements being determined by a series of ciphering characters con- stituting an. external cipher key. 

31. A mechanism of the character described,. 

comprising a set·of elements constituting a key45. board, a set of elements constituting a signaling 

bank, and including electrica_l connections between said, sets of elements; a switching device 

for varying the connections between the two sets· 

of elements; means for angularly displacing the 

50 switching device in an aperiodic manrier, the~ 

angular .displacements being uriequal, the inequality .in angular dispiacements being determined by an external key, said key comprising a non-repeating series of ciphering characters 

55 arranged in random, ·unintelligible order; 

32. A mechanism of the character described, 

comprising a. set of elements constituting a keyboard, a set of elements constituting a· signaling 

bank, and ·including electrical connections be-

. 60 tween said sets of elements; a switching device for 

varying the connections between the two sets of 

elements; means for angularly displacing the 

switching device in an aperiodic manner, the an- gular displacements being unequal, the inequality 

65 in angular ·displacements being determined by an ·external ·key, said key comprising· a nonre- peating series of· ciphering characters arranged. 

in random, unintelligible order;the said ciphering 

characters being· employed successively to en-. 70 cipher successive characters of the message. 33~. A. cryptogr?-ph, compr~sing an operatively 

associated electrical· circuit and including a cur- rent source; =a: rotatable commutator bearing a 

. ,, 

t 

continuity of an electrical path for tni(displace- 2.;\ ; 

ment of the commutator; means for rotating the ·,, _ __, 

commutator; m·eans operative with said commu- • tator to cause aperiodic interruption in its rota-· 

tion; and means to start and stop the commutator. 

34. In a cryptograph, the combination of a bank :011. 

of twenty-six signaling elements in electrical circuit connection·.with a twenty-six element keyboard, said. keyboard comprising a corresponding 

number of contacts for closing said circuit con- nections; a plural-unit code cipher-key trans- ;5.~, 

mitter coordinated with said keyboard to jointly · · control said signaling elements; means for changil].g th~ :elect:rical paths between. the keyboard ele- . m:ents and signaling elements,. saii:l means ·con'-' 

sisting of a.commutator provided with' a first set <!o· 

Of twenty-six contacts equidistantly distributed on the obverse face of said wheel; a second and 

homologous set of twenty-six contacts· equidistantly distributed on the reverse face of said 

wheel; ·conductors respectiveiy connecting the 45 

contacts of.one face with the contacts of the·other 

face; twenty-six sets of pins mounted on the rim 

of said wheel and positioned for permutative 

operation according to the permutations of a fiveunit code; a commutator transmitter comprising 50 a first set of five contact levers electrically operable with ten paired contact points, said levers 

being actuated oy the pills c:if said commutator 

when electrically operated through said lever~ and five of said contact points, to set up a first 5,; 

set of five progressive· steps in the continuity of an electrical circuit· for the displacement of the 

commutator;,a·second and similar·set of five con- tact levers electrically operable with ten paired 

contact points, said contact levers ·being actuated GO 

by the cipher-key transmitter, when operated 

through its contact levers and five of its ten 

associated contact points, to set up a seco.nd and 

simila.r set of five progressive steps in the continuity of the same electrical circuit for the dis- 65 

placement of the .commutator; means dependent 

upon the continuity of said electrical circuit to 

effect displacements of the commutator until the' 

first set of five progressive steps exactly matches 

the second set of five progressive steps in the 70 

continuity of said electrical circuit. 

WILLIAM F. FRIEDMAN. 

GEORGE A: GRAHAM . 

.~_~ .. 

:•, 

' J, ,,"'t .... 

:): 

~' t 

.• 
Jan. 28, 1936. 

~/G.2. 

2 

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REF Il):A416157i 

' \ 

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iv. F. FRIEDMAN ,ET AL 

\ CRYPT~GRA~HIC SYST~M 

Filed Jan. 23, 1932 

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REF ID:A416l577 

· Jan. 28, 1936. W. 'F. -FRIEDMAN Et AL 

CRYPTOGRAPHIC SYSTEM 

Filed Jan. 23, 1932 

2,028,772 

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