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· Jan. 28, 1936. W. ·F. FRIEDMAN ET AL I 

2,028,772 

CRYPTOGRAPHIC SYSTEM 

Filed Jan. 23, 1932 2 Sheets-Sheet 1 

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CRYPTOGRAPHIC SYSTEM 

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Patented Jan. 28, 1936 2,028,772 

UNITED STATES PATENT OFFICE 

2,028,'7'72 

CRYPTOGRAPIDC 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 manufactured and used by or for the Government for 

governmental purposes, without the payment to 

us of any royalty thereon. 

5 This invention relates to cryptographic systems 

e,nd 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 

Hl cryptograms unsolvable without the key. 

A further object of this invention is the provision of a cryptograph controlled by means coordinated 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 

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

characters of which are restricted to the twentysix letters of the alphabet. In this respect the 

cryptograph excludes the usual six extra Baudot 

2,, characters, the transmission of which occasions 

much difficulty 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 in80 vent.ion. 

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

4il 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 crly 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 25 

·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 carrying 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 

mcitor; 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 keyboard except that only twentysix keys corresponding to the twenty-six letters 

of the alphabet are included. Each key of the 45 

keyboard OIJ€rates an electrical contact, as shown 

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

bar which is actuated 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- 55 
REF ID:A521770fl' 

2 2,028,77~ 

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 fa.ce 5, of 

IS 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 1, which serves as an axis 

16 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 fixed 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 

25 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 re30 spectively connected by conductors to the contacts 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 

36 which are shown as at II. 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 established 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, con- 45 tact 11 of cipher wheel 2, contact 18 of plate 4, 

conductor 19, through lamp 20, conductor 21 to 

negative of battery 11. 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, tn en- ciphering, W=Q in deciphering. The same re- ciprocal relationship can be established through110 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 obverse 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 between plain-text and cipher letters is 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 6 

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 arc positioned for permutative operation in accordance 10 

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

is meant, we may say that according to the Baudot code, the permutation of elements i'or 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 positioned fer positi•1e operation, the - sign, that it is to be left in its inop- 20 

erative or inactive position. In Figure 2 there 

ls shown a view in side elevation of a. section of 

the rim of the cipher wheel or commutator, \'Tith 

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 ::;ignals for the 3o 

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 or inactive 

positions to correspond with any sequence of signals of the Baudot code, and hence this sequence ~ may be varied at will. 

The function of 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- llO 

sentially of a set of 5 contact-levers movable between paired left and right contacts. Formally, 

these contact-levers are held against the lc!t con- tact, by the action of respective retractile springs, 

but when a pin on the rim of the cipher wheel ls "

5 

in its active or operative position. as in the case o-f pin 48 in Fig. 1, and can therefore present 

itsetr to the contact-lever with which it is associated, it presses against the contact-lever and causes it to make contact at the right. Pins in ;JO 

their inactive positions do not, 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 ~ transmitter will be explained presently. 

A portion o! 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 60 contains twenty-six equidistantly-spaced teeth, 

only five of which are shown in Figure 3, one 

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

ratchet wheel is the pawl shown at 24, Figures 1 05 and 3. The ratchet wheel and pawl. together 

with electro-magnet 25 and its armature 41, Fig- ures 1 and 3, determine the stop position of the 

cipher wheel in its rotation on the shaft l. under 

the drive of coiled spring 6, which is wound or 70 maintained under a desired tension by a motor M. 

Referring to Fig. 5,- the spring 8 m.a,y be conveniently housed in a barrel in, fixed on the shaft. 

l for integral movement therewith and with said 

cipher wheel, which is also keyed or otherwise 7 ~ 
REF ID~A521770-

2;028,772 3 

secured to the shaft 1. A worm wheel 48 having 

a hollow hub 49 is journaled for rotation on shaft 

7 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 

J;) 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 undPt" 

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

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

is sufficiently tensioned~ the circuit is interrupted 

to stop the motor and is onl~· started again by 

closing the circuit when the tension has been decreased below a predetermined minimum. For :::J the purpose of controlling this action, the circuit 

arrangement in operative connection with th<> 

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 slid~ 

:::) 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 55 due 

to the resistance of said spring 8. Thus the worm 

;,.J wheel 48 tends to move the worm gear as indicated by the arrow and progresses the entire 

shaft 58 from the slide coupling to the right <see 

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

60 which is rigidly secured to shaft 58, is opera- , .. , tive through the adjustable L-shaped arm 6 ! with 

spring contact member 62, said member being 

adapted to ride on insulated block 53, conveniently mounted on bearing 64, in which shaft 53 

is journaled. Block 53 is provided with a not.ch 

.;'i or groove SS, into which the projection 6'5 of 

spring contact member 62 will drop and brea.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 7 is held 

,1_.i from rotation, normally, by the armature 41 of 

magnet 25. 

While a spring motor drivir.g- mechanism for 

the cipher wheel is here disclosed by way of example, it is understood that other methods are ;;:1 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 

rn slightly modified Baudot code tran.smitter such as is employed with printing telegraph equipment 

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

being well known in the art. It is sufficient to 

·;·:: say here that a tape containing perforations permuted in accordance with the Baudot code is 

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

i;l is, of course, also provided with a tape-stepping 

magnet 21, the function of which is to step the 

tape forward at p1·oper intervals. The principal differ~nce between the transmitter as used in 

standard printing telegraph equipment and a.s 

, ·' used in our invention consists in the way in which 

the left and right paired contacts of the normal 

Baudot t.'l.pe 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- ;; 

cnt circuits; in t!ie transmitter as modified for 

our purposes the five contact-levers and their ten 

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

in the next paragraph. 10 

The cipher-key transmitter 25, is associated 

and functions jointly with the commutator transmitter ~2. to control the angular displacements 

of the cipher wheel er commutator in the following manner. Note relay 28, which is energized 15 

by cunent from batt-ery 2!l, through a path which 

begins at conductor SO and includes only ten of 

the twenty contacts and all the contact-levers of 

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

Note also the illustrative set-up of contacts and contact-le~·ers at 22 and 2$ in F'igure 1, in which 

a. specific case is presented. It is assumed there 

that the arrangement cf operative pins on the 

c'.pher wheel which are a.t 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 se·c-up within the cipher-key trans- 30 

mitter 26, al.so corresponds to. the letter Z. Note 

that in view of the manner in which the twenty 

contacts and the ten contact-levers of 22 and 26 

a.re interconnected, the circuit from battery 29 

through relay 28 is completed only when the 3:; 

whole set of electrical connections established at 

the cipher-key transmitter 26, coincides with the 

whole set of connections established at the commutator t.ransmitter 22, Hence, if Z is set up in 

cipher-key transmitter 26, relay 28 will operate _.O 

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 26, relay 28 

will operate cnly when X is set up in the commutator transmitter 22. The complete path of 45 

the cmTent when such coincidence of connections in tra.nsmit.ters 22 and 28 is estatJlished is as follows: 

From positive of battery 29 along conductor 30, 

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

ciated closed ccntacts of transmitters 26 and 22, 

conductor 31 to back contact 32, of armature 33, 

windlng of relay 23, conductor 34, to negative of 

battery 29. It is obvious that since the armature 

33 and ba.ck contact 32 of relay 28 form parts of 56 

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 

broken at. contact 32. Since armatm·e 33 is under 

tension of a retractile spring, if not prevented 60 

from being pulled back into its normal position 

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

But the mechanical arrangements arc such that 

when armature 3:! is first drawn up by relay 28 it 65 

passes by and is immediately engaged by lever 35 

and held from returning to its retracted position 

whe're it can reestablish contact at 32, until lever 

Z5 is displaced by mc::hanical aetion to be described later. Arr:1ature 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 JG 
REF ID:A521770-

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 

G sufficient tension, t;he 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 i) 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, conducl ~ tor 39, back contact 40, armature 41, conductor 42, 

winding of magnet 25, conductor 43, to negative of 

battery 37. 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, returns 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 

2 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 

cipher-key transmitter, thus causing the completion of the circuit through relay 28 as already 

described, and thus, when contact 36 is opened, a 'i 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 cE>nnot 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 

•5 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 21 of the cipher-key transmitter 26, in the following manner: The tapestepping magnet 21 is {lctuated 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 2 l 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 i::; 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 engagement with armature 33. The latter immediately returns to its normal, retracted position, 

allowing contacts to be reestablished at 32 and 36. 

In the meantime t.he tape-stepping magnet hav- 5 

ing been actuated as described above, one of two 

things can happen as regards the set-up of connections 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 sequence on the tape, the same set of connections 

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

(1) 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 !orwa.rd. It will continue to do so until that set-up z:s 

of pins on the rim o! the cipher wheel corre- sponding to letter X presents itself to the contact-levers of the commutator transmitter 22, 

whereupon relay 28 is energized, contact at 36 

is broken, magnet 2:> deenergized, and the cycle 30 

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 pasi- ,!O 

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;; 

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 it 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 i\5 

of similar permutations does not, however, reduce the cryptographic security o! the system In 

any degree whatsoever. 

In 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 necessax:y 

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

view. For this purpose reference is made to 

U. S. Patent No. 1,416,765, issued May 23, 1922, 

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

In the patent to which re!erence 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 seleded to accomplish the 7/S 
REF ID:A521770-

S-J.M8r.7'Zg D 

suppression- of. the six: extra. cha.tacters. result.a. in Figure-1;. or between: the contacts of plate 4 and 

increasing: the number of character& to be· trans- the slgna.llng elements in bank io. Another 

mitted by as· much as 16 ta 30 per cent.. In our sou.ree- lies ln eonstructlng· the cipher wheel in 

invention, both these disadvantages have- been two sections,. an. upper and lower, so- that the two 

s eliminated. in the simplest manner possible, viz.. sections- can be positioned or jmr.taposed at any G 

by arrangements which necessitate only 2& of. the one of. twenty-six different points of coin32 Ba.udot permut.ations for cryptographie: pur- cidence- with respect. to each other,. thus varying 

poses. · So fa;r as- ayptographic: technique is con- ther cipher resultants-.. Another source lies· in the 

cerned, basically our arra.ngements for eliminat- cha.nging of connections between the contacts 

:to ing: the· six extra ch3'I'acters ordinarily introduced on the obverse and rever,se faces of the· cipher 19 

by. the use or the, Baudot code for cryptographic wheel. Finally, ~n im·PC>Ftant source- of va.riaIJUl'POses differ from. those described in the· pat- tion Iles in the changing of the connections beent: referred. to above in the followi-ng respect. tween fue. hamologous coo.tacts of the clpherIil. the cryptographic system llllderlyil'lg the .key transmitter :?&:, and the commutator trans15 latter method. the cipher resultants in the cryp- mitter 22. AH these sources· of variation exist- 115 

tographfc proCl:!ss are the resultants· of electrical ing within the mechanism- itself are subsidiary., 

interaction between a set of signaling elements however, to the princlpaJ source inherent in con- in the Baudot code set UP' by· a message: char- stant. change 'Joi key tapes, and It may be said 

aete:c· and a set of signaling elements in the same that. so long as a giv.en key tape is coextensive In 

2El code: set up· by a key character.;: these resultants number of characters With that of the intelli- 20 can. :not be restricted to but 26 of the 3Z possible genee to. be enciphered·, so· that no two messages 

Ba;udot permutations because of this interaction. a.re ever enciphe:red by. the same key tape or In oor ccyptag?:aphi~ system the cipher- result- portion thereof, and so long as these key taJ>eS 

ants in the cr.yptographic' process are not at· all consist. of unintelligible, entirely randomized se- .25 the resultants of electrical interaction between quences. of characters, the message& eaeiphered 25 

two. sets of stgna;lfug elements· in the· Baudat code; according to such a s;,stem are absolutely indethe signaling- element representing the message ciphel'able without. &ctl.J&l possession of the key 

characfer is not: at. all.in the Baudot code and tapesemployecHn t.beir encipherment or· a knowlcroes. not ·Interact directly with the signaling ele- edge of the sequence of the characters on such 

:W ments re?resenting the key charaeter, nor ts the key· tapes.. 30 

cipher resultant represented by signaling ele- We'. claim: 

i:nents tn the Baudot code. The role the Bandot 1. In a. cryptogra.phie system adapted for use ·code plays :tn our sys.t~m is~ so far as signaling with a plural unit. code transmitter; means com- eiernents. are concerned. only an fndirect one-, and prising electrically operable. elements for coordi- .~ that ts why in our system the re.striction of cipher nating the transmitter. with. said system; and cir- 35 

characters to a sat of only 26 is rendered easy, cuit· means :for lnt<!'rcouneeting said elements for 

without a.ny apparatus specifically rntroduced to cryptogEaphic purposes, said means comprising 

suppres8 the six extra characters. conta.ct levers and. Paired contact points permu- . ·jtrs. obvious that. instead ot·having the crypto- tatively positioned and operative in series relation. 

:40 graph function to produce visuat signals of the a. In. a cryptogrnph, a keyboard comprising 40: 

tYPe- indicated in the foregoing description, it ls character elements in operative: electrical connecposSi'ble to provide at Cit, Figure l, a set of 26 tlon with corre;;iponding signaling elements; 

electro-magnets: instead of a set of 26 lamps, means. comprising a commutator for varying the 

whtcli magnets would' act through proper plung- connections between. the keyboard elements and 

.45 ers· or aririatures dh-ectly ·upon the keyboard of a. said signa.ling elements; a commutator transmit- 41 

typewriter wfth w·hich they- are associated, so ter; a cipher-key transmitter: and means eoor- as to cause the· f.ypewriter to print. the. letters of dinated with said tra.nsmitters for effecting prothe cipher ines5age, in the case of enciphering, gressive operation· of the commutator. 

and the Jetter& of. the plafh-t.e:xt message., in the & •. In a cryptogEaph, a keyboard comprising 

·so case of deciphering. character elements in operative electrical connec- 50 

Again, these magnets,. instead of being asso- tion with corresponding signaling elements; 

elated with the keyboard of an ordinary type- means: comprising a commutator for varying the 

writer,. mfght be associated. with the keyboard of cormectloDS between the character elements and an automatic telegraph transmitter keyboard, said signaling elements; a cipher-key transmit-

·55 and thu&·, in the case or enciphering, bring about ter mechanism; a.nd means coordinating said 55 

the transmissfon of signals correspondfng to en- mechanism with the commutator for effectmg its 

cfphered letters. At the receiving end of this progressive operation. 

system, the received signal& would act directly 4. In a. cryptograph, a· keyboard comprising 

upon the keyboard of the cryptograph, and the character elements in operative electrical con- 60 latter woul'd ·cause the received cryptographed nection with corresponding signaling elements; 60 

signals to .be deciphered and, if the cryptograph means comprising a commutator for varying the 

connections between the ·chara.cter elements and 

at the receiving en:l is associated With a tYi>ewriter said signaling elelru'nts; a cipher-key transmitter as described tn the preceding paragraph, the mechanism; and mP.an:i comprising a.commutator 

65 cryptograph would cause a written record to be transmitter coordinating said mechanism with 65 

made of the deciphered message. the commutator for effecting its progressive oper- It is also oov.ious that the mechanism which ation. 

we have provided permits of variations in. crypto- 5. In a' cryptograph, · a keyboard comprising 

graphic resultants other than those introd\JCed character element& in operative electrical con70 hy changing the key tape. One of these sources nection with a corre.sponding number of signal- 70 

of. variations. lies in the .. possibility of changing ing elements~ means. comprising a. commutator 

.the permutations o! . operative. and inoperative for varying the connections between the keypins. on tbe· rim of. the· cipher wheel. Another board elements and said signaling elements; a source lies in the changing of connections between. commutator traDfilnitter; a cipher-key tra.nsmit75 .the keyboard: contacts and the.contact&of plate&, ter; and circuit means coordinated with said '15 
REF ID:A521770-

!2,0!38, 77!3 

transmitters for · effec.ting progressive operation 

of the commutator. 

6. In a cryptograph, a keyboard comprising 

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

connections between the keyboard elements and 

said signaling elements; a commutator transmitter; a cipher-key transmitter; and circuit means 10 coordinating both of said transmitters for jointly 

effecting progressive operation of the commutator. 

7. In a cryptograph, a keyboard comprising 

character elements in operative electrical con- 15 nection with corresponding signaling elements; 

means comprising a commutator for varying the 

connections between the keyboard elements and 

said signaling elements; a commutator transmitter; a cipher-key transmitter; and means co- 20 ordinating said commutator and cipher-key 

transmitter through the commutator transm~tter 

for effecting progressive operation of the commutator. 

8. In a cryptograph, a keyboard comprising 

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

connections between the keyboard elements and 

said signaling elements; a commutator trans30 mitter; a cipher-key transmitter mechanism; 

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

commutator, said cipher-key transmitter mechanism being controlled by a keying element which 

35 is independent of the cryptograph. 

9. In a cryptograph, a keyboard comprising 

character elements in operative electrical con- nection with corresponding signaling elements; 

means comprising a commutator for varying the 

•lO connections between the keyboard elements and 

said signaling elements; a commutator transmitter; a cipher-key transmitter mechanism; and means coordinated with both of said transmitters 

for effecting progressive operation of the commu- 45 tatorr, said cipher-key transmitter mechanism being controlled by a tape bearing perforations permuted in accordance with a plural unit code. 

10. A cryptograph, comprising an electrical 

circuit and including a current source; a relay in 

,3u said circuit; a set of contact levers and 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 

;;.:; means for completing said circuit and energizing 

said 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 nn established within the second set of contact levers 

and their associated contact points. 

11. A cryptograph, comprising an electrical 

circuit and including a current source; a relay in 

·said circuit; a set of contact levers and paired 

6::; 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 

70 the said sets o.f 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 

contact points, permutatively positioned and op7fi erative 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 

ea.ch of the said sets of contact levers, the pennutative variations being in accordance with the II 

same plural unit code for both sets of contact 

levers. 

13. A cryptograph, 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 operative therewith in said circuit; a second set of 

contact levers and contact points associated in 

similarly operative relation with said circuit; 

means for completing said circuit and energi.Zing 11 

said relay only at such times as the entire series 

of connections established within the first set of 

contaet levers and their associated contact points 

is identical with the entire series of connections 

established within the second set of contact levers 20 

and their associated contact points; and means 

.for permutatively varying as a set each of the 

two sets of contact levers, the permutative variations being in accordance with the same plural 

unit code for both sets of contact levers. M 

14. A cryptograph, comprising an electrical 

circuit and including a current source; a relay in 

said circuit; a set of contact levers and pa.ired 

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

contact levers and contact paints as.sociated in 

similarly operative relation with said circuit; and 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 other 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 

in said circuit; a set of contact levers and 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; ·45 

means for completing said circuit and energizing 

·said relay only at such times as the entire series 

of connections established within the first set 

of contact levers and their associated contact 

paints is identical with the entire series of con- :jO 

nections established within the second set of 

contact levers and their associated contact 

points; and means for permutatively varying as 

a set each of the two sets of contact levers, the 

permutative variations for one of said sets of ·,3,; 

levers being in accordance with one pluraJ-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 GO 

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 o.f said rim and corresponding in number of groups to a predetermined se- rn 

lection 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 its obverse and reverse faces respectively a series of equidistantly 70 

spaced contact elements arranged in a ring adjacent to the periphery; and means for establishing fortuitous electrical connections between 

the contact elements of said faces. 

17. In a cryptograph, a connection changing 75 

.. 
' 

/-

2, 028, 772. 

device comprising a rotatable drum, bearing a series 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 current 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 

a predetermined selection of characters; a trans-

:!5 mitter controlled by said pins, said transmitter 

comprising a set of contact points and contact 

levers operative therewith in series circuit relation. 

19. A cryptograph, comprising an operatively 

:10 associated electrical circuit and including a current source; a rotatable commutator bearing a series of pins arranged in groups about its rim 

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 con- 4-0 tact levers operative there"'ith 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 

said series circuit. 

4.:5 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 

;;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 

oo 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 

for operating said relay. 

G.3 21. 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 

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 v,.ith 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 

cipher-key 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 ,, 

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 commu-

~ator 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 commutator 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.'S 

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 combination of a commutator transmitter; a cipher-key tram;mitter; and a rotatable com- mutator bearing on its rim a series of pins arranged in sets, the sets corresponding in number 'O 

to a predetermined selection C'f characters. said 

pins being positioned permut.atively 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. 411 

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 1)0 

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 5:5 

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 combinat.ion 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 r,,; 

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 711 
REF ID:As21770-

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 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 

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 transmitter 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 

transrni tters. 

29. A mechanism of the character described, 

comprising a set of elements constituting a keyboard and a set of elements constituting a sig25 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 

s"'itching device in an aperiodic manner, the 

angular displacements being unequal, the in40 equality in angular displacements 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 electrical connections between said sets of elements; a switching device 

for varying th~ connections between the two sets 

of elements; means for angularly displacing the 

60 switching device in an aperiodic manner, the 

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

66 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 be60 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 displacen;ients 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 cryptograph, comprising an operatively 

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

series of pins positioned for permutative operation 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 five of said contact 

points, to set up a fir3t 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- J .:; 

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 circuits are completed through the contact levers of said cipherkey transmitter and five of the contact points, to 

set up a second set of five progressive steps in the 

continuity of an electrical path for the displace- :.'.! 

ment of the commutator; means for rotating the 

commutator; means operative with said commu- tator to cause aperiodic interruption in its rotation; and means to start and stop the commutator. 

34. In a cryptograph, the combination of a bank :\• 1 

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

number of contacts for closing said circuit con- nections; a plural-unit code cipher-key trans- :::; 

rnitter coordinated with said keyboard to jointly 

control said signaling elements; means for changing the electrical paths between the keyboard elements and signaling elements, said means con- sisting of a commutator provided with a first set 41l 

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 respectively connecting the 4; 

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 t.ransmitter comprising Gil 

a first set of five contact levers electrically operable with ten paired contact points, said levers 

being actuated by the pins of said commutator, 

when electrically operated through said levers 

and five of said contact points, to set up a first ii~ 

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 oo by the cipher-key transmitter, when operated 

through its contact levers and five of its ten: 

associated contact points, to set up a second and 

similar set of five progressive steps in the continuity of the same electrical circuit for the dis- 6;3 

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, f 

l 

i