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REF ID:A36296B 

United States Patent Office 2,877,565 

Patented Mar. 17, 1959 

1 

2,877,565 

ELECTRICAL CRYPTOGRAPH 

William F. Friedman, Washington, D. C. 

Application August 11, 1944, Serial No. 549,086 

8 Claims. (Cl. 35-4) 

(Granted under Title 35, U. S. Code (1952), sec. 266) 

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. 

This invention relates to a device or machine, which 

may be used either as a cryptograph for enciphering 

and deciphering communications, or as an authentograph 

for testing the authenticity of messages. 

The primary object of this invention is to provide a 

cryptograph or cipher device which is simple in construction and maintenance, but nevertheless affords a 

high degree of security, is light and readily portable, and can be readily dissassembled and rearranged to vary the 

cipher keying elements. 

Another object of this invention is to provide an 

authentograph, that is, a device for testing the authenticity of a message or signal, thereby providing means 

for assuring that such a message or signal originated 

at an authorized source and is to be considered authentic. 

An additional object is to provide a novel keyboard 

for use with a cryptograph and an authentograph. 

Another object is to provide a novel method for the 

authentication of messages. 

Other objects of the invention will become apparent 

from a reading of the following specification and claims. 

In the drawings: 

Figure 1 is a top or plan view with the covers closed. 

Figure 2 is a top or plan view on an enlarged scale 

with the keyboard cover and parts of the rotor cover omitted. 

Figure 3 is a side elevation with the covers closed. 

Figure 4 is a cross section on line 4-4 of Figure 2 

with the rotor cover omitted. 

Figure 5 is a perspective view of the rotor latch. 

Figure 6 is a perspective view of the rotor actuating 

mechanism. 

Figure 7 is a diagram showing schematically the electric circuits and the mechanical operating mechanisms. 

Figure 8 is a view of a portion of the device, illustrating a modified keyboard and switching means. 

Figure 9 is a view of a rotor such as is used in the 

·device of this invention. 

The embodiment of the invention selected from among 

others for illustration in the drawings and description in 

the specification is as follows. Referring to Figure 7, 

the device will be seen, in general, to consist of a source 

10 of electricity, connected to a pair of wires 11 and 12 across which are connected a plurality (in this instance, 

twenty-six) indicators 13A, 13B, 13C, etc. These indicators are illustrated as being electric lamps arranged 

beneath a keyboard and indicator panel 14 (see Figure 2) 

and each arranged to illuminate one perforation closed 

by a transparent cover 15 bearing one letter 16 of the 

alphabet thereon. Panel 14 is secured in place over a 

gasket 14' of soft rubber or the like by means of screws as 

14". Across lines 11and12 are also connected manually 

operable switches 17A, 17B, 17C, etc., each in series 

2 

with one of the indicators 13A, 13B, etc., arranged for 

operation by pushbuttons 18 projecting through keyboard 

14 in proximity to the covers 15. 

Connected to each of the indicators 13A, 13B, etc., 

G is a multicontact electric switch, generally indicated as 

19. It comprises a number of relatively juxtaposable 

and rotatable cryptographic switching wheels or rotors, 

19A, 19B, 19C, and 19D, in cascade, each rotor having 

a plurality of spring input and output contacts 19' thereon 

10 (see Figure 9), and a final wheel 19E, which may hereinafter be called the reflecting rotor or reflector, the 

output contacts of which are connected in pairs, as shown diagrammatically at 20' in Figure 7. Each electrical path, as 20, through the rotor system 19 leads from 

15 one stationary contact 20" through the cryptographic 

rotors, and back, through 20', to another stationary con- tact 20". These paths or circuits 20 are rearranged 

each time one of the rotors is turned. 

In conductor 11 there is a normally-closed electric 20 switch 21. Between one of the indicators, in this case 

13E, and multi-contact switch 19, there is a normallyclosed electric switch 22. In parallel with wire 11 is 

wire HA containing an authenticating switch 23 having 

26 an operating handle 24. Wire llA also contains a normally-open switch 25. 

Turning now to Figures 1, 2 and 3 for a disclosure 

of the mechanical features of the invention, the device 

is shown as enclosed in a casing 26 to which are hinged 

30 or otherwise attached a back cover 27 and a front covei; 

28. 

The front cover, protecting the keyboard, is secured to 

casing 26 by means of a double hinge 28', 28". This 

arrangement permits the cover to fit snugly upon gasket 

35 14', thereby to provide a substantially dust-proof and 

water-proof closure for the keyboard 14, and yet permits it to lie flat in front of the machine or to be folded 

therebeneath. The back part of the casing 26, adjacent 

the rotor assembly, is provided with a lip 26'. (see Fig40 ure 2). Back cover 27 is adapted to fit over this lip, 

and has a gasket 27', which provides, upon closure of the 

back cover, a dust-proof and moisture-proof seal. The 

front and back covers when closed are secured by means 

of hasps 23' and 23", respectively. 

45 In the top of casing 26 there is an opening 29 through 

which a counter 30 is visible. As is most readily seen in Figure 6, casing 26 has two projecting walls 26A and 

26B, which are supported and strengthened by a rod 

26C. The cryptographic switching assembly 19 is re60 tained between these walls by a mechanism which will now be described. Wall 26A has an orifice therein 

through which may be pushed pin 30A having a knurled 

head 31 (Figure 2) and a latch 32 cooperating with a 

retaining spring 33. Also pivoted on wall 26A is a 55 spring latch 34 of U-shape, one arm being bent back 

parallel to the other. The free end 34A of latch 34 

is perforated to allow pin 30A to pass through it and 

bears cam surfaces 35 thereon. Stationary cam 36 

has a surface complementary to cam surfaces 35 so 60 that when latch 34 is moved from the substantially horizontal position, in which it is shown in Figures 2, 4, 

and 6, into the vertical position, in which it is shown 

in Figure 5, the free end 34A of latch 34 is moved away 

from wall 26A and compresses the entire rotor-reflector 

65 assembly so as to insure good contacts through the 

spring contacts 19' thereof. 

The manually operated means for rotating the cryptographic rotors 19 will next be described. As seen in Figures 1, 2, 3, and 6, casing 26 has a recess 37 in its top 

70 into which fits a plunger consisting of fingerpiece 38 having a sliding fit in the recess and a rod 39 upon which the 

fingerpiece is mounted. Rod 39 causes U-shaped stirrup 
REF ID:A36296B 

2,877,665 

3 4~ to turn on its pivots in walls 26A and 26B. On stirrup 

40 is a cam 41, which actuates follower 42 fast on shaft 

43 of counter 30. Stirrup '10 also has a member 44 to 

which spring 45 is attached and which carries cam face 

46. Detent 47 is pivoted at 48 in walls 26A and 26B and 5 

is stressed by spring 49 so that cam 50 engages cam face 

46. Spring detents 60 normally hold rotors 19 in their 

relative positions but allow movement of these rotors 

under the actuation of pawls 58. Detent teeth 51 are moved in and out of the ratchet depressions in the surface 10 

of the rotors 19 upon each movement of stirrup 40, as will be hereinafter further described. 

Stirrup 40 carries a pin 52 on which are pivoted a plurality of cam-and-pawl devices, 53A, 53B, 53C, and 

53D, which are urged by springs 54 against the rotors (see i;; 

Figure 9). Device 53B, for example (Figure 6), has a cam 55B and a pawl 58B, and these are adapted to co· operate, respectively, with ratchet depressions 56 of rotor 

19A and pawl notch 55D on the rotor 19B. 

The operation of this device is as follows: Cover 28 20 

is . opened to expose the keyboard 14. If, as frequently 

happens, limitations of space require, the cover may be 

folded back beneath the machine. For enciphering or deciphering, handle 24 is operated so that switch 23 is 

open. That push button 18 which is associated with the 25 

desired letter is depressed and the switch controlled thereby is operated. For example (to encipher the letter E), 

if push button 18 associated with the letter E is depressed, 

switch 17E (Figure 7) is thereupon closed, and connec- tion is made from battery 10 through line 11, switch 21, ·30 

line llB, switch 17E, lamp 13E, and line 12 back to source 10, illuminating lamp 13E. This action also closes 

connections from battery 10 through lines 11, llB, 

through switch 17E, then along line llC, through switch 

22, line 20, thence through rotors 19A, B, C, D and re- 35 

fiector 19E, rotors 19D, C, B, A, to line 20B, lamp 13Z, 

thence through line 12, back to source 10. Lamps 13E 

and 13Z are simultaneously lighted, and this indicates that 

the cipher equivalent of the letter E is Z. To decipher 

the letter Z, the push button 18 associated with the letter 4.0 

Z is depressed and the circuit is as follows: battery 10, 

line 11, switch 21, line llD, switch 17Z, line 20B, through 

the rotor-reflector assembly, line 20, switch 22, line llC, 

lamp 13E, line 12, back to battery 10. Lamp 13E would 

be illuminated, giving E as the plain-text equivalent of Z. 45 At the same time the lamp 13Z would also be lighted by 

the closing of switch 17Z and by a circuit which is essen- tially similar to the one described in connection with the 

closing of switch 17E. Thus, since rotors 19 connect all 

the lamps 13A, 13B, etc., and all the switches 17A, 17B, 50 

etc., together in pairs, each letter has another corresponding to it. 

For rotating the cryptographic rotors 19 and thus varying the connections between the various pairs of lamps 13 

and switches 17, the plunger 38 is depressed, stirrup 40 S5 

is rotated about its pivots and the members 53A, etc., 

moved. A pawl 58 will normally ride on a rim 57 of a rotor, and, under these conditions, its associated cam face 55 cannot enter a ratchet depression to step an adjoining rotor notwithstanding the urging of its spring 54. 60 As soon, however, as a pawl falls into a pawl notch 550 

it and its cam member move upwardly somewhat and 

toward the rotors and the latter engages a ratchet depression. Then, on movement of stirrup 40, the rotor in 

question is stepped. It will be noticed that, in view of 65 the manner in which tang 59 of device 53A underlies 

device 53B, etc., device 53A cannot move upwardly un- less device 53B has so moved. The pawl member of device 53D rises on each operation of stirrup 40, as it drops over shoulder 58' of member 60'. The result is that 70 rotor 19E steps each time the stirrup 40 moves, rotor 19D 

steps once for each revolution of 19E, 19C steps once for 

each revolution of 190, etc. 

It is, in other words, the cam face 55 engaged in a 

peripheral slot 56 and impelled by rotary motion im- 715 

4 

parted to it by plunger 38-39 which actually serves to 

step the rotor. The cam face cannot, however, enter into one of the notches until the cooperating pawl enters an auxiliary notch 550. , Whenever a cam 55 drops into a notch 56, and the 

movement of the plunger 39 is completed, the corresponding rotor 19 is moved one step. This re-arranges the con- nections through the rotors and connects different pairs 

of lamps 13A, etc., together. Counter 30 is moved one numeral because follower 42 is depressed by cam 41 and 

spring returned. Detent 47 prevents overstepping of the 

rotors 19 because teeth 51 enter notches in rotors 19. 

A detailed description of the operation of the device as an authentograph for insuring the authenticity of a mes- sage or a signal will now be given. Assuming that agreement has been previously reached by the two parties con- cerned as to the wiring of the several rotors and their 

arrangement in the device, the counter is set to zero, and 

switch 23 is closed by snapping handle 24. Plunger 39 

is then depressed, opening switches 21 and 22 and closing 

switch 25. This movement moves counter 30 one position forward and also one or more rotors 19 one step. 

The following circuit is then established: Source 10, line 

11, line llA, closed switch 23, closed switch 25, line 20, 

thence through the rotor system to whichever lamp happens to be paired with lamp 13E at the moment. Suppose it to be K. The circuit to lamp 13E is at this time 

open at switch 22 so that lamp E is not illuminated but 

only the lamp corresponding to its enciphered equivalent, 

namely K. The letter which is thus paired with 13E 

becomes an authenticator, which will, of course, be duplicated on a machine similarly set to the same key. 

Now suppose that the device is being used to authenticate a plain-language message sent from station A to station B. Having transmitted the message, station A operates its device and finds the authenticating letter to be K, 

for example. This letter is transmitted as the authentication; station B, operating its device, finds that K is correct 

and hence is warranted in its belief that the message comes from an authorized source. Upon the next authentication, the letter will be different, since one or more of 

the rotors will have been advanced on the operation of 

the plunger 38. 

To remove the rotors 19, cover 27 is opened, latch 34 

moved from the upright position of Figure 5 to the horizontal position of Figure 6 which allows cam 35 to enter 

the corresponding groove in stationary cam 36. The 

compression on the rotor assembly is relieved and, when 

pin 30 is removed, the rotors can be readily lifted out. 

To replace the rotors they are merely set in their approximate positions, pin 30 pushed through wall 26A up to its 

head 31, and latch 34 raised. In the preferred embodiment, the latch, when lowered, extends beyond the end 

of wall 26A. It thus prevents the closing of the rear cover 27. Since the back cover should normally be 

closed, the feature mentioned serves to assure that the 

latch will be up and the roto-reflector assembly properly 

compressed. 

The modification of Figure 8 includes a viewing panel 

60, similar in appearance to the viewing panel and keyboard 14 of Figure 2 and similarly secured to the ma- chine by screws, as 60'. In place of push buttons 18, 

however, viewing panel 60 is provided with contacts only, as 61. These contacts, as shown, consist merely of small 

circular elements of conducting material all connected by a common return wire 12 to the battery 10. With ref- erence to Figure 7, contacts 61 may be considered as replacing switches 17A, 17E, etc. In place of the push 

buttons 18, a stylus 62 is provided and this may be con- sidered to be connected to conductor 11 of Figure 7. 

Encipherment or decipherment is accomplished by making contact between stylus 62 and a desired contact 61 on panel 60. 

The above description is in specific terms, but it is to 

be understood that the invention is not limited to the 
REF ID:A36296B 

2,877,585 

5 

precise structures and circuits shown and described. In· 

stead, for the true scope of the invention, reference should 

be had to the appended claims. 

I claim: 

1. In a cryptograph having relatively rotatable electric 5 

switches arranged in cascade therein, a plunger arranged 

for manual operation, means associated with said plunger 

and cooperating upon depression thereof with one of said 

electric switches for angularly displacing the same, means 

associated with said plunger and cooperating upon depres- 10 

sion thereof with another electric switch for angularly 

displacing the same after a predetermined angular displacement of said first mentioned switch, and a brake operable by said plunger through a lost-motion connection 

for preventing more than a desired angular displacement 15 

of any switch. 

2. The combination with a cryptographic ·device having 

a plurality of electrical inputs for the characters to be 

enciphered, a plurality of electrical outputs for the enciphered equivalents of said characters, a viewing panel 20 

including a lamp for each character, a switch associated 

with each lamp and with a source of current, and a plurality of circuits each including said source, one of said 

switches, a lamp associated therewith, an input corresponding to the character represented by said lamp, and 25 

a lamp corresponding to the output associated with the 

last mentioned input, whereby the closing of one of said 

switches will light a lamp representing a character to be 

enciphered and a lamp representing the enciphered equivalent of said character. 30 

3. In a keyboard for a device of the character described, a switch for each character which may be utilized, 

a push button extending through the keyboard and adapted upon depression to close a switch, an indicator for each 

character which may be utilized, each of said indicators 35 

being adjacent to one of said push buttons, and means for 

connecting said indicators and said switches whereby depression of a push button will energize the indicator adjacent thereto and another indicator to show the enciphered character. 40 

4. In a device of the character described utilizing rotors 

having ratchet depressions in the periphery thereof and 

a pawl notch, means for stepping the rotors including a 

stirrup having a limited rotary movement, means for normally holding said stirrup in an inoperative condition, a 45 

plurality of cam-and-pawl devices carried by said stirrup, 

a cam being adapted for cooperation with a ratchet depression of a rotor and a pawl being adapted for cooperation with a pawl notch of another rotor, means for mov- 60 ing said stirrup, means dependent upon said movement 

6 

for causing a cam of a cam-and-pawl device to cooperate 

with a ratchet depression of a rotor, and means for preventing another cam from cooperating with a ratchet 

depression of another rotor unless the pawl of said last 

mentioned cam-and-pawl device is also cooperating with 

a pawl notch. 

5. The invention of claim 4, further characterized by 

means including detent teeth dependent upon movement 

of said stirrup for moving into engagement with ratchet 

depressions of the rotors, thereby to prevent overstepping 

thereof. 

6. The invention of claim 4, further characterized by 

spring detents adapted to rest in the ratchet depressions 

of the rotors to inhibit the rotation thereof. 

7. In a cryptograph including a source of current, a 

plurality of indicating devices, a normally open switch 

for each said indicating device, a plurality of permutable 

electric paths interconnecting said indicating devices in 

pairs, and means for permuting said paths, two circuits 

closable by closing each said switch, one including said 

source of current, the closed said switch, and the said 

indicating device thereof, and the other including said 

source of current, the closed said switch, one of said permutable paths, and the interconnected said indicating device. 

8. A cryptograph according to claim 7, further characterized by a manually operable switch, and a further 

switch having two operable positions interposed in a selected one of said other circuits alternatively to connect 

in its first position the permutable path of said selected 

circuit to said normally open switch thereof and in its 

second position to connect said permutable path of said 

selected circuit to said manually operable switch, means 

operable by said permutting means for causing said further switch to assume its said second position thereby to 

close an authenticator circuit including said source of 

current, said manually operable switch, said further switch, 

said permutable path of said selected circuit, and the interconnected said indicating device. 

References Cited in the file of this patent 

UNITED STATES PATENTS 

1,096,168 

1,657,411 

1,683,072 

1,705,641 

1,733,886 

1,938,028 

Hebern --------------- May 12, 1914 

Scherbius -------------- Jan. 24, 1928 

Hebern --------------- Sept. 4, 1928 

Korn ------------------ Mar. 19, 1929 

Korn ----------------- Oct. 29, 1929 

Korn ------------------ Dec. 5, 1933