REF ID:A557819 

Patented Mar. 5, 1946 2 395 863 

, ' 

UNITED STATES PATENT OFFICE 

2,395,863 

CRYPTOGRAPHIC DEVICE 

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

Application October 19, 1939, Serial No. 300,212 

19 Claims. (Cl. 35-2) 

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

The invention described herein may be manu- factured and used by or for the Government for 

governmental purposes, without the payment to me of any royalty thereon. 

This invention relates to cryptographic devices 

and has for its object the provision of a handoperated device capable of affording a relatively 

high degree of security without involving the use of_ complicated mechanisms. 

Another object is to provide a device useful in 

cryptographic and cryptanalytic investigations 

requiring the use of sliding alphabets. · The invention is described with reference to 

the accompanying drawings, in which: 

Fig. 1 is a perspective showing one form or em- bodiment of the invention; 

Fig. 2 is a top plan view of another embodiment 

of the invention; 

Fig. 3 is a cross-section taken on the line 3-3 

of Fig. 2; 

Fig. 3a is a fragment of the same section on an enlarged scale showing the T -grip for the guide 

rule in operative position; 

Fig. 4 is a top view oCthe form of invention of 

Fig, 1 showing the guide rule in shifted position; 

Fig, 5 is a top plan view showing another em- bodiment of the invention in which the base is 

composed of separate detachable grooved sec- tions; 

Fig, 6 is a perspective showing one of the 

grooved sections; and 

Fig. 7 is a perspective showing a frame structure 

and sub-base on which said grooved sections may 

be assembled. 

Referring to Fig. 1, in this embodiment the device comprises a base I, on which are horizontally 

fastened a series of cylindrical rods 2, forming a set of channel ways 3, into which character bearing strips 4, may be inserted and slid from left 

to right or vice versa. In the specific embodiment 

disclosed herein the device comprises twenty-five 

such channel ways, but the device is by ;no means limited to this number. The number chosen in 

this embodiment is merely a convenient number, 

and it may be increased or decreased within cer- tain limits in other embodiments without ma- terially departing from the spirit of the invention. 

A rule, or reading guide 5, attached to a reading 

guide slide 6, can be slid to the left or right on a reading guide slide rail 7. End bars 8 and 9, serve as stops against which the reading guide 

5 may be brought at the end of its travel to the 

left or right. To the back of the base I is fastened a hinged support I 0, which can be pulled 

out to support the device in a slanting position as 

it rests upon a table, desk, or other plane surface. 

Or, if the operator prefer8 to lay the device fiat 

upon the table, the rubber feet 11, at the four corners of the bottom of base I will support the 

5 device and keep it from sliding about on the 

table. 

As stated above, into the channel ways 3 there are inserted character strips 4 of paper or other 

suitable material, hereinafter called alphabet 

10 strips, upon which appear sequences of lette:s of 

the alphabet, each sequence being repeated on the strip, and the letters being equidistant from one another throughout. The purpose of the 

duplication of sequence will appear presently. 

15 Th~ letters on the alphabet strips may be in nor- mal order or in disarranged order; if the latter, 

the various alphaoets may or may not be different. Assuming, however, different alphabets are being used, each strip bears an identifying 

llO mark such as a number 14, so that the alphabet 

strips may be inserted into the channel ways 3 

according to some preagreed key. For example, 

in Fig. 1 is shown a set of twenty-five channel 

ways into which twenty-five different 'alphabet 

25 strips 4 have been inserted according to the following key, reading from the top downward: 

14-16-9-6-22-25-23-5-12-24-13-21-

18-1-f-I 7-20--19-15-8:_1f-2-3-10-4 

30 If another embodiment of the device should include more than twenty-five channel ways, additional alphabet strips may be inserted, according 

to a longer key. ' 

Having inserted the alphabet strips into the 

35 channel ways in key order, the device is now ready 

for use either to encipher a plain language message or to decipher a cryptogram which has been 

enciphered by means of the device, alphabets, and 

key shown in Fig. 1. Suppose this plain-text mes- 40 sage is to be enciphered: 

ACCORDING TO AN OFFICIAL REPORT 

FROM MILITARY AUTHORITIES 

Moving the reading guicie 5 to the left, and 

45 bringing it against the left end bar 8, the operator 

proceeds to align, in a column immediately to 

the right of the reading guide, the first twentyfive letters of the message. This i.s most conven- iently done by placing the eraser end of a pencil 

50 upon the successive desired letters as found on the successive alphabet strips 4 from the top 

downwards, and pulling or pushing the alphabet 

strips in their channel ways- toward the reading 

guide so that each strip stops with the proper 

55 letter just to th.e ;right of the right-hand edge of 
REF ID:A557819 

2,395,863 

the reading guide 5. When the alphabet strips are being aligned on the left-hand side of the 

device, as in the above procedure, the operator 

confines his search: for letters to the left-hand 

half of the duplicated sequence on each alphabet 

strip. When all twenty-five alphabet st1ips have been 

aligned as indicated, there is disclosed a multiplicity of columns of letters to the right of the · plain-text column of letters thus aligned. All 

these columns of letters, except one, are col- umns of cipher letters, each column representing a cipher equivalent of the plain-text column. 

The single exception is the column which is the 

twenty-fifth removed from the plain-text column 

set up by the· operator, and is merely a repetition of that plain-text column. One of these 

cipher columns is selected at random and is 

recorded in five-letter groups. The ·reading guide 

5 is useful in this operation, since by placing it 

alongside the column selected, reading of the 

cipher column is facilitated. Suppose that the 

reading guide 5 be moved so that its left-hand 

edge aligns a column of cipher text. As shown 

in Fig. 4, such a column would read as follows: 

SNAFJ LXRJG GVWVA ATVWW PVNUT 

These letters are recorded and constitute the 

cipher letters for the twenty-five plain-text letters. 

The reading guide 5 is now moved to the ex- treme right of the device, up against the rigb,t 

end bar 9; the next twenty-five letters of the 

plain text are aligned against the left edge of the 

reading guide 5. Again a set of columns. of 

cipher letters are disclosed to the left of the 

reading guide. One of these columns is selected 

at random and again a set of twenty-five cipher 

letters representing the second set of twentyfive plain-text letters is recorded. If the mes- sage contains more than fifty letters, the foregoing procedure is repeated until the .entire mes- sage has been enciphered. There is no need to 

indicate to the recipient of the message which 

co1umn is selected for the cipher equivalent of 

each set of twenty-five plain-text letters, as will 

be noted presently. 

To decipher the message, having the alphabets 

and the key according to which they have been 

arranged, the operator merely proceeds as in 

encipherment, aligning the alphabet strips in 

their channel ways so that the first twenty-five 

cipher letters of the cryptogram are in one col- umn. He then examines all the other twentyfive ·columns of letters,· looking for one which 

contains intelligible text throughout its extent 

from top to bottom. There will be one and only one such column, and this will be the plaintext equivalent of the column of cipher text 

set up on the device. The reading guide 5 is 

useful in this search for the plain-text column, as it can readly be moved to scan the successive col- umns from left to right, or from right to left. 

The plain-text column thus found is recorded 

in word lengths and the operator proceeds to i:;et 

up the next twenty-five cipher letters on the 

right-hand side of the device. Again he looks 

for a plain-text column and records it when 

found. He continues this process until the mes- sage has been completely deciphered. 

In the form of invention shown in Fig. 2, the 

device comprises a pair of hinged components 

F-F' of metal, Bakelite or other suitable material and foldable on one another in the manner 

Gf a book.. As here shown, the grooved slideways 3 are formed on the inner faces of the said 

components ·by milling, or in the case where a condensation product such as Bakelite is used, 

may be molded in the material. In the embodiment disclosed there are a total of thirty such 5 slideways, fifte~n in each component, though it 

will be understood that the invention is not limited to any particular number .. It will be noted 

that the slideways are open at their opposite ends 

10 so that the alphabet strips may be readily inserted and freely extended outwardly therefrom as they are slid into different positions in the 

operations of enciphering and deciphering. As 

in other forms of the invention, a T-grip 6 is at115 tached to the guide rule 5 at its end for the purpose of manipulating the rule, and is slidable in 

a channel 20 having therein undercut grooves 21 

and 22 formed laterally along its inside edges. 

The grip 6 is provided with a spring-pressed ele20 ment 23 engaging in bottom groove 2l, and having an oppositely disposed bead 24 engaging in 

the opposite groove 22 whereby the grip 6 is 

maintained under suitable sliding tension in the 

channel 20, and whereby the guide rule 5 is 

25 manipulated transversely in relation to the alphabet strips 4; and the opposite end of the rule 

is adapted to slide freely in a lateral undercut 

groove 25 formed in component F'. The grip 6 

is rigidly secured to the guide rule 5 in the man- 30 ner of a T-square and may be so manipul~ted 

that the rule affords a positive means of obtaining an accurate alignment in column formation 

of the characters on said alphabet strips and in 

varying relations for cryptographic purposes. 

35 This foldable form of device presents a number of 

practical advantages, among which may be men- tioned its compactness and portability; also the 

foldable feature permits exclusion of dust and 

dirt. 

40 While in one form of device here disclosed, cylindrical r.ods are secured to a base at regular 

intervals from one another to form the channel 

ways into which the alphabet strips are inserted, 

it should be understood that any other means -15 may be employed to form the channel ways. 

For ·example, a series of elongated metal strips 

known in the trade as "card holders," used 

ordinarily to hold narrow strips of paper bearing names of mail-box owners in apartment houses, 

50 etc., may 1be used to form the channel ways; 

these card holders may be riveted to the base, or spot welded to it, or attached in any other 

suitable manner. Or as disclosed in connection 

with Fig. 2, the channel ways may be formed 

55 by milling grooves in the base I itself, which 

may be made of molded Bakelite, for example. 

In such case the grooves are made by a rotating cutter which :undercuts at the two edges, 

forming a channel way such as is commonly 

60 found in slide-rules. Figure 6 shows such a sec- tion in the form of a piece of Bakelite or similar 

material. 13, in. which five such channef ways 3 

have been cut. Sections with equal or unequal 

numbers of channel ways may be easily provided 

65 and given identifying' symbols such as letters, 

A,B, C, ... 

In Fig. 7 there is shown a sub-base suitable for use with such sections of channel ways. Thus, 

instead of having all the channel ways on a single 

70 base, as is the case in Fig. 1, the~ sub-base is 

merely made in the form of a fiat surface onto 

which sections of channel ways may be positioned 

and temporarily fixed, so that rearrangements of 

sections can be made according to subsidiary keys. 

75 Referring to Fig. 7, the sub-base la is a plane 
REF ID:A557819 

surface \vhich is r>1'0Vided with an undercut slot 

14, for carrying a sliding clamp 15, provided with a kfititled thumb screw 16, for fastening the clamp 

into position, End bars 8 and 9 elevated above 

the base by sU.pports 11 and back stop ol 8, serve the same purpose as similarly designated end bars 

of Fig, 1. 

btmring thereon alphabetic character sequences 

$d individually movable in said ways; and m~ans 

adjustable transversely of said strips tu facilitate 

the reading of said characters in varying relations 

:s for ·enciphering and deciphering messages. 

5. A cryptographic device comprising ·a base 

having vertically gronved slide-ways formed 

therein; strips bearing thereon alphabetic chs,racter s-equences and individually slidable in said 

10 ways; and means adjustable transvers-ely of said 

strips for facilitating the reading of said characters in varying relations for errciphering ana. de-ciphering messages. 

Using a sub-base such as that shown in Fig. 7, 

with several sections such as that shown in Fig, 6, one method of operation of this embodiment of 

the invention is shown in Fig. 5. In that figure 

there are five sections of 3, 4, 5, 7 and 8 channel 

ways, giving a total of twenty-seven channel ways. 

First, the sections are temporarily fastened to the 

base in the alphabetical order of their identifying 

symbols. Then the twenty-seven alphabet strips 

would be inse1·ted in the twenty-seven consecutive 

channel ways according to the predetermined 

numerical key already referred to above in con- nection with Fig. 1. To encipher a given mes- sage, there would then be a subsidiary or specific 

key, also arranged for in advance by means of an illdicator in the message, which would direct that 

the sections be now placed onto the base in a mixed order, say E-D-A-B-C, as shown in !!5 

Flg. 5. ·The encipherment of a message would 

then proceed exactly as before. In at1other mes- sage, the indicator for the-sectional arrangement 

might be different, say one calling for the sequence of sections D-A-C-E-B. Thus, with 

five sections there could be 120 different arrangements of sections on the base, even though only one set of alphabet strips is employed. The purpose of this is, of course, to increase the keying 

possibilities of the device, and to impart unique- ness to successive messages, without going to the 

trouble of making a complete rearrangement of 

6. A cryptographic device comprising a bas-e 

15 provided with a plurality of channel ways; alphabet beating strips adapted to be individually inserted and aligned in varying relations in said 

ways for cryptographic purposes; and a slidable 

g-uide rule for making excursions trarrsvers-ely 

20 along the channel ways and in relation to said 

strips for enciphering and deciphering messages. 

7. A cryptographic device comprising a base 

having a supporting foot hingedly attached to 

the under surface of said base; a plurality of 

members :fiXed to the obverse surface of the base 

at equidistant intervals to form a plurality of 

channel ways; strips bearing alphabetic se- quences of characters individually slidable in said 

ways; a guide rule adapted to be moved trans30 versely of said strips to facilitate the reading of 

s-elected sequences of characters in varying relations for cryptographic purposes; and stop, mem- bers for the guide rUle disposed at opposite ends 

of said channel ways. 

35 8. A cryptographic device comprising a subbase; interchangeable base-sections having 

grodves formed therein to provide a plurality of 

channel ways; means for removably attaching 

said sections in position on said sub-base to per- all alphabet strips in the set of twenty-five channel ways. 

The many uses of this device, with variable 

alphabets, in crytographic or crypta'nalytic studies 

will be apparent to all skilled in the art and 

nothing further need be said on this score except 

that there has existed for many years a hitherto 

unfulfilled need for a simple device of this type, 

suitable for the insertion of sliding alphabets. 

Changes, modifications and equivalent arrangements are contemplated within the scope of the 

invention as defined by the appended claims. 

I claim: 

1. A cryptographic device comprising a base 

provided with a plurality of horizontal channel 

ways; strips provided with discrete sequences of 

equally spaced alphabetic characters adapted for 

insertion therein and adjustable independently of one another and means for facilitating the reading of said characters in selected columns. 

2. A cryptographic device comprising a base, 

said base being provided with a plurality of vertical channel ways, and individually adjustable 

strips bearing discrete sequences of equally spaced 

alphabetic characters adapted to be slidably inserted therein; and means for facilitating the 

reading of said characters in selected columns 

and in different relations for cryptographic purpases. 

3. A cryptographic device comprising a base 

formed with horizontally grooved slide-ways 

therein; individually adjustable alphabetic strips 

slidable in said ways; and means to facilitate the 

reading of selected alphabetic columns in varying 

relations for cryptographic purposes. 

4. A cryptographic device comprising a base 

formed with grooved slide-ways therein; strips 

40 mit different arrangements of said sections in 

juxtaposed relationship for cryptographic purpases; character bearing strips adapted for slidable insertion in said channel ways; and a slidable guide rUle movable transversely across said 

45 channel ways and in varying relations to said 

strips for enciphering and deciphering messages. 

9. A combination according to 'claim·s in which 

said grooved sections are of the same size and 

contain equal numbers of channel ways. 

liO 10. A combination according to claim 8, in 

which said grooved sections are of different sizes 

and contain unequal numbers of channel ways. 

11. A combination according to claim 8 in 

which stops are provided at the opposite ends of 

55 the channel ways to limit the movement of the 

slide rule at the end of its travel. 

12. A cryptographic device comprising a frame 

structure and including a sub-base formed therein; a series of base-sections having grooves 

60 therein to provide a plurality of channel ways; means for removably attaching said sections on said sub-base to permit different Juxtaposed ar- rangements thereof for cryptographic purposes; 

strips bearing alphabetic sequences of characters 

65 slidable in said ways; and a slidable guide rule 

movable transversely of said strips and alignable 

in varying relations with respect to said characters for enciphering and deciphering messages. 

13. A cryptographic device comprising a frame 

70 structure and including a sub-base therein; 

base-sections grooved to provide a plurality of 

channel ways, said sections having different num- bers of said channel ways and being differentiated from one another by distinguishing sym7G bols; means for detachably securing said sections 
REF ID:A557819 

4 2,8915,863 

on the sub-base to permit different juxtaposed 

arrangements thereof for cryptographic purposes; strips bearing alphabetic sequences of 

characters movable in said channel ways; a guide 

rule slidable transversely of said strips and alignable in varying relations with said characters for 

enciphering and deciphering messages; and stop 

members at oppasite ends of the channel ways to 

limit the movement of the slide rule at the end 

of its travel. 

14. A cryptographic device comprising a multiple base formed of separate sections, said sec- tions being interchangeable with one another to 

permit different juxtaposed arrangements for 

cryptographic purpases; a plurality of channel 

ways in said sections; strips bearing sequences of 

characters and individually slidable in said ways; 

and a guide rule movable transversely of said 

strips and alignable with said characters in varying relations for enciphering and deciphering 

messages. 

15. A cryptographic device including a multiform base composed of separate sections, said sec- tions having grooved slide-ways therein and being intercha.ngeable with one another to permit 

different juxtaposed arrangements for cryptographic purposes; strips slidable in said ways 

and bearing thereon sequences of alphabetic 

characters; and guide means disposed transversely of said strips and movable to facilitate 

alignment Of the characters in varying relations 

for enciphering and deciphering messages. 

16. A cryptographic device compased of hinged 

sections foldable upon one another, said sections 

having grooved slide-ways formed on their inner 

faces; strips slidable in said ways and bearing 

thereon sequences of alphabetic characters; and 

guide means disposed transversely of said strips 

and movable to facilitate alignment of the characters in varying relations for enciphering and 

deciphering messages. 

17. A cryptographic device composed of hinged 

sections foldable upon one another, said sections 

5 being provided on their inner faces with openended slide ways; strips slidable in said ways and 

bearing thereon sequences of alphabetic characters; and a guide rule hinged to fold with said 

sections, said rule being disposed transversely of 

10 said strips and movable to facilitate reading of 

the characters in varying relations for enciphering and deciphering messages. 

18. A cryptographic device comprising a pair 

of hinged components foldable upon one another, 

15 said components being provided on their inner 

faces with open-ended slide ways; a guide rule 

hinged to fold with said components; means operative with one of said components to maintain 

said rule in a position transversely of said strips 

20 and movable to facilitate reading of the characters in column formation and in varying relations for enciphering and deciphering messages; 

and terminal stops to limit the movements of 

said rule at either end of its travel. 

25 19. A cryptographic device comprising hinged 

components foldable upon one another, said com- ponents being provided on their inner faces with a plurality of slide ways; a guide rule hinged to 

fold with said components; a grooved channel 

30 formed along the edge of one of said components 

in parall2lism with the slide ways; means including a spring-tensioned element slidable in said 

channel for operating the said rule while main-

.taining the same in a position transversely of 

35 said strips, said rule being movable to facilitate 

reading of the characters in varying relations and 

in column formation for enciphering and deciphering messages. 

WILLIAM F'. FRIEDMAN. 

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REF ID:A5518 9 

March 5, 1946. 

W. F. FRIEDMAN 

2,395,863 

Filed Oct. i9, 1939 

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March s; 1946. 

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REF ID:A557819 

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CRYPTOGRAPHIC DEVICE 

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REF ID:A557819 

W. F. FRIEDMAN 2,395,863 

CRYPTOGRAPHIC DEVICE 

Filed Oct. 19, 1939 3 Sheets-Sheet 1 

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