US2458406A - Ciphering and checking device - Google Patents

Description

H. J. NICHOLS CIPHERING AND CHECKINGDEVICE Jan. 4, 1949.

Filed Sept. 28, 1945 Tape Punch 5 Sheets-Sheet 1 Translator No. 2

Translator Cyphering Uni? Line No.4

lu h C n U P 8 D. O

v17/ v v INVENTOR Hal /7 J. Nichols BY M7 @TORNEYS Jan. 4, 1949. H. J. NICHOLS CIPHERING AND CHECKING DEVICE 5 Sheets-Sheet 2 Filed Sept. 28, 1945 INVENTOR 1'71 J. Nichols Jan. 4, 1949.

Filed Sept. 28, 1945 H. J. NICHOLS CIPHERING' AND CHECKING DEVICE 5 Sheets-Sheet 3 I25 '5 a 3 1; I24

5 I I A23 INVENTOR 4 Jan. 4, 1949. H. J. NICHOLS 2,458,406

' CIPHERING AND CHECKING DEVICE 5 Sheets-Sheet 4 v FiledSept. 28 1945 J M S /V m m M aw Nu m /6 Wm; M 7 1 1 w 7 T u H W m U! I l W i I l n E r .F 2 m M Jan. 4, 1949. H. J. NICHOLS 0 CIPHERING AND CHECKING DEVICE I I Filed Sept 28, 1945 5 Sheets-Shet 5 IIIIH'EIE Ill" INVENTOR Patented Jan. 4, 1949 ,isact STATES ATNT orrlce orrnaamo AND CHECKING DEVICE Harry J. Nichols, New York, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application September 28, 1945, Serial No. 619,222

3 Claims.

This invention relates to code and cipher systems, and more in particular to systems wherein language messages are translated automatically to and from a coded or ciphered form.

For some purposes, the terms code and cipher have been used interchangeably, but this has led to some confusion. For convenience, the term code is here used to designate a system such as the Baudot code, where each of the letters of the alphabet is represented by a specific signal with the same signal being used for any specific letter each time that that letter appears; and, the term cipher is here used to designate a system of secret communication where t ere is a substitution of characters or other effect whereby, for example, a spec fic letter of the alphabet is not represented by the same signal each time that that letter appears. In the illustrative embodiments of the invention, a coded message may be translated into an irregular chain cipher which is a cipher system where the ciphering effect is changed constantly during the ciphering of a message. Normally the cipher key is incoherent and, for all practica1 purposes. the cipher herein explained is an endless chain cipher wherein the cipher key need not be repeated during the length of the normal message.

An object of this invention is to provide a simple and versatile code and c pher system which will code and decode as well as encipher and decipher language messages in a rapid and dependable manner. A further object is to provide for the systematic or monsystematic coding of messages with simple apparatus. A still further object is to provide apparatus for carrying out the above which is compact and sturdy in construction, inexpensive to manufacture and maintain, and which is adaptable to many uses without material changes in construction. A still further object is to provide apparatus of the above nature wherein the cipher system can be easil changed or annulled. Theseand other objects will be in part obvious and in part pointed out below.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts and in the several steps and relation and order of each of the same to one or more of the others, all as will be illustratively described herein, and the scope of the ap- 2 plication of which will be indicated in the following claims.

In the drawings:

Figure 1 is a partially schematic showing of a system representing one embodiment of the invention;

Figure 2 is a partially schematic wiring diagram representing the coding and ciphering arrangement of the embodiment of Figure 1;

Figure 3 is a plan View of the ciphering arrangement of Figure 1 with certain parts broken away;

Figure 4 is a horizontal section showing mechanism for changing the cipher key manually;

Figure 5 is a sectional view on the line 55 of F gure 3;

Figure 6 is a sectional view on the line 6-6 of Figure 5;

Figure 7 is a perspective view of a single cipher disc; and I Figure 8 is a partially schematic view representing one manner of changing the cipher key automatically.

In the illustrative embodiment of the invention represented in Figure 1, a typewrlting, signal-transmitting and signabreceiving station is represented. This station includes: two electric typewriters I and 2 which are each shown as being a commercially known form of electrically operated typewriter and which are designated Typwr. No. 1 and Typwr. No. 2, respectively; two translators 3 and l designated Translator No. 1 and "Translator No. 2, respectively, and associated with the respective typewriters; a tape reader 5 which is of the type disclosed in my coending application Serial No. 552,991, filed September '7, 1944, entitled Tape reader, and which is for the purpose of producing electric signals in accordance with a coded message punched in a tape; two tape punches 5 and l, designated Tape punch No. l and Tape punch No. 2, respectively, and each of the type disclosed in my co-pending application Serial No. 561,179, filed October 31, 1944, entitled Tape punch, Patent No. 2,432,787, dated December 16, 1947, each tape punch being for the purpose of punching coded or ciphered messages in tape in accordance with electric signals received from the typewriter or from another source; a ciphering unit 8 of the type shown in Figures 3 to '7,

' closed.

inclusive, and designated Ciphering unit; and, electrical wires and switches connecting the various units of the system and here represented schematically by lines and arrows.

Typewriters l and Z and translators 3 and 6 are interconnected so as to form a system of the type disclosed in United States Patent No. 2,307,153 and reference may be had to that patent for a detailed disclosure of this portion of the present system and for the details of construction of the typewriters and translators. It should. be, noted. that each of the typewriters includes a permutation unit, and the pressing of one of the typewriter keys causes the corresponding character to be typed b the typewriter and also causes the permutation unit to produce a set of signal impulses representing the character of the key pressed. These signal impulses are in accordance with the Bandot code. and constitute the coded message which is, transmitted over multi-conductor cables to other elements of the system in a manner discussed morefully below.

Each of the translator units is adapted to receive signal impulses representing such a coded message and to translate eaclr'set of signal iropulses into a designation of a particular key on the typewriter associated with that translator. That is, the set of signal impulses representing a character in accordance with the Baudot code is received by the translator, and these impulses are translated by a series of individually movable cascade-arranged switch elements, whereby one chain or cascade only of. the switch el-ementsis The closing of the chain or cascade of switches completes a circuit to the proper hey solenoid of the typewriter so as to cause. the typewriter to type the character represented by the set of signal impulses.

In accordance with the present invention, the message. is translatedinto a. coded message. for example, in accordance with the Baudlot code. and then enciphering isproduced by superimposing the effect of cipher-signal impulses. upon those of. the coded message. In this way some or all of thesets of code signal impulses. are changed to other permutations so that,.in terms of the Baudot code. they represent characters other than the characters which they originally represented. Thus, the original language mes sage is translated into signals of the Baudot code in accordance with the usual code system, and thereafter the coded message resulting from the code signals is altered so as to produce, in effect. afurther substitution or one Baudot code element for another. However, this second substitution. is not produced in the usual way, but is produced in accordance with an. additive. and subtractive system, whereby certain of the code elements are changed; by onev or the other of alternative transformations, Whereas others are not.

Illustratively; the system is operated in accordance with a live-unit Baudot' code wherein the various letters of the alphabet are represented by a five-place binary code of signals. Each of the typewriters i and 2 is capable of typing a language message with the keys being actuated individually by hand or by lrey solenoids. The key solenoids may be energized fro A a translator, such as 3 and i, which receives the coded message and completes the proper circuits to energizethe respective key solenoids on the typewriter; Furthermore; when the typewriter is a remote station.

operated, it may produce the message in coded form through the permutation unit in its base. Tape reader 5 is adapted to receive a tape which is punched with a coded message, and in turn the tape reader produces the message in the coded form, and this message from the tape reader may be transmitted to one of the translators 3 or 4 or it may be transmitted elsewhere.

Each of the tape punches is adapted to receive the coded message, for example, from one of the typewriters or irom the tape reader, and the tape punch produces a punched tape having holes therein corresponding to the coded mes sage; this punched tape being of the same type asthat which is used to operate the tape reader 5.

The ciphering unit 8 also operates in accordance \t'ith a five unit Baudot binary code and it is adapted toreceive the signal-impulse coded messages from either of the typewriters or from the tape reader, or it may receive a message from The ciphering unit in turn enciphers orscrambles the message in accordance with a predetermined sequential transformation or cipher key, producing a new series of signal-impulse signals based upon the signalimpulse coded. message which it receives. The enciphered. signal-impulse message may be utilized at the same or a remote station by a tape punch so as to produce a punched tape of the message in cipher, or by a translator and its typewriter to type the message in cipher.

When messages. are transmitted. in ciphered form, it is desirable that the characters be dividedinto equal groups regardless of the number oi characters. in the words of the message. Illustratively, the characters are divided into code groups of five characters per group with the groups separated automatically by spaces, which the preferred form for so-called coded telegraphic messages. The basic coding and enciphering systems include the designation of all oi: the letters of the alphabet, and the spacings between the words of the message, and the auxiliary functions, by code characters; and when the message-is enciphered, all of these code characters areenciphered. However, during the cod ing and enciphering operation, the characters are counted automatically and the telegraphic code character for a space is inserted after each fifth character. The enciphered message then comprises code groups of five enciphered characters each separated by an unciphered telegraphic space character. Thus, if more or less than five characters appear in a group, it is apparent that a fault has occurred either by the omission of. a character or characters or by the insertion of extra characters. In this Way the remainder of the. enciphered or coded message can be translated, and the group where the fault appears can be deciphered or translated separately.

The. dividing of the coded or enciphered message into five-character groups also aids when the message is to be read manually, as for example, in transmitting it over a telegraph line. It has been found as a practical matter that an operator can transmit or receive characters in groups of five even though the characters are incoherent; Furthermore, the hiding of the word division aids in preventing deciphering by unauthorized persons, and yet the division of the characters into groups gives the benefits of a broken. chain of characters. Under some cir cumstances it is desirable to omit the grouping of the characters and yet to continue the coding or ciphering operations in the usual manner. With the illustrative coding and ciphering system, it is possible to produce a coded or enciphered message having the characters in groups or in an unbroken chain, depending upon which is desired.

In Figure l the heavy lines having arrows thereon indicate a particular operating condition for the system which is used to explain the operation; the light lines with arrows thereon represent alternative operating arrangements, all as outlined below. It is assumed that tape reader 5 is readin a tape 9 having a straight language message punched therein in accordance with the Baudot code. For purposes of better understanding, a portion of the tape is shown enlarged and with the language message typed along the edge of the tape. Tape reader 5 transmits the signal-impulse code message to translator 3 over a five-channel electric circuit represented by line Ill, and translator 3 closes the circuits of the proper key solenoids through wires represented by line H to cause typewriter I to type the language message which is being read by the tape reader. This message is typed on a sheet l2, a section of the sheet with the message thereon being enlarged in the insert at the right of the typewriter. The electric-impulse code message from tape reader 5 is also supplied to tape punch 6 through five-channel circuits represented by line l3, and the tape punch reproduces the punched message on a tape 14 a portion of which is shown enlarged in the insert below the tape punch; thus, tape M is a reproduction of the original tape 9. Simultaneously the signal-impulse code message from tape reader 5 is transmitted to ciphering unit 8 through a five-channel circuit represented by line 15.

As explained more fully below, 'ciphering unit 8 enciphers the coded message superimposing onto the original signal-impulse code message a ciphering efiect which is the signal-impulse code equivalent of a predetermined incoherent language message, and the resulting signal-impulse enciphered message is transmitted through a five-channel line l6 to tape punch 1. The signalimpulse enciphered message is also transmitted through a five-channel line I65 to translator 4 which controls typewriter 2 through wires indicated by line H36 so that the typewriter types the enciphered message.

The operation of the ciphering unit will now be explained using the five-unit Baudot code with thirty-two character symbols to represent the twenty-six letters of the English alphabet and six added symbols, as for example, numerals 2 to 7 inclusive, which represent non-alphabetic symbols or functions such as Space, Carriage Return, Letters, Figures, etc. Thus, each of the thirty-two language characters is represented by a combination of five signal elements of two characteristics, that is, on and off or plus and minus current impulses. The following Table No. 1 represents these thirty-two characters with the five signal elements for each character symbol represented opposite the respective language characters, the asterisk representing "on or plus and the dash representing off or "minus; and for reasons to be explained more fully below, Table No. 2 ,represents these same character symbols in the same order except that the sign of each signal element in the lefthand row (row #1) has been changed so that each on in this row is now "off and each "ofi' is now "on scrambled or mixed alphabet which results from changing the sign of each signal element in row #1. By this simple procedure, each of the code symbols is afiected and a completely new derived or mixed alphabet is obtained. By changing the signs of the elements in the various rows, it is possible to obtain thirty-two different mixed alphabets. Thus, any one language character may be represented indiscriminately by any other language character, and if the derived mixed alphabet is changed after each signal impulse, there is no determinable relationship between the sequence of characters in the enciphered message and the sequence of characters in the original message. The application of periodicity and probability tables, slide rules, and other devices employed in the cryptanalysis, is thereby defeated. In practice, the sign of one or more of the five signal elements is changed after each character has been enciphered, and the resulting substitution is in accordance with a predetermined but incoherent cipher key; this results in an endless-chain incoherent cipher or a systematic irregular-chain cipher.

In accordance with the illustrative embodiment of the present invention, the code signals of the message to be enciphered are transmitted to a switching device, and if no cipher effect is desired, each code signal remains unchanged and performs its usual functions to indicate its original language character. However, if it is desired that the message be enciphered, a cipher signal is imposed upon each code signal of the message whereby each symbol is changed by reversing the sign of one or more of the signal elements. A message which has been enciphered may be deciphered by imposing the same cipher signals in the same order for a second time upon the respective signals of the message; that is, the deciphering is brought about by again reverslng the signs ofthe same signal elements In Figure 2 a circuit arrangement is illustrated whereby a language message which is produced in code by a permutation unit is enciphered automatically by the ciphering unit 8. This enciphered message may be used in the same manner in which any signal-impulse message is used; that is, the enciphered message may be transmitted over suitable channels to a distant station, or it may be used at the same station to operate an electric typewriter, a tape punch or other devices. Referring particularly to the lower left-hand portion of Figure 2, the switch assembly of a permutation unit (of typewriter I or 20f Figure 1) is operated by an electric typewriter (not shown), and the switch assembly includes five permutation switches I! to 2!, inclusive, and two additional switches 22 and 23. The permutation switches are closed'by the electric typewriter in various combinations to produce the respective code signals for the various language characters written by the typewriter, illustratively, in accordance with the Baudot code. Switch 22 represents an uncoded function, such as the carriage return and has a keysolenoid assembly 24.

Switch 23 has a normally closed switch unit which is in the circuit of a latch-retaining solenoid 25 which is normally energized by a battery 26. Switch 23 is opened momentarily during each revolution of the permutation shaft, with the result that solenoid 25 is deenergized, and this releases a latch 2! so that a spring 28 swings the latch downwardly and releases a cam 29. When cam 29 is released, it turns one revolution during which time it momentarily closes an impulse switch 35 so as to complete a circuit from battery 26 through switch 3!! and thence through such of the permutation switches I! to 22 as are then closed.

The ciphering unit 8 is represented schematically above and to the right of the permutation unit and includes at the top a set of differential relays to 35 and a set of two-position switches 36 to 40, and at the right a set of switches 4! to 45. Differential relays 3! to 35 have two-position switches 46 to 56, respectively, and differentially wound coil assemblies 5! to 55, respectively. Each of the two-position switches 45 to 50 has a normally closed upper switch-unit designated by the svffix -2 and a normally open lo er switchunit designated by the suffix -1. Each of the coil assemblies 53 to 55 comprises a pair of identical differentially-opposed coils which are designated respectively by the suffixes -l and -2; each pair of coils is connected at a common tap to ground, and either or both of the coils may be energized by connecting the appropriate ungrounded coil end or ends to battery 26. When one only of the coils of any particular coil assembly is energized, the armature of the associated switch is attracted with the result that the armature is moved down so that the upper switch unit is opened and the lower switch unit is closed. However, when both coils of any particular coil assembly are energized, the two coils neutralize each other with the result that the switch armature is not attracted and the associated switch units remain in their normal conditions. Thus, the energization of any one coil causes a reversal of the switch armature; that is, for example, it

Thus, identical apparatus operatthelower:coil .5!-2 of coil assembly 5! is energized, switch-unit 46-2, will be opened and switch-unit 46-2'closed and switch-unit 46-! coils 5!-! and 5!-2 are energized, the switch armature will remain in its normal position with switch-unit 46-2 closed and switch-unit opened. On the other hand, if coil 5l-2 is not energized, the energization of coil 5!-! opens switch-unit 46-2 and closes switch-unit 46-!. It is, thus, seen-that the energization or deenergization-of any one coil in any of the coil assemblies' will' cause a reversal of the position of the associated switch armature.

The'two-position switches 36 to 40 are similar to switches-46 to 50 and have normally open lower switch-units designated with the suffix -1 and normally closed upper switch-units designated by the suffix -2. The normally closedswitch-units 46-2 to 56-2 are connected in series with the normally open switch-units 36-! to 40-i, respectively, and the normally open switch-units 46-! to 50-! are connected in series with the normally closed switch units 36-2 to 40-2, respectively. Thus, switch pairs are formed by switches 36 and 46 and 3'! and 4'! etc., wherein the normal position of the two movable blades of a pair results in an open circuit, but the reversal of one of the movable blades of each pair gives a closed circuit through the two switches. The movable blades of switches 45 to 50 are connected to the ungrounded side of battery 26 and the movable blades of switches 36 to 40 are connected, respectively, to the fivechannel circuit lines-designated 56 to 65, Thus, assuming that the movable blades of switches 36. to 40 remain in their normal upper positions, the moving down of the blade of one of switches 46 to 50 connects the battery to the corresponding line to 66. Similarly, assuming that the movable blades of switches 46 to 55 remain in their normal upper positions the moving down of the blade of oneof switches 36 to 45 connects the battery to the corresponding line 56 to 60.

In this embodiment, the lower coils 5!-2 to 55-2 are connected, respectively, to permutation switches" to 2! and the upper coils 5 I to 55-! are' connected, respectively, to switches 4! to '45; Thus, coils 5l-2 to 55-2 are energized in accordance with the code symbols of the various language characters written by the typewriter; whereas, coils 5!-! to 55-! are energized in accordance withwhichever of the particular switches 4! to 45 are closed at the time impulse switch 30 is closed. Switches 4! to 45 are closed in accordance with the cipher key, in the manner outlined above, by cipher discs 5! to which are described more fully below. Cipher discs 6! to 55 are provided with projecting means so that as the discs are rotated in step-by-step fashion, they engage and close their respective switches in accordance with the cipher key.

As indicated above, the closing of impulse switch 35 transmits through the permutation unit the code signals which correspond to the character which is thenbeing written by the typewriter. Furthermore, the closing of the various permutation switches results, in the corresponding coils 5!-2 to 55-2 being energized with the result that-the armatures, or movable blades, of the appropriate switches 45 to 58 are moved down closing the lower switches and connecting the battery to the appropriate lines 56 to 66. However, this is upon the assumption that the upper coils 5!-! to 55-!- are deenergized',

. lay M to line 58.

and the energization of any one of these upper coils causes a reversal of the corresponding switch 45 to Thus, the sign of the code element passing over a particular line 56 to 60 is reversed by the energization of the appropriate coil 5ll to 55-i. In this way if the code element on a particular line from the permutation unit is on or plus, the energization of the corresponding upper coil 5ll to 55-l reverses the sign of that code element to an oil or minus; and similarly, an off or minus" ele-- ment is changed to an on" or :plus" code element. Assume, for example, that switch 4| is closed and switches 42 to 45 remain open; then the closing of impulse switch 36 transmits a signal impulse through such of permutation switches I! to 2! as are then closed and simultaneously sends a signal impulse through switch A! to energize coil El-I. This reverses every code element which passes over the #1 line 56 so that the code alphabet of the above Table No. 1 is changed to the scrambled alphabet of Table No. 2.

A further reversal Of the individual code elements is performed by switches 36 to 40 there being cipher discs '56 to it which move the respective switch blades from their normal upper positions to their lower positions in accordance with a predetermined cipher key. Thus, a preliminary enciphering efiect is imposed onto the coded message by switches ii to 55 and a second enciphering effect is imposed by switches 36 to 40. Switches M to E5 are connected to switch 30 through a manual switch H which may be opened to stop the enciphering operation by these switches. Discs it to may be stopped in a position where all of the movable switch blades are in the upper position so that this cipher effect is not imposed. In this way, the code symhols from the permutation unit are transmitted unciphered over lines 53 to Sit.

As indicated above, the code characters of a message are separated into five-character groups by inserting a space after each fifth code character. The telegraphic code signal for a space is, according to the conventional five-unit code, an impulse over line #3 only, and therefore, means is provided to transmit an impulse over this line (line 58) after each fifth code character. This operation is performed by a circuit shown at the right-hand side of the wiring diagram, there being a switch 12 which. is associated with cipher switches ii to 45 and which is connected at one side through a manual switch E3 to battery 26 and at the other side through a self-opening re- Switch 12 is provided with a disc 75 which closes switch 72 when the character after each fifth character is to be transmitted. Thus, switch ill is closed as the permutation switches it to El and the cipher switches 4! to 45 are being arranged for he transmitting of the sixth code symbol and each fifth code symbol thereafter; i. e., the eleventh, sixteenth, etc. The closing of switch l2 causes an initial impulse to pass through the switch of relay 14 to line 58, and simultaneously, the coil of relay i4 is energized so that the switch of the relay is immediately opened. In this way, a space signal is transmitted over the line prior to the transmitting of the character signal, and the opening of the switch relay i i prevents interference with the code signal which is transmitted by the closing of impulse switch 36.

In a system of this type, it is desirable to proto insure that each code signal is transmit-ted to the receiving station. Accordingly, as shown at the left of the figure, means is provided to give such an automatic check. Thus, a rockable ratchet member I 6 is frictionally held in the central position shown, but it is adapted to rock clockwise to close a switch l! or to rock counterclockwise to close a switch 18. On the righthand side of the ratchet member is a set of ratchet teeth which are engageable by a dog on the end of a swingable armature l9, and similarly, on the left-hand side of the ratchet member is a set of oppositely disposed ratchet teeth which are adapted to be engaged by a dog on a swingable armature 8S. Armature 19 is urged to the upper position as shown by a spring 8|, and it is swung downwardly by the energization of a solenoid 32 which has one side grounded and the other side connected to a normally open switch unitof switch 23 so that solenoid 82 is energized each time that the impulsing solenoid 25 is deenergized. Armature as is urged to its upper position by a spring 83 and it is swung downwardly by the energization of the solenoid 84. Solenoid 84 has one side grounded and has its other side connected through a line 85 to a monitoring unit of the system (such as typewriter #2 in Figure 1), and the arrangement is such that a signal impulse is transmitted over line 85 to energize solenoid $34 each time that a character symbol is received at the monitoring unit.

Each time that armature l9 swings down, its dog engages a tooth on the ratchet member, and when the solenoid 82 is deenergized, spring 8! pulls the armature up and swings the ratchet member counterclockwise the distance of one tooth. Due to the friction mounting of the ratchet member, the ratchet member remains in each new position unti1 moved further. In a similar manner each time that the armature swings downwardly, its dog engages a tooth on the ratchet member, and when the solenoid 84 is deenergized, spring 83 pulls the armature back up and swings the ratchet member clockwise the distance of one tooth. Thus, the alternate energization of solenoids 82 and 84 produces oscillation of the ratchet member from and to the position shown. However, if a signal grou is transmitted which is not received, solenoid 82 is energized more often than is solenoid 84 with the result that the ratchet member is stepped counterclockwise sufficiently to close switch 13. Switch 18 is connected to a bell 86 the other side of which is grounded and when switch 18 is closed the bell is energized and this notifies the operator of the faulty operation. Similarly, switch 11 is connected to a bell 87, the other side of which is rounded, and if a fault occurs in the system so as to cause an extra signal to appear in the receiving station, solenoid 84 is energized more often than is solenoid 82; and, this causes the ratchet member to swing clockwise sufiicient- 1y to close switch Ti so that bell 87 is energized and the operator is notified of this fault.

The construction and operation of switches 36 to 82), ii to 45, and "i2, and the cipher discs which operate these switches will now be discussed with specific reference to Figures 3 to 7. Referring particularly to Figure 3, switches 36 to 4B are shown at the right of the figure in a vertical bank designated at 94 mounted on a bracket 9! together with their cipher discs 66 to Hi. These discs are designated at 92 and are mounted together so as to form a cipher disc assembly which is manually rotatable as a unit about a fiXed asmsgroa vertical shaft 93. At the center of the figure switches GI to 45 and i2 are shown in a similar vertical bank, designated 94 mounted on a bracket and the cipher disc assembly, formed by operating discs (SI to 65 and "i5, is designated at 95 and is rotatably mounted on a vertical shaft 97.

Switches ii to 15 and I2 are operated individually by their cipher discs through levers 98 pivoted at 99 on bracket 95 with each lever having at its left-hand end a fiber disc I98 which engages the movable blade of its switch. When the lever is rocked between the normal position and the position shown, the movable blade is moved to close the switch. Levers 98 are rocked 'by engagement with removable U-shaped clips it! carried by the cipher discs, the construction of which is shown best in Figures and 7. Each disc has sixty peripheral slots I02 (Figure '7) each of which is adapted to carry a removable U-shaped clip llil (Figure 5). Eight discs are mounted together on a hexagonal mandrel I03, these being the cipher discs BI to 65, spacing disc and two additional discs Hi l and IE5. Mandrel m3 also carries at its lower end a ratchet wheel I 96. The discs are clamped on the mandrel by a knurled nut I81 and the hexagonal shape of mandrel 5&3 holds the discs from turning on the mandrel.

Reverting to Figure 3, the cipher disc assembly 936 is rotated step-by-step on its fixed vertical shaft 9'! by a solenoid-operating unit I68. This solenoid-operating unit includes a U -shaped ma netic core I09 which carries a solenoid Ill] and which has a cylindrical air gapin which is rockably mounted an armature III. Armature HI is pivoted at H2 and is urged to the position shown by a tractile spring H3, fixed at one end to core H39 and having its other end extending around and attached to a sleeve H4 carried by the armature shaft. Thus, when solenoid H9 is energized, armature III is rocked counterclockwise against the tension of spring H3; then, when the solenoid is deenergized, spring I I3 rocks the armature back to the position shown.

Pivoted to the lowerend of armature III and in alignment with ratchet Wheel IE5 is a sliding dog M5, the nose end of which is adapted to engage the teeth of the ratchet wheel. The rocking of armature I I l which results from the intermittent energization of solenoid HQ causes dog M5 to slide longitudinally, and the movement is such that each time that the dog is retracted, the end of the dog picks off one tooth of the ratchet wheel. Ehereafter, when solenoid III! is deenergized the armature III is swung back to the position shown and rotates the cipher disc assembly the distance of one tooth. At the left-hand side of the nose of dog H5 is a fixed post I56 and as the dog slides to the position shown, its nose engages post H6 so as to hold the dog into engagement with the ratchet wheel (as shown). When the dog is thus positioned the ratchet wheel and therefore the entire cipher disc assembly is locked in position so that it cannot rotate. The relationship between the nose of dog H5 and the end of levers 98 is such that each time that the cipher disc assembly is stopped, there is a slot I82 directly at the ends of the levers. If the particular slot at the end of a lever carries a clip iGI, the end of the clip engages the lever and swings the lever to the position of the top lever shown thereby swinging the switch blade to the switch-closing position.

Dog H5 carries a pin IIG' which is positioned in the fork of a yoke II! which is pivotally held 12 by a screw H8 and the opposite end of which is operatively engaged with the movable blade, II!) of a two-position switch l-Zil. When blade H9 is engaging contactor I2I (as shown), the circuit to solenoid IIO may be closed, but when the armature rocks into engagement with the other contactor I22, the circuit to this solenoid Ma is open, and further, a keyboard-locking mechanism is energized to lock the keyboard of the transmitting typewriter. Thus, each time the dog reaches its fully retracted position as it oscillates to rotate the cipher disc assembly, switch lift effects the-deenergization ofsolenoid l I El and alsoeffects the locking of the typewriter keyboard.

With apparatus of this type it is desirable: to provide for setting the cipher disc assembly 96 to a predetermined home position at the start of a message; and disc I (Figures 5 and 6) initiates the carrying out of this function automatically. The switch in bank 93 which is operated by'disc 505 is connected in serieswith' a manual homing switch (not shown) to provide a power circuit through switch I20 tosolenoid H6. It' will be noted that disc I95 carries a clip It! in, all of its slots I02 except the slot designated IEl2-I. Slot ifl2-i is the slot whichis at thelever 98 for this disc at the time the disc assembly is in the home position. Thus, when the disc assembly is in any position other than the home position, the switch associated with disc i623 is closed and the closing of the manual homing switch completes a circuit through switch IZdto solenoid I It! so as-to energize the solenoid; the disc assembly is rotated step-bystep as long as the homing switch is held closed or until the disc assembly reaches the home position with slot Ill2-l at the lever 98.

As pointed out above, the cipher key depends upon] which of switches 4| to are closed during the enciphering of the various characters. With this particularset of cipher discs GI to 65, etc., there are sixty slots in each disc and the clips IllI are placed around each disc in a random manner. Thus, starting from the home position, the vertical rows of slots are passed serially stepby-step past the levers 98, and in each stationary position of the cipher discs one (or more) of the levers is rocked to impose the cipher effect in accordance with the cipher key. When it is desirable to change the cipher key, nut I01 is removed and the various discs are turned about-the mandrel to new positions, and the nut is then replaced. For a further changing of the keys, the positions of, the various clips IBI may be changed andclips may beadded or taken away,

Cipher disc assembly 92 is similar to disc as sembly 95 except that the discs 6'6 to 10 are smaller and have only thirty slots. The slots are here designated I2-3- and the clips which are the same as clips Iill are-designated I24; The top of disc assembly 92 carries aplate I25 which is marked to indicate the position of the disc assembly, with relation to a pointer on the stationaryshaft 93, At the base, the disc assembly has a ratchet wheel I26 by which the disc assemby is'rotated. A spring-pressed detent I21 holds the disc assembly from clockwise movement and a springpressed dog I28 has its nose engaging the ratchet wheel and is pivotedat'its opposite end on a lever 29 which is rockably held by a screw I30. Lever IZ9=extends from the front of the machine and is swung counterclockwise from the position shown to causethe nose of the dog I28 to gather a tooth of theratchet wheel; lever I29' is then released,

and a spring I3I returns the elements to their positions shown, and in doing so, advances the disc assembly the angular distance of one tooth which is also the angular distance between adjacent slots I23. The switches of bank 90 are operated by levers I32 which are pivoted at I33 and operate in the same manner as do levers 38. The clips I24 on the discs of the disc assembly 92 are placed random in accordance with the cipher key, and they impose their ciphering efiect as outlined above. In practice the position of disc assembly 92 is changed manually in accordance with a predetermined key so that the ciphering effect imposed by these cipher discs is constant for some period. However, as outlined above, the ciphering effect of switches 4| to 45 and discs BI to 65 is changed after each character has been transmitted so that it repeats its cipher after sixty characters have been enciphered. When desirable, the ciphering effect of disc assembly 92 and its switches may be changed after every sixty characters so that an endless chain cipher is obtained.

In accordance with one embodiment of the invention, the discs of the two cipher disc assemblies 92 and 96 are individually mounted and rotated step-by-step in accordance with a predetermined key. Thus, after each character has been enciphered, one or more of the various cipher discs is moved to the next position. In this way, the cipher key depends upon the position of the clips in the slots on the cipher discs and also upon the key by which the various discs are rotated. In Figure 8, an arrangement is represented schematically for advancing the cipher discs individually. By this arrangement, the advancing of the discs is under the control of a slowly rotating cam assembly, and the rotation is performed by a solenoid assembly. In Figure 8 only a single cipher disc is represented, it being understood that additional discs would involve a duplication of the structure shown. Accordingly, a disc I33 is mounted on a shaft I34, but a friction clutch (not shown) prevents free rotation of the disc. A ratchet wheel I 35 fixed to the disc provides for a step-by-step rotation of the disc by a dog I36 engaging the ratchet wheel. Dog I36 is carried by a lever I 37 which is pivoted at I38 and urged clockwise by a spring I39. A constantly rotating cam I45 is positioned so as .to rock lever I31 counterclockwise against the action of spring I39. At the bottom of the lever a solenoid I4I may be energized to hold the lever against the action of the sring so that the upper end of the lever does not follow the same. Thus, by energizing solenoid MI, the lever remains stationary, but if the solenoid is deenergized during one revolution of cam I48, spring I39 causes the lever to follow the cam so that the dog is retracted and it gathers one tooth on ratchet wheel I35. Upon further rotation of the cam, the cam swings the lever back, andthe cipher disc is rotated the distance of one tooth pitch.

When dog I36 is projected counterclockwise, its nose moves beneath a fixed pin I51 (shown in broken lines) so that the cipher disc is latched in position at the end of each step-by-step movement. Thus, a cipher-disc locking arrangement somewhat similar to that shown in Figures 1 to 7 is provided. In Figure 8 the clips are indicated at I58, the switch lever is indicated at I59, and the two-position switch is indicated at I60. However, the operation is the same as in the embodiment of Figures 1 to 7.

w Solenoid MI is energized by a battery- I42 r i4 through a switch I43, and the switch is new mally open but is closed in accordance with the contour of a cam I44. The contour of cam I44 is such that it closes switch I43 and thereby energizes solenoid -I4I inaccordance with a predetermined key. Thus, at the beginning of a ciphering operation the cipher discs are in a predetermined home position and the cams, including cam I44, are started rotating and they step the cipher discs ahead on shaft I34 in accordance with the contour of the cams. The arrangement is such that one or more of the cipher discs is stepped ahead cyclically. Thus, the cipher efiect is changed after the transmitting of one or more characters. The cipher key may be readily changed by merely changing the cams or by changing the cipher discs.

As indicated above, at the beginning of the ciphering operation, the cipher discs are in a predetermined home position. Accordingly, shaft I34 carries a homing disc I45 which has a tooth I46 which may be engaged by a homing lever I43. Homing lever I I! is spring-urged upwardly to the position shown by a spring I48 and is drawn down to engage tooth I46 by the energization of a solenoid I 19. A similar homing lever I50 is mounted so as to engage a tooth I5! on disc I33. Lever I50 is spring-urged upwardly by a spring I52 and is drawn down by the energization of a solenoid I53. One side of solenoid its is grounded and the other side may be connected through a manual switch I54 to a battery I55 the other side of which is grounded. Similarly, one side of solenoid I53 is grounded, and the other side may be connected through a switch I53 to battery I55. Each of the cipher discs has a similar homing lever and solenoid mechanism and all of the homing solenoids I53 are connected in parallel.

Prior to the beginning of a ciphering operation, switch I55 is closed manually, and cam I40 is positioned so that its flat is engaged by its lever I33,- also, solenoid It! is deenergized with the result that dog I36 is withdrawn from the ratchet wheel; the corresponding dogs on the other cipher discs are also withdrawn. Shaft I 34 is then rotated through a slip clutch (not shown), and this rotation carries each of the cipher discs arounduntil its tooth I5I engages its homing lever I58; the cipher discs then are held even though the shaft is rotated, and the cipher discs are positioned in a predetermined home position. Thereafter, with solenoids still energized, switch I 54 is closed so as to ener ize solenoid I49 and swing homing lever I4? to the position shown. On the next revolution of shaft I 35, tooth I46 engages lever I47, and the rotation of the shaft is stopped. In this way the cipher discs are positioned in a predetermined position on shaft I34 and shaftv I311 is held in a predetermined position. Therefore, all of the cipher discs can be rotated together to give them a predetermined starting position other than the normal home position.

As indicated above, Figure 1 represents an operating condition where the tape reader controls the other elements of the system so that typewriter #1 types a plain language message on a sheet, I2, tape punch #1 produces a punched tape I I which is identical with the tape 5 being read, typewriter #2 types the enciphered. language message on a sheet III), and tape punch #2 punches a tape III bearing the enciphered code message. For purposes of explanation, tape 9 asthma bears in plain language the three words" or the message which appears punched thereinandithis portion of themessage is as follows:

"After encipliering; these three Words of "the message are-Written on sheet lln'by typewriter and punched into tape 'l'H 'intape;punch *#2 asfollows:

It. will be noted that the twelve letters forming the first three words of. the message and the three spaces following these words are enciphered I;

character, can be readily detected. Tape I'H may be read by another tape reader and transmitted over an outgoing signal channelas desired.

As many possible embodiments may be made of the mechanical features of the above invention and as theart herein described might be varied in I various parts, all without departing from the scope of the invention, it is to be understood that all matter hereinabove set forth, or shown in the accompanying drawings is to be interpreted. as illustrative and not in a limiting. sense.

I claim:

1. In ciphering apparatus having means-.for producing successive character codesignals representing a straight language messagev according to a, predetermined combinational-position code system and a first group of contacts each selectively adjustable to an on and an off electrical condition in correspondence to said code signals and a group of differential coderelays each having a first coil corresponding to contacts of said first group of contacts and a second coil corresponding to contacts of a second group of contacts, said first coils being responsive to the electrical condition of the corresponding contacts of said first group of contacts; a second group of contacts corresponding to contacts of said first group and each connected to a corresponding second coil of said code relays for rendering said coil responsive thereto when said second group of contacts are selectively adjusted to 'on and off electrical conditions to produce a signal for each of said character code signals; a series of cipher discs each corresponding to contacts of said second group of contacts and mounted in spaced relation on a rotatable shaft and in spaced relation to contacts of said second-group; a ratchet wheel fixedly mounted on said shaft; actuating devices attachable to and detachable from the periphery of said discs to enable said disc upon rotation to selectively adjust the electrical condition of saidv second group of contacts in a preselected cyclic pattern and means forvrotating said discs in step-by-step fashion, said means including a rotatable solenoid-operated armature resiliently urged againstrotation, a dog .pivotally 16' mountedon said armaturerrom the center thereof- :and extending etherefrom f into urged: engagement with the periphery of said ratohet wheel so that :energization or the solenoid caus'es said :armature to rotatein one-direction and said do'g to engageLthe n'ex-ttooth of the ratchet wheel :and deenergization thereof causes the armature to be rotated in -the other direction and rotate said shaft i an amountcorresponding to the: displacement .of 1 one I tooth of :the ratchet wheel.

., 2. 111 cipheringapparatus five pairs of contacts and a pair of grouping contacts-each having on and-oft electricaliconditionsrepresenting, positive and negative imanifestations; five cipher r-discs, a :ratchetnwheel and a 'grou'ping "disc mounted in spaced rela'tion on acommon shaft;- each "cipher :disc corresponding to one i of '-said-=contact "pairs and-t saidr grouping disc oor-responding -toasaid grouping contacts actuating "devices" attachable to and detachable from the peripheries of said discs for changin'g the electrical condition thereof at presele'cte'd timesduring the rotation'of said discs; means for rotating said discs in =step-bystepifashion; said: means including a rotatable solenoid-operatedzarmature 'spring urged against rotation, a :dog pivotallymoun'ted on said :ar-mature: fromithe centerthereof and extending therefrom :intourged engagement with the periphery cream .ratchet wheel so that energization of the solenoid causesvsaid'iarmature toaro'tate in-one direction and said dog: to: engage the next tooth of-1-the ratchet wheel I and .deenergization thereof .causesthe armature to be rotated in the rather dinectionandrotate .s'aid s'hait an amount corresponding to .a idisplacement et one tooth of the :ratchetzwheel ;a series of pivotally. mounted arms veach:correspondin'g to one of lsaid discs and one of said. .pairs 'of contacts and :having one end eurged toward its=correspondirigdisc and operative -.at;its aother' end. to changer-the electrical condition of. :the corresponding contact pairwhen ro- Ltatedifromxthe disc, said-actuating devices con- ;tacting .the acorres-ponding pivoted farms to "effect rotation of that iarm from the disc immediately :after preselected stepP-by-step operations of the ratchet wheel said' actuating (devices being ariranged on the-periphery of 's'aicl :grouping disc to iclose saidigroupingcontacts upon each fifth manifestation; aitrelay in seriesuwithrfsaid grouping iCOI'itaCtS'. and energized "upon the closing-thereof to open the circuit toits armature.

.i 3.: In .cipheringsapparatus. having a first =line carrying signals corresponding to-the enciphered :signals producediandasecond line. carrying signals corresponding tot-the .enciphered: signals received-by a= monitoring-unit; :a rotatablev ratchet wheel carrying an arm extending therefrom and .havinga first and-a second-series of teeth, each ion. oppositev portions of :the periphery thereof, one

of. said :series being arrangedto effect rotation inonedireot-ion and the otherin the opposite direction; afirst and -asecond solenoidijenergizable from said first and second lines respectively; a first and 1a secondarmature actuated respective- ;ly bywsaidrsolerroids; a firstsdogmounted on the first armature;andwengageable with the teeth of one of -said seriesi whensaid: first solenoid is en- "ergized-and-a-second dog mounted on th'e second armatuneand engageable-with. the teeth of the iother of saidseries when said second :s'olenoid is -energized; a pair of contacts having. ofi and on electrical conditions pontrolled by said arm and qmoun'tedfon eithersideof saidttarm inspaced relation thereto; an indicating device: connected to each; pair of contacts. and operablein accordance 2,458,406 17 with the electrical condition of said contacts; REFERENCES CITED spring members attached to each of said arma" The following references are of record in the tures and operable when the respective solenoids file of this patent. are deenergized to rotate said ratchet wheel to displace said arm a predetermined distance, jal- 5 UNITED STATES PATENTS ternate deenergization of said first and second Number Name t solenoids causing equal and opposite displace- 923,511 Greenbaum June 1, 1909 ment of Said m and consecutive deenergization 1,310,719 Vemam July 22 1919 Of either s d ca sing a closing of the corre- 1,502,376 Damm July 22, 1924 Sponding P f contacts by said arm to operate 10 1,9129% Jipp June 6, 1933 the indicating device connected thereto. 2,351,014 Connery June 13 1944 2,406,023 Locke Aug. 20, 1946 HARRY NICHOLS- 2,406,024 McCann Aug. 20, 1946

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