US2437255A - Graphic privacy system - Google Patents

Description

March 9, 1948.

J. v. L. HOGAN Er Al.A

GRAPHIC PRIVACY SYSTEM Filed June 4, 194s 3 Sheets-Sheet l &

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ATORNEY March 9, 1948. J. v. I HoGAN'i-rr AL GRAPHIC PRIVACY SYSTEM vFiled June 4, 1943 3 Sheets-Sheet 2 INVENTOR Jail/lv VLJo r M ORNEY March 9, 1948. y.1. v, L. HOGAN E Al.

GRAPHIC PRIVACY SYSTEM Filed June 4, 1943 3 Sheets-Sheet 5 Patented Mar. 9,

UNITED STATES 2.437.255 Acanarino PRIVACY SYSTEM John V. L. Hogan, Forest Hills, and Hugh C. Ressler, Bayside, N. Y., assignors to Faximlle,

Inc., New York, N. Y.,

g Wale a corporation of Dela- Application June 4, 1943, Serial No. 489,654

7 Claims. 1

VThe present invention concerns enciphering and deciphering of graphic material for privacy by automatic machinery.

One object is to provide means for mechanically and automatically enciphering and deciphering graphic material for privacy purposes.

v Another object is to provide an enciphering and deciphering machine in which a very large number of ciphering key combinations are possible.

Still another object is to provide a machine in which the key combinations may be readily changed.

A further object is to provide a machine capable of varying degrees of privacy from a moderate order to a very high order.

A still further object is to provide a. machine for enciphering graphic material in a form particularly Well adapted to facsimile transmission.

These and other objects will be evident from the detailed description of the inventionY given in connection with the various figures of the drawing.

The ciphering loperations to be accomplished by the devices of the present invention consist of four fundamental operations. The first operation is, in effect, dividing the clear subject copy into a number of horizontal strips of predetermined width. The second operation is the transposition of these strips in an order predetermined by the horizontal key selected, which key must be known by both the sender and the receiver of the ciphered subject copy. The third operation consists of dividing the partially enciphered copy (produced by operations 1 and 2) into strips of predetermined width but at right angles to the f'irst dividing operation. The fourth step is the transposition of the resulting strips according to a mutually known key for the vertical randomiz- King of the copy, which' may differ from the key first used. The result of the four operations is a ciphered message which can be delivered to its destination by mail, by courier, by facsimile or otherwise.

Where additional security is required, the sub'- ject copy ciphered as above describedmay be same four operations two or more times. Where a second ciphering isused, it is preferred that the effective dividing of the copy be done along lines which fall midway between the dividing lines used for the first ciphering. Where three successive cipherings are used,the second and third divisions "may each be displaced by one-third of the strip-width, etc.

While theenciphering offthe message in the -manner described above may be carried out by means of cutting the message in strips, assembly in predetermined order, cutting at rightangles and reassembly in another predetermined order 5 and the deciphering may be accomplished by mean-s of a mask which exposes the squares in a predetermined order, the subject of the present application is a machine for carrying out the enciphering and deciphering automatically.

l0 The enciphering and deciphering machine of thepresent invention consists of a drum to which copy to be enciphered or deciphered is attached, a drum carrying photographic paper or film on which the enciphered or deciphered copy is re-` produced and means for projecting the copy from the first drum on to the sensitized material on the second drum strip by strip in a predetermined order. f In particular, both drums are rotated at different speeds and a Strobotron lamp is flashed at predetermined instants whereby stripsv ond drum. The second copy, when developed, is

a positive copy of the original randomized in two dimensions. 4

An additional factor may be added by exposing only a portion of each drum, say one third, at ,I each run, repeating a second and third time to completely cover the field in three runs. A simple mask may be used to accomplish this additional randomizing. The mask is shifted and the key changed, or a new starting point chosen as each portion of thecopy is randomized.

The completely enciphered copy may be-transferred by any suitable means to a receiving point as, for instance, by wire or radio facsimile. At the receiving point the'message may be deciphered by repeating the enciphering process in rereciphered or remutilated by subjecting it to the verse. The same machine above described is suitable for this deciphering.

In the drawing:

Fig. l shows a simple geometrical figure to be transmitted privately and a second figure included to add confusion.

Fig. '2 shows the figures of Fig. 1 partially enciphered.

including a large triangle representing the iigure which it is desired to transmit to a receiving point and a small triangle added to confuse a possible interceptor.

Fig. 2 shows the result of dividing Fig. 1 into eight equal vertical strips and rearranging these strips in a predetermined order. according to a key. Fig. 2 represents a partially enciphered copy. f

Fig. 3 shows the result of dividing the partially enciphered copy of Fig. 2 into eight equal horizontal strips and arranging these strips in a second predetermined order according to a second key. Fig. 3 represents the fully enciphered copy.

'Ihe original copy may be restored by reversing the process, first restoring the original order of horizontal strips and second restoring the order of the vertical strips. It will be noted in the enciphered copy of Fig. 3 that the portions of the small triangle appear as confusing elements of the same character as the portions of the large desired triangle.

Fig. 4 shows a machine, according to the present invention, for enciphering or deciphering graphic COPY.

of predetermined width is projected upon second drum I8 by means of suitable optical system I1. Drum Il is rotated at a substantially constant speed by means of motor I6, while drum I8 is advanced a step at a, time by a stepping device I9. For each position of drum I8 a predetermined section of copy 22 is projected onto drum I8 by means of the high speed flash lamp 5. A sheet of photographic paper or film is attached to the surface of drum I8 which when developed will reproduce copy 22 in randomized strips. Two strips are shown on drum I8 at 29 and 2l.

When drum I8 has completed one revolution and the paper or film developed, a negative randomized strip image of copy 22 is produced. This represents the first step in enciphering the copy. To accomplish the second step, the partially enciphered negative is attached to the surface of drum I turned at right angles to the original position, so that the strips run around the drum. The step by step randomized copying process is carried out with a second photographic paper or nlm on drum I8 and using a second randomizing key. The result when this second paper or filmV is vdeveloped is a copy randomized in two dimensions that is in small squares. This second enciphered copy will be a positive copy which may be transmitted to a receiving point by any well known means as, for instance, by facsimile. Still further privacy may be provided by exposing only a portion of the length of the copy at each revolution of drum I8 and repeating the rotations until the entire drum is covered. A further degree of privacy may be added or substituted for this past process by displacing the second copy by a fraction of a strip width on drum I and repeating the two enciphering steps any desired number of times.

Lamp 5 may be ashed once at some predetermined point during each revolution of drum I and drum I8 stepped once at each revolution, or lamp 5 may be ashed two or more times at each revo- The subject drum I carries on its surface'- graphic copy 22. A longitudinal strip of copy 22 `2 of drum I.

4 lution of drum I,'stepping drum I8 once at each flash to produce an inter1aced" randomizing.

order oi' Momo@ second and may be triggered by means of an electrical impulse. The timer unit 23 may be any well known device for flashing lamp 6 in accordance with electrical impulses fed to it over wires 24, 21 and 29. Electrical impulses spaced corresponding to the desired strip width are generated by tone wheel 3 attached to shaft The number of teeth on tone wheel 8 correspond to the number of strips to be produced from copy 22. Magnet 4 generates the tone wheel impulses which are fed to timer 23 over wire 24. Impulses from tone wheel 3, however, are not passed to lamp 5 unless the circuits thru leads 21 and 29 are completed. The sequence of flashing of lamp 5 is controlled by the circuits connected to these leads 21 and 29.

On the same shaft with motor I6, driving drum I, are mounted a commutator I4 and collector rings 6, 1, 8. 9, etc. There are as many ycommutator segments in I4 as the number of strips into which the copy is to be photographically divided. `Assuming that the circumference of drum I would take subject copy 8" x 8 in size and that adequate privacy would be provided by using V2" strips, there would be 16 commutator segments and 16 collector rings, and 16 impulses per revolution would be generated by tone wheel 3. The commutator I4 has a single stationary contact I5,

and individual stationary contacts i3, I2, IIl I0,

connecting through contact I5 and the appropri,

ate collector ring contacts I3, I2, II, I0, etc. If connection is made to I2, for example, the lamp circuit will be closed when the second strip is opposite the aperture lens I1; if connection is made through Il), the Strobotron circuit will be closed when the fourth strip of the clear subject copy is opposite the lens I1, etc.

Functionally, the rotating switch 4I controls the lamp circuit and the stepping operation of the copying drum I8. This switch has a rotary arm turned continuously by a back-geared motor not shown and sweeping continuously over the series of contacts shown. The third, sixth, ninth, twelfth, etc., contacts are marked 65, 69, 12, 15, etc. Immediately after `each such contacts are contacts marked 66, 10, 13, 16, etc., and all of these contacts are connected together by means of connection 61. After each of these contacts fand before the next of the rst set of contacts are blank interval contacts marked 68, 1I, 14, 11, etc., which are not electrically connected. After the final contact of the rst set of con- Lamps which provide illuminaadvantageous to gear the shaft of the switch 4I to the motor I6. l

'I'he operation of the rotary switch is such that as the arm 80 sweeps over the contacts, it rst closes a lamp selecting circuit from 65' (through a transportation block or set of blocks to be 'described) to some one of the collector ring contacts I3, I2, etc.; this latter contact corresponding to' the particularstrip of the subject copy on drum I which is to be photographed in the first 'or top position on the sensitive paper carried by drum I8. After leaving 65, the arm 80 passes to'contact 66 which actuates the step-motor ISof drum I8, so as to rotate drum I8 through an angle corresponding to one strip; this operation exposesl the second strip of the sensitive paper on drum I8 through the lens I1. Rotary arm 86 next passes across idle contact 68 so allowing suiicient time for all mechanical transients to die down bel fore the next photographing operation.' In some cases the idle periods represented by contacts 66, 1I, etc., may be minimized or eliminated, or merged into contacts 66, 10', etc. reaches contact 69 which is connected to another one of the I3, I2, etc. collector contacts by way of the transposition block or set of blocks, so setting up the lamp circuit to photograph a different key-selected strip from the clear copy on drum I in the second position on drum I8. This cycle is repeated until the rotary .arm 80 has passed over all I6 of the 65, 69, etc. contacts and the drum I8 has rotated through al1 I6 of its positions, with the result that the whole of the subject copy has been photographed upon the sensitive paper mounted on drum I8. The arm 80 then passes to stop-contact 64 which may automatically disconnect power from all parts ,of thel machine andsignal that the operation has been completed by turning on a lamp or buzzer.

A simple form of transposition blocks for providing changes in the'key is shown. They comprise cylinders 30, 42, 46 and 50, carrying numbersof contacts 3|, 43, 41, 5I, etc., placed axially in rows of sixteen, and arranged to'be rotated either by hand orA automaticaly in steps by stepping motors 40, 45, 49 and 53, which may be simple magnetic pawls and ratchets. On one side of the cylinders 30, etc.,'there are sixteen stationary contacts 3|, 43, 41, 5I`, etc., respectively connected to the collector ring contacts I3, I2, II, IIJ, and on the other side are sixteen similar stationary contacts which are connected to contacts 65, 69, 12, 15, etc., of the rotary switch 4I. Within the transposition block there are cross connec-" tions for each position between opposite sets of contacts, so that with transposition block 3l! in its first position, it will beconnected to a predetermined advanced contact on switch 4I. The step control 40, etc., of the vtransposition blocks may be connected to contact 64,so that. the transposition block will be moved forward one step for each revolution of the rotary switch 4I. 'I'his will result in selecting, in accordance .with the connections within the various transposition blocks, the order in which the strips of the subject copy on drum I will be photographed on drum I8. For example, if in the iirst position of drum I (exposing the top strip) and therst position of the transposition block, collector ring contact I6 is connected to rotary switch contact 65, the fourth Arm 80 next strip on drum I will bephotographed into the :rst position on drum I8. In the second position of the transposition block, the twelfth strip on drum I' might be selected for photographing in the first position on drum I8, etc. Thus, the key'of the cipher is changed by rotating the transposition blocks 30, 42, 46, from one step to another, or by substituting another diierently-connected transposition block. Evidently the invention is not limited to the number of transposition blocks used as all four may be combined in one, two or any desired number of composite blocks or they may be further divided.

In order to avoid irregularities in the timing of the lamp 5 such as might result from contact diiculties if the commutator contact I5 alone were `relied upon, it is proposed to use the commutator I4 only to establish the desired circuit corresponding to the strip to be photographed, and to rely upon a sharp impulse from a tone wheel 3-to ignitethe lamp at exactly the instant when the desired strip to be photographed on drum I is centered under lens I1.

The deciphering operation is mechanically and electrically the inverse `of that whichihas been described for` ciphering. 'I'he same transposition blocks are used', but connected reversely, solas to replace the randomized strips upon'rephotographing, into their original positions. The ciphered subject copy is placed on drum I and the resulting clear copy will come from drum I8 (after either two or four operations, according to the mutilation process used in ciphering).

The system of the present invention can be so applied as to give a long term of privacy for graphic material,whether pictorial or textual. The only means of breaking the system would appear to be the tedious piecing together of the small square elements, Since these elements are identical in size and shape, their contours offer no clues for their reassembling. If they 'are made sufficiently small in relation to the character of subject copy, the time required for their assembly should be quite substantial.

The limitation of the system in term of privacy appears to be determined principally by the mechanical and optical precision that canA be built into the ciphering and deciphering machine; it

is proposed. that by using the tone wheel and 'po-y sitioning stops of relatively large radius, a satisfactorilyhi'gh degree of mechanical' precision can be had Without too great diiiiculty.

The speed of operation of the system is not too strictly limited'. If half-inch strips, for example, gave adequate privacyfit is possible to make the sixteen photographic exposures for each operation, in less than sixteen secondal and allowing two minutes each for developing, washing and blotting the photographs and replacing them on drum I, the enciphered message is produced in less than five minutes for a single cross mutilation land in less than ten minutes for a double cross mutilation. This relatively short time required for enclphering or decipheringv is made possible of strips and number of photographingoperations, the term of privacy can be extended by givmay be shown as a series of dots'or dashes, thaty continental outlines or other identifying characingattention to the character of the original clear subject copy.v For example, contour lines ters may be omitted and the bench mark and overlay principle applied, and also that the clear multiples of 90 degrees.

-for the copy to be transmitted, and filling the excess .area with similar graphic material having no significance. These and similar expedients would incr-ease the difficulty of breaking the ciphered message byattempting to solve it as a picture puzzle, and thus increase the term of privacy. (To date, no other way of breaking the cipher has been discovered.)

A further element of complexity, based on the same principle of automatically randomizing the positions of equal-sized and identically shaped elements, may comprehend e, series of operations in which the subject copy is processed three times at angles of 60. This would result in the randomizing of a large number of equilateral triangles, rather than squares, but, while the process would generaly follow the square-element method outlined in the foregoing, the machine involved would be considerably more complicated. It is believed that adequate privacy can be obtained by the square method without introducing the complications inherent in dividing the clear copy into triangular or hexagonal units,

Fig. shows a modified optical system which may be substituted for the optical system I1 of Fig. 4 in order tr.- transfer graphic material from drum I to drum I8 a small square at a time instead of in strips. This optical system oi' Fig. 5 includes suitable lenses 8i and 82 mounted in lens tube 89 for projecting a predetermined small square area 98 from drum I to a corresponding square area 99 on'drum I8. Drums I and I8 are rotated as in Fig. 4 and optical system 8 I-82-89 is moved along the axial direction of drums I and I8 by suitable means as, for instance, motor 85 and gear 94 driving gears 92 and 93 attached to lead screws 90 and- 9I. Lens assembly 8I-82-89 is mounted on lead screws 98 and 9| and is hence moved back and forth in accordance with the energizing of motor 95, Motor 9 5' is energized over leads 96-91 from a contact or contacts as contact 63 on rotary switch 4I. Thus the motions of lens system 8I-82--89 and drums I and I8 permit randomizing the copying of vmaterial from drum I on drum I8 a square at a time in a predetermined sequence. A circumferential strip on the drums may be copied with the squares randomized within the strip, the lens system shifted the width of a strip, and the process repeated until the entire copy is transferred.

A further element of randomizing may be added by the use of means for rotating the squares being transferred by varying integral This may be accomplished. for instance, by means of the totally refleeting 90-4545 prism 83 which is included in the optical path between drums I and I8. This is a wel1 known optical device which rotates the image by an amount equal to twice the physical rotation of the prism. Thus the orientation of the material within a square may be randomized, Prism 83 may be rotated by any suitable means as, for instance, motor 88, gear 85 attached to the shaft of motor 86 and ring gear 84 attached to lens tube 89 carrying prism 83. The exact positioning of prism 83 at angular positions which are integral multiples of 45 degrees may be insured by detent operating on a notch in the side of ring gear 84 and at a relatively long radius for high accuracy. Motor 88 may be energized also from apoint on rotary switch 4I thru leads 81-88. Hence, with the machine ofFig. 4 as modiiied in Fig. 5, is capable of dividing copy into a large number of squares in which the image within the individual squares is rotated by 0, 90. or 270 degrees and in which the location of the squares is randomized within any circumferential strip. Complete randomization oi the p0- sitions of the squares may be accomplished by moving. either drum I or drum I8 along its axis by predetermined amounts during the copying process.

Any degree of privacy may be attained by repeating the randomizing process with the copi' randomized in a previous operation displaced alongdrum I by a predetermined fraction oi a square width. For instance, the randomizlng may be carried out three times with the partially enciphered copy displaced one-third and two-thirds of a square width for the second and third passes respectively.

Further privacy may be attained using any given degree of randomizing by special treatment of the copy to be enciphered. One very effective method of preparation is to use dotted lines on the original copy, so that no continuous lines appear at the edges of the squares to assist in matching. Preparation of the copy so that only one dot appears in each square and especially if this one dot is made to appear at the center of ths square provides enciphered copy which is impossible of breaking" within moderate period of privacy.

The machines described above have been explained as applied to the enciphering process. The enciphered copy is transmitted to a receiving point by facsimile, messenger or other suitable means. The received copy may be deciphered on the same machine used for enclphering, by inverting the order of randomizing. y

While one embodiment of the present invention with a few modifications has been shown and described, many modifications are possible within the spirit and scope of the invention, as set forth in the appended claims.

What is claimed is:

1. In an enciphering device for graphic materia1 privacy, the combination of, means for reproducing the original graphic'material in strips mixed in a predetermined manner, and means for determining the order of mixing to form an enciphered copy.

2. In an enciphering device for graphic material privacy, the combination of, means for reproducing the original graphic material in squares mixed ina predetermined manner, and means forv determining the order `of mixing t0 form an enciphered copy.

3. In an enciphering device for graphic material privacy, the combination of, nieans for reproducing substantially square area portions of said graphic material, means for rotating predetermined squares by predetermined amounts, and means for mixing the rotated and unrotated squares in predetermined order to form an enciphered copy.

4. In an enciphering device for graphic material privacy, the combination of', a drum for carrying copy to be enciphered, a drum for receiving enciphered copy, an optical system and light source for photographically transferring the copy from the first said drum to the second said drum a. portion at a time, means for rotating said drums, and means for energizing said light source when said drums are in various predetermined relativepositions for forming an enciphered copi1 on the second said drum.

5. In an enciphering device for graphic material privacy,V the combination of. a drum for carrying copy to be enciphered, a drum for receiving enciphered copy, an optical system and llight source for photographically transferring the copy from the first said drum to the second said drum a portion at a time, means for rotating said drums, and an interchangeable key-block for energizing said light source when said drums are in various predetermined relative positions for forming an enciphered copy on the second said drum.

6. In an encipherlng device for privacy of graphic material, the combination of, means for holding original copy to be enciphered, means for holding a photo-sensitive sheet to receive an enciphered copy, an optical system for projecting a. small square area from the original copy to the Vphoto-sensitive sheet, a high speed flash Ylamp for illuminating said small area of copy,

means for moving the original copy, photo-sensitive sheet, and optical system thru a plurality. of relative positions to scan the original copy, and means for flashing said lamp at predetermined relative positions to form an enciphered copy of said original on said photo-sensitive sheet. 7. In an enciphering device for privacy preparation of graphic material, the combination oi', means for holding original copy to be enciphered, means for holding a photo-sensitive sheet to receive an enciphered copy. an optical system in- REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,855,370 Trenor Apr. 26, 1932 D. 29,195 Standing Aug. 9, 1898 156,851 Joseph Nov. 17, 1874 280,878 Stranders July 10, 1883 '2,078,646 Treinis Apr. 27, 1937 1,379,905 Down May 31, 1921 2,089,632 Watson Aug. 10, 1937 1,383,097 Gibson June 28, 1921 FOREIGN PATENTS Number Country Date 7 ,280 Great Britain e 1913 OTHER REFERENCES Websters 1939 Unabridged Dictionary under Random pages 2059 and 2060.

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