REF ID:A362663 

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inventor: r'r ledman, 

! ~ t'1 .. ' . ...,, . Invention: i"aosimile enolph3r1ng system 

Serial No.: 

78193 Henry 13. Stauffer 

'.Patent Date: Army Security I.6ency 

May 15' 1951 ~he '•entag~n ,.. Patent No.: '#,ash• 2Cj • 1] • · •-

25525

'- Sl _The .FIH~ FE~ ~F THIRTY DOLLABS has been 

-+'-' received in this application on 

DEPARTMENT OF COMMERCE ?tone re~1uired u. s. PATENT OFFICE ela WASHINGTON. D. C. Commissioner of Patents. 

PO-l62C FINAL FEE AND INDEX FORM COMMERCE OEPA.RTME.NT U. S. PATENT OFFICE 

@'pproved for Release by NSA on 07-22-2014 pursuantto E.O. 1352a 
May 15, 1951 

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REF ID:A362663 

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W. F. FRIEDMAN '" 

FACSIMILE ENCIPHERING SYSTEM 

Filed March 6, 1943 

2,552,548 
REF ID:A362663 

Patented May 15, 1951 2 552 54·g 

' ' 

UNITED 

1 

STATES PATENT 

2,552,548 

FACSIMILE ENCIPHERING SYSTEM 

William F. Friedman, Washington, D. C. 

Application March 6, 1943, Serial No. 478,193 

5 Claims. (Cl. 178-5.ll 

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

OFFICE 

2 

The invention described herein may be manu- Figure 3 is a circuit diagram of the receiver 

factured and used by or for the Government for in block form. 

governmental purposes, without the payment to In the one embodiment of my invention which me of any royalty thereon. has been selected from among others, my device 

The subject matter of this invention is a sys- O is shovm as comprising a transmitter section 

tern for enciphering facsimiles. having a motor I driving shaft 2 carrying transThis invention relates to means for secretly parent drum 3 surrounded by message sheet 4 

communicating information by transmitting a and also carrying transparent drum 5 surrounded 

facsimile of the message in a graphic form of by control sheet 6. Within drums 3 and 5 are any sort such as a writing, type-writing, pie- JO located electric lamps 1 and B which serve as ture, photograph or the like. Secrecy is obtained sources of light and which are energized from a by transmitting a series of impulses caused in source of electricity 9. Opposite lamps 1 and B 

part by the message to be transmitted and in so as to receive a beam of light therefrom and, 

part by a control in graphic form such as any respectively, under the control of message sheet. 

writing, pictm"e or random arrangement of dots 15 4 and control sheet 6, are located light-sensi- or lines. Such a control does not necessarily tive cells 10 and 11 which form parts of cirhave any intelligibility in itself. It operates as cuits including amplifiers I 2 and I 3 and relay a random key. At the receiving end, a dupll- coils 14 and 15. These relays also include mov- cate of this control is employed. This duplicate able contacts 16 and I 7 biased in one direction 

control is moved in synchronism with the move- 20 by springs 18 and 19 and, in the other direction, 

ments of the control at the transmitting end and by coils 14 and 16, respectively, when these coils causes a series of impulses which co-operate with are energized, and engaging one or the other of 

the impulses received from the transmitter, the stationary contacts 20 and 21. Contacts IS, 17, 

interaction between the two series of Impulses 2'0 and 21 form parts of a circuit, including a serving to produce a facsimile of the original 23 source of current 22 and relay coil 23, which, 

message. when energized, attracts movable contact 24 into 

It is an object, therefore, of my invention to engagement with stationary contact 25, over- provfde apparatus comprising a transmission sys- coming the pull of spring 26. Contacts 24 and 

tem including a transmitter section and a re- 25 control a circuit including transmitter 21 

ceiver section. Each of said sections has, as a ;;o having an output element 28, shown as an anpart thereof, an electric circuit including the tenna. 

contacts of a plurality of relays interconnected At the place to which it is desired to transin such a way as to cause a plurality of impulses mlt the intelligence, there is located a receiving 

to circulate in said circuit. In the transmitter system having a receiving element, indicated 

section these impulses represent the combined ;;,1 as an antenna 29, forming part of receiver 

effects due to the message to be transmitted and 30 which is connected into circuit so as to can- to a control element. An impulse can only occur trol relay coil 3 I. This relay also includes mov- in this circuit when both of the relays have not able contact U stressed away from coil 31 by 

moved their contacts to the same position. In spring 33 and co-operating with stationary con- the receiver section these impulses represent 40 tacts 34. Motor 35 drives shaft 36 carrying transthose caused by the original message, since the parent drum 31 surrounded by second control 

impulses due to the control have been removed sheet 38, which is a duplicate of control sheet 

by the use of a duplicate of the control in the 6. Within drum 31 is located electric lamp 39, 

receiver section. energized by a source of electricity 40. OppoFor a further exposition of my invention refer- 45 site lamp 39 so as to receive a beam of light 

ence may be had to the annexed drawings and therefrom under the control of second control 

specification at the end whereof the novel fea- sheet 38, is located Iig·ht-sensitiv-e cell 41 which 

tures of my invention will be specifically pointed forms a part of a circuit including amplifier 42 

out and claimed. and relay coil 43. This relay also i.ncl11des mov- In the drawings: 50 able contact 44 biased in one direction by spring 

Figure 1 is a circuit diagram of the transmit- 45 and, in the other direction, by coil '13, when 

ter with parts designated by blocks bearing a.p- this coil is energized, so as to engage one or propriate labels. the other of stationary contacts 46. Contacts 34 

Figure 2 is a tabulation illustrating the im- and 46 form parts of a circuit including a source 

pulses comprising the intelligence transmitted. 66 of electricity 41 and a relay coil 48. This re-.. 
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REF ID:A362663 

2,552,548 

3 4 

lay includes movable contact 49 stressed away duced in coil 48, which is represented in Figure 2 

:from coil 48 by spring 50 and co-operating with by the line labeled "Message." Following 

stationary contact 51. Contacts 49 and 51 are through the other columns of Figure 2 shows 

parts of a circuit including a source of electricity that when coils 31 and 43 are simultaneously 

52 and coil 53. which is the operating element 6 energized or de-energized, no impulse appears in 

of a facsimile reproducer of any convenient type. coil 48. Likewise, while either coil 31 or 43 is 

The operation of my device is as follows: The energized when the other is de-energized, coil 48 

message.and the.control sheets are in any graphic is energized. The energization of coil 48 causes form such as a writing, printing, drawing, photo- coil 53 to be energized and coil 53 operates a graph or the like. They may be said to consist 10 stylus or other marking mechanism and thus 

of pluralities of spots or elemental parts each of message sheet 4 is reproduced. 

which is either black or white depending upon It will be understood that, whereas the forethe part of the message which it forms. Rela- going. description calls for the transmission of a tive movement is provided bet.ween lamp l and -signal when one only of the coils 14 and i 5 is enermessage sheet 4, between lamp 8 and control sheet lG gized, the apparatus will function just as well and 

6, and between lamp 39 and second control sheet achieve just as great privacy if rearranged 

38 in any convenient manner heretofore used in slightly, as by giving an opposite bias, a normal 

the art of facsimile transmission. This causes closed condition, t.o switch 24-25. In such case, 

the beam of light emitted by each lamp to scan of course, a signal will be transmitted whenever 

every spot or element of the message or control 20 coils 14-15 are in the same condition instead of 

associated with it. In the transmitter this scan- when they are in different conditions. 

ning thus produces a series of impulses in the I claim: 

amplifying circuits through the action of the ligllt 1. Means for secretly transmitting graphic insensitive cells ID and I I. For convenience of de- formation, said means comprising, a message in 

scription, these impu:ses can be said- to be pro- ::!5 graphic form which it is desired to transmit, a duced by black spots in the message or control. scanner arranged to scan and reproduce said 

Thus coils 14 and 15 are· energized every time message as a series of electric impulses of vary- an impulse occurs in the amplifying circuit asso- in3 int€nsity, a screen having vary:ing portions, 

ciated therewith~ The action of the relays con- a .~econd scanner arranged to scan and reproduce 

trolled by these coils produces in the circuit.asso- ;;u the variations of said screen as-a second series of· 

ciated. with them a series of impulses distributed electric impuJses of varying intensity, a relay 

in time as shown in Figure 2 of thecdrawings in connected under the control of said scanner and 

which the term "X".represents an in1pulse. This arranged to be moved by each of said impulses 

figure shows the four possible cases. Thus it will to one of two positions, a second relay connected 

be seen in column 1. that energizing coil I Ii by ;;;; under the control of ·said second scanner and 

message sheet 4 without ener;;izing coil i :l ty·co;1-· arranged to be moved by each of said second imtrol sheet S causes an impulse.in the circuit con·· pulses to one of two positions, an electric circuit 

taining coil 23 and labeled ·"Result" in F'igc.re 2. including parts of said relays and-adapted to be 

This energizes coil 23 and causes transmitter 27 closed only when there is instantaneously an imto emit an impulse. As seen in column 2; when 4lJ pulse in either series but not in the other; a both coils I 4 and 15 are energized no impulse transmitter connected under the control of said 

appears in the circuit containing coil 23. As seen electric circuit so as to emit impulses whenever 

in column 3; energizing coil 15 but not energizing said circuit is closed, a receiver arranged to re- coil 14 causes an impulse in the circuit containing ceive the impulses emitted by said transmitter 

coil 23. Column 4 shows that when no impulse is 45 and having an output comprising a third series 

present in either amplifier 12. or 13 and. conse- of electrical impulses of varying intensity; a quently, neither coil 14 ·nor 15 is energized, no second screen duplicating said· first mentioned 

impulse appears int.he circuit containing coil 23. screen, a third scanner arranged to scan synchroTo put it another way, an impulse only appears nously with the scanning of said second scanner in coil 23 and, therefore, an impulse is only sent 50 and reproduce the variations of said second screen 

out from transmitter 27. when coils ! .!! and 15 are. as a fourth series of electric impulses of varying 

not in the same condition, i. e., are not· simul- intensity, an electromechanical interlock con- taneously energized or de-energized. This is dt!e nected under the control of said third and of said 

to the fact that simultaneous energization or de- fourth series of impulses and arranged to be ener- energization of coils 14 and 15 causes movable. 55 gized whenever an impulse occurs in one of said· 

contacts I 6 and 11 to engage stationary contacts third and fourth series and no impulse occurs 20 and 21, respectively, which are connected to simultaneously in the other of said third· and 

the same side or polarity. of source 22. fourth series; and a recorder connected under the 

The series of impulses emitted by the output control of said interlock and· arranged to operate 

element 2& of transmitter 21 is received by the 60 whenever said interlock is energized and to 

input element 29 of receiver 30. Each· impulse thereby reproduce said message. so received energizes coil 31. Motor 35 produces 2. Means for secretly transmitting~graphic inrelative movement between second· control sheet formation, said means comprising, a message in 

38 and light 39 so that control sheet 38 is scanned graphic form which it is desired· to transmit, a in synchronism with control sheet S. Since sec- 65 scanner arranged·to scan and reproduce said mes- ond control sheet 38 is a duplicate of control sheet sage as a series of electric impulses of varying 

6; coil 43 is energized in synchronism with the intensity, a screen having varying portions, a. energizations of coil 15. Referring again to Fig- second scanner arranged to scan and.reproduce 

ure 2, the line labeled "Result" represents the the variations of said screen as a second ·series-of 

impulses which pass through receiver 30 and ener- 70 electric impulses of varying intensity; an electi·ogize coil 31. while the line labeled "Control" repre- mechanical interlock ·connected under-the-control 

sents the simultaneous impulses .caused by con..,.· of both of said series of impulses and arranged· 

trol sheet 38 and which energize coil 43. Figure 2; to be energized whenever an impulse occurs in 

column I, shows that when there is an impulse one of said series and does not occur simultanein coil 31 and none in coil 43, an impulse is pro- 15 ously in the other of said series, a transmitter 
REF ID:A362663 

12,cuua,048 

5 

connected under the control of said interlock so 

as to emit impulses whenever said interlock is 

energized, a receiver arranged to receive the impulses emitted by said transmitter and having 

an output comprising a third series of electrical 

impulses of varying intensity, a second screen duplicating said first mentioned screen, a third 

scanner arranged to scan synchronously with the 

scanning of said second scanner and reproduce 

the variations of said second screen as a fourth 

series of electric impulses of varying intensity, a 

second electro-mechanical interlock connected 

under the control of said third and of said fourth 

series of impulses and arranged to be energized 

whenever an impulse occurs in one of said third 

and fourth series and no impulse occurs simultaneously in the other of said third and fourth 

series, and a recorder connected under the control 

of said second interlock and arranged to operate 

whenever said second interlock is energized and 

to thereby reproduce said message. 

3. Means for secretly transmitting graphic information, said means comprising, a message in 

graphic form which it is desired to transmit, a 

scanner arranged to scan and reproduce said 

message as a series of electric impulses of varying 

intensity, a screen having varying portions, a 

second scanner arrang~d to scan and reproduce 

the variations of said screen as a second series 

of electric impulses of varying intensity, a relay 

connected under the control of said scanner and 

arranged to be moved by each of said impulses 

to one of two positions, a second relay connected 

under the control of said second scanner and ar- ranged to be moved by each of said second impulses to one of two positions, an electric circuit 

including pa.rts of said relays and adapted to be 

closed only when there is instantaneously an impulse in either series but not in the other, a transmitter connected under the control of said 

electric circuit so as to emit impulses whenever 

said circuit is closed, a receiver arranged to receive the impulses emitted by said transmitter 

and having an output comprising a third series of 

electrical impulses of varying intensity, a second screen duplicating said first mentioned screen, a third scanner arranged to scan synchronously 

with the scanning of said second scanner and 

reproduce the variations of said second screen 

6 

transmitting graphic information, means for 

scanning a message to be transmitted to derive 

therefrom an electric signal irregularly assuming a succession of values responsive to the photo5 graphic density of the message at the point of 

scanning, means for substantially simultaneously 

scanning a camouflage message to derive a second 

electric signal irregularly assuming a succession 

of values depending upon the photographic den10 sity of the camouflage message at the point of 

scanning the second said electric signal being nonsynchronous with the first with respect to the 

variations therein, a switch having two circuitclosing positions, means for causing said switch 

15 to assume one of its circuit-closing conditions 

when said first-mentioned electric signal assumes 

one value and the other of its circuit-closing con- ditions when the said first-mentioned signal assumes another of its values, a second switch hav20 ing two circuit-cJosing conditions, and means for 

controlling said switch responsive to said second 

electric signal, a third switch, a control circuit 

for said third switch said circuit serving to close 

said switch when the first-mentioned two switches 

25 are in predetermined circuit-closing positions 

only, and means for transmitting a signal when 

said third switch is in closed condition. 

5. Means for secretly transmitting graphic information comprising a device for scanning a 

30 message to be transmitted and reproducing said 

message as a series of electric impulses of varying 

intensity, a second device for scanning a camou- flage message and reproducing the same as a 

series of electric impulses of varying intensity the 

35 impulses of said second series being non-synchronous with the impulses of the said first series, a relay connected under the control of said first 

device and arranged to be moved by each of said 

impulses to one of two positions, a second relay 

40 connected under the control of said second device 

and arranged to be moved by each of the impulses of said second series of said impulses to one of two positions, an electric circuit including 

said relays adapted to be closed only when pre4G determined combinations of closed positions in 

said relays occur simultaneously, and a transmitter connected under the control of said electric 

circuit so as to emit impulses only whenever said 

circuit is closed. 

WILLIAM F. FRIEDMAN. 

REFERENCES CITED 

The following references are of record in the 

rue of this patent: 

as a fourth series of electric impulses of varying 50 

intensity, a third relay connected under the control of said third scranner and arranged to be 

moved by each of said impulses of said fourth 

series to one of two positions, a fourth relay 

connected under the control of said receiver and 

arranged to be moved by each of said impulses 55 UNITED STATES PATENTS 

of said third series to one of two positions, an 

electric circuit including parts of said relays and 

adapted to be closed only when there is instantaneously an impulse in either said third or said 60 fourth series but not in the other, and a recorder 

connected under the control of said circuit and 

arranged to be energized whenever said circuit 

is closed to record the original message. 

4. In an apparatus of the nature described for 65 

Number 

1,310,719 

1,312,574 

1,657,366 

1,763,358 

l,848,839 

1,868,967 

2,300,664 

Name Date 

Vernam ------------ July 22, 1919 

Pierce ------------- Aug. 12, 1919 

Belin -------------- Jan. 24, 1928 

Jenkins ----------- June 10, 1930 

Ranger ------------- Mar. 8, 1932 

Cartier ------------ July 26, 1932 

Francis------------- Nov. 3, 1942