WO1993015491A1

WO1993015491A1 - Apparatus for scrambling and unscrambling documents

Info

Publication number: WO1993015491A1
Application number: PCT/US1993/000959
Authority: WO
Inventors: Efraim Arazi; Yitzchak Pomerantz
Original assignee: Efraim Arazi; Yitzchak Pomerantz
Priority date: 1992-02-04
Filing date: 1993-02-03
Publication date: 1993-08-05
Also published as: IL100863A0

Abstract

Apparatus for scrambling documents which includes apparatus for providing output signals representing the contents of a document (15), apparatus for operating on the output signals to produce modified output signals representing a scrambled version of the document (60) and writing apparatus receiving the modified output signals and producing a scrambled version of the document.

Description

APPARATUS-FOR SCRAMBLING AND UNSCRAMBLING KX JMENTS

The present invention relates to creation and transmission of confidential documents.

There has long existed a need for secure handling of confidential documents. It is well known to protect information for transmission along unprotected channels by scrambling or enciphering the information upon transmission and unscrambling or deciphering the information upon receipt, using a common secret key which is known both to the transmitter and recipient. Modern telefax machines such as the NTTFAX-43 of NTT, Japan, offer protection for confidential transmissions by locking confidential transmitted messages in the receiving machine and releasing them only in response to an appropriate access code which identifies the intended recipient.

Automatic scrambling systems for documents are described, for example, in "A confidential message handling facility for facsimile communication" by Tominaga et al, in Transactions of the Institute of Electronics and Communication Engineers of Japan, Nov. 1982, the disclosure of which is hereby incorporated by reference. In such systems, scrambling is carried out on electrical signals bearing the confidential information. Once the document appears in a hard-copy format, it is no longer protected. In summary, the prior art does not permit confidential handling of confidential documents in hard-copy format in a normal office environment. The present invention seeks to provide improved apparatus for handling confidential information in hard copy format. There is thus provided in accordance with a preferred embodiment of the present invention apparatus for scrambling documents including: apparatus for providing output signals representing the contents of a document; apparatus for operating on the output signals to produce modified output signals representing a scrambled version of the document; and writing apparatus receiving the modified output signals and producing a scrambled version of the document. There is also provided in accordance with a preferred embodiment of the present invention apparatus for unscrambling documents including: a scanner receiving a document to be unscrambled and providing output signals representing the contents of the document; apparatus for operating on the output signals to produce modified output signals representing a unscrambled version of the document; and writing apparatus receiving the modified output signals and producing a unscrambled version of the document. In accordance with a preferred embodiment of the present invention the apparatus for operating is controlled by a coded input to provide a selected one from a plurality of possible modifications to the output signals. Additionally in accordance with a preferred embodiment of the invention, the apparatus .is embodied in a photocopier. Further in accordance with a preferred embodiment of the invention, the apparatus is embodied in a telefax. Additionally in accordance with a preferred embodiment of the invention, the apparatus is embodied in a computer. Additionally in accordance with a preferred embodiment of the present invention the apparatus for operating is operative to change the relative positions of multi-pixel regions of a document, without modifying the information content within each of the multi-pixel regions. Further in accordance with a preferred embodiment of the present invention, the apparatus for operating is operative to leave unchanged certain predetermined regions of the document. Additionally in accordance with a preferred embodiment of the present invention, the apparatus for providing includes a scanner receiving a document to be scrambled and providing output signals representing the contents of the document. Further in accordance with a preferred embodiment of the invention, verification of correct unscrambling is provided. Such verification may be carried out by the use of a registration area in the document or by edge correlation operations on adjacent scrambled pixels. Throughout the specification and claims, the term "scrambling" is used in an extremely broad sense, to include any suitable reordering of the information in the document. Scrambling may include encryption, but need not involve encryption. The present invention will be more fully appreciated from the following detailed description, taken in conjunction with the drawings in which: Fig. 1 is a generalized illustration of apparatus for creating and transmitting scrambled documents constructed and operative in accordance with a preferred embodiment of the present invention; Fig. 2 is a generalized illustration of "paper flow" in accordance with a preferred embodiment of the present invention; Fig. 3 is a block diagram illustration of the use of a digital copier in a preferred embodiment of the present invention; Fig. 4 is an illustration of one embodiment of document scrambling useful in accordance with the present invention; Fig. 5 is an illustration of the utilization of edge correlation in unscrambling a document in accordance with a preferred embodiment of the present invention.

Reference is now made to Fig. 1, which is a generalized illustration of apparatus for creating and transmitting scrambled documents constructed and operative in accordance with a preferred embodiment of the present invention. Ordinary, conventional office machines, such as a computer printer 10 and a typewriter 12 may provide a hard copy document, which alternatively may be handwritten. The document is readable by any person without required authorization and is normally human-readable. In accordance with a preferred embodiment of the present invention, the hard copy document is provided to a scrambling copier 15, preferably a modified version of a digital copying machine such as a Canon 8580, which is capable of scanning hard copy documents into its memory and then printing them to make copies. In accordance with a preferred embodiment of the present invention, the digital copying machine is modified to scramble the contents of the hard copy document which is stored in its memory in accordance with a predetermined scrambling protocol, an example of which is described hereinbelow. Alternatively, a computer generated document may be transmitted directly from a computer 16 via an electronic fax machine 18, such as a fax modem, which generates a readable document which is supplied to the scrambling copier 15. As will be described hereinbelow, the scrambling copier 15 provides a scrambled hard copy document, which can be handled in any conventional office procedure, such as copying, filing, mailing and faxing, without having the information contained therein disclosed to an unauthorized reader. An authorized reader can, at any time, take the scrambled document, or a copy thereof and "copy" it on an unscrambling copier 20 and thus turn it into an ordinarily, human readable document. Unscrambling copier 20 is preferably a digital copying machine such as a Canon 8580, which is capable of scanning scrambled hard copy documents into its memory and then printing them to make unscrambled, preferably human readable, copies. In accordance with a preferred embodiment of the present invention, the digital copying machine is modified to unscramble the contents of the hard copy document which is stored in its memory in accordance with a predetermined unscrambling protocol, an example of which will be described hereinbelow, and which is the inverse of the scrambling protocol used to scramble the document. It will be appreciated that preferably the scrambling copier 15 and the unscrambling copier 20 are respectively capable of scrambling and unscrambling a document in a multiplicity of different ways, which are selected by the input of a given code to the copier. The scrambling and unscrambling codes may need to be known to both the transmitter or recipient and may be configured in accordance with any suitable known scrambling and encryption technique. Alternatively, if a public key is used, the recipient need not know the scrambling code. Fig. 2 graphically illustrates a dual paper flow path in a typical office environment in accordance with the present invention. A regular document 50 is dealt with in an entirely normal way in all normal office procedures, such as copying, faxing, mailing and filing. If such a document is desired to be maintained confidential, it is copied on a scrambling copier, such as an enciphering copier and is thus converted into an enciphered document 60 which cannot normally be read by a person. This enciphered document can be dealt with in all office procedures identically to the regular document, but cannot be read by unauthorized persons. An authorized person receiving the enciphered document 60 and being in possession of an. appropriate unscrambling code may readily copy the enciphered document 60 on an unscrambling copier 20, which may or may not be the same copier as scrambling copier 15 and may be remotely located therefrom. All that is required is that the unscrambling copier 20 operate in an inverse manner to the operation of scrambling copier 15. The result of unscrambling is a regular document, which may be entirely identical to original regular document 50 or may contain some indicia to indicate that it has undergone enciphering and deciphering. In certain operations copiers 15 and 20 operate on fixed scrambling and unscrambling protocols and thus do not require the application of scrambling and unscrambling codes. Alternatively and preferably, the copiers 15 and 20 are capable of operation in a multiplicity of different scrambling and unscrambling modes of operation, which are selectable by appropriate codes. In accordance with one embodiment of the invention, the unscrambling code, or part thereof may be carried by the document itself and may be readable by the unscrambling copier. Any other suitable technique of transmitting unscrambling code information may alternatively be employed. Reference is now made to Fig. 3, which illustrates the general structure of the scrambling and unscrambling copiers 15 and 20. In each case, the copier comprises a document scanning unit 70 which outputs to a memory 72 which is interactively connected with an enciphering or deciphering program 74, as appropriate, which is typically embodied on a VLSI chip and which outputs to a printing unit 76. At the scrambling or enciphering end, a human readable document is scanned by the scanning unit 70 and an enciphered document is produced by the printing unit 76. An enciphering key is provided to the enciphering program 74 for this purpose. At the unscrambling or deciphering end, a scrambled document is scanned by the scanning unit 70 and a deciphered document is produced by the printing unit 76. A deciphering key is provided to the deciphering program 74 for this purpose. Fig. 4 illustrates a typical scrambling transformation wherein a multiplicity of multipixel areas 80, here termed "gixels", are transformed from their original relative spatial orientation on a human readable document 82 to a different, scrambled, relative spatial orientation on a scrambled document 84. The contours of the gixels are indicated herein as dotted lines, it being appreciated that such dotted lines do not have to appear on either the original or scrambled document. It is appreciated that within each gixel, the pixel arrangement is unscrambled. Preferably the size of the gixel can be selected by the user. Larger gixels provide a more readable scrambled document, thus enabling faster processing. Small gixels provide a more scrambled document which is harder to read, but requires more processing time. The minimum gixel size is a single pixel. Information regarding the gixel size can be incorporated as part of the scrambling code, or alternatively it may appear on an unscrambled part of the document or be ascertained empirically by an examination of a scrambled document. Arrows 90 indicate a typical spatial transformation, it being appreciated that any suitable spatial transformation may alternatively be provided. Preferably part of the document area is not scrambled. The unscrambled area normally contains information that is intended to be readable by all persons, such as the date, addressee, identification of the sender, company logo and general instructions on how to unscramble the document. The non-scrambled area may include a heading portion, as well as a peripheral edge strip 88, as seen in Fig. 4. The peripheral edge strip 88 may provide a registration frame. Alternatively, any other suitable registration marks may alternatively or additionally be provided.lt is appreciated that the registration frame or other registration marks do not normally appear on the original document, but rather are added to the scrambled document by the scrambling program and removed by the unscrambling program. In accordance with a preferred embodiment of the present invention, verification of correct scrambling and descrambling is provided by the scrambling and unscrambling copiers. As illustrated in Fig. 5, such verification can readily be performed by considering the edges of adjacent gixels to confirm matching between light and dark regions thereon. Conventional spatial correlation techniques may be employed for this purpose. As seen in Fig. 5, the adjacent edges of two adjacent gixels 92 and 94, indicated respectively by reference numerals 96 and 98, are seen to have identical or nearly identical patterns. A computer program for scrambling, descrambling and verifying correct descrambling appears in Appendix A. This computer program can readily be incorporated in conventional digital photocopiers such as those mentioned hereinabove. It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims which follow:

'PROGRAM TO DEMONSTRATE SCRAMBLING, UNSCRAMBLING 'AND VALIDATION.

'THE PROGRAMS CREATES AN ARBITRARY INPUT IMAGE, 'CREATES A SCRAMBLING TABLE USING AN ARBITRARY 'SCRAMBLING CODE, AND THEN SCRAMBLES THE INPUT ' (LEFT SIDE) IMAGE INTO A SCRAMBLED (RIGHT SIDE) 'IMAGE. THEN THE PROGRAM ASKS THE USER TO 'SUGGEST AN UNSCRAMBLING CODE, AND TRIES TO 'RECONSTRUCT THE INPUT IMAGE USING THIS CODE. 'THE RESULT IS DISPLAYED ON THE LEFT SIDE, 'INSTEAD OF THE INPUT IMAGE. THEN THE PROGRAM 'CLACULATES A MEASURE OF THE QUALITY OF THE 'UNSCRAMBLING, AND PRINTS IT ON THE TOP-RIGHT 'CORNER OF THE SCREEN. THEN THE PROGRAM ALLOWS 'THE USER TO TRY A DIFFERENT UNSCRAMBLING CODE.

SCREEN 9: 'THIS VERSION IS WRITTEN IN BASIC, FOR

A VGA SCREEN DIM TXT$(20) DATA "+ - +"

DATA ^■: THIS PAGE WILL BE DECODED : " DATA " : BY SHUFFLING IT AFTER : " DATA " : SEGEMNTATION :" DATA "+ - +^»

FOR I = 1 TO 5: 'THIS TEXT WILL BE USED AS A

PART OF THE SAMPLE DOCUMENT

READ TXT$(I)

EMP(6000), B(10), C(10)

FOR I = 0 TO 1: 'THESE ARE TWO RECTANGLES TO

FRAME ORIGINAL & SCRAMBLED DOCS. LINE (9 + 300 * I, 19) - (301 + 300 * I, 350),

15, B LINE (10 + 300 * I, 20) - (300 + 300 * I, 349),

2 + I, BF NEXT PSET (150, 200) : 'THIS POLYLINE WILL BE A PART

OF THE GRAPHICS ON THE INPUT SAMPLE FOR I = 1 TO 25 X = 12 + RND * 276: Y = 22 + RND * 325:

LINE - (X, Y) NEXT FOR I = 1 TO 10: 'THESE RINGS WILL BE PART OF

THE GRAPHICS ON THE INPUT SAMPLE CIRCLE (150, 110), 120 - 8 * I, 1 PAINT (150, 100), 4 + I, 1 NEXT

LINE (130, 90) -(170, 130), 0, BF FOR N = 19 TO 23: 'PRINTING THE TEXT ON THE

SAMPLE DOCUMENT LOCATE N, 7: PRINT TXT$ (N - 18) NEXT LOCATE 1, 6

SUBSTITUTE SHEET ' THE BASIC TILE IS 5X7 PIXELS. IMAGE SIZE IS

290X349 PIXELS (58X47 TILES) HH = 58: W = 47: 'HH AND W ARE HORISONTAL AND

VERTICAL TILE RESOLUTIONS PRINT "CALCULATING A SHUFLING TABLE ("; HH;

" X "; W; ") GRID" 5000 : CODX = 43: CODY = 41: 'CODX AND CODY ARE

THE SECRET SCRAMBLING CODES 'THE CODE TO BE ENTERED IS "4341". THE USER CAN 'CHANGE THE CODE BY CHANGING THE TWO NUMBERS IN 'LINE 5000. CODES THAT WORK NICELY: 47/41, 53/37 NCODX = CODX: NCODY = CODY: 'NCODX AND NCODY ARE

TEMPORARY SHUFLING COUNTERS ' THE FOLLOWING LOOP PREPARES A SIMPLE

SCRAMBLING TABLE BY ASSIGNING EVERY TILE ' OF THE INPUT IMAGE TO A UNIQUE TILE IN THE

SCRAMBLED IMAGE, USING "MOD". FOR I = 1 TO HH FOR J = 1 TO W

DI(I, J) = NCODX: DJ(I, J) = NCODY NCODX = (NCODX + CODX) MOD (HH) : NCODY =

(NCODY + CODY) MOD (W) NEXT NEXT

LOCATE 3, 42

PRINT "HIT ANY KEY TO START ENCIPHERING" 200 IF INKEY$ = "" THEN GOTO 200 LOCATE 1, 6: PRINT " LOCATE 1, 41: PRINT "SCRAMBLING:" LINE (309, 19) -(601, 350), 3, BF: HC = 290 / HH:

VC = 329 / W FOR I - 1 TO HH: 'SCRAMBLING THE TILES ACCORDING

TO THE SCRAMBLING TABLE FOR J = 1 TO W XSTRT = 10 + (I - 1) * HC: YSTRT = 20 + (J - 1)

* VC GET (XSTRT, YSTRT) - (XSTRT + HC - 1, YSTRT +

VC - 1) , BOX XPUT = 310 + (DI(I, J)) * HC: YPUT = 20 +

(DJ(I, J)) * VC PUT (XPUT, YPUT) , BOX, PSET NEXT NEXT

600 ' INITIATE UNSCRAMBLING

LOCATE 1, 3: PRINT " "

LOCATE 1, 3: INPUT " SECRET UNSCRAMBLING CODE

(4 DIGITS) : "; CODE LOCATE 1, 3: PRINT "PREPARING AN UNSCRAMBLING TABLE FOR";

CODE; " " 'PREPARING A TENTATIVE SCRAMBLING TABLE FOR THE 'SUGGESTED CODE. IF THIS IS NOT THE RIGHT CODE, 'THE UNSCRAMBLING WILL NOT RECONSTRUCT THE 'ORIGINAL IMAGE CODX - INT(CODE / 100) : CODY = CODE - 100 * CODX

SUBSTITUTESHEET NCODX = CODX: NCODY = CODY

FOR I = 1 TO HH

FOR J = 1 TO W

DI(I, J) = NCODX: DJ(I, J) = NCODY

NCODX = (NCODX + CODX) MOD (HH) : NCODY =

(NCODY + CODY) MOD (W) NEXT NEXT

LOCATE 1, 3

PRINT "UNSCRAMBLING "

LOCATE 1, 75: PRINT "WAIT" LINE (9, 19) -(301, 350), 1, BF: 'CLEARING THE

LEFT PAGE FOR RECONSTRUCTION FOR I = 1 TO HH FOR J = 1 TO W ' RECONSTRUCTING THE INPUT IMAGE BY TRANSFERRING

TILES FROM THE SCRAMBLED IMAGE ' ACCORDING TO THE NEW UNSCRAMBLING TABLE XSTRT = 310 + (DI(I, J)) * HC: YSTRT = 20 +

(DJ(I, J)) * VC GET (XSTRT, YSTRT) - (XSTRT + HC - 1, YSTRT +

VC - 1) , BOX XPUT = 10 + (I - 1) * HC: YPUT = 20 + (J - 1)

* VC PUT (XPUT, YPUT) , BOX, PSET NEXT NEXT

'CHECKING VALIDITY OF THE UNSCRAMBLED IMAGE GET (10, 20) -(11, 349), BOX: Q = 0 LOCATE 1, 60: PRINT "QUALITY CHECK: " LOCATE 1, 3: PRINT "VALIDATING: " D = 0

'THE QUALITY OF THE IMAGE IS CHECKED BY 'CORRELATING THE IMAGE ACROSS LIMITS BETWEEN 'TILES. EVERY INSTANCE OF EQUAL COLOR ACROSS 'BORDERS (IF NOT ZERO) ADDS TO THE QUALITY MARK D. FOR I = 1 TO HH STEP 5 XPUT = 10 + (I - 1) * HC FOR J = 1 TO 340 STEP 5 GET (XPUT + HC - 1, 20 + J) - (XPUT + HC, 21

+ J), B GET (XPUT + HC, 20 + J) - (XPUT + HC + 1, 21

+ J), C 'PRINT B(l) , C(l)

IF C(l) = B(l) AND C(l) <> 0 THEN D = D + 1 NEXT J

LOCATE 1, 20: PRINT INT(100 * I / HH) ; "%"; NEXT I

LOCATE 1, 75: PRINT D - 470 GOTO 600 END

SUBSTITUTESHEET

Claims

C L A I M S

1. Apparatus for scrambling documents comprising: an output signal generator providing output signals representing the contents of a document; a scrambler operating on the output signals to produce modified output signals representing a scrambled version of the document; and a scrambled document writer receiving said modified output signals and producing a scrambled version of the document.

2. Apparatus according to claim 1 and wherein said scrambler is controlled by a coded input to provide a selected one from a plurality of possible modifications to the output signals.

3. Apparatus according to any of the preceding claims when embodied in a photocopier.

4. Apparatus according to any of the preceding claims 1 - 2 when embodied in a telefax.

5. Apparatus according to any of the preceding claims when embodied in a computer.

6. Apparatus according to any of the preceding claims and wherein said scrambler is operative to change the relative positions of multi-pixel regions of a document, without modifying the information content within each of the multi-pixel regions.

7. Apparatus according to any of the preceding claims and wherein said scrambler is operative to leave unchanged certain predetermined regions of the document.

8. Apparatus according to any of the preceding claims and wherein said output signal generator comprises a scanner receiving a document to be scrambled and providing output signals representing the contents of the document.

9. Apparatus for unscrambling documents comprising: a scanner receiving a document to be unscrambled and providing output signals representing the contents of the document; an unscrambler for operating on the output signals to produce modified output signals representing a unscrambled version of the document; and an unscrambled document writer receiving said modified output signals and producing a unscrambled version of the document.

10. Apparatus according to claim 9 and also comprising an unscrambling verifier for verification of correct unscrambling.

11. Apparatus according to claim 10 and wherein said unscrambling verifier receives and employs a registration frame on the document.

12. Apparatus according to claim 10 and wherein said unscrambling verifier comprises an edge correlator for carrying out edge correlation operations on adjacent scrambled pixels.

13. Apparatus according to claim 9 and wherein said unscrambler is controlled by a coded input to provide a selected one from a plurality of possible modifications to the output signals.

14. Apparatus according to any of the preceding claims 9 - 13 when embodied in a photocopier.

15. Apparatus according to any of the preceding claims 9 - 13 when embodied in a telefax.

16. Apparatus according to any of the preceding claims 9 - 13 when embodied in a computer.

17. Apparatus according to any of the preceding claims and wherein said scrambler is operative to change the relative positions of multi-pixel regions of a document, without modifying the information content within each of the multi-pixel regions.

18. Apparatus according to claim 9 and wherein said unscrambler is operative to change the relative positions of multi-pixel regions of a document, without modifying the information content within each of the multi-pixel regions.

19. Apparatus according to claim 9 and wherein said unscrambler is operative to leave unchanged certain predetermined regions of the document.

20. Apparatus for scrambling documents for use in conjunction with a document writer and an output signal generator providing output signals representing the contents of a document, the apparatus comprising: a scrambler operating on the output signals to produce modified output signals representing a scrambled version of the document and to provide the modified output signals to the scrambled document writer, for writing of a scrambled version of the document.

21. Apparatus for unscrambling documents for use in conjunction with a document writer and a scanner receiving a document to be unscrambled and providing output signals representing the contents of the document, the apparatus comprising: an unscrambler operating on the output signals to produce modified output signals representing a unscrambled version of the document and to provide the modified output signals to the document writer, for producing an unscrambled version of the document.

22. A method for scrambling documents for use in conjunction with a document writer and an output signal generator providing output signals representing the contents of a document, the method comprising the steps of: operating on the output signals to produce modified output signals representing a scrambled version of the document and to provide the modified output signals to the scrambled document writer, for writing of a scrambled version of the document.

23. A method for unscrambling documents for use in conjunction with a document writer and a scanner receiving a document to be unscrambled and providing output signals representing the contents of the document, the method comprising the steps of: operating on the output signals to produce modified output signals representing a unscrambled version of the document and to provide the modified output signals to the document writer, for producing an unscrambled version of the document.

24. A method for scrambling documents comprising: providing output signals representing the contents of a document; operating on the output signals to produce modified output signals representing a scrambled version of the. document; and receiving said modified output signals and producing a scrambled version of the document.

25. A method for unscrambling documents comprising the steps of: receiving a document to be unscrambled and providing output signals representing the contents of the document; operating on the output signals to produce modified output signals representing a unscrambled version of the document; and receiving said modified output signals and producing a unscrambled version of the document.