CA1232080A - Security system - Google Patents
Security systemInfo
- Publication number
- CA1232080A CA1232080A CA000478592A CA478592A CA1232080A CA 1232080 A CA1232080 A CA 1232080A CA 000478592 A CA000478592 A CA 000478592A CA 478592 A CA478592 A CA 478592A CA 1232080 A CA1232080 A CA 1232080A
- Authority
- CA
- Canada
- Prior art keywords
- data
- encoded
- algorithm
- optical
- image
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09C—CIPHERING OR DECIPHERING APPARATUS FOR CRYPTOGRAPHIC OR OTHER PURPOSES INVOLVING THE NEED FOR SECRECY
- G09C5/00—Ciphering apparatus or methods not provided for in the preceding groups, e.g. involving the concealment or deformation of graphic data such as designs, written or printed messages
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Record Information Processing For Printing (AREA)
- Controls And Circuits For Display Device (AREA)
- Storage Device Security (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention provides security systems for pro-tection of computer software against unauthorized access such as to inhibit the running of computer programs whilst still permitting the software to be copied and in the pro-duction of encoded documents, lables and tags which cannot be read but again, can be copied. The present invention provides a system to inhibit unauthorized access to data comprising output means to transpose two or more components of an element of said data in accordance with a preselected algorithm, and thus produce an encoded element, and decoding means to rearrange said encoded element, thereby recreating the element of said data, the output means comprising at least one microprocessor programmed with said algorithm and means for displaying the encoded element in visible form, and the decoding means comprising at least one optical element capable of rearranging said encoded element.
The invention provides security systems for pro-tection of computer software against unauthorized access such as to inhibit the running of computer programs whilst still permitting the software to be copied and in the pro-duction of encoded documents, lables and tags which cannot be read but again, can be copied. The present invention provides a system to inhibit unauthorized access to data comprising output means to transpose two or more components of an element of said data in accordance with a preselected algorithm, and thus produce an encoded element, and decoding means to rearrange said encoded element, thereby recreating the element of said data, the output means comprising at least one microprocessor programmed with said algorithm and means for displaying the encoded element in visible form, and the decoding means comprising at least one optical element capable of rearranging said encoded element.
Description
~3~
M&C FOLIO: 230P49982 WANGDOC.0319s T i t le:- S~CURIT~ SYSTEMS
This invention relates to a security system and, in one particular embodiment, to security systems for protection of computer software against unauthorised access. One specific application for this invention is 5 to inhibit the running of computer programs whilst still permitting the software to be copied. A further specific application of the invention is in the production of encoded documents, labels and tags which cannot be read but again, can be copied o Both in industry and in commerce, there is a demand to restrict access to information. One way of doing this is to prevent unauthorised access to documents, computer tapes or other storage media. This has the disadvantage that all copying, transport and backup work has to be carried GUt by authorised personnel. Even with precautions being taken in this manner, it is possible that passwocds and information may still be copied.
In the related field of computer software sales, especially in the mainframe micro and mini computer ED markets, software piracy is a large and growing problem. The needs of the vendor in preventing copying 1~3~8~) of programs conflict with the needs of the user to copy valuable software as a hedge against corruption of storage media.
In the still further related field of label production, 5 it is often necessary to provide a label on an article which cannot be read by a potential buyer. but can be read by one offering to sell. Clearly, apparatus for reading the information should be readily portable and rapidly usable.
o In a still further related field of database managment it is occasionally preferable for a host to restrict user access to specific files.
It is one object of the present invention to provide a method of storage which allows copying but restricts l5 user access.
United States Patent 4480179 provides an apparatus for coding and/or decoding a written document comprisinq a plurality of fibre-optic light paths which re-arrange the relative positions of parts of the document while Jo the document is being photocopied. The apparatus thus produces an encoded document which can be read by reversing the coding process.
~;~3~
According to one aspect of the present invention there is provided a system to inhibit unauthorised access to data comprising;
a) output means to transpose two or more components of an element of said data in accordance with a preselected algorithm, and thus produce an encoded element, and, b) decoding means to rearrange said encoded element, thereby recreating the element of said data, CHARACTERISED IN THAT, the output means comprise at least one microprocessor programmed with said algorithm and means for displaying the encoded element in visible form, and the the decoding means comprise at least one optical element capable of rearranging said encoded element.
lS By employing a microprocessor to encode the element of data in accordance with a preselected algorithm and employing an optical element capable of rearranging the encoded element when displayed in visible form, it is possible to enable an authorised user to access the 20 element of data by providing the user with an optical element. Clearly, the particular configuration of the optical element will depend on the particular form of the preselected algorithm. The term microprocessor is ~23~8~
intended to include those elements of a computer which perform the functions of a microprocessor, such as, for example, the central processing unit.
Typically, the element of said data comprises an S alphanumeric character.
By employing alphanumeric characters as the elements of the data it is possible to display a password, price tag or other quantitative or qualitative information to a user equipped with the optical element.
In a first preferred embodiment of the present invention, the element of said data is selected at random from a range of elements and comprises the password for access to the data.
By employing a range of elements from which the element of said data is selected at random it is possible to prevent a user from having future access to the data without the user possessing the optical element.
Thus, in a particular application of this first embodiment of the present invention, the system further comprises input means for input of alphanumeric characters and comparator means for comparing the input with the element of said data selected at random from 5 ~L2~2~
the data.
By employing input and comparator means as defined above, it is possible to enable the data to be copied without consequently allowing the copied data to be accessed. Only a user who is in possession of the optical element may decode the coded element and therefore input the correct alphanumeric character or characters to access the data. It is envisaged that the invention will find a particular utility in systems o which are intended to protect computer software or similar data held either in a static or dynamic memory device. In the case of computer software, a randomly or pseudo-randomly selected password is shown on the screen for the user to input. The password is however displayed in an encoded form which cannot be read until viewed through the optical element. It is envisaged that the algorithm which encodes the data will be itself held as part of the data, as would a suitable password-generating program, and a suitable comparator program.
? o In certain embodiments the data would furthec comprise a set of machine readable instructions for the deletion or corruption of the data, or for the generation of a warning message for display either to the user or at some other location.
~5 It is generally supposed that the display means would ~23~
comprise the VDU screen in embodiments which employ a computer unit as part of the system, however it should be noted that the invention is not to be considered as limited to such embodiments and extends to other 5 embodiments employing light-emitting diodes, liquid crystal displays, or other visual signal generating means.
Furthermore, the invention is not limited to embodiments in which the data is held in or on a magnetic form, such 1O as on a reel of magnetic tape or a floppy or fixed disk. Therefore the invention is intended Jo extend to those embodiments in which data is encoded in other machine-readable forms, such as laser disks, punched tape or semiconductor arrays. Moreover some of the data 5 may be recorded in other forms, such as photographic film materials or video tape or disk, and thus the invention extends to a system for the prevention of unauthorised access to, for example, a cable television or other diffusive system, including but not limited to Jo systems in which at least part of the data is transmitted down fibre optic, telephone, or radio links or the like.
The display may be static or may scroll in a direction such that the optical element is caused to scan the 25 encoded element. If an image is formed of the encoded ~2~
element this image may in some embodiments be a real image while in others may be a virtual image.
In a second ereferred embodiment of the present invention, the means for displaying the encoded element in visible form comprise a printing apparatus.
By employing a printing apparatus to display the encoded element it is possible to provide a permanent or shard"
copy of the encoded element of the data.
Thus, in a particular application of this second Jo embodiment of the present invention, the means for displaying the encoded element of data, provide labels having the encoded element of data printed thereon.
By providing labels having encoded data printed upon them it is possible to enable articles to be marked with 5 elements of data which cannot be read by the casual observer. It is envisaged that this particular embodiment of the invention will be useful in those areas of commerce and trade in which, for example, goods are to be labeled with data which is not for the view of ~0 potential customers but is required by sales staff.
The manner of labelling shall not exclude the use of magnetic inks or other machine-readable printed formats.
~L;2 3~B~
Clearly, the computer software required to run the label printing embodiment of the invention will differ from that in the access inhibition system described generally above. It will however still include means for 5 transposing portions of the element of data before display, although there is not in tnis embodiment a requirement that the element of data so encoded is selected at random, rather the element to be encoded will be selected specifically for coding under user or ;o system control.
According to a second aspect of the present invention there is provided an optical element capable of transforming a first image into a second image by the transposition of at least two portions of said first 15 image, CHARACTERISED IN THAT, the said optical element is substantially planar and at least one optical parameter of the said optical element varies across the said plane.
By providing an optical element which is capable of 2D transposing portions of an image and is substantially planar it is possible to provide a readily portable means for decoding an element of data which has been encoded by the transposition of portions of the said data.
1232~
Conveniently, the optical element comprises an array of light-transmissive elements each capable of deflecting a ray of light from a first path to a second path whereby at least two of said elements are so disposed to transpose the two portions of the first image.
By employing a light-transmissive element is is possible to enable the optical element to be constructed in a variety of ways. For example, optical element may bring about the transposition of the elements of the encoded o data by means of refraction at a surface or within a body of light-transmissive material having a varying refractive index. It is envisaged that the surface of each light-transmissive element may be flat or curved, discontinuous or continuous, and that the optics of each ~5 light-transmissive element may be axisymmetric or non-axisymmetric, magnifying or non-magnifying, polarising or non-polarising.
Alternatively, the optical element may comprise an array of light-reflective elements each capable of deflecting 20 a ray of light from a first path to a second path whereby at least two of said elements are so disposed to transpose the two portions of the first image.
Once again there is a varieey of ways in which the optical element may be constructed within the definition ~3~
given above. Again, it is envisaged that the surface of each element may be flat or curved, continuous or discontinuous.
In both the above embodiments it is intended that the 5 invention should extend to those optical elements which employ the techniques of holography. By employing a holograph as the optical element it is possible to make duplication of the element more difficult, without access to specialist equipment and therefore inhibit lo further unauthorised access to the data. Furthermore the use of a holograph allows the precise optical configuration of the optical element to be varied during manufactuce, as well as enabling easy mass production of the optical elements by a suitable photographic process.
In an embodiment of the present invention, each said light-transmissive element comprises a prism.
By employing a prism as each said light-transmissive element it is possible to manufacture the optical elements cheaply and quickly from a suitable plastics Jo material, for example by stamping, pressing and/or moulding operations.
According to a third aspect of the present invention, there is provided an optical element for use with the ~23~V8~) system according to the first aspect of the present invention and capable of transforming a first image into a second image by the transposition of at least two portions of said first image, 5 CHARACTERISED IN THAT, the said optical element is a substantially planar, light-transmissive body having at least one optical parameter which varies across the said plane.
By employing an optical element as defined above it is lo possihle to rearrange the encoded element of data in accordance with the predetermined algorithm and thereby to reproduce said rearranged components Apparatus in accordance with the invention can be used for the protection of magnetically and optically 15 recorded media, such as computer software or video recordings. As described above, it can also be used foe decrypting printed material. The system can also be used in an electro-optical system internal to a machine or robot viewing device, i.e. without human vision.
Jo The light source for the device is obtained from a luminous screen or an array of light emitting devices, or in the case of printed material, natural or artificial light. Natural or artificial light would be ~23~
used for liquid crystals or other non-light emitting devices.
The invention will now be particularly described with reference to the accompanying drawings, in which :-Figure 1 shows decoding of a displayed symbol, Figure 2 another method of decoding a differentlyencoded displayed symbol, Figure 3 a decoding device including means for magnification, O Figure 4 illustrates a means of modifying the decoding device of Figure 4 in order to facilitate alignment, Figure 5 shows a further means of modification to prevent cross-talk, Figure 6 shows a mounting for the device of Figure 4, IS Figure 7 shows a diagram illustrating a method of setting up a device in accordance with the invention, Figure 8 shows a mounting means for a decoder device, ~23;~
Figure 9 shows a means of incorporating a decoder device into a cassette tape holder, Figure lO is a block diagram of a data security system incorporating a device as described herein and, I F;gures lla-lld illustrate possible flow charts for a microprocessor system which embodies the present invention.
Refering now to Figure l of the drawings, an encoded alphanumeric character is displayed in dot-matrix form lo on a screen (l). The dots making up the character to be read are deviated from their correct positions by distances and in directions determined by a predetermined algorithm so that the particular character cannot be recognised. Mounted before the display screen l5 is a multi-faceted prism device (3) having facets (4) to rearrange the dot pattern to provide a decoded display or image of the display on screen (l). The dot pattern may include bogus dots which are either deflected to an insignificant position or are not transmitted by the Jo prism. In this as in other embodiments of the present invention the mathematical mapping between the display on the screen and the image of the screen may be a one-one, many-one, many-many or one-many mapping.
In the arrangement of Figure l vertical columns of dots forming the character have been deviated sideways by various distances to alter their order.
In the decoding prism (3) the angles of the prisms (4) have been calculated to deflect the vertical columns to their correct order. On the viewing side of the prism, an eye (S) sees the dot matrix reareanged to display the decoded character (6), which in this example is the english alphabetic character ~'R".
lo The device is primarily intended to protect magnetically and opticaly stored data and under these conditions the algorithm for encrypting a character may be stored with the data on a suitable media.
Figure 2 shows a system in which the dots (7) of a lo dot-matrix character have been deviated in vertical and horizontal directions. The decoding optical element has the angles of the facets (9) calculated to correct the vertical and horizontal deviations. The resultant display (10) as seen by the user when the eye is Jo positioned behind the device has been corrected by the optical system.
There may be any number of optical elements in the optical path betwen the display and the viewer.
~3;~8~) Examples of optical techniques separately or in combination which may be used for encrypting data are faceted optical surfaces, axisymmetric optical systems, non-axisymmetric optical systems, refracting elements, 5 lenses, prisms, graded index optical media and materials of differing refractive indices. Additionally the following may be employed either in combination with other techniques or in isolation; mirrors, pin holes, tubes and baffles, masks, polarisers, optical components o with continuous (smooth) shapes, optical components with discontinuous shapes, fibre optics and waveguides, diffraction gratings and interference gratings or masks, holographic lens elements, and retroreflecting devices.
Figure 3 shows a decoding device which contains a single l5 compound magnifying element (11). An alternative is to add a magnifying element to each of the lenses within the construction, forming a lens array. These magnifying elements serve to aid vision. or to project the pattern onto a photoelectric detector.
Spacing arms (13) (Figure 4) may be added to the construction (14). Any suitable shape of spacing arms may be used to obtain the correct viewing distance or spacing of the decoder device from the display screen.
In the embodiment of Figure 5 individual facets of a ~3~
prism are each set in separate channels (15) to avoid cross-talk. Alternatively. tubes or perforated baffles may be used, or part or parts of the device darkened (16a). An optical system in accordance with the 5 invention may be sealed into a construction by means of a clear cover as shown in figure 6.
In the arrangement of Figure 7 the correct viewing distance is found by displaying two reference points which are superimposed by means of reference facets.
Jo The alignment points (19) may be identified by shape, flashing, intensity or colour. The physical position of the device is correct when the specific parts of the pattern overlap at the viewing position (22).
Figure 8 shows how a decoder device (23) can be mounted l5 on or built into a convenient size holder (24) to assist with the handling. The holder may have printing if required to identify the lens system and may include any of the features detailed in the previous Figures.
Figure 9 shows how the features illustrated in Figures 4 Jo and 8 can be combined so as to mount the optical system into the container or packing or recorded printed media. In the example shown in Figure 9 the optical system (22) is built into the lid of a cassette tape 1~32~
holder (26). The length of the lid (27) provides the correct viewing distance.
The optical system may be incorporated into any convenient part of a container or packing material or 5 with a suitable fitting attached to any piece of equipment. As an alternative to single facets to deflect predetermined dots of a matrix, multi-faceted prisms may be used, with a plurality of facets to deflect dots in a predetermined position. This would o have the advantage that the individual areas viewed are smaller than the dots of the matrix so facillitating alignment.
Alternatively, a liquid crystal mask may be used as a decoder device, such as is described in Kowel et al.
5 (Applied Qptics, 23. 16. pp. 2774-2777). This has the two advantages that it makes the device more difficult to copy fraudulently and that its optical parameters may be changed under program control.
A complete system is depicted in Figure lO, in which an encrypted character is displayed on a display device (28). The display is decoded by a decoder (29). In response to the displayed character, a trigger device (30) generates a signal which is fed to a selector device (31) which permits or prevents access to further ~3~!8~) data according to the signal generated by the trigger device.
Figures ~la-lld show possible slow charts for the operation of a computer system which embodies the 5 present invention. It should be understood that the manner in which computer systems display information is particularly variable from machine-type to machine-type and therefore the particular details of the program to perform this function will vary considerably over a range of machines; thus a general sceme is given by way of example.
Turning now to figure lla. there is shown a general sceme for the flow chart of a program to be used as described herein. The processor unit starts by loading a randomly or pseudo-randomly selected character into RCl, and follows this by loading a second random or pseudorandom character into RC2. The processor then calls Subroutine which displays the characters. The next routine excecuted is Subroutine B which reads the
M&C FOLIO: 230P49982 WANGDOC.0319s T i t le:- S~CURIT~ SYSTEMS
This invention relates to a security system and, in one particular embodiment, to security systems for protection of computer software against unauthorised access. One specific application for this invention is 5 to inhibit the running of computer programs whilst still permitting the software to be copied. A further specific application of the invention is in the production of encoded documents, labels and tags which cannot be read but again, can be copied o Both in industry and in commerce, there is a demand to restrict access to information. One way of doing this is to prevent unauthorised access to documents, computer tapes or other storage media. This has the disadvantage that all copying, transport and backup work has to be carried GUt by authorised personnel. Even with precautions being taken in this manner, it is possible that passwocds and information may still be copied.
In the related field of computer software sales, especially in the mainframe micro and mini computer ED markets, software piracy is a large and growing problem. The needs of the vendor in preventing copying 1~3~8~) of programs conflict with the needs of the user to copy valuable software as a hedge against corruption of storage media.
In the still further related field of label production, 5 it is often necessary to provide a label on an article which cannot be read by a potential buyer. but can be read by one offering to sell. Clearly, apparatus for reading the information should be readily portable and rapidly usable.
o In a still further related field of database managment it is occasionally preferable for a host to restrict user access to specific files.
It is one object of the present invention to provide a method of storage which allows copying but restricts l5 user access.
United States Patent 4480179 provides an apparatus for coding and/or decoding a written document comprisinq a plurality of fibre-optic light paths which re-arrange the relative positions of parts of the document while Jo the document is being photocopied. The apparatus thus produces an encoded document which can be read by reversing the coding process.
~;~3~
According to one aspect of the present invention there is provided a system to inhibit unauthorised access to data comprising;
a) output means to transpose two or more components of an element of said data in accordance with a preselected algorithm, and thus produce an encoded element, and, b) decoding means to rearrange said encoded element, thereby recreating the element of said data, CHARACTERISED IN THAT, the output means comprise at least one microprocessor programmed with said algorithm and means for displaying the encoded element in visible form, and the the decoding means comprise at least one optical element capable of rearranging said encoded element.
lS By employing a microprocessor to encode the element of data in accordance with a preselected algorithm and employing an optical element capable of rearranging the encoded element when displayed in visible form, it is possible to enable an authorised user to access the 20 element of data by providing the user with an optical element. Clearly, the particular configuration of the optical element will depend on the particular form of the preselected algorithm. The term microprocessor is ~23~8~
intended to include those elements of a computer which perform the functions of a microprocessor, such as, for example, the central processing unit.
Typically, the element of said data comprises an S alphanumeric character.
By employing alphanumeric characters as the elements of the data it is possible to display a password, price tag or other quantitative or qualitative information to a user equipped with the optical element.
In a first preferred embodiment of the present invention, the element of said data is selected at random from a range of elements and comprises the password for access to the data.
By employing a range of elements from which the element of said data is selected at random it is possible to prevent a user from having future access to the data without the user possessing the optical element.
Thus, in a particular application of this first embodiment of the present invention, the system further comprises input means for input of alphanumeric characters and comparator means for comparing the input with the element of said data selected at random from 5 ~L2~2~
the data.
By employing input and comparator means as defined above, it is possible to enable the data to be copied without consequently allowing the copied data to be accessed. Only a user who is in possession of the optical element may decode the coded element and therefore input the correct alphanumeric character or characters to access the data. It is envisaged that the invention will find a particular utility in systems o which are intended to protect computer software or similar data held either in a static or dynamic memory device. In the case of computer software, a randomly or pseudo-randomly selected password is shown on the screen for the user to input. The password is however displayed in an encoded form which cannot be read until viewed through the optical element. It is envisaged that the algorithm which encodes the data will be itself held as part of the data, as would a suitable password-generating program, and a suitable comparator program.
? o In certain embodiments the data would furthec comprise a set of machine readable instructions for the deletion or corruption of the data, or for the generation of a warning message for display either to the user or at some other location.
~5 It is generally supposed that the display means would ~23~
comprise the VDU screen in embodiments which employ a computer unit as part of the system, however it should be noted that the invention is not to be considered as limited to such embodiments and extends to other 5 embodiments employing light-emitting diodes, liquid crystal displays, or other visual signal generating means.
Furthermore, the invention is not limited to embodiments in which the data is held in or on a magnetic form, such 1O as on a reel of magnetic tape or a floppy or fixed disk. Therefore the invention is intended Jo extend to those embodiments in which data is encoded in other machine-readable forms, such as laser disks, punched tape or semiconductor arrays. Moreover some of the data 5 may be recorded in other forms, such as photographic film materials or video tape or disk, and thus the invention extends to a system for the prevention of unauthorised access to, for example, a cable television or other diffusive system, including but not limited to Jo systems in which at least part of the data is transmitted down fibre optic, telephone, or radio links or the like.
The display may be static or may scroll in a direction such that the optical element is caused to scan the 25 encoded element. If an image is formed of the encoded ~2~
element this image may in some embodiments be a real image while in others may be a virtual image.
In a second ereferred embodiment of the present invention, the means for displaying the encoded element in visible form comprise a printing apparatus.
By employing a printing apparatus to display the encoded element it is possible to provide a permanent or shard"
copy of the encoded element of the data.
Thus, in a particular application of this second Jo embodiment of the present invention, the means for displaying the encoded element of data, provide labels having the encoded element of data printed thereon.
By providing labels having encoded data printed upon them it is possible to enable articles to be marked with 5 elements of data which cannot be read by the casual observer. It is envisaged that this particular embodiment of the invention will be useful in those areas of commerce and trade in which, for example, goods are to be labeled with data which is not for the view of ~0 potential customers but is required by sales staff.
The manner of labelling shall not exclude the use of magnetic inks or other machine-readable printed formats.
~L;2 3~B~
Clearly, the computer software required to run the label printing embodiment of the invention will differ from that in the access inhibition system described generally above. It will however still include means for 5 transposing portions of the element of data before display, although there is not in tnis embodiment a requirement that the element of data so encoded is selected at random, rather the element to be encoded will be selected specifically for coding under user or ;o system control.
According to a second aspect of the present invention there is provided an optical element capable of transforming a first image into a second image by the transposition of at least two portions of said first 15 image, CHARACTERISED IN THAT, the said optical element is substantially planar and at least one optical parameter of the said optical element varies across the said plane.
By providing an optical element which is capable of 2D transposing portions of an image and is substantially planar it is possible to provide a readily portable means for decoding an element of data which has been encoded by the transposition of portions of the said data.
1232~
Conveniently, the optical element comprises an array of light-transmissive elements each capable of deflecting a ray of light from a first path to a second path whereby at least two of said elements are so disposed to transpose the two portions of the first image.
By employing a light-transmissive element is is possible to enable the optical element to be constructed in a variety of ways. For example, optical element may bring about the transposition of the elements of the encoded o data by means of refraction at a surface or within a body of light-transmissive material having a varying refractive index. It is envisaged that the surface of each light-transmissive element may be flat or curved, discontinuous or continuous, and that the optics of each ~5 light-transmissive element may be axisymmetric or non-axisymmetric, magnifying or non-magnifying, polarising or non-polarising.
Alternatively, the optical element may comprise an array of light-reflective elements each capable of deflecting 20 a ray of light from a first path to a second path whereby at least two of said elements are so disposed to transpose the two portions of the first image.
Once again there is a varieey of ways in which the optical element may be constructed within the definition ~3~
given above. Again, it is envisaged that the surface of each element may be flat or curved, continuous or discontinuous.
In both the above embodiments it is intended that the 5 invention should extend to those optical elements which employ the techniques of holography. By employing a holograph as the optical element it is possible to make duplication of the element more difficult, without access to specialist equipment and therefore inhibit lo further unauthorised access to the data. Furthermore the use of a holograph allows the precise optical configuration of the optical element to be varied during manufactuce, as well as enabling easy mass production of the optical elements by a suitable photographic process.
In an embodiment of the present invention, each said light-transmissive element comprises a prism.
By employing a prism as each said light-transmissive element it is possible to manufacture the optical elements cheaply and quickly from a suitable plastics Jo material, for example by stamping, pressing and/or moulding operations.
According to a third aspect of the present invention, there is provided an optical element for use with the ~23~V8~) system according to the first aspect of the present invention and capable of transforming a first image into a second image by the transposition of at least two portions of said first image, 5 CHARACTERISED IN THAT, the said optical element is a substantially planar, light-transmissive body having at least one optical parameter which varies across the said plane.
By employing an optical element as defined above it is lo possihle to rearrange the encoded element of data in accordance with the predetermined algorithm and thereby to reproduce said rearranged components Apparatus in accordance with the invention can be used for the protection of magnetically and optically 15 recorded media, such as computer software or video recordings. As described above, it can also be used foe decrypting printed material. The system can also be used in an electro-optical system internal to a machine or robot viewing device, i.e. without human vision.
Jo The light source for the device is obtained from a luminous screen or an array of light emitting devices, or in the case of printed material, natural or artificial light. Natural or artificial light would be ~23~
used for liquid crystals or other non-light emitting devices.
The invention will now be particularly described with reference to the accompanying drawings, in which :-Figure 1 shows decoding of a displayed symbol, Figure 2 another method of decoding a differentlyencoded displayed symbol, Figure 3 a decoding device including means for magnification, O Figure 4 illustrates a means of modifying the decoding device of Figure 4 in order to facilitate alignment, Figure 5 shows a further means of modification to prevent cross-talk, Figure 6 shows a mounting for the device of Figure 4, IS Figure 7 shows a diagram illustrating a method of setting up a device in accordance with the invention, Figure 8 shows a mounting means for a decoder device, ~23;~
Figure 9 shows a means of incorporating a decoder device into a cassette tape holder, Figure lO is a block diagram of a data security system incorporating a device as described herein and, I F;gures lla-lld illustrate possible flow charts for a microprocessor system which embodies the present invention.
Refering now to Figure l of the drawings, an encoded alphanumeric character is displayed in dot-matrix form lo on a screen (l). The dots making up the character to be read are deviated from their correct positions by distances and in directions determined by a predetermined algorithm so that the particular character cannot be recognised. Mounted before the display screen l5 is a multi-faceted prism device (3) having facets (4) to rearrange the dot pattern to provide a decoded display or image of the display on screen (l). The dot pattern may include bogus dots which are either deflected to an insignificant position or are not transmitted by the Jo prism. In this as in other embodiments of the present invention the mathematical mapping between the display on the screen and the image of the screen may be a one-one, many-one, many-many or one-many mapping.
In the arrangement of Figure l vertical columns of dots forming the character have been deviated sideways by various distances to alter their order.
In the decoding prism (3) the angles of the prisms (4) have been calculated to deflect the vertical columns to their correct order. On the viewing side of the prism, an eye (S) sees the dot matrix reareanged to display the decoded character (6), which in this example is the english alphabetic character ~'R".
lo The device is primarily intended to protect magnetically and opticaly stored data and under these conditions the algorithm for encrypting a character may be stored with the data on a suitable media.
Figure 2 shows a system in which the dots (7) of a lo dot-matrix character have been deviated in vertical and horizontal directions. The decoding optical element has the angles of the facets (9) calculated to correct the vertical and horizontal deviations. The resultant display (10) as seen by the user when the eye is Jo positioned behind the device has been corrected by the optical system.
There may be any number of optical elements in the optical path betwen the display and the viewer.
~3;~8~) Examples of optical techniques separately or in combination which may be used for encrypting data are faceted optical surfaces, axisymmetric optical systems, non-axisymmetric optical systems, refracting elements, 5 lenses, prisms, graded index optical media and materials of differing refractive indices. Additionally the following may be employed either in combination with other techniques or in isolation; mirrors, pin holes, tubes and baffles, masks, polarisers, optical components o with continuous (smooth) shapes, optical components with discontinuous shapes, fibre optics and waveguides, diffraction gratings and interference gratings or masks, holographic lens elements, and retroreflecting devices.
Figure 3 shows a decoding device which contains a single l5 compound magnifying element (11). An alternative is to add a magnifying element to each of the lenses within the construction, forming a lens array. These magnifying elements serve to aid vision. or to project the pattern onto a photoelectric detector.
Spacing arms (13) (Figure 4) may be added to the construction (14). Any suitable shape of spacing arms may be used to obtain the correct viewing distance or spacing of the decoder device from the display screen.
In the embodiment of Figure 5 individual facets of a ~3~
prism are each set in separate channels (15) to avoid cross-talk. Alternatively. tubes or perforated baffles may be used, or part or parts of the device darkened (16a). An optical system in accordance with the 5 invention may be sealed into a construction by means of a clear cover as shown in figure 6.
In the arrangement of Figure 7 the correct viewing distance is found by displaying two reference points which are superimposed by means of reference facets.
Jo The alignment points (19) may be identified by shape, flashing, intensity or colour. The physical position of the device is correct when the specific parts of the pattern overlap at the viewing position (22).
Figure 8 shows how a decoder device (23) can be mounted l5 on or built into a convenient size holder (24) to assist with the handling. The holder may have printing if required to identify the lens system and may include any of the features detailed in the previous Figures.
Figure 9 shows how the features illustrated in Figures 4 Jo and 8 can be combined so as to mount the optical system into the container or packing or recorded printed media. In the example shown in Figure 9 the optical system (22) is built into the lid of a cassette tape 1~32~
holder (26). The length of the lid (27) provides the correct viewing distance.
The optical system may be incorporated into any convenient part of a container or packing material or 5 with a suitable fitting attached to any piece of equipment. As an alternative to single facets to deflect predetermined dots of a matrix, multi-faceted prisms may be used, with a plurality of facets to deflect dots in a predetermined position. This would o have the advantage that the individual areas viewed are smaller than the dots of the matrix so facillitating alignment.
Alternatively, a liquid crystal mask may be used as a decoder device, such as is described in Kowel et al.
5 (Applied Qptics, 23. 16. pp. 2774-2777). This has the two advantages that it makes the device more difficult to copy fraudulently and that its optical parameters may be changed under program control.
A complete system is depicted in Figure lO, in which an encrypted character is displayed on a display device (28). The display is decoded by a decoder (29). In response to the displayed character, a trigger device (30) generates a signal which is fed to a selector device (31) which permits or prevents access to further ~3~!8~) data according to the signal generated by the trigger device.
Figures ~la-lld show possible slow charts for the operation of a computer system which embodies the 5 present invention. It should be understood that the manner in which computer systems display information is particularly variable from machine-type to machine-type and therefore the particular details of the program to perform this function will vary considerably over a range of machines; thus a general sceme is given by way of example.
Turning now to figure lla. there is shown a general sceme for the flow chart of a program to be used as described herein. The processor unit starts by loading a randomly or pseudo-randomly selected character into RCl, and follows this by loading a second random or pseudorandom character into RC2. The processor then calls Subroutine which displays the characters. The next routine excecuted is Subroutine B which reads the
2~ keyboard, as with the display of characters the particular manner in which a machine reads the keyboard will vary. Subroutines A and B are described in more detail below.
The character read from the keyboard is now loaded into 1~3~80 the register KC1 and a second keyboard reading operation is performed. The second character is also loaded into a register, this time KC2.
The comparator now considers whether or not RCl=KC1 and 5 RC2=KC2. If this is true, then the protected software may be run, otherwise the user is given a further chance to access the data as the program selects a further set of random characters.
Should the user fail to enter the correct figures in, ofor example, three sucessive attempts then the system denies access to the protected data and may in some embodiments delete or corrupt the data.
Figure llb. gives a subroutine for the display of characters RC1 and RC2 in encoded form. The system 15 first clears the screen and then displays a set of lens alignment points. Subroutine C is then called, which displays RC1 or RC2 in an encoded form. The subroutine ends at this point with a return instruction. It is important to note that the algorithm of subroutine C for Jo encoding may be loaded into the microprocessor from the data itself.
Figure llc. shows a schematic of subroutine B, that is the subroutine which reads the keyboard. The subroutine 32~8[) starts by setting a time period counter which holds a number indicative of the time since the subroutine was called. The keyboard is then read; this is normally done by scanning the keyboard or reading the keyboard 5 buffer. If there is no input then the time period counter is reduced and a check is made to see whether or not the time period counter has reached zero. If the time period has expired then the subroutine is exited with a return instruction. If the time period has not l expired then the keyboard is scanned again.
On input, the scanning loop is exited and a check is made as to whether or not the keyboard signal indicates that the user wishes to increase or decrease the size of the display. If a size change is reqired then 15 subroutine A is called to erect a new display with the size factor E changed.
The purpose of the size changing facility is to enable the system to be used with varying sizes of monitor screens. If no size change is required then the input 20 character is stored and the subroutine exited.
Figure lld. shows subroutine C, which displays the encoded character. In this example it is assumed that the particular computer in which the program is contained employs an eight by eight matrix for the ~23~8C) display of characters. The subroutine contains two nested loops the outer one of which repeats for each byte and the inner one of which repeats for each bit.
Each bit is read in turn and, if it is true that the 5 bit=l then the screen co-ordinates for that bit are calculated and if necessary expanded by the factor E.
In the case of the first bit, the display co-ordinates which are calculated are those which the algorithm states the first bit is to be transposed to, and so on lo for each bit.
The algorithm may be stored as a table of required deviation or alternatively as a matrix of suitable dimensions to transform the coordinates of the character selected for coding. In the former the algorithm is l5 changed by altering the contents of the table.
when each bit has been checked for whether the bit=l, transposed and displayed the subroutine is exited with a return instruction.
The character read from the keyboard is now loaded into 1~3~80 the register KC1 and a second keyboard reading operation is performed. The second character is also loaded into a register, this time KC2.
The comparator now considers whether or not RCl=KC1 and 5 RC2=KC2. If this is true, then the protected software may be run, otherwise the user is given a further chance to access the data as the program selects a further set of random characters.
Should the user fail to enter the correct figures in, ofor example, three sucessive attempts then the system denies access to the protected data and may in some embodiments delete or corrupt the data.
Figure llb. gives a subroutine for the display of characters RC1 and RC2 in encoded form. The system 15 first clears the screen and then displays a set of lens alignment points. Subroutine C is then called, which displays RC1 or RC2 in an encoded form. The subroutine ends at this point with a return instruction. It is important to note that the algorithm of subroutine C for Jo encoding may be loaded into the microprocessor from the data itself.
Figure llc. shows a schematic of subroutine B, that is the subroutine which reads the keyboard. The subroutine 32~8[) starts by setting a time period counter which holds a number indicative of the time since the subroutine was called. The keyboard is then read; this is normally done by scanning the keyboard or reading the keyboard 5 buffer. If there is no input then the time period counter is reduced and a check is made to see whether or not the time period counter has reached zero. If the time period has expired then the subroutine is exited with a return instruction. If the time period has not l expired then the keyboard is scanned again.
On input, the scanning loop is exited and a check is made as to whether or not the keyboard signal indicates that the user wishes to increase or decrease the size of the display. If a size change is reqired then 15 subroutine A is called to erect a new display with the size factor E changed.
The purpose of the size changing facility is to enable the system to be used with varying sizes of monitor screens. If no size change is required then the input 20 character is stored and the subroutine exited.
Figure lld. shows subroutine C, which displays the encoded character. In this example it is assumed that the particular computer in which the program is contained employs an eight by eight matrix for the ~23~8C) display of characters. The subroutine contains two nested loops the outer one of which repeats for each byte and the inner one of which repeats for each bit.
Each bit is read in turn and, if it is true that the 5 bit=l then the screen co-ordinates for that bit are calculated and if necessary expanded by the factor E.
In the case of the first bit, the display co-ordinates which are calculated are those which the algorithm states the first bit is to be transposed to, and so on lo for each bit.
The algorithm may be stored as a table of required deviation or alternatively as a matrix of suitable dimensions to transform the coordinates of the character selected for coding. In the former the algorithm is l5 changed by altering the contents of the table.
when each bit has been checked for whether the bit=l, transposed and displayed the subroutine is exited with a return instruction.
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1) A system to inhibit unauthorised access to data comprising;
a) output means to transpose two or more components of an element of said data in accordance with a preselected algorithm, and thus produce an encoded element, and, b) decoding means to rearrange said encoded element, thereby recreating the element of said data, CHARACTERISED IN THAT, the output means comprise at least one microprocessor programmed with said algorithm and means for displaying the encoded element in visible form, and the the decoding means comprise at least one optical element capable of rearranging said encoded element.
a) output means to transpose two or more components of an element of said data in accordance with a preselected algorithm, and thus produce an encoded element, and, b) decoding means to rearrange said encoded element, thereby recreating the element of said data, CHARACTERISED IN THAT, the output means comprise at least one microprocessor programmed with said algorithm and means for displaying the encoded element in visible form, and the the decoding means comprise at least one optical element capable of rearranging said encoded element.
2) A system as claimed in claim 1, wherein the element of said data comprises an alphanumeric character.
3) A system as claimed in claim 2, wherein the element of said data is selected at random from a range of elements and comprises the password for access to the data.
4. A system as claimed in claim 3, wherein the system further comprises input means for input of alphanumeric charac-ters and comparator means for comparing the input with the ele-ment of said data selected at random from the data.
5. A system as claimed in claim 2, wherein the means for displaying the encoded element in visible form comprise a printing apparatus.
6. A system as claimed in claim 5, wherein the means for displaying the encoded element of data, provide labels having the encoded element of data printed thereon.
7. A system as claimed in claim 1, wherein the micro-processor is arranged to be programmed with said algorithm from said data.
8. An optical element for use with the system of claim 1, capable of transforming a first image into a second image by the transposition of at least two portions of said first image.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8408603 | 1984-04-04 | ||
| GB8408603 | 1984-04-04 | ||
| GB848425017A GB8425017D0 (en) | 1984-10-03 | 1984-10-03 | Security systems |
| GB8425017 | 1984-10-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1232080A true CA1232080A (en) | 1988-01-26 |
Family
ID=26287554
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000478592A Expired CA1232080A (en) | 1984-04-04 | 1985-04-04 | Security system |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0176538A1 (en) |
| AU (1) | AU4154285A (en) |
| CA (1) | CA1232080A (en) |
| ES (1) | ES8802093A1 (en) |
| IL (1) | IL74782A0 (en) |
| WO (1) | WO1985004746A1 (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH555577A (en) * | 1972-06-09 | 1974-10-31 | Gretag Ag | METHOD AND DEVICE FOR CONVERTING CLEAR GRAPHICAL INFORMATION INTO ENCRYPTED GRAPHICAL INFORMATION AND REVERSE |
| US3814904A (en) * | 1972-10-20 | 1974-06-04 | Rca Corp | Cryptographically coded cards employing synthetic light modifying portion |
| US3937565A (en) * | 1974-06-03 | 1976-02-10 | Alasia Alfred Victor | Process of coding indicia and product produced thereby |
| GB2101376B (en) * | 1981-07-11 | 1986-05-21 | John Gordon Lawrence | Method and apparatus for use against counterfeiting |
-
1985
- 1985-04-01 EP EP85901505A patent/EP0176538A1/en not_active Withdrawn
- 1985-04-01 AU AU41542/85A patent/AU4154285A/en not_active Abandoned
- 1985-04-01 WO PCT/GB1985/000130 patent/WO1985004746A1/en not_active Application Discontinuation
- 1985-04-02 IL IL74782A patent/IL74782A0/en unknown
- 1985-04-03 ES ES541987A patent/ES8802093A1/en not_active Expired
- 1985-04-04 CA CA000478592A patent/CA1232080A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| WO1985004746A1 (en) | 1985-10-24 |
| EP0176538A1 (en) | 1986-04-09 |
| ES8802093A1 (en) | 1987-01-16 |
| IL74782A0 (en) | 1985-07-31 |
| ES541987A0 (en) | 1987-01-16 |
| AU4154285A (en) | 1985-11-01 |
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| MKEX | Expiry |