Note: Descriptions are shown in the official language in which they were submitted.
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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
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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.
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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
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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
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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
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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
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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.
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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.
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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
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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
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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
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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,
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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.
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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.
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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
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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
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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
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18
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
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19
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
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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.
