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BACKGROUND OF THE INVENTION
The present invention is in the field of computer memory devices and more
specifically relates to a combination of method and apparatus that
frustrates the unauthorized copying of protected data that has been
recorded on a floppy disk or other memory medium.
Billions of dollars are spent each year for computer software. Typically
the software is sold in recorded form on a floppy disk. Once the consumer
has read the program into the core of his computer from the floppy disk,
it is conceivable that the consumer might read the program out of the core
and record it on a second floppy disk, thereby creating an unauthorized
copy of the program. It has been estimated that 50 percent of all software
has been copied without authorization.
The proprietor of the software that has been recorded on an authorized copy
and sold to a consumer wishes to prevent the consumer from making and
selling unauthorized copies. The present invention permits copies to be
made, but with the present invention the copies are unusable and therefore
of no value.
Typically, the instructions and other data recorded on the disk at the
factory include an initializing procedure and a main application program.
The initializing procedure takes care of formatting and other operational
formalities, including the setting up of an operating system directory
that tells the computer the actual location, within the hardware, at which
certain files will be found.
THE PRIOR ART
In U.S. Pat. No. 4,214,280 issued July 22, 1980 to Halfhill, et al., there
is disclosed a method and apparatus for recording data on a disk having
defective areas. The method involves locating the defective area so that
the data can be written on the parts of the disk that are not defective.
The invention is directed, not to securing the recorded data against
copying, but instead, toward permitting defective disks to be used. The
defects are not introduced intentionally, and no attempt is made to write
data on the defective areas.
In an article entitled "Recorded Data Security Device" by A. F. Shugart in
the IBM Technical Disclosure Bulletin, Vol. 4, No. 10 of March 1962, there
is described a device that prevents certain protected data from being read
out of a disk memory. The disk memory in this instance consists of at
least two disks mounted for rotation on a common shaft. One of the disks
contains recorded control signals that control the operation of the
read/write heads of the remaining disks. In response to security signals
on the first disk, the read/write heads of the remaining disks are
electrically disconnected from their amplifiers, thereby preventing
read-out of the protected data. Although this invention makes use of a
special channel for security purposes, the use made of that channel is
completely different from the techniques employed in the present
invention.
In U.S. Pat. No. 4,086,634, issued April 25, 1978, Cook discloses a method
and apparatus for preventing unauthorized duplication of magnetic tapes.
The method involves recording a high-frequency modulated signal together
with audible program material on a magnetic tape so that subsequent
copying of the program material and modulated signal onto an unauthorized
magnetic tape with conventional high frequency bias recording will produce
on the copied tape detectable and identifiable interference signals which
will produce an audible playback noise that spoils the copied tape.
Although Cook's invention is directed toward preventing unauthorized
duplication of recorded material, his method is entirely different from
the technique used in the present invention.
It is anticipated that a separate prior art statement will be lodged in the
file of the present application. The present inventor is not aware of any
prior art that anticipates or suggests the present invention.
SUMMARY OF THE INVENTION
The present invention is intended primarily for use with floppy disks on
which software has been recorded and which are mass distributed to
consumers. A major objective of the invention is to prevent the consumer
from making an unauthorized copy of the authorized copy which he has
purchased.
The consumer certainly has the right to use his authorized copy for its
intended purpose, and for this reason, inventions which deny access to the
recorded data are not applicable to the problem at hand. In contrast the
present invention falls into the class of techniques for preventing
unauthorized duplication of the protected material, i.e., the production
of an unauthorized disk. At the same time the present invention does not
impair an unauthorized disk. At the same time the present invention does
not impair the consumer's right to read the protected material.
As will be seen below, the present invention cannot prevent the consumer
from attempting to transcribe the protected material onto an unauthorized
disk, but the present invention does guarantee that the unauthorized copy
will be unusable.
The present invention requires a combination of apparatus and method for
its practice.
Authorized disks made in accordance with the present invention are
physically distinguishable from the blank disks which consumers would use
for making unauthorized copies. In some embodiments of the present
invention, the modifications which characterize the authorized disks are
relatively simple and not readily detected. The physical features
(indicia) which distinguish the authorized disks may be thought of as an
identifying fingerprint for that disk.
The method aspect of the present invention is centered about a security
check procedure that is incorporated into the initializing routine that is
recorded on the authorized disk and that is executed prior to the reading
out of any of the protected data. The protected data may typically be an
application program, but in other circumstances the protected material may
comprise data in various forms, including (without limitation) binary
signals and analog signals.
The initializing routine must be executed before the protected material can
be read out of the disk, and the read/write head of the computer is under
control of the initializing routine.
The security check procedure involves a test to determine whether the disk
on which it has been recorded has of does not have the physical
fingerprint that is the hallmark of an authorized disk. If the fingerprint
is present, the security check procedure enables the read/write head to
read out the protected material; however, if the fingerprint is absent, as
it would be from an unauthorized disk, the security check procedure
prevents the read/write head from reading out the protected material.
In a preferred embodiment, if the fingerprint is not present, the security
check procedure instructs the read/write head to obliterate or to erase
the protected material.
Thus, the material recorded on a disk, including the initializing routine
as well as the protected material, may be transcribed to an unauthorized
disk. The recorded material will be identical o the authorized disk and on
the unauthorized disk.
However, upon attempted use of the unauthorized disk, the security check
procedure will determine that the distinguishing fingerprint that
characterizes an authorized disk is absent, and at that juncture the
security check procedure will prohibit read-out of the protected material
or will obliterate it.
The novel features which are believed to be characteristic of the
invention, both as to organization and method of operation, together with
further objects and advantages thereof, will be better understood from the
following description considered in connection with the accompanying
drawings in which several preferred embodiments of the invention are
illustrated by way of example. It is to be expressly understood, however,
that the drawings are for the purpose of illustration and description only
and are not intended as a definition of the limits of the invention.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 a block diagram showing the apparatus used in the third embodiment
of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
In a first embodiment of the invention, which is preferred for its
simplicity, a localized permanent defective area is intentionally created
at the factory on the unrecorded disk at a random location on the
recording surface, on the portion of the recording surface reserved for
the material to be protected. The effect of the defect is to render the
affected portion of the disk incapable of accurately reading out a piece
of data that previously a write head had attempted to record on the
defect.
Thereafter, at the factory, the exact location of the defect on the disk is
determined. In one embodiment this is accomplished by recording 1's at all
locations and then reading back the data. Those locations from which 1's
are not read back constitute the defective area.
The locations constituting the defect are collectively regarded by the
computer as a file (call it File D), and the location of this file is
stored in the initializing procedure that is recorded on the disk. The
initializing procedure also includes steps which constitute the security
check.
At this point the main application program or other data to be protected
may be recorded on the disk at the factory. Alternatively, at this point
the disk may be sold to someone who wants to record a secure program on
the disk.
Thereafter, every time the disk is played, the initializing procedure
including the security check is executed. The security check procedure
includes the steps of opening File D, writing a particular piece of data
there, closing the file, re-opening File D, reading out the contents, and
comparing the contents with the particular piece of data that was written.
If the read-out data is identical to the written data (as would be the case
if the disk were an unauthorized copy not containing a defect) the
security check procedure orders the files in which the protected data is
stored to be opened and the contents to be obliterated.
If the read-out data differs from the data that was written (as is normal
for an authorized disk since it contains a defect) the security check
procedure enables the protected data to be read. Thus, an unauthorized
copy of the disk will not yield the protected data, thereby frustrating
unauthorized copying.
Second Embodiment
In a second embodiment, which permits a higher level of security than the
first embodiment, a special recording medium is used on one band of the
disk. This band may include several tracks.
The special recording medium is a material that can be recorded on by a
special recording head at the factory where the disk is produced, but
which cannot be written on by the read/write head of any computer with
which the disk might be used.
In one embodiment, the special recording medium is a ferromagnetic material
having such large domains that the domains can only be magnetized by
application of a magnetic field greater than that produced by the
read/write heads of existing computers.
In another expression, the special recording medium is a "harder" magnetic
material than the material used on ordinary floppy disks so that the
limited magnetic field produced by the write heads of existing computers
cannot write on the special recording medium. Also, the special recording
medium should have a coercivity that is large compared to the magnetic
field produced by the write/erase heads of existing computers so that data
written in the special recording medium cannot be erased by the computer.
The tracks on which the special recording medium are used thus constitute a
read-only memory which the computer's read/write head can read but cannot
write on or alter.
When the disk is produced at the factory, the special recording head there
writes a permanent "fingerprint" number (such as a string of 1's) onto the
tracks of the special recording medium.
An initializing procedure of the program commands that the file located at
the special tracks be opened and that the file be filled with 0's.
Now, if the disk is a normal disk onto which the program has been copied
without authorization, this command will be carried out, and the file at
the location of the special tracks will be filled with 0's.
But, if an authorized disk (one which includes the special tracks) is the
one being played, the computer's recording head will be unable to affect
the special tracks, which will continue to hold the "fingerprint" number.
The security check then calls for reading the file. If only 0's are read,
the security routine commands that all files, including the main
application program, be opened and be filled with meaningless numbers,
thereby rendering the copy useless. If the "fingerprint" number is read,
the security check routine will enable read-out of the main application
program.
Third Embodiment
A third embodiment, shown in FIG. 1, permits a higher degree of security to
be attaind than is possible with the first and second embodiments.
However, the third embodiment requires special apparatus 12 that is an
integral part of the jacket of the disk.
In the third embodiment, one track 14 of the disk 16 is dedicated for
exclusive use with the security check procedure. When the disk 16 leaves
the factory and before it has been used, this dedicated track contains a
sync signal followed by a File X that contains a definite number N.sub.o.
The same number N.sub.o is contained in the security check routine in
machine language in a File Y.
When the disk 16 is inserted in the computer, the computer first executes
the initializing routine, before the main application program or other
data to be protected is read into the computer's core (from which it could
be read onto another disk for the purpose of making an unauthorized copy).
The security check procedure concludes the initializing routine.
The security check procedure includes instructions that increment the
number N.sub.o initially contained in File Y to obtain a new number
N.sub.1, which is then stored in File Y. Thereafter, the number in File Y
is compared with the number then in File X. If the numbers are equal, the
computer is enabled to read the main application program into the core. If
the numbers are not equal, the computer is instructed to obliterate all
files including those containing the main application program.
Clearly, the latter result will obtain unless the number N.sub.o initially
stored in File X has previously been incremented by the same amount that
the number N.sub.o initially stored in File Y was incremented.
A special apparatus 12 is incorporated into the jacket of the disk as an
integral part of the jacket. The purpose of this special apparatus is to
increment the number in File X each time the disk 16 is played. The
incrementing occurs within the first two revolutions of the disk 16 and
thus is completed before the security check procedure is executed. In
normal use, the special apparatus 12 causes the number in File X to equal
the number in File Y so that the main application program can be read into
the core of the computer by the computer's read/write 18 head under
control of the initializing routine.
If an unauthorized copy is made of the protected data once it has been read
into the core of the computer, and if this copy is recorded on a
conventional disk, rather than a secure disk like that of the present
invention, the copy will be unusable simply because the conventional disk
lacks the special apparatus 12 for incrementing the number in File X.
Thus, the apparatus and procedure of the present invention frustrate
unauthorized copying.
Further, if the special apparatus 12 is tampered with and thereby rendered
inoperative, the original disk will become unusable, since File X cannot
be incremented without the use of the special apparatus.
As shown in FIG. 1, the special apparatus 12 comprises, in this
illustrative embodiment, a read/write head 20, and amplifier 22, and
incrementing and storing system 24, and a battery 26 which powers the
other components. All of this special apparatus 12 is mounted in the
jacket of the disk. The read/write head 20 is extremely thin and is
positioned on the jacket in such a fixed position that it has access to
only the special dedicated security track 14 on the disk 16.
It is assumed for purposes of illustration that the track 14 of the disk 16
that is dedicated to security is Track 3. The special apparatus of FIG. 1
operates as follows.
Upon being commanded to read in the program from the disk 16 the computer
starts the disk 16 to rotate. During the first revolution, the disk's
read/write head 20 senses an initial sync pulse on Track 3, the dedicated
track 14. This sync pulse is used to turn on the amplifier 22 and the
incrementing and storing system 24.
As the disk 16 continues to turn, the disk's read/write head 20 reads a
number N.sub.o that follows the first sync pulse on Track 3. That number,
N.sub.o, is incremented by a number stored in the incrementing and storing
system 24 to obtain an incremented number N.sub.1.
During the second revolution of the disk 16, the sync pulse is again sensed
by the disk's read/write head 20. This second sync pulse switches the
amplifier 22 to pass the number N.sub.1 to the disk 16 where N.sub.1 is
written over N.sub.o on Track 3. The incrementing and storing system 24
causes the amplifier 22 to ignore further sync pulses that may
subsequently be read. The operating system directory assigns a name to
Track 3: Track 3 is File X.
As described above, the program includes a security check procedure in
which a number N.sub.o, stored in machine language in the initializing
routine, is incremented in the same manner as before, to produce in a File
Y the number N.sub.1. The initializing routine then compares the number in
File X with the number in File Y. If the number in File X equals the
number in File Y, then the protected data is transferred by the computer's
read/write head 18 into the computer's core. If the number in File X does
not equal the number in File Y, then the security check procedure commands
the computer's read/write head 18 to fill all files, including those
containing the protected data, with meaningless numbers.
In the simplest form of this embodiment the numbers in the Files X and Y
are incremented by the same amount each time the disk is played. In a
slightly more complicated variation, the incremental amount changes each
time the disk is played. This can be accomplished by altering a number
stored in a special increment file each time the disk is played.
Conclusion
Thus, three embodiments have been described of a method and apparatus for
frustrating the unauthorized copying of protected data that has been
recorded on a floppy disk. Clearly the method and apparatus are adaptable
to other recording media.
In each embodiment, a fingerprint is imparted to an authorized disk, which
permits the authorized disk to be distinguished physically from an
ordinary disk on which an unauthorized copy would be made.
In the first embodiment the fingerprint is an intentionally introduced
defective area having a random location. In the second embodiment the
fingerprint is an unalterable magnetic signature recorded on a special
read-only portion of the disk. In the third embodiment, the fingerprint is
a magnetic signature that is recorded on a dedicated track of the disk and
that is altered each time the disk is used.
In each embodiment, the initializing routine recorded on the disk contains
a security check procedure that tests for the presence of the known
fingerprint, and that prevents read-out of the protected data if the
fingerprint is absent, as it would be from an unauthorized copy.
The foregoing detailed description is illustrative of several embodiments
of the invention, and it is to be understood that additional embodiments
thereof will be obvious to those skilled in the art. The embodiments
described herein together with those additional embodiments are considered
to be within the scope of the invention.
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