Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND SYSTEM FOR AUTHENTICATING AN OPTICAL DISC
USING PURPOSEFULLY PROVIDED DATA ERRORS
RELATED FIELD OF THE INVENTION
The present invention is related to a method and system for preventing the
unauthorized duplication of an optical disc, and in particular, for using
purposefully induced
errors on such a disc to determine whether the disc is legitimately
manufactured or an
illegitimate copy. Accordingly the present invention determines whether
information on the
disc is to be accessible or not.
BACKGROUND
The misappropriation of software is rampant irrespective of whether the data
storage
medium is magnetic or optical. Both magnetic and optical storage discs are
particularly
susceptible to piracy due to the ease in which illegitimate copies can be
made.
The computer industry has long been plagued by the illegal misappropriation of
software products. The Software Publisher's Association (SPA), an organization
with
devotes significant resources to tracking and analyzing piracy problems, has
determined that
in 1994 alone the personal computer software industry lost in excess of $8
billion due to
illegal copying of business application software. The SPA further estimated
that virtually
half of the business software in use in 1994 was pirated, and this estimate
does not include
the illegal copying of operating systems, education, entertainment or personal
productivity
software. The piracy problem is particularly acute in more developed markets
such as the
United States.
Accordingly, it is desirable to have additional techniques
forpreventingunauthorized
access to data provided on store media such as optical discs.
SUMMARY OF THE INVENTION
The present invention is a method and system for the protection of optical
disc data
against copying and/or unauthorized use. In particular, the present invention
contemplates
purposefully inducing a physical alteration of one or more portions of an
optical disc surface
during the manufacturing process, within the data area, for the purpose of
creating either a
correctable or uncorrectable defect within the data stream of an attempted
read of one of the
physically altered portions of the optical disc. In particular, such read
attempts may be
performed in response to a query by a software module, either provided on an
optical disc
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manufactured according to the present invention, or external thereto, wherein
the module is
used for verifying the authenticity of the optical disc. Moreover, in
verifying the authenticity
of an optical disc, in at least some embodiments, the present invention does
not require the
changing of any specific bit, rather, it utilizes the data area of the optical
disc as a canvas on
which to a paint or distribute defects, subject to the requirement that such
defects reside
within some specific area of the optical disc. The physical alteration of the
optical disc
surface for providing the defects can be accomplished by first providing
corresponding
defects within an optical disk master from which the optical disk may be
manufactured.
Alternatively, the defects in the optical disc may be manufactured into the
optical disc after
the optical disc has had data from the master disc transferred to it.
The disclosure herein provides additional inventive aspects related to U.S.
Patent
Application Serial No. 091646,141, filed September 13, 2000, which is fully
incorporated
herein by reference.
Other features and aspects of the present invention will become evident from
the
detailed description and the accompanying figures herewith.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates an enlarged view of a data portion on an optical disk with
pits 2010
aligned in rows or tracks extending radially outwardly in the direction 24
from a point about
which the optical disk is intended to rotate when data is written or read.
Further, this figure
shows pit 2020 of extended length in the tracking direction 2025, wherein this
extended pit
is intentionally generated during the manufacturing of the optical disk and
where this pit is
detected as a defect in the optical disk.
Fig. 2 is identical to Fig. 1 except that the extended pit 2020 is replaced by
an
extended land 2022.
Fig. 3 is similar to Figs. l and 2, except that the intentionally manufactured
defect
2026 spans multiple rows or tracks on the optical disk;
Fig. 4 is a high level flowchart illustrating the purposeful insertion of
errors in the
process for manufacturing optical discs so that errors are provided on the
resulting optical
discs in a manner that these errors can be used to determine the authenticity
of the discs; and
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Fig. 5 is a high level flowchart of the steps performed when a user attempts
to access
the information in an optical disc manufactured according to the present
invention.
DETAILED DESCRIPTION
Regarding the aspect of the present invention related to the manufacturing of
defects
into an optical disc, the following techniques 1 through 4 hereinbelow are
within the scope
of the present invention.
1. A defect in a master disc (a mastered defect) may be created by: (a)
generating a continuous data land or data pit of sufficient length in the
tracking direction; or
(b) generating a series of defective data lands and/or data pits of sufficient
frequency andlor
length and/or data encoding peculiarity in the tracking direction to induce
either a correctable
or uncorrectable data error when the defect is transferred to an optical disc
and an attempt to
read the optical disc is performed by an optical disc reader. To generate such
mastered
defects, note that the process of mastering involves the conversion of a
digital or analog
source signal to code for subsequent translation into a digital pattern of
pits and lands,
wherein the transitions between lands and pits of the master disc are intended
to then
translate into readable data on an optical disc generated from the master
disc. Accordingly,
in one embodiment, the software for the present invention is intended to be
incorporated into
the software for controlling a master disc generating device. In particular,
this software
modifies the code derived from the source signals by replacing portions
thereof with code
interleaved with one or more encodings of purposefully induced defects. In
some
embodiments, the appropriate information (e.g., programs and/or data) to
decode a specified
encoded pattern of purposefully induced defects is incorporated into the
original program
content.
The placement of the defects is controlled such that the created errors are
individually
detectable. One method of performing this may be the placement of defects in
no more than
every third sector, so that the effect of the normal interleaving of the
original data is negated
such that a detected error in a specific block of three sectors can be
identified as being the
effect of a purposefully induced defect in a specific sector.
Further, this software may determine the areas of a master disc in which to
place each
purposefully induced defect by its sector address or time code. Subsequently,
the software
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of the present invention causes the master disc generating device to use the
modified code
in place of the code derived directly from the source signals to thereby
generate defects on
a master disc. For example, the defective code may be a continuous data
pattern of 1 s or a
continuous pattern of 0's, which, in turn causes an LBR (Laser Beam Recorder)
of a master
disc generating device to either remain in an "on" condition, creating a
continuous pit, or to
remain "off', creating a continuous land, as one skilled in the art will
understand.
Accordingly, by replacing a valid data pattern within an area of the master
disc with a
continuous data pit 2020 (Fig. l) or data land 2022 (Fig. 2), a corresponding
digital error can
be generated on an optical disc generated from the disc master, wherein the
error is either
correctable or uncorrectable, depending on the size of the defect and its
position with regard
to surrounding data bits. For example, an uncorrectable such continuous data
pit or data land
may be at least approximately 300 pin in length, and a correctable such data
pit or data land
may be less than approximately 300 pin in length. Such a defect 2020 or 2022
may be of
normal track width in the radial direction 2024 for the optical disc medium.
Note that in a
typical optical disc manufacturing process, commercially distributable optical
discs have their
data encodings created through a variety of manufacturing processes including:
inj ectionlcompression molding, utilizing a metal stamper which is a generated
metal part that
is the "inverse image" of the original master disc, or in some cases, the
original master disc,
where the original master disc is inscribed with the inverse image of the
final disc data
pattern; and a printing method that creates the data pattern on a subsurface
of the final disc.
2. Alternatively, a mastered defect may be created that spans multiple tracks.
In Fig. 3, a mastered defect 2026 is shown that is of multi-track width in the
radial direction
2024. The defect 2026 may be of sufficient length in the tracking direction
2028, or include
a long enough series of smaller mastered defects that are of mufti-track width
in the radial
direction 2024 so that either a correctable or uncorrectable data error is
generated when a
read is attempted.
Accordingly, such a defect 2026 can replace the legitimate data that would
normally
reside in that particular area.
3. In another embodiment, a mastered defect may be etched into either a glass
master or one of the series of metal parts generated from it. Accordingly, the
etched defect
will be duplicated in the commercially distributable optical discs that are
either directly or
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S
indirectly generated from the master so that the commercially distributable
optical disks have
corresponding defects of sufficient length in the tracking direction or there
are a series of
etched defects of sufficient quantity and length in the tracking direction to
cause either a
correctable or uncorrectable data error to be generated when such a generated
commercially
distributable disk is supplied to an optical reader. The process of etching in
defects may be
accomplished by any means that is adequate to create the desired defect (for
example: laser
etching, burning, drilling, cutting, slicing, punching, etc.). Such a defect
replaces the data
that normally resides in the area etched. The defect can be either of normal
track width or
of multi-track width in the radial direction 2024 for that particular optical
disc medium. Such
etching may also be controlled by a locating technique which provides a
similar data location
accuracy as provided by the software program described hereinabove for placing
defective
data pits or data lands on a master disc. This locating technique may involve:
(a) inscribing
a radial line outwardly from a center of the surface of the disc; (b)
utilizing a testing device
to locate both this radial line and the location of a specific data area with
respect to the radial
line; and (c) having the testing device provide the position of the specific
data area with
respect to the radial line, wherein the defect will be created on this
specific area.
4. In another embodiment, one or more defects can be created in each
commercially distributable optical disc by physically damaging each such
optical disk
directly during the manufacturing process by techniques such as cutting,
slicing, punching,
burning, etching, painting, sticking the disk with a sharp pointed implement,
etc., so that a
purposefully induced defect of sufficient length in the tracking direction is
produced, or a
series of physical defects of sufficient quantity and length in the tracking
direction is
produced to generate one or more correctable or uncorrectable data errors when
a read of the
defective area is attempted. As in previous embodiments, the defects for the
present
embodiment replace the data that would normally reside in the particular areas
having the
defects. Moreover, such one or more defects are either of normal track width
or of multi-
track width in the radial direction for the particular optical disc medium
being utilized.
Note that in each of the above techniques for purposely creating defects
(errors) in
an optical disc, the purposely induced errors may be trackable or non-
trackable, wherein the
term "trackable" is intended herein to mean that an optical disc reader is
able to maintain
tracking of an optical medium (e.g., an optical disc), and the term Anon-
trackable" refers to
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errors that cause the optical disc reader to lose its ability to track through
an instance of an
untrackable error. The correctable purposely created errors discussed
hereinabove are both
correctable and trackable. That is, such correctable errors have invalid (but
correctable) data
encodings therein such that the optical disc reader is able to read, error
correct, and track
through the invalid data so that uncorrupted data can be read that is adjacent
to the invalid
data and is, e.g., on the same track(s). However, for the uncorrectable errors
discussed
h~reinabove, these errors may be either traclcable or non-trackable.
Accordingly, an
uncorrectable trackable error is one wherein the optical disc reader functions
substantially
as in the correctable case described above except that the purposely
invalidated data cannot
be error corrected to recreate the original data that was purposely changed.
Alternatively, for
uncorrectable errors that are non-trackable, data adjacent to such an error on
the optical disc
is not able to be sequentially accessed from the non-trackable error portion
of the disc.
In one method of the present invention for purposely creating instances of
trackable
errors, at least some error instances are such that they are each created
between two
predetermined readable non-error disc locations. Accordingly, since the
optical disc reader
corrects such errors, a copy of the disc will not have these error instances
therein. Thus, if
such trackable errors are used to encode an identifier onto the optical disc,
then an illicit copy
of the disc will not have the identifier encoded therein. Moreover, the
encodings used may
include one or more of (or an encrypted version thereofj: (a) an
identification number (e.g.,
serial number) unique to one or more optical discs, (b) a product identifier
identifying the
products) encoded the optical disc, (c) a company identifier, (d) a date,
and/or (e) other
information useful in authenticating the optical disc. Moreover, such
information may also
be used in tracing the optical disc from its manufacturing source and through
its primary
distribution sources.
Accordingly, a program (e.g., provided on the optical disc) may attempt to
identify
such purposefully created trackable errors by deriving an identifier encoded
by the trackable
errors, and compare the derived identifier with authentication data provided
elsewhere on the
optical disc or alternatively input by a user. Moreover, such a program may
derive the
identifier from the trackable error instances and perform the comparison using
the following
steps once the optical disc is inserted into the optical reader:
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Step (A): For each of a plurality of data partitions (e.g., each partition
being one or
more sectors on the optical disc) of a predetermined portion of the disc: scan
the partition
read errors, and log a descriptor (denoted an "error descriptor" herein)
having information
indicative of any (or each) error (e.g., error free, correctable error(s),
trackable error(s), or
untrackable error(s)) encountered in the partition.
Step (B): For each error descriptor, resulting from Step (A), assign a
predetermined
corresponding value (denoted herein a "descriptor value") indicative of
whether the error
descriptor: is error free, has an error, and optionally, the type of error
(e.g., correctable,
trackable, untrackable), thereby obtaining a resulting sequence of such
descriptor values.
Step (C): Optionally, perform Steps (A) and (B) for one or more additional
predetermined portions of the optical disc, thereby obtaining one or more
additional
sequences of descriptor values. Subsequently, assuming each of the
predetermined portions
for an authentic optical disc has ideally an identical sequence of descriptor
values, compare
these initial sequences for deriving a final sequence. In particular, for each
error descriptor
position p =1, 2, ... , N, in each of the initial sequences, use the
collection of corresponding
descriptor values at the position p (one per initial sequence) to determine a
most likely final
descriptor value for position p.
Step (D): Compare the resulting sequence obtained from Step (B) (optionally,
the
final sequence from Step (C)) with a predetermined sequence of values
indicative of an
authentic optical disc (such a predetermined sequence may, e.g., reside on the
optical disc or
may be obtained via a network communication such as occurs on the Internet).
If the
comparison yields a sufficiently close (e.g., exact) match, then the optical
disc is deemed
authentic.
Note that each of the partitions referenced in the steps above may be a
collection of
three (consecutive or otherwise) sectors on the optical disc. Moreover, in one
embodiment,
in Step (C) at least two additional predetermined portions of the optical disc
are scanned for
errors. Accordingly, Step (C) may determine each most likely final descriptor
value (i.e., for
each position p) as the descriptor value that occurs most frequently. Thus, if
each descriptor
value is binary (i.e., indicating "error" or "no error"), then no more than
two additional
predetermined portions of the optical disc need be scanned to disambiguate
each final
descriptor value at each position p.
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In another method of the present invention for purposely creating instances of
non-
trackable errors, each such instance may be created so that the instance is
detected by the
optical disc reader as an unrecorded area. That is, the optical disc reader
may view the area
of a non-trackable error instance in the same way it views a normally
unrecorded area of the
disc a~dlor an area where no optical medium is present. For example, an
obstruction may
be placed at some location on the optical disc (i.e., on the surface andlor on
a sub-surface
layer such as a mid-polycarbonate layer) such that the optical disc reader can
not read data
from the location. Thus, the non-error data for that location may be replaced
with non-valid
data or no data prior to the data stream (for optical recording) being encoded
onto a master
disc, or, after the data is recorded onto the master disc, some of the data
may be erased.
Accordingly, the optical disc reader is unable to copy the data in such an
area, and an illicit
copy of the optical disc will not have such non-trackable error instances.
In one implementation for providing non-trackable error instances, the present
invention provides these instances as one or more non-trackable rings,
concentric about the
center (or center of rotation) of the optical disc. Moreover, by having these
non-trackable
rings coincide with the area on the optical disc where data for a
predetermined file should be
located, any illicit copy of the file onto another optical disc will not have
the non-trackable
rings, and, in some circumstances, no copy of the file may be produced.
Additionally, since
.a program for determining certain characteristics of such a file may also be
encoded on the
optical disc, this program may be used to determine the authenticity of the
optical disc. Tn
particular, the program may determine if the file exists, and if so what
portions of the file can
be read and/or what data is associated with particular offsets within the
file. Additionally,
if there are two such non-trackable rings residing in the optical disc area
for the file (at, e.g.,
some random radii from the center of the optical disc), the program may
require that valid
data between the rings be read in order to allow a user to have access to
additional data on
the optical disc. Thus, if an illicit copy of the optical disc is made, and
the file happens to
exist, the data therein will be in different relative locations since the non-
trackable rings are
not present.
The above discussed methods for purposely creating trackable and untrackable
error
instances may be combined and implemented within the context of any of the
four
manufacturing techniques discussed hereinabove. In one exemplary embodiment of
such a
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hybrid technique for copy protection, both the non-trackable rings and the
identifier encoded
in the trackable error instances may be provided on an optical disc together
with a
corresponding authentication program(s). For example, Fig. 4 is a flowchart
illustrating the
various combinations of places where errors can be purposefully embedded when
manufacturing of a copy protected optical disc. In particular, an operator or
another program,
P, may provide input for indicating the path to be taken when exiting each of
the decision
steps 408, 416, 428, 432, 440, 452, 456 and 464. Thus, during creation of a
master glass disc
(step 404), at least one of the steps 408 and 416 may be performed:
periodically, randomly,
at specified locations on the master disc, and/or at specified locations
within the data stream
being encoded onto the master disc depending on the input provided by an
operator or the
program P. Thus, purposely positioned non-trackable error instances may be
interleaved
with trackable error instances (within a common file or otherwise) for thereby
creating a
noncopyable sequence or encoding of error instances that can be used to
identify the optical
disc as authentic.
Fig. 5 shows a high level flowchart of the steps performed during an attempt
to use
an optical disc copyprotected according to the present invention. In step 504,
such an optical
disc is inserted into an optical disk player. In step 508, a determination is
made by the user
as to whether, e.g., a program or other information residing on the optical
disc is to be
installed on the user's computational device attached to the optical reader.
Assuming
installation of the program (and/or the data stored on the optical disc) is
desired, step 516 is
encountered wherein a determination is made as to whether an action must be
performed (by
the user or otherwise) that results in the creation and/or the erasure of an
error on the optical
disc. Thus, the user may be required to generate an error on the optical disc
that is
substantially unique to the user, or, the user may be required to remove a
particular error from
the optical disc. Regarding error removal, since it is also within the scope
of the present
invention to remove or optically change a coating or layer of an optical disc
from opaque to
clear. Thus, an error generated by such a coating or layer can be erased or
removed by, e.g.,
requesting the user to remove the coating (e.g., by peeling it off) or by
inputting a identifier
which may be subsequently used to irradiate (via the reading laser) a
particular opaque
portions) of the optical disc and thereby removing errors by chemically
changing such
portions to clear. Note, that this latter technique of removing optical disc
errors via
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irradiation may be particularly advantageous in both authenticating the
optical disc and
determining a maximal use thereof. For example, such an optical disc may be
designed for
at most five uses, wherein there are five distinct areas of the optical disc
which are opaque
such that with each use one of the five areas is irradiated and thereby an
error is removed.
5 Thus, if the disc were copied the entire disc is likely to be scanned which
would render both
the new disc unusable since there would be no errors to be subsequently
erased, and the disc
from which the copy was made would be rendered unusable since all such errors
would also
be erased. Moreover, this latter technique of removing errors may be performed
automatically without additional user actions the user would not do otherwise.
10 Thus, assuming a defect is to be created andlor erased, in step 520, a
defect is
created/erased automatically or by the user performing a predetermined action
for
purposefully damaging the optical disc. Alternatively, if no such defect is to
be
createdleras ed by the user (and/or automatically), step 524 is performed
whereby the program
is installed on the user's computational system.
Subsequently, in step 528, the program can be activated, wherein the program
determines in step 532 whether optical disc defects should be analyzed for
determining the
authenticity of the optical disc. Assuming such analysis should be performed,
step 536 is
encountered wherein defects such as those described hereinabove and/or
patterns thereof are
attempted to be located. Subsequently, in step 540, a determination is made as
to whether
there are a sufficient number of optical disc defects for satisfying an
authenticity condition
either known or accessible to the program (e.g., via a communication on the
Internet). If so,
then step 544 is performed wherein the program continues and thereby allows
the copy
protected portions of the optical disc to be accessed for use by the user.
Alternatively, if
insufficient defects and/or patterns thereof are not encountered, then step
548 is encountered
wherein the program aborts, and the remaining content of the optical disc is
unavailable to
the user.
It is important to note that embodiments of the present inventions may also be
used
with data storage media different from optical discs. In particular,
embodiments of the above
disclosed methods for assuring that information residing on a data storage
medium is
legitimately accessible, maybe applied to substantially any such storage media
wherein there
is a corresponding error detection and correction capability whose output is,
e.g.,
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programmatically accessible for further analysis, and wherein programs for
performing such
analysis are available at end user sites. Accordingly, embodiments of the
present invention
may be used with magnetic disks, or hybrid combinations of magnetic and
optical discs, or
other data storage media that may be used for the mass distribution of data.
Thus, the present
invention may be used for copy protecting and/or providing predetermined
limited access
(e.g., a predetermined number of accesses) to substantially any data, e.g.,
music, movies,
maps, satellite telemetered data, confidential information, military plans or
orders, business
plans, electronic coupons, educational materials, etc.
The foregoing discussion of the invention has been presented for purposes of
illustration and description. Further, the description is not intended to
limit the invention to
the form disclosed herein. Consequently, variations and modifications
commensurate with
the above teachings, within the skill and knowledge of the relevant art, are
within the scope
of the present invention. The embodiments described hereinabove are further
intended to
explain the best mode presently known of practicing the invention and to
enable others
skilled in the art to utilize the invention as such, or in other embodiments,
and with the
various modifications required by the particular application or uses of the
invention. It is
intended that the appended claims be construed to include alternative
embodiments to the
extent permitted by the prior art.
