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FIELD OF THE INVENTION
The present invention is in the area of Compact Disk Read-Only Memory
(CD-ROM) disks and pertains more specifically to programmable access
control of data on such disks.
BACKGROUND OF THE INVENTION
CD-ROM is an extension of CD audio, the high-quality disk technology of the
music industry. A conventional CD-ROM disk, measuring only 43/4 inches in
diameter is capable of storing an equivalent of up to 250,000 pages of
text, 1,500 floppy disks, 74 minutes of audio, or thousands of images, any
of which can be retrieved in seconds by a computer-based CD-ROM player.
CD-ROM products are available to users in a wide variety of fields such as
library science, education, publishing, online database services,
government, banks, insurance, law, engineering, and medicine.
CD-ROM disks typically have a single, spiraling track that is about three
miles long. The track is typically read from the inside out. Data on the
track is divided into sectors, each equal in length, containing equal
amounts of information and having absolute addresses. FIG. 1 illustrates a
standard data format. In this format, each sector 13 on CD-ROM disk 11
comprises 2,352 bytes of information with 12 bytes of synchronization, 4
bytes of identification, 288 bytes of error-correction code and 2,048
bytes of data.
A CD-ROM master is made by use of a high-power laser to form a series of
tiny indentions in the surface of a blank forming the single spiral track.
The pattern and length of the indentions along the track represent the
recorded information digitally. The original blank is used to make a
master, typically of wear resistant material, for use in molding replicas,
which become the familiar CD-ROM disks. The pattern from the master disk
is reproduced on the surface of a polymer substrate, which is then a copy
of the original.
The stamped replicas are coated with a highly reflective material,
typically vapor deposited aluminum, and a protective coating is applied
over the thin reflective film.
Early CD-ROM disks comprised digitized analog information designed to be
used primarily in linear format with limited user control of playback.
Other CD-ROM disks were programmed to use the disk player's microprocessor
and limited internal memory. Today's more highly developed CD-ROM systems
provide potentially limitless interactivity as their programs are
typically under the supervision of an external computer.
To read CD-ROM data a laser-equipped drive in a CD-ROM player changes its
rate of spin, turning the disk more slowly as sectors farther from the
disk center are read. As the disk is spinning, the low-power read laser is
focused on the spiral track through the thickness of the polymer disk, and
reflected light is picked up by a photodetector that converts the presence
or absence of indentions into electrical signals interpreted as digital
data by the computer. The read laser "sees" the indentions from the side
opposite where they were produced, and therefore sees an indention as a
protrusion toward the laser source.
When the read laser encounters the land of an indention, the focused light
from the laser is largely scattered, so the light reflected to the
photodetector is diminished. In the area where there is no indention from
the opposite side, more light is reflected to the photodetector.
FIG. 2 illustrates a series of indentions formed in the surface of a CD-ROM
disk 31. Surface 23 is the original disk surface, and level 25 indicates
the level of penetration into the original surface of the formed
indentions. The Figure is not to scale, as the indentions are almost
infinitesimally small in depth relative to the thickness of the disk. The
read laser operates in the direction of arrow 24.
CD-ROM, much like other high-density storage systems, relies on channel
codes for storage and retrieval of data. The channel code typically used
for CD-ROM is called eight-to-fourteen modulation (EFM).
In the EMF system, each time the moving disc translates an "edge" past the
laser beam, the reflected light intensity changes, signalling a transition
27 that is decoded as binary 1 by the host's reading system. Binary 0's
occur everywhere else, and the number of 0's between "1" transitions is a
function of the length along the spiral track of the land between
indentions. In operation, the channel code is converted into digital bytes
and data blocks by reference to stored look-up tables. The typical system
of encoding and decoding is well known in the art.
A complete CD-ROM file system consists of three major components: logical
format, which defines the disk's directory structure and operating
characteristics through decoder programs that determine such matters as
where to find the directory of the files on the CD-ROM disk, how the
directory is structured, and how to perform error correction on disk data;
origination programs, which write the data on the disk according to the
logical format; and destination programs, the reading component on the
host computer that understands the logical format and can use it to
provide access to the files on the CD-ROM and read and translate the data
structure.
Most CD-ROM disks have their own operating systems that respond to calls
from a file manager that is exclusively used by CD-ROM. CD-ROM disks also
contain their own search decoder programs that define where sectors are
located so the computer knows where to locate the stored data. These
search decoders typically have a menu-driven interface on the computer.
CD-ROM programs typically require 640 kilobytes of computer memory to run,
and may allocate their own storage addresses on the computer's hard disk
for its data access driver and destination programs.
Nearly all CD-ROM disks and CD-ROM players available today conform to what
is known as the High Sierra standard or to a more recent upgrade, the ISO
9660 standard. The connection between CD-ROM players and computers also
has been for the most part standardized. CD-ROM players typically use the
Small Computer Systems Interface (SCSI) to link with a computer.
CD-ROMs appear to be reasonable and convenient vehicles for marketing large
application programs rather than using large numbers of floppy disks. They
easily provide enough space and their cost is low, about $0.50 a disk when
produced in large volumes. The cost of CD-ROM drives is also becoming more
reasonable as well.
Despite apparent advantages, there remain some serious drawbacks to use of
CD-ROMs for marketing large application packages. The most serious is that
there is no reliable method or mechanism whereby comprehensive versions
and features may be recorded on a single disk, and only certain portions
enabled for a particular customer.
Also the lack of satisfactory copy protection of CD-ROM disks remains a
problem. CD-ROM disks are typically shipped with a companion floppy disk
that contains data access driver and destination programs that must be
installed on the user's computer in order for CD-ROM to run. The floppy is
copy-protected but the CD-ROM disk is not. This method of copy protection
is no more effective than copy protection for floppies in general. The
contents of CD-ROM can be copied to hard disk and the floppy protection
scheme can be defeated by any of a number of available copy programs.
Multi-application packages such as Ethernet, Windows, and AutoCad, and many
others, therefore, continue to be furnished on multiple floppy disks. Many
of these programs have become so diverse that as many as 20 to 40 floppy
disks may be required to install a complete set of programs on a host
computer.
What is needed is a means whereby vendors of large and diverse applications
can record all of an application on a single CD-ROM, and then selectively
enable access of portions of the data at time of purchase. Also a means is
needed to copy-protect CD-ROM disks so floppies are not the sole means for
protection. With these improvements a vendor could cost-effectively
mass-produce one full version of a product on a single CD-ROM disk, have
the disk copy-protected, and selectively control use of its applications.
The user, who only has to make a one-time purchase of a basic package on a
single disk, could have access to other applications on the disk by simply
paying the vendor for them as needed.
SUMMARY OF THE INVENTION
In an embodiment of the present invention, a method for providing data in a
secure fashion on a compact disk read-only memory (CD-ROM) disk and
enabling retrieval of the data by a host computer is provided, comprising
steps of (1) storing data on the disk in the manufacturing process; and
(2) programming a password into the CD-ROM disk after manufacture of the
CD-ROM disk by altering selected sectors on the CD-ROM disk to be
unreadable by conventional laser-read control routines. The digital
sequence comprising the password is a digital sequence identified by a
sequence of readable and unreadable sectors. The password is characterized
by being programmed in the programming area of the CD-ROM over a region
having at least one megabyte of data storage capacity, which is a large
enough area to defeat known interception programs and schemes.
In some cases, the data to be read may be recorded in an encrypted fashion,
and the password is really a decryption key.
In another aspect of the invention multiple features and versions of a
large program may be placed on a single CD-ROM disk, and selected portions
enabled at point of sale by programming on the disk selected passwords
and/or decryption keys.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration of addressable sector content in the prior art
for a sector on a CD-ROM.
FIG. 2 is a section view through a track of a CD-ROM in the prior art,
showing indentions for indicating bit transitions.
FIG. 3 is a plan view of a CD-PROM in an embodiment of the present
invention, showing data storage and programming regions.
FIG. 4A is an isometric view of a programming device according to an
embodiment of the invention.
FIG. 4B is a largely diagrammatical view of internal elements of the
programming device of FIG. 4A.
FIG. 4C is a section view of a CD-ROM mounted in the programming device of
FIG. 4B and 4A, showing the relative convergence of a focused laser beam
in the device.
FIG. 5 is an illustration of the concept of passwords as decryption keys
according to an embodiment of the invention.
FIG. 6 is a logic flow diagram indicating the steps in a method of
decrypting data according to an embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention, termed CD-PROM for Compact Disk Programmable Read
Only Memory, is in one aspect a means for selectively enabling data on
CD-ROM disks after mastering and pressing but before providing the disks
to an end user. The data storage capacity of a conventional CD-ROM disk is
about 600 megabytes. Of that amount, some few megabytes are typically
devoted to the disk's operating system (OS). Typically large applications
programs such as Windows, Ethernet, and AutoCad require no more than 100
megabytes of storage area. That leaves nearly 500 megabytes of data
storage area free for use in access enablement schemes and other
programming.
The present invention involves in one aspect encoding into a CD-PROM disk,
by a unique laser programming means, digital patterns comprising coded
passwords that enable access to selected data on the disk.
FIG. 3 is a plan view of a CD-PROM disk 31 according to an embodiment of
the present invention. A small region 33 near inside opening 32 is
dedicated to the disk's operating system (OS). This OS is automatically
loaded on a host computer when a disk is placed in the drive of an
attached optical disk player, assuming the computer control system has
been configured for the drive. Region 35 on the disk, occupying perhaps
100 megabytes, is used for data storage. In this region all data pertinent
to an application may be stored. For example, for a program like AutoCad,
all features, versions, etc. are stored in region 35. The size of region
35 is variable, depending on the application.
All of the data in region 35 is encrypted. A multitude of schemes exist for
doing such encryptions such as reverse alphabet, letter substitution, word
inversion, number-to-letter substitution, and variations of combinations
of these and many other methods.
The remainder of the CD-PROM disk, region 37, which may be typically up to
about 500 megabytes in usable capacity, is the programming area. In this
area passwords are recorded and programming is done. The means of enabling
various parts of data region 35 are provided in programming area 37.
FIG. 4A is an isometric view of a laser programming device 39 according to
an embodiment of the invention. Externally device 39 may appear much like
a conventional CD-ROM disk drive. It has in this embodiment a disk tray 41
for receiving a CD-ROM disk 34, an open/close actuator 43, and a dip
switch 45. In other embodiments, there may be other control actuators as
well.
Laser programming device 39 also resembles a conventional CD-ROM disk drive
internally, except where the read laser unit is typically installed, a
higher-power laser unit is used that is capable of destroying sectors on a
CD-PROM disk. Also, the laser unit in device 39 is controllable to
selectively destroy sectors to accomplish a programming function.
FIG. 4B is a largely diagrammatical illustration of internal elements of
programming device 39. The electronic circuitry is quite similar to that
of a standard CD-ROM disk drive and is not diagrammed in FIG. 4B.
To operate programming device 39, a CD-ROM disk 34 is placed in disk drawer
41 with its read side down, that is, the reflective layer is on the side
opposite the laser device. A laser system generally indicated by elements
46, comprising a laser, focusing elements, and tracking mechanisms, is
located in about the position the corresponding elements would be located
in a CD-ROM drive.
Control routines operating on a host computer 57 in this embodiment over a
communication link 47 to on-board control circuitry 52 provide control
operations to drive programming device 39. The same control routines
provide a user-interface on the host computer display, allowing an
operator to control and alter the operations of device 39.
In operation a laser beam 49 is selectively enabled from laser emission
device 50 when a signal is received from the host. Beam 49 is focused in
this embodiment through a prism 51 and an objective lens 53 onto the
spiral track of CD-ROM disk 34. Actuators 58 control focusing adjustments,
drive 55 spins the CD-ROM disk, and translation actuator 56 shifts the
laser system radially along rails to follow the spiral track.
FIG. 4C is an enlarged section through one portion of a spiral track of
CD-ROM disk 34 with laser beam 49 focused through the thickness of the
disk onto the indentions in the spiral track. The thickness D1 of a CD-ROM
is typically about 1.2 mm, and the depth D2 of the depressions is
typically about 0.12 micrometers. A track is typically about 0.6
micrometers wide, and the dimension between tracks is typically about 1.6
micrometers. In this section, the disk is shown with a lacquer topcoat 36.
It is seen, then, that the magnitude of the depressions in the surface of
the CD-ROM disk is but a very small portion of the thickness of the disk,
and the depressions themselves are quite shallow.
Keeping in mind the relative and typical dimensions given above, there are
at least two mechanisms by which the energy from laser beam 49 may be
concentrated at the spiral track, in a manner that is not injurious to the
bulk of the disk, and whereby selected sectors in the track may be altered
in a manner to be unreadable by a conventional reading mechanism. One
means is by focusing beam 49 at a large included angle A so the power per
unit area remains proportionally small until the track region is reached.
Another is by selecting the wavelength for the laser to be a wavelength
for which the material of the disk is relatively transparent. In different
embodiments of the present invention, different combinations are used.
Also, the presence of the reflective layer immediately at the track
interface is an aid in obliterating data recordation in selected areas, as
a portion of the laser energy tends to be reflected at this interface.
Moreover, alteration or local destruction of the reflective layer itself
by the energy of beam 49 has been found to contribute to the ability to
obliterate selected sectors.
In embodiments of the present invention the pattern of sectors damaged or
destroyed and not damaged or destroyed sequentially along the spiral track
in region 37 (see FIG. 3) becomes a recognizable digital string for use by
the operating system in decrypting data stored in region 35. Literally any
programmed information may then be placed in a selected region on a CD-ROM
disk, providing therefrom a CD-PROM disk according to a preferred
embodiment of the present invention.
It is not necessary that an enabling password or other programmed data be
in a serial sequence. There can be patterns within patterns, and the
organization of sectors to produce a single password or data for another
purpose might be scattered over entire programming region 37. There may be
many passwords on a disk, each capable of enabling a different
application.
The concept of password enablement as practiced in embodiments of the
present invention is illustrated with the aid of FIG. 5, which shows an
index table 61 of passwords 63, each yielding a digital key 65 to enable a
selected portion of (for example) a region 37 on a CD-PROM according to an
embodiment of the invention. The selected portion keyed by such a password
may be an application 66 such as AutoCad, or some other useful, and
separable, data group, as indicated in FIG. 5. The individual keys enable
separately bootable features or versions of the application.
Such a password table is, of course, a useful mechanism for understanding
the selective enablement concept of the present invention. This password
table does not really ever get written to memory anywhere. If it did, it
could be copied and used to break the code. Instead, the ability to find
passwords is programmed into the OS, and the actual passwords are
discarded as quickly as used.
A password enablement scheme according to an embodiment of the present
invention is flowcharted in FIG. 6. At the start, a CD-PROM disk is
inserted in the disk drive at event 67. The OS program is loaded on the
computer at event 69. An early function is checking for a serial number at
function 71 (at the discretion of the vendor). In this particular path, if
the licensing serial number does not check, the enablement process may be
aborted (function 73). The OS in this embodiment next searches programming
region 37 for a first password (function 75).
When the OS finds a password at function 77, the password is passed to the
decryptors at function 79, and used to unlock data keyed addresses. The
system then reads the unlocked data (function 83), typically loading the
decrypted data to a location on the host system's hard disk. At function
85 the password is discarded. The discarding function is not necessarily a
separate step in the operation, and may be a natural function of the data
flow as controlled by the operating system.
After all the passwords are found and the data meant to be accessible is
accessed, control passes to end function 89.
"Unlocking" with a password can be as simple as enabling a sequential range
of sectors by beginning address and length to be read into memory or it
can be extremely complex. An example of a simple unlocking scheme would be
the case where a password gives instructions to "read every 5th sector in
a range beginning at a specific address." Another scheme could change the
unlocking instruction on a daily basis by requiring, for example, "if it
is the 23rd hour of the day, a predefined number be added to every 6th
sector."
An example of a more complex unlocking scheme could be as follows: The OS
looks for password #1, say an 8-bit digital word, and finds it. This
password is a key for an algorithm to be loaded that searches for another
key in data region 37 in one of 24 different patterns, one pattern for
each hour of the day, as determined by querying the clock on the computer.
Password #2 is the actual enabling key that is available from all 24
search patterns or any one of them. The added factor of basing the search
on time with the first password effectively adds another layer that a
person would have to solve to defeat the system.
In another embodiment of the invention there can be a means of sending an
enabling password to a user who wants to access more applications on a
CD-PROM disk than he/she originally purchased. In this embodiment a user
interface in the form of a query from the computer to enter the actual
password would not be needed. Instead the password could be an addition to
the CONFIG.SYS file, a keystroke sequence, or other means to enable the OS
to find the password key already on the CD-PROM disk to unlock the desired
application in data region 37.
An additional feature is the built-in copy-protection that CD-PROM provides
with the data on the disk being encrypted. The disk can be copied but the
encrypted data will be unusable. With the CD-PROM disk itself
copy-protected, the more vulnerable method of providing copy protection on
a companion floppy disk is not necessary.
Because of the large capacity of programming region 37, there is a very
broad range of possibilities in programming. For instance, the system can
be used by companies that sell mailing lists to track the use of the
lists. An entire mailing list can be sold on a single CD-PROM together
with all the necessary routines to use it to print labels, cards, or even
"self-mailers." These companies could charge for a mailing list on CD-PROM
based on the number of times the user uses the mailing list. Programming
on the CD-PROM disk along with the OS could be used to customize the list
to include a fictitious recipient with an address that goes to the vendor.
In this way the vendor would receive a mailer addressed to the fictitious
party every time the customer uses the mailing list. This would enable the
vendor to keep track of how many times the mailing list is actually being
used.
In yet another embodiment of the present invention, a data area of several
hundred sectors, comprising several megabytes of storage area, is
selected, and a password is programmed in the area by damaging selected
sectors on the CD-ROM, as is described above. The area of several hundred
sectors extends along the spiral recording track of the CD-ROM from the
first damaged sector to the last, and may be considered a "protect" area.
When the CD-ROM is presented to a host computer with a CD-ROM drive, the
password must be entered, as in other systems, or the CD-ROM cannot be
read.
The efficacy of this embodiment lies in the fact that, to copy the data on
the protected CD-ROM, one must employ an "interceptor" program, and such
programs must copy the entire protect area to RAM on a host to read the
data on the CD-ROM. As there are practical limits to the on-board RAM for
most computers that are also used for reading CD-ROMS, it is only
necessary to be sure the protect area is larger than the RAM complement of
a host. In some cases it will be necessary to have "good" data in the
undamaged sectors in such a protect area, and this is accomplished by
pre-writing, at the time of manufacture, arbitrary data to an area of the
proper size where the password will be later programmed by damaging
selected sectors.
It is common, at the time of this application, to have as much as 16
megabytes of RAM on a personal computer, but the purpose of such large RAM
is to be able to run relatively large operating systems, secondary systems
like Windows.TM., and ever larger applications. After loading all the
necessary software to RAM, there will seldom be, in even such a RAM-rich
system, more than two to four megabytes of memory free for use with an
interceptor program to defeat a super password of the sort contemplated by
the present invention.
The inventor is confident that a password area of 1 magabyte would be
sufficient to defeat an interceptor program for many existing personal
computers, and that a password area of 4 megabytes would defeat
interceptors for all but a very few existing personal computers.
The super-password concept of passwords too large to be handled by
interceptor programs and techniques is also applicable to decrypting
keywords and the like, as described in a number of different embodiments
above, and to multiple passwords and keywords for enabling and decrypting
multiple applications and versions of applications on a CD-ROM. For
example, given a recording area of 100 megabytes, as shown in FIG. 3, and
a programming area of as much as 500 megabytes, as also shown in FIG. 3,
one could program a relatively large number of passwords and keywords in
the 500 megabyte area for selectively enabling and decrypting an equally
large number of different portions of data in a data region. In an area of
500 megabytes, for example, one could program fifty ten-megabyte passwords
and keywords, each extending over a ten-megabyte protect area.
It will be apparent to one skilled in the art that there are many changes
that may be made in the embodiments described without departing from the
spirit and scope of the present invention. Some alternatives have been
described above. For example, provisions may be made to add a secondary
level of access control to give the user the option to "pay as you go" for
extra applications that are available on the CD-PROM disk. Another
variation adds a copy protection scheme to the CD-PROM disk.
There are also a number of equivalent ways the several features described
for the invention might be implemented without departing from the spirit
and scope of invention as well. For example, the aforedescribed
embodiments could be rendered in different sizes. For instance, data bases
exist today that are larger than 500 megabytes and can not fit on a single
CD-PROM disk. The concept of a single CD-PROM disk presented in this
invention could be expanded to the production of a set of CD-PROM disks as
a way to accommodate extra large data bases in an orderly manner and still
provide enablement control and copy protection on the single disks.
Another variation would utilize one or more of the large 12-inch size
video disks for CD-PROM storage as dictated by the size of the data base.
Many other such alterations fall within the spirit and scope of the
invention.
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