|Publication number||US7792001 B2|
|Application number||US 10/423,737|
|Publication date||Sep 7, 2010|
|Priority date||Oct 5, 1998|
|Also published as||CN1192379C, CN1290395A, CN1494080A, DE69935124D1, DE69935124T2, EP1046163A1, EP1046163B1, US6580682, US20030185130, WO2000021085A1|
|Publication number||10423737, 423737, US 7792001 B2, US 7792001B2, US-B2-7792001, US7792001 B2, US7792001B2|
|Inventors||Franciscus L. A. J. Kamperman, Antonius A. M. Staring|
|Original Assignee||Koninklijke Philips Electronics N.V.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (14), Non-Patent Citations (1), Referenced by (1), Classifications (23), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This is a continuation of U.S. patent application Ser. No. 09/408,792 filed Sep. 30, 1999, Now U.S. Pat. No. 6,580,682.
The invention relates to an information carrier comprising information arranged according to a recording format, the information being recorded according to predefined encoding rules and including format information indicative of parameters of the recording format.
The invention further relates to a player for reproducing information from the information carrier, the player comprising format means for providing parameters of the recording format, and reading means for retrieving the information in dependence on the parameters of the recording format.
The invention further relates to a recorder for recording information arranged according to a recording format on an information carrier, the recorder comprising recording means for recording the information according to predefined encoding rules and for including format information indicative of parameters of the recording format.
The invention further relates to a method for recording information arranged according to a recording format on an information carrier, in which method the information is recorded according to predefined encoding rules, and format information is included indicative of parameters of the recording format.
A system for copy protection of recorded information comprising an information carrier, a player and a recorder, is known from U.S. Pat. No. 5,737,286 (D1 of the list of relevant documents). Copy protection may comprise preventing the creation of a digital copy on a different carrier, allowing some copy activity (e.g. only a first generation of copies), or controlling, verifying or restricting the access to protected information. The information carrier comprises information recorded according to an existing recording format, e.g. the CD-ROM format. The format prescribes the structure of recorded information, such as what type of information is recorded at which location on the disc, e.g. that the recorded area starts with a lead-in area at a predetermined diameter. Such a format may also include other parameters such as a type of recording layer (recordable, pre-recorded, etc), a number of recording layers and physical parameters of the recording process (density, reflectivity, etc). Format information, which gives actual values of parameters of the recording format used on an information carrier in question, is included in the recorded information on said record carrier, and is intended for use by the player when reproducing user information from said information carrier, e.g. format parameters in sector headers or a Table Of Contents (TOC) which comprises information on where the user information starts and ends. The information on the information carrier is recorded according to predefined encoding rules, such as the channel code (EFM) for translating the user bytes into lengths of optically readable pits in the CD, and error coding and sector structuring rules. Such encoding rules are usually a predefined part of the recording format, and are not indicated in the format information recorded on the disc. The player for reproducing the information carrier comprises reading means for reading and decoding the recorded information according to the inverse of said encoding rules.
In the system of D1 the player and information carrier form a system for controlled information reproduction, in which reproduction of illegally copied information is counteracted. Copy protection has a long history in audio or video publishing. The presently installed base of equipment, in particular Personal Computers (PC) with audio/video cards, provide little protection against unauthorized copying. In any copy-protection scheme, the most difficult issue is that a pirate can always attempt to playback an original disc, treat the content as if it were an analog home recording and record this. However the best quality is only available when a digital copy can be made. For digital storage media such as Digital Compact Cassette (DCC), “copy bits” have been defined, which bits indicate a copyright status, e.g. “no copy allowed”, “free copy” or “one generation of copy allowed”. Other copy bits may indicate that the medium storing the information must be a “professional” medium manufactured by pressing and not a “recordable” disc. However such copy bits can easily be ignored by the pirate, e.g. using a PC as copy engine. Devices which do not obey the rules of a format are called ‘non-compliant’ devices.
The copy protection of the system known from D1 is based on a so-called medium mark, i.e. a physical mark representing a bitpattern indicating the copyright status of the medium, e.g. a “professional” disk manufactured by pressing. The medium mark itself is not copyable or changeable by standard recording equipment and said bitpattern is to be verified by the compliant player and may even be required for reproduction, e.g. a descramble code for recovering information stored as scrambled information. On the record carrier of D1 information is recorded in the track in a predefined manner represented by optically readable patterns formed by variation of a first physical parameter, such as the height of the scanned surface. The medium mark is constituted by a variations of a second parameter of the track which are modulated according to said bitpattern, e.g. an excursion in a transverse direction of the track formed by a pregroove, also denoted as wobble. If the information of the known record carrier is copied “bit-by-bit” by a pirate on a writable information carrier using a non-compliant device, the information of this copy cannot be reproduced by a compliant player, because the copy does not comprise the medium mark corresponding to the illegally copied information. However detecting the medium mark and retrieving said bitpattern requires additional elements in the compliant player, whereas a compliant recorder preferably also detects any medium mark on a recordable disc. Hence, the known system for copy protection requires expensive and complex players and recorders.
It is an object of the invention to provide a system in which accessing and copying recorded information is controlled and which is less complex.
For this purpose, the information carrier as described in the opening paragraph is characterized in that, while said encoding rules correspond to rules of a different recording format that prescribes a predefined location on the information carrier for recording the format information, the predefined location comprises a confusion pattern and in that the format information is recorded at a second location different from the predefined location. The player as described in the opening paragraph is characterized in that the format means are arranged for detecting the recording format of the information carrier, and in that the format means are arranged for supplying predefined parameters or for retrieving the format information from the second location when said recording format is detected. The recorder as described in the opening paragraph is characterized in that the recording means are arranged for recording a confusion pattern at the predefined location and for recording the format information at a second location different from the predefined location.
Existing, non-compliant read devices will try to read the format information from said predefined location, but will read the confusion pattern instead. This confusion pattern will cause the existing devices to stop reading, or to use wrong settings for the reading means, which causes the reading process to malfunction. This has the effect, that existing devices are prevented from accessing copy protected audio/video information from the information carrier, because they cannot read the format information. Hence a digital copy cannot be made using non-compliant players or recorders, even if they are not aware of (or manipulated to disregard) any copy protection information bits. While the format information is hidden for existing players, it can be easily retrieved by the player according to the invention. This has the advantage, that the reading means, although comprising complex decoding and error correction circuits, can be manufactured relatively cheap because substantially all components are common to existing players.
The invention is based on the recognition, that the format information must be available, but cannot be manipulated in non-compliant devices. By relocating the format information uncontrolled playback of copy protected discs by existing, non compliant devices, can be prevented. In particular, the reading and/or recording of format information cannot be controlled or manipulated by a pirate, because such steps are usually built in a control unit in the basic read or write engine. As an alternative to relocating the format information, it would be possible to change the predefined encoding rules of an existing recording system for copy protection purposes. This however increases the cost of a new copy protected recording system, because complex IC's must be redesigned and produced specifically for the new players and recorders. So in practice the encoding rules must be equal to the encoding rules of an existing system, e.g. the Compact Disc (CD) or Digital Versatile Disc (DVD) system, and non-compliant devices comprising such encoding and decoding means are available. A record carrier recorded with said encoding rules could be played back on a non-compliant device, e.g. on the PC, and manipulation of audio/video information would be possible. However by relocating the format information according to the invention, non-compliant players are prevented from uncontrolled playback, because they rely on the format information, such as the TOC in CD or Physical Format information in DVD, for accessing the audio/video information.
A preferred embodiment of the system is characterized in that the second location is variably selected within a predefined area of the information carrier and/or in that the format information located at said second location is encrypted using an encryption key. Variably selected means that when an audio/video production is put on a master disc for mass reproduction, a specific second location for that production is selected randomly from the range of possible locations. Alternatively or in combination one encryption key is generated randomly for each new production. This has the advantage, that it is more difficult for a pirate to locate or retrieve the correct format information.
These and other aspects of the invention will be apparent from and elucidated further with reference to the embodiments described by way of example in the following description and with reference to the accompanying drawings, in which
Corresponding elements in different Figures have identical reference numerals.
The record carrier comprises information recorded according to a recording format. The recording format prescribes the way information is recorded, encoded and logically mapped. The way of recording information in the format includes parameters of the recorded information, e.g. the type and number of recording layers, data speed, etc. Further the format includes encoding rules, such as channel coding, error coding or sector structuring rules. An example of a sector structure is given in
In an embodiment of the information carrier according to the invention the format information comprises user key information for processing the user information. As the format information is relocated as indicated above, and because the user key information is required to process the user information, a pirate player cannot fully retrieve the user information even if it manages to read information from the user area. The processing may comprise decryption of user audio or video information, or access control to certain options within a computer program, or verification or transfer of a copy control status. In an embodiment only part of the user information is encrypted. For example decryption is required only for some sectors of the user information area as indicated by a bit in the reserved bytes (RSV) 53 in the sector structure shown in
In an embodiment the information carrier comprises access information. The access information is indicative of the CPS location of the format information. A pointer to the CPS location may be included in the confusion pattern or the reserved bytes 16-2047 in
In an embodiment the access information includes Copy Protection System Index information (CPSI), which indicates that CPS locations are present and a confusion pattern is recorded in the predefined location. The CPSI comprises a pointer value for searching the relocated format information in the CPS locations is included in the six reserved bytes 53 in the sector structure shown in
The control unit 20 comprises format means for providing said parameters of the recording format by retrieving the format information from the CPS location. The CPS location may be known to a compliant device, and in that event the format information can be read immediately. Alternatively a set of parameter values may be predefined and stored in control unit 20, and said stored parameter values are supplied when said format information is not retrievable from said predefined location. In an embodiment the player comprises detection means for detecting the retrievability of the format information from said predefined location by detecting the confusion pattern and/or the access information. The control unit embodies said detection means, which first read the predefined location, and based on the information read determine if the information carrier is recorded according to the existing format. If the information read is the confusion pattern, this is detected from recognizable wrong values for certain parameters, e.g. all zero's or a too large area for user data. The record carrier may comprise access information, which explicitly indicates the recording format according to the invention, such as a bit in the sector header (see
According to the invention the control unit 20 of the recording device is arranged for recording a confusion pattern at the predefined location and recording the format information at a CPS location different from the predefined location. In further embodiments of the recording device the control unit 20 is arranged for recording the format, access or key information as defined above for the information carrier with reference to
Although the invention has been explained by embodiments using audio or video, the invention can be applied also to computer data. In the embodiments the information carrier is embodied by an optical disc, but any other carrier can be used in the invention, such as tape or broadcast, as long as format information is supplied on the carrier corresponding to an existing format prescribing a predefined way which cannot be easily manipulated. Further, the invention lies in each and every novel feature or combination of features described above.
U.S. Pat. No. 5,737,286 (PHN 13922)
Closed information system with physical copy protection
WO 98/16014-A1 (PHN 16452)
1 bit ADC and lossless compression of audio
WO 98/33325-A2 (PHN 16372)
Copy protection system based on watermarking and control ticket.
Applied cryptography, by Bruce Schneider
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|U.S. Classification||369/53.21, 369/59.25|
|International Classification||G06F21/24, G11B7/007, G06F12/14, G11B7/003, G11B20/10, G11B7/0045, G11B20/12, G11B19/12, G11B20/00, G11B19/04, G11B20/18|
|Cooperative Classification||G11B20/00615, G11B19/04, G11B20/00086, G11B20/00884, G11B19/12|
|European Classification||G11B20/00P14, G11B20/00P6C, G11B19/12, G11B20/00P, G11B19/04|