Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
2000-02-09
2004-07-20
Patel, Gautam R. (Department: 2655)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S053220, C369S059250, C369S275300
Reexamination Certificate
active
06765852
ABSTRACT:
The invention relates to a method of storing a disc-ID on a record carrier comprising tracks in which information can be stored, said disc-ID comprising a predetermined number of disc-ID bits.
The invention also relates to a device for reading a record carrier, comprising a system for detecting and reading information present on the record carrier, the system comprising detection means for detecting a disc-ID on the record carrier, said disc-ID comprising a predetermined number of disc-ID bits.
The invention also relates to a device for writing a record carrier, comprising write means for inducing a detectable change on a layer of the record carrier, the write means being further adapted to write a disc-ID on the record carrier, said disc-ID comprising a predetermined number of disc-ID bits.
The invention further relates to a record carrier comprising a disc-ID stored on the record carrier, said disc-ID comprising a predetermined number of disc-ID bits.
The method according to the invention may be used in various types of generally known record carriers such as, for example, CD-R, DVD+RW, MO-disc.
Since the literature uses a plurality of terms for disc-IDs, such as identifier, disc-identifier, ID, disc code, identification tag, it will be noted for the sake of clarity what is to be understood by disc-ID in the description of this invention. The disc-ID consists of information of a predetermined bit length, stored on a record carrier, with the purpose of being able to distinguish this record carrier from other record carriers of the same type.
It should be clear from the above that the disc-ID of a record carrier is comparable with, and may perform the same function as, finger prints. It is important that the presence of a disc-ID provides the possibility of distinguishing individual record carriers from each other and not only the type of record carrier (for example, CD-ROM, CD-R or CD-RW).
The method according to the invention is not limited to circular record carriers but may also be used in non-circular record carriers such as tapes and cards.
The registration of a unique disc-ID on a record carrier is important for different reasons. European patent application EP 0 785 547 A2, hereinafter referred to as document D
1
, states, as an advantage of registering a unique disc-ID, that a computer system using these record carriers can keep track of a list of errors present on various record carriers. The system can then easily detect when a given record carrier does not function or should be replaced or copied. The registration of a disc-ID on a record carrier may also be important in a method of cryptocommunication. In this case, the disc-ID is used for providing, together with keys (for example, what is referred to as shared secret) present in a recorder or player, access to encrypted information on the record carrier. The use of a disc-ID on a record carrier is also recommendable in the field of copy protection, because copy protection is considerably simplified when individual record carriers can be distinguished from each other. To make this possible, each record carrier receives a unique identification code, the disc-ID. By means of this disc-ID, the data (for example, Audio/Video (A/NV) data) is coupled to the physical medium, i.e. the record carrier.
A method of the type described in the opening paragraph is known, inter alia, from document D
1
. This document describes a method of storing one disc-ID (whose letters ID stand for identification) on a record carrier. If there is no disc-ID on the record carrier, a unique disc-ID is generated for this purpose and registered on a reserved area of the record carrier. When an MO disc is used, an unused sector in the defect management area (DMA) may be used as a reserved area. When a CD-R is used, the table of contents (TOC) in the lead-in zone may be used as a reserved area.
The disc-ID as described in document D
1
is registered on a reserved area of the record carrier. The disc-ID is thus vulnerable to attempts of hacking and removing the disc-ID. Not only will it be easy to find a disc-ID registered in a reserved area on a record carrier, but it will also be easy to remove this disc-ID, for example, by giving all the bits constituting the disc-ID the same binary value. Moreover, it will be easier to make a number of discs all of which have the same disc-ID so that they cannot be distinguished from each other.
It is an object of the invention to realize a reliable disc-ID on record carriers, which is difficult to trace and remove.
To this end, the method according to the invention is characterized in that the disc-ID bits are stored on the record carrier in a scattered way.
The invention is based, inter alia, on the recognition that, by storing the disc-ID bits on the record carrier in a scattered way, it will be more difficult to trace the entire disc-ID and possibly remove it. Storage of the bits on the record carrier in a scattered way is understood to mean that one disc-ID is stored in a number of portions of limited bit size on the record carrier. Overwriting such a portion with a limited bit size is not easy and overwriting a single bit is not very well possible with the current equipment (for example, the CD-R and CD-RW recorders). A minimum bit size which can be realized in a single write action is of the order of several tens of bits, for example, 32 bits. The ratio between this minimal bit size and the size of the entire disc-ID is, for example, 20%. This corresponds to a disc-ID of 160 bits (5×32 bits). By scattering the different disc-ID bits on the record carrier in groups which are smaller than this minimal bit size, the disc-ID will be difficult to remove. This has, inter alia, the advantage that, if the disc-ID forms part of a copy protection system or of a system for crypto communication, these systems will be more reliable and can less easily be hacked.
Another embodiment is characterized in that the disc-ID bits are stored in groups of one bit on the record carrier in a scattered way.
By storing the disc-ID bits on the record carrier in a scattered way in groups of one bit, it will be more difficult to trace the entire disc-ID and possibly remove it.
A further embodiment is characterized in that the disc-ID bits are stored at positions reserved for storing non-data bits.
It is known that a number of bits (referred to as non-data bits) is not used for storing data on a number of types of frequently used record carriers, but have different other reasons for their presence. For example, in the description of the standard physical format of the Audio-CD (referred to as the Red Book), non-data bits are defined, inter alia, as error correction bits, merging bits and sync bits. For details, reference is made to the standard format of the Audio-CD (see International Standard IEC 908).
It is also clear from the foregoing that the data capacity of the record carrier is reduced if the disc-ID is stored on a reserved area of the record carrier where data can also be stored. By using the non-data bits for storing the disc-ID bits, a disc-ID is realized which does not result in a reduction of the total data capacity of the record carrier.
Moreover, it is to be noted that the disc-ID bits can also be stored at positions which, in accordance with the description of the standard physical format of the relevant record carrier, do not fulfill a function. These positions are suitable because the value of the bits at these positions can be freely chosen. This freedom provides the possibility of storing any desired disc-ID on the record carrier.
Another embodiment is characterized in that the disc-ID bits are stored in a preamble of the data bits on the record carrier.
By storing the disc-ID in the preamble of the data bits on the record carrier, the disc-ID is stored on a reserved area of the record carrier, where only non-data bits are stored. The data capacity of the record carrier is not reduced thereby. For a description of the preamble of the data bits and its function, reference is made to the description of
Staring Antonius A. M.
Van Den Enden Gijsbert J.
Koninklijke Philips Electronics , N.V.
Patel Gautam R.
LandOfFree
Method of storing a disc-ID on a record carrier, device and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of storing a disc-ID on a record carrier, device and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of storing a disc-ID on a record carrier, device and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3204640