Electrical computers and digital processing systems: support – Data processing protection using cryptography – By stored data protection
Reexamination Certificate
2000-02-25
2004-12-21
Moise, Emmanuel L. (Department: 2133)
Electrical computers and digital processing systems: support
Data processing protection using cryptography
By stored data protection
C713S176000, C380S201000, C380S203000
Reexamination Certificate
active
06834349
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention generally relates to a digital audio or video player or recorder and, more specifically, to a method of and a system for protecting the copyright of a program recorded on a storage medium such as a video tape, an optical disc, semiconductor memory, etc. in such a player or a recorder.
2. Description of the Prior Art
A variety of copy protecting schemes for various recording media have been proposed so far. In Digital Audio Tape (DAT) recorders for example, the Serial Copy Management System is used in which copy operation is controlled such that an original DAT tape is permitted to be copied only once.
As one of such copy protecting schemes, there is also known the Copy Generation Management System (CGMS) that uses two-bit copy generation management signals or flags. In this system, if the value of the two-bit signals recorded on a recording medium is “00”, then the copying of the recording medium is permitted unlimitedly; if “10”, then the copying is permitted only once; and if “11”, then the copying is prohibited. In the above-mentioned case of “10” in the two-bit signals, the copying involves a change of the value of the two-bit signals from “10” to “11”.
In one copy protection scheme used in video recorders that stores, on a recording medium, a transport stream (TS) based on the MPEG-2 (Moving Picture Experts Group phase 2) standard, a digital water mark is embedded in the transport stream in recording operation. The water mark is detected in playing operation to determine whether the recording medium should be played.
However, if a recorded recording medium is copied by using a player and a recorder, then any of the above mentioned authentication signals, i.e., the Serial Copy Management signal, the two-bit copy generation management signals and the digital water mark will be transferred from the player to the recorder. This gives an attacker a chance to counterfeit such the transferred authentication signal(s) such that the counterfeited authentication signal(s) has a value indicative of permission to copy the recording medium, permitting the attacker to make copies of the recording medium.
One solution to this problem was given by U.S. Pat. No. 5,659,613, which discloses “Method and apparatus for copy protection for various recording media using a video finger print”. The method and apparatus use a combination of a Video Finger Print Signal and an Authenticating Signature to permit the player to handle either copy-protected or non-copy-protected media, in a manner that is difficult to compromise. The patent is hereby incorporated by reference.
However, it is preferable for the recording media player and/or recorder to have a higher copy protection capability. Though the higher the better, if the system becomes the more complicated, it won't be desirable. It is also preferable for the recording media player and/or recorder to have a high degree of flexibility in dealing with recording media of various copy conditions such as a freely copy-able type, a one-generation copyable type (or a type having a one-time copy permission and having not been copied), a play-only type, and a pirated and even-play-prohibited type.
It is therefore an object of the invention to provide a recording media player and a recording media recorder provided with a high-security copy protection system of less complexity.
It is another object of the invention to provide a recording media player and a recording media recorder provided with a copy protection system stubborn to attacks and highly flexible in dealing with recording media of various copy conditions.
SUMMARY OF THE INVENTION
The above problems are overcome by a method of and an apparatus for recording a digital data stream on a recording medium in a recording format. The data stream includes a first protection level value indicative of a protection level of the program. The recording format comprises the cycle of a user area for containing data to be recorded and a system area for containing data necessary for the format. The system area includes an area whose data can not be rewritten by a second user (hereinafter, referred to as “user-unrewritable area”). The method and apparatus comprise the steps of and means for (a) recording the data stream on the recording medium by filling one user area after another, the data stream including a program of contents data, (b) recording a second protection level value indicative of the protection level assigned to the program in a first field of the user-unrewritable area, (c) recording a flag indicative of whether a source of the data stream is original or not in the first field, (d) generating a first value arbitrarily, (e) recording the first value in a second field of the user-unrewritable area, and (f) recording a second value given as a function of the first value in a third field of the user-unrewritable area.
According to an aspect of the invention, a prerecorded recording medium having a recording format comprising a cycle of a user area for containing data to be recorded and a system area for containing data necessary for the format is provided. The system area includes a user-unrewritable area whose data can not be rewritten by a user. The recording medium stores a sequence of digital data recorded in the user areas on the recording medium. The digital data sequence includes a program of content data in a predetermined format. A first protection level value indicative of a protection level of the program is embedded in the digital data sequence. A second protection level value indicative of the protection level assigned to the program is recorded in a first field of the user-unrewritable area. A flag indicating that the recording medium is original is also recorded in the first field. An arbitrarily generated first value is recorded in a second field of the user-unrewritable area. A second value given as a function of the first value is recorded in a third field of the user-unrewritable area.
According to another aspect of the invention, a method of and an apparatus including playing means for playing a recording medium already storing a sequence of digital data are provided. The sequence of digital data includes a program of compressed contents data in which a first protection level value indicative of a protection level of the program is embedded. The recording medium further stores, in at least one user-unrewritable area, a second protection level value indicative of the protection level assigned to the program, a flag indicative of whether the recording medium is original, an arbitrarily generated first value and a second value given as a function of the first value. The method or the playing means comprises the steps of or a plurality of means for (a) extracting the compressed contents data in the digital data sequence; (b) selecting one of predetermined modes of operation according to a combination of the second protection level value and the flag; (c) changing the selected mode to a play-prohibited mode if the selected mode is a copy permitting mode and if the recording medium is determined to be pirated from the first protection level value; (d) changing the selected mode to the play-prohibited mode if the selected mode is a presentation mode in which only expanded contents data is output and if the function is not true to the first and second values; (e) expanding and decoding the contents data into an expanded decoded contents data; (f) converting the expanded decoded contents data into an analog contents data; (g) terminating the steps or means (a), (e) and (f) in case of the play-prohibited mode; (h) outputting the analog contents data in case of the a presentation mode; and (i) outputting the analog contents data and the compressed contents data in case of the copy permitting mode.
The data stream may be encrypted with a key assigned for the program into an encrypted data stream, which is recorded on the recording medium. In this case, the key is encrypted with a master key into an encrypted key for use
Higurashi Seiji
Sugahara Takayuki
Connolly Bove & Lodge & Hutz LLP
Moise Emmanuel L.
Victor Company of Japan Ltd.
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