# US 7,610,626 B2 · Recording medium, recording apparatus, reading apparatus, and program and method therefore

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- Number: US 7,610,626 B2
- Document ID: US7610626B2
- Status: Granted
- Kind: B2
- Application number: 10/395,135
- Filed: 2003-03-25
- Published: 2003-12-18
- Granted: 2009-10-27
- Earliest claimed: 2002-03-25
- Assignees: Panasonic Corporation
- Inventors: Takahiro Nagai; Kaoru Murase; Hideshi Ishihara
- Web page: https://patentgrep.com/patent/US7610626B2

## CPC

- H04N 21/43615: {Interfacing a Home Network, e.g. for connecting the client to a plurality of peripherals (home Audio Video Interoperability [HAVI] data switching networks H04L12/2805)}
- G11B 20/00086: {Circuits for prevention of unauthorised reproduction or copying, e.g. piracy (indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00)}
- G11B 20/0021: {involving encryption or decryption of contents recorded on or reproduced from a record carrier}
- G11B 20/00333: {the key being stored in header data, e.g. in sector headers}
- G11B 20/00507: {wherein consecutive physical data units of the record carrier are encrypted with separate encryption keys, e.g. the key changes on a cluster or sector basis}
- G11B 20/00536: {wherein encrypted content data is subjected to a further, iterated encryption, e.g. interwoven encryption}
- G11B 20/00746: {wherein the usage restriction can be expressed as a specific number}
- G11B 20/00753: {wherein the usage restriction limits the number of copies that can be made, e.g. CGMS, SCMS, or CCI flags}
- G11B 20/00768: {wherein copy control information is used, e.g. for indicating whether a content may be copied freely, no more, once, or never, by setting CGMS, SCMS, or CCI flags}
- H04N 5/913: for scrambling {; for copy protection}
- H04N 21/235: Processing of additional data, e.g. scrambling of additional data or processing content descriptors
- H04N 21/4345: {Extraction or processing of SI, e.g. extracting service information from an MPEG stream}
- H04N 21/435: Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
- H04N 21/4367: Establishing a secure communication between the client and a peripheral device or smart card
- H04N 5/765: Interface circuits between an apparatus for recording and another apparatus
- H04N 5/775: between a recording apparatus and a television receiver
- H04N 5/781: on disks or drums
- H04N 5/85: on discs or drums
- H04N 9/7921: {for more than one processing mode}
- H04N 9/8042: {involving data reduction}
- H04N 2005/91314: {the copy protection signal being a pulse signal inserted in blanking intervals of the video signal, e.g. pseudo-AGC pulses, pseudo-sync pulses}
- H04N 2005/91321: {the copy protection signal being a copy protection control signal, e.g. a record inhibit signal}
- H04N 2005/91328: {the copy protection signal being a copy management signal, e.g. a copy generation management signal [CGMS]}
- H04N 2005/91364: {the video signal being scrambled}
- H04N 2005/91371: {the video color burst signal being modified}
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

An MPEG2-PS format digital stream is composed of VOBUs and each VOBU except an RDI-Pack at the top is encrypted using a content key Kc. The content key Kc is an encryption key obtained by adding a title key Kt to CCI, and then converting a time varying coefficient using the sum. Accordingly, the resulting content key Kc differs for each VOBU. Since each content key Kc is all different for such a small unit of VOBU, copyright of the digital stream is firmly protected. CCI contained in RDI-Pack represents conditional Copy Freely status which allows the digital stream to be copied on condition that the digital stream is recorded only in encrypted form.

## Claims

### Claim 1

A recording medium on which a digital stream is recorded, wherein
the digital stream is associated on a segment-by-segment basis with copy control information indicating whether a segment has a Conditional Copy Freely status, the Conditional Copy Freely status indicating the segment is permitted to be freely copied on a condition that the segment is recorded in a copy destination in an encrypted form, and
each segment recorded on the recording medium is in an encrypted form, the encryption being performed using a predetermined encryption key,
each segment recorded on the recording medium is associated with a check code, the check code being obtained by converting the copy control information using the encryption key, and the check code has a different value depending on whether the copy control information indicates the Conditional Copy Freely status, and
each check code and a corresponding copy control information are contained in each corresponding segment and recorded on the recording medium together with the digital stream, the check code being used to determine whether unauthorized tampering with the copy control information has occurred,
each encryption key for a segment is calculated from three parameters, a first parameter including analog protection information for the segment, a second parameter including a time varying coefficient obtained from the segment, and a third parameter including data unique to the recording medium,
the analog protection information indicates whether a copy control is applied to analog signals converted from the segment,
the time varying coefficient takes on a different value depending on where the segment is located in a playback time axis of the digital stream,
each segment is located on the recording medium with a predetermined offset from a location of a corresponding time varying coefficient, and
the predetermined offset is determined based on a sum of time taken to calculate the encryption key from the three parameters and to obtain the check code by converting the copy control information using the encryption key.

### Claim 2

A recording apparatus comprising:
a judging unit operable to judge a copy attribute of signals inputted from an external source, the signals representing a segment of a digital stream;
a writing unit operable to write, when the copy attribute indicates that the segment is conditionally permitted to be freely copied, the segment onto a recording medium in association with copy control information indicating a Conditional Copy Freely status, the Condition Copy Freely status indicating that the segment is permitted to be freely copied on a condition that the segment is recorded in a copy destination in encrypted form; and
an encrypting unit operable to encrypt the segment using a predetermined encryption key, wherein
said writing unit writes the encrypted segment on the recording medium in association with a check code,
the check code is obtained by converting the copy control information using the encryption key, and the check code has a different value depending on whether the copy control information indicates the Conditional Copy Freely status, and
each check code and a corresponding copy control information are contained in each corresponding segment and recorded on the recording medium together with the digital stream, the check code being used to determine whether unauthorized tampering with the code control information has occurred,
each encryption key for a segment is calculated from three parameters, a first parameter being analog protection information for the segment, a second parameter being a time varying coefficient obtained from the segment, and a third parameter being data unique to the recording medium,
the analog protection information indicates whether a copy control is applied to analog signals converted from the segment,
the time varying coefficient takes on a different value depending on where the segment is located in a playback time axis of the digital stream,
each segment is located on the recording medium with a predetermined offset from a location of a corresponding time varying coefficient, and
the offset is determined based on a sum of time taken to calculate the encryption key from the three parameters and to obtain the check code by converting the copy control information using the encryption key.

### Claim 3 (depends on 2)

The recording apparatus according to claim 2, wherein
the encryption key takes on a different value depending on whether the copy control information indicates the Conditional Copy Freely status.

### Claim 4 (depends on 2)

The recording apparatus according to claim 2, wherein
the copy control information contains generational management information and an extension flag, and
the copy control information indicates the Conditional Copy Freely status when (1) the generational management information is set to a value representing that the segment is prohibited from being copied, and (2) the extension flag is set to ON.

### Claim 5

A duplicating apparatus for copying a digital stream recorded on a source recording medium to a destination recording medium, comprising:
a reading unit operable to read from the source recording medium a segment of the digital stream and copy control information associated with the segment, the digital stream being in encrypted form;
a decrypting unit operable to (1) generate a check code, (2) compare the generated check code with a check code that is pre-recorded in the source recording medium, and (3) when the two check codes match, decrypt using an encryption key the segment read by said reading unit, the encryption key being unique to the source recording medium;
an encrypting unit operable to encrypt the decrypted segment using an encryption key unique to the destination recording medium; and
a writing unit operable to write, when the copy control information indicates a Conditional Copy Freely status, the encrypted segment onto the destination recording medium in association with the copy control information, wherein
the generation of the check code is performed by encrypting the copy control information using the encryption key, and the check code has different value depending on whether the copy control information indicates the Conditional Copy Freely status, and
each check code and a corresponding copy control information are contained in each corresponding segment and recorded on the destination recording medium together with the digital stream, the check code being used to determine whether unauthorized tampering with the copy control information has occurred
each encryption key for a segment is calculated from three parameters, a first parameter including analog protection information for the segment, a second parameter including a time varying coefficient obtained from the segment, and a third parameter including data unique to the recording medium,
the analog protection information indicates whether a copy control is applied to analog signals converted from the segment,
the time varying coefficient takes on a different value depending on where the segment is located in a playback time axis of the digital stream,
each segment is located on the recording medium with a predetermined offset from a location of a corresponding time varying coefficient, and
the predetermined offset is determined based on a sum of time taken to calculate the encryption key from the three parameters and to obtain the check code by converting the copy control information using the encryption key.