Information-recording apparatus, information reproduction apparatus, information-recording method, information reproduction method and computer program

• US 7,650,646 B2
• Filed: 07/24/2002
• Issued: 01/19/2010
• Est. Priority Date: 08/09/2001
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Asano, Tomoyuki, Nakamura, Masanobu
• Primary Examiner(s): Moazzami; Nasser G
• Assistant Examiner(s): ABEDIN, SHANTO
• Application Number:
  US10/398,517
• Publication Number:
  US 20040030902A1
• Time in Patent Office: 2,736 Days
• Field of Search: 713/176, 713/193, 713/168, 380/30, 380/201, 705/51, 705/50, 705/57, 386/37, 386/94, 726/26, 726/27
• US Class Current: 726/32
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: 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
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: 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
• CPC Class Codes: G11B 20/00514 wherein the entire content is encrypted with the same key, e.g. disc key or master key
• CPC Class Codes: G11B 20/00528 wherein each title is encrypted with a separate encryption key for each title, e.g. title key for movie, song or data file
• CPC Class Codes: 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
• CPC Class Codes: G11B 20/00884 involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
• CPC Class Codes: H04N 2005/91321 the copy protection signal being a copy protection control signal, e.g. a record inhibit signal
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

A recording or reproduction apparatus is provided which utilizes copyright information in operations to record content data onto a recording medium or reproduce content data from the recording medium. Copyright information for the contents includes information identifying an input source of the content data. The information identifying an input source is stored in the recording medium along with the content data. When the contents are reproduced from the recording medium, the input source information is acquired and used as a basis for determining whether the contents can be reproduced and output. Thus, it is possible to impose an output restriction on an operation to reproduce the contents in accordance with the input source.

Claims

1. An information recording apparatus, comprising:

an input interface operable to receive content data, said input interface being of a particular interface type that is one of a predetermined plurality of available interface types;

a processor operable to generate copyright information associated with the content data, the copyright information including input source information which indicates the particular interface type of the input interface through which the content data is received; and

a recording unit operable to record the content data and the associated copyright information onto a recording medium, the recorded input source information being readable from the recording medium to determine an output format restriction on the content data that is based on the particular interface type of said input interface,

wherein the copyright information indicates whether the content data includes copy control information, the copyright information indicates whether the content data is received as input to the information recording apparatus through an IEEE-1394 interface, the copyright information includes information indicating whether the content data include copy control information, and when the information included in the copyright information indicates that the content data include copy control information, the copyright information further includes information indicating whether the copy control information is added to each of a plurality of transport stream (“

TS”

) packets containing the content data recorded on the recording medium or is added as a digital watermark to the content data recorded onto the recording medium.

2. The information recording apparatus as claimed in claim 1, wherein said processor is further operable to generate check data, the check data being usable to determine whether the copyright information is falsified, and said recording unit is further operable to record the check data onto the recording medium in association with the content data and the copyright information.

3. The information recording apparatus as claimed in claim 1, wherein said copyright information indicates whether the content data include digital data or analog data.

4. An information recording apparatus, comprising:

an input interface operable to receive content data, said input interface being of a particular interface type that is one of a predetermined plurality of available interface types;

a processor operable to generate copyright information associated with the content data, the copyright information including input source information which indicates the particular interface type of the input interface through which the content data is received;

a recording unit operable to record the content data and the associated copyright information onto a recording medium, the recorded input source information being readable from the recording medium to determine an output format restriction on the content data that is based on the particular interface type of said input interface; and

a memory operable to store a plurality of encryption keys, the plurality of encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses,

the processor being further operable to perform a process of decrypting an enabling key block (“

EKB”

) containing one of the plurality of node keys to obtain one node key, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or one of the plurality of leaf keys, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the one node key belongs,

the processor being further operable to decrypt the EKB to obtain check data, the check data being usable to determine whether the copyright information is falsified, and

the recording unit being further operable to record the check data on the recording medium in association with the copyright information.

5. An information recording apparatus, comprising:

an input interface operable to receive content data, said input interface being of a particular interface type that is one of a predetermined plurality of available interface types;

a processor operable to generate copyright information associated with the content data, the copyright information including input source information which indicates the particular interface type of the input interface through which the content data is received;

a recording unit operable to record the content data and the associated copyright information onto a recording medium, the recorded input source information being readable from the recording medium to determine an output format restriction on the content data that is based on the particular interface type of said input interface; and

a memory operable to store a plurality of encryption keys, the plurality of encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses, and

the processor being further operable to perform a process of decrypting an enabling key block (“

EKB”

) containing one of the plurality of node keys to obtain one node key, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or one of the plurality of leaf keys, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the one node key belongs, the processor being further operable to decrypt the EKB using the one node key to obtain check data, the check data being usable to determine whether the copyright information is falsified, and

the processor being further operable to encrypt the content data using the one node key to form encrypted content data, and

the recording unit being further operable to record the encrypted content data onto the recording medium.

6. An information reproduction apparatus, comprising:

a reading unit operable to read out content data and copyright information from a recording medium, the copyright information including input source information which indicates a particular interface type of an input interface through which the content data was received, the particular interface type being one of a predetermined plurality of available interface types; and

a processor operable to determine reproducibility of the content data in accordance with an output format restriction on the content data, the output format restriction being determined based on the particular interface type of the input interface as indicated by the read out input source information,

wherein the copyright information includes information indicating whether the content data includes copy control information and indicates whether the content data is received as input to the information recording apparatus through an IEEE-1394 interface, the copyright information includes information indicating whether the content data include copy control information, and when the information indicates that the content data include copy control information, the copyright information further includes information indicating whether the copy control information is added to each of a plurality of transport stream (“

TS”

) packets containing the content data recorded on the recording medium or is added as a digital watermark to the content data recorded on the recording medium.

7. The information reproduction apparatus as claimed in claim 6, wherein said processor is further operable to generate check data from the copyright information read out from the recording medium, and compare the check data with a check value stored on the recording medium to produce a result indicating whether the copyright information has been falsified, and the processor is operable to reproduce the content data only when the result does not indicate that the copyright information has been falsified.

8. The information reproduction apparatus as claimed in claim 6, wherein the copyright information includes information indicating whether the content data include digital data or analog data.

9. An information reproduction apparatus, comprising:

a reading unit operable to read out content data and copyright information from a recording medium, the copyright information including input source information which indicates a particular interface type of an input interface through which the content data was received, the particular interface type being one of a predetermined plurality of available interface types;

a processor operable to determine reproducibility of the content data in accordance with an output format restriction on the content data, the output format restriction being determined based on the particular interface type of the input interface as indicated by the read out input source information; and

a memory operable to store a plurality of encryption keys, the plurality of encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses, and

the processor being further operable to perform a process of decrypting an enabling key block (“

EKB”

) containing one of the plurality of node keys to obtain one node key, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or one of the plurality of leaf keys, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the one node key belongs, the processor further being operable to decrypt the EKB using the one node key to obtain check data, the check data being usable to determine whether the copyright information is falsified.

10. An information reproduction apparatus, comprising:

a reading unit operable to read out content data and copyright information from a recording medium, the copyright information including input source information which indicates a particular interface type of an input interface through which the content data was received, the particular interface type being one of a predetermined plurality of available interface types;

a processor operable to determine reproducibility of the content data in accordance with an output format restriction on the content data, the output format restriction being determined based on the particular interface type of the input interface as indicated by the read out input source information; and

a memory operable to store a plurality of encryption keys, the encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses, and

the processor being further operable to perform a process of decrypting an enabling key block (“

EKB”

) containing one of the plurality of node keys to obtain the one node key, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or one of the plurality of leaf keys, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the one node key belongs, and

the processor being further operable to reproduce the content data stored on the recording medium by decrypting the content data, using the one node key obtained by decrypting the enabling key block.

11. A method of recording information, comprising:

receiving content data through an input interface, said input interface being of a particular interface type that is one of a predetermined plurality of available interface types;

generating copyright information associated with the content data, the copyright information including input source information which indicates the particular interface type of the input interface through which the content data is received; and

recording the content data and the associated copyright information onto a recording medium, the recorded input source information being readable from the recording medium to determine an output format restriction on the content data that is based on the particular interface type of said input interface,

wherein the copyright information indicates whether the content data includes copy control information, and the copyright information indicates whether the content data is received as input to the information recording apparatus through an IEEE-1394 interface, the copyright information includes information indicating whether the content data include copy control information, and when the information included in the copyright information indicates that the content data include copy control information, the copyright information further includes information indicating whether the copy control information is added to each of a plurality of transport stream (“

TS”

) packets containing the content data recorded on the recording medium or is added as a digital watermark to the content data recorded onto the recording medium.

12. The method of recording information as claimed in claim 11, further comprising:

generating check data, the check data being usable to determine whether the copyright information is falsified; and

recording the check data onto the recording medium in association with the content data and the copyright information.

13. The method of recording information as claimed in claim 11, wherein the copyright information indicates whether the content data include digital data or analog data.

14. A method of recording information, comprising:

receiving content data through an input interface, said input interface being of a particular interface type that is one of a predetermined plurality of available interface types;

generating copyright information associated with the content data, the copyright information including input source information which indicates the particular interface type of the input interface through which the content data is received;

recording the content data and the associated copyright information onto a recording medium, the recorded input source information being readable from the recording medium to determine an output format restriction on the content data that is based on the particular interface type of said input interface;

storing a plurality of encryption keys by an information recording apparatus operable to perform said method of recording information, the plurality of encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses;

performing a process of decrypting an enabling key block (“

EKB”

) containing one of the plurality of node keys to obtain one node key, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or one of the plurality of leaf keys, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the one node key belongs;

decrypting the EKB using the one node key to obtain check data, check data using the check data being usable to determine whether the copyright information is falsified; and

recording the check data on the recording medium in association with the copyright information.

15. A method of recording information, comprising:

receiving content data through an input interface, said input interface being of a particular interface type that is one of a predetermined plurality of available interface types;

generating copyright information associated with the content data, the copyright information including input source information which indicates the particular interface type of the input interface through which the content data is received;

recording the content data and the associated copyright information onto a recording medium, the recorded input source information being readable from the recording medium to determine an output format restriction on the content data that is based on the particular interface type of said input interface;

storing a plurality of encryption keys by an information recording apparatus operable to perform said method of recording information, the plurality of encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses;

performing a process of decrypting an enabling key block (“

EKB”

) containing one of the plurality of node keys to obtain one node key, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or one of a plurality of leaf keys, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the one node key belongs;

decrypting the EKB using the one node key to obtain check data, the check data being usable to determine whether the copyright information is falsified;

encrypting the content data using the one node key to form encrypted content data; and

recording the encrypted content data onto the recording medium.

16. A method of reproducing information, said method comprising:

reading out content data and copyright information from a recording medium, the copyright information including input source information which indicates a particular interface type of an input interface through which the content data was received, the particular interface type being one of a predetermined plurality of available interface types; and

determining reproducibility of the read out content data in accordance with an output format restriction on the content data, the output format restriction being determined based on the particular interface type of the input interface as indicated by the read out input source information,

wherein the copyright information includes information indicating whether the content data includes copy control information and indicates whether the content data is received as input to the information recording apparatus through an IEEE-1394 interface, the copyright information includes information indicating whether the content data include copy control information, and when the information indicates that the content data include copy control information, the copyright information further includes information indicating whether the copy control information is added to each of a plurality of transport stream (“

TS”

) packets containing the content data recorded on the recording medium or is added as a digital watermark to the content data recorded on the recording medium.

17. The method of reproducing information as claimed in claim 16, further comprising:

generating check data from the copyright information read out from the recording medium, and

comparing the check data with a check value stored on the recording medium to produce a result indicating whether the copyright information has been falsified, and

reproducing the content data only when the result does not indicate that the copyright information has been falsified.

18. The method of reproducing information as claimed in claim 16, wherein the copyright information includes information indicating whether the content data include digital data or analog data.

19. A method of reproducing information, comprising:

reading out content data and copyright information from a recording medium, the copyright information including input source information which indicates a particular interface type of an input interface through which the content data was received, the particular interface type being one of a predetermined plurality of available interface types;

determining reproducibility of the read out content data in accordance with an output format restriction on the content data, the output format restriction being determined based on the particular interface type of the input interface as indicated by the read out input source information;

storing a plurality of encryption keys, the plurality of encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses;

performing a process of decrypting an enabling key block (“

EKB”

) containing one of the plurality of node keys to obtain one node key, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or one of the plurality of leaf keys, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the one node key belongs;

decrypting the enabling key block using the one node key to obtain check data, the check data being usable to determine whether the copyright information is falsified.

20. A method of reproducing information, comprising:

reading out content data and copyright information from a recording medium, the copyright information including input source information which indicates a particular interface type of an input interface through which the content data was received, the particular interface type being one of a predetermined plurality of available interface types;

determining reproducibility of the read out content data in accordance with an output format restriction on the content data, the output format restriction being determined based on the particular interface type of the input interface as indicated by the read out input source information;

storing a plurality of encryption keys, the encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses, and

performing a process of decrypting at least one enabling key block (“

EKB”

) containing one of the plurality of node keys, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or a leaf key belonging to one of the leaves of the hierarchical tree structure, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the node key belongs, and

reproducing the content data stored on the recording medium by decrypting the content data using the one node key obtained by decrypting the enabling key block.

21. A recording medium having information recorded thereon for performing a method of recording information, said method comprising:

receiving content data through an input interface, said input interface being associated with a particular interface type that is one of a predetermined plurality of available interface types;

generating copyright information associated with the content data, the copyright information including input source information which indicates the particular interface type of the input interface through which the content data is received; and

recording the content data and the associated copyright information onto a recording medium, the recorded input source information being readable from the recording medium to determine an output format restriction on the content data that is based on the particular interface type of said input interface,

wherein the copyright information indicates whether the content data includes copy control information, and the copyright information indicates whether the content data is received as input to the information recording apparatus through an IEEE-1394 interface, the copyright information includes information indicating whether the content data include copy control information, and when the information indicates that the content data include copy control information, the copyright information further includes information indicating whether the copy control information is added to each of a plurality of transport stream (“

TS”

) packets containing the content data recorded on the recording medium or is added as a digital watermark to the content data recorded on the recording medium.

22. A recording medium having information recorded thereon for performing a method of reproducing information, said method comprising:

reading out content data and copyright information from a recording medium, the copyright information including input source information which indicates a particular interface type of an input interface through which the content data was received, the particular interface type being one of a predetermined plurality of available interface types; and

determining reproducibility of the read out content data in accordance with an output format restriction on the content data, the output format restriction being determined based on the particular interface type of the input interface as indicated by the read out input source information,

wherein the copyright information includes information indicating whether the content data includes copy control information, and indicates whether the content data is received as input to the information recording apparatus through an IEEE-1394 interface, the copyright information includes information indicating whether the content data include copy control information, and when the information indicates that the content data include copy control information, the copyright information further includes information indicating whether the copy control information is added to each of a plurality of transport stream (“

TS”

) packets containing the content data recorded on the recording medium or is added as a digital watermark to the content data recorded on the recording medium.

23. A recording medium having information recorded thereon for performing a method of recording information, said method comprising:

receiving content data through an input interface, said input interface being of a particular interface type that is one of a predetermined plurality of available interface types;

generating copyright information associated with the content data, the copyright information including input source information which indicates the particular interface type of the input interface through which the content data is received;

recording the content data and the associated copyright information onto a recording medium, the recorded input source information being readable from the recording medium to determine an output format restriction on the content data that is based on the particular interface type of said input interface;

storing a plurality of encryption keys by an information recording apparatus operable to perform said method of recording information, the plurality of encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses;

performing a process of decrypting an enabling key block (“

EKB”

) containing one of the plurality of node keys to obtain one node key, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or one of the plurality of leaf keys, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the one node key belongs;

decrypting the EKB using the one node key to obtain check data, check data using the check data being usable to determine whether the copyright information is falsified; and

recording the check data on the recording medium in association with the copyright information.

24. A recording medium having information recorded thereon for performing a method of recording information, said method comprising:

receiving content data through an input interface, said input interface being of a particular interface type that is one of a predetermined plurality of available interface types;

generating copyright information associated with the content data, the copyright information including input source information which indicates the particular interface type of the input interface through which the content data is received;

recording the content data and the associated copyright information onto a recording medium, the recorded input source information being readable from the recording medium to determine an output format restriction on the content data that is based on the particular interface type of said input interface;

storing a plurality of encryption keys by an information recording apparatus operable to perform said method of recording information, the plurality of encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses;

performing a process of decrypting an enabling key block (“

EKB”

) containing one of the plurality of node keys to obtain one node key, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or one of a plurality of leaf keys, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the one node key belongs;

decrypting the EKE using the one node key to obtain check data, the check data being usable to determine whether the copyright information is falsified;

encrypting the content data using the one node key to form encrypted content data; and

recording the encrypted content data onto the recording medium.

25. A recording medium having information recorded thereon for performing a method of reproducing information, said method comprising:

reading out content data and copyright information from a recording medium, the copyright information including input source information which indicates a particular interface type of an input interface through which the content data was received, the particular interface type being one of a predetermined plurality of available interface types;

determining reproducibility of the read out content data in accordance with an output format restriction on the content data, the output format restriction being determined based on the particular interface type of the input interface as indicated by the read out input source information;

storing a plurality of encryption keys, the plurality of encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses;

performing a process of decrypting an enabling key block (“

EKB”

) containing one of the plurality of node keys to obtain one node key, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or one of the plurality of leaf keys, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the one node key belongs;

decrypting the enabling key block using the one node key to obtain check data, the check data being usable to determine whether the copyright information is falsified.

26. A recording medium having information recorded thereon for performing a method of reproducing information, said method comprising:

reading out content data and copyright information from a recording medium, the copyright information including input source information which indicates a particular interface type of an input interface through which the content data was received, the particular interface type being one of a predetermined plurality of available interface types;

determining reproducibility of the read out content data in accordance with an output format restriction on the content data, the output format restriction being determined based on the particular interface type of the input interface as indicated by the read out input source information;

storing a plurality of encryption keys, the encryption keys including a plurality of node keys and a plurality of leaf keys, each node key being unique to a node of a plurality of nodes of a network having a hierarchical tree structure, the plurality of nodes including a plurality of leaf nodes corresponding to each of a plurality of leaves of the hierarchical tree structure, each of the leaf nodes including a respective one of a plurality of information recording apparatuses, each of the leaf keys being unique to one of the plurality of information recording apparatuses, and

performing a process of decrypting at least one enabling key block (“

EKB”

) containing one of the plurality of node keys, the one node key having been encrypted using at least one of a second node key of the plurality of node keys or a leaf key belonging to one of the leaves of the hierarchical tree structure, the second node key being unique to a node of a layer of the hierarchical tree structure subordinate to the layer of the hierarchical tree structure to which the node of the node key belongs, and

reproducing the content data stored on the recording medium by decrypting the content data using the one node key obtained by decrypting the enabling key block.