Information Recording/Playback Apparatus and Method
First Claim
1. An information recorder to record information to a recording medium, the apparatus comprising:
- a cryptography means having a node key unique to each of nodes included in a hierarchical tree structure in which a plurality of different information recorders is included as each of leaves of the tree structure and a leaf key unique to each of the information recorders, and which encrypts data to be stored into the recording medium;
the cryptography means generating an encryption key based on encryption key generating data built in the information recorder to encrypt data to be stored into the recording medium; and
the encryption key generating data being data which can be renewed with at least either the node key or leaf key.
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Abstract
In a tree-structural key distribution system, renewed data of a master key and medium key are sent along with a key renewal block (KRB). KRB is such that each of devices included as leaves of a tree structure has a leaf key and restricted node key. A specific KRB can be generated for a group identified by a specific node and distributed to the group to restrict a device for which the key can be renewed. Any device not belonging to the group cannot decrypt the key, whereby the security of key distribution can be assured. Especially in a system using a generation-managed master key, a master key renewed with KRB can be distributed.
104 Citations
58 Claims
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1. An information recorder to record information to a recording medium, the apparatus comprising:
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a cryptography means having a node key unique to each of nodes included in a hierarchical tree structure in which a plurality of different information recorders is included as each of leaves of the tree structure and a leaf key unique to each of the information recorders, and which encrypts data to be stored into the recording medium;
the cryptography means generating an encryption key based on encryption key generating data built in the information recorder to encrypt data to be stored into the recording medium; and
the encryption key generating data being data which can be renewed with at least either the node key or leaf key. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 48, 49, 50)
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13. An information player to play back information from a recording medium, the apparatus holding a node key unique to each of nodes included in a hierarchical tree structure in which a plurality of different information recorders is included as each of leaves of the tree structure and a leaf key unique to each of the information recorders, comprising a cryptography means to decrypt encrypted data stored in the recording medium;
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the cryptography means generating a decryption key based on decryption key generating data built in the information recorder to decrypt the encrypted data stored in the recording medium; and
the decryption key generating data being data which can be renewed with at least either the node key or leaf key.
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25. An information recording method for recording information to a recording medium, the method comprising the steps of:
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renewing encryption key generating data to generate an encryption key for encrypting data to be stored into a recording medium with at least either a node key unique to each of nodes included in a hierarchical tree structure in which a plurality of different information recorders is included as each of leaves of the tree structure or a leaf key unique to each of the information recorders; and
generating an encryption key based on the encryption key generating data to encrypt data to be stored into the recording medium.
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36. An information playback method to play back information from a recording medium, the method comprising the steps of:
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renewing decryption key generating data from which there is generated a decryption key for decryption of encrypted data stored in the recording medium with at least either a node key unique to each of nodes included in a hierarchical tree structure in which a plurality of different information players is included as each of leaves of the tree structure or a leaf key unique to each of the information players; and
generating the decryption key from the decryption key generating data having renewed in the renewing step to decrypt the data stored in the recording medium.
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47. An information recording medium capable of recording information, having stored therein a key renewal block (KRB) derived from encryption of a renewed node key with at least either a node key unique to each of nodes included in a hierarchical tree structure in which a plurality of different information recorders is included as each of leaves of the tree structure and a leaf key unique to each of the information recorders.
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51. A recording medium producing apparatus for producing an information recording medium, the apparatus comprising:
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a memory to store a key renewal block (KRB) derived from encryption of a renewed node key with at least either a node key unique to each of nodes included in a hierarchical tree structure in which a plurality of different information recorders is included as each of leaves of the tree structure and a leaf key unique to each of the information recorders; and
a control unit to control write of the key renewal block (KRB) stored in the memory to the recording medium. - View Dependent Claims (52, 53)
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54. A recording medium producing method comprising the steps of:
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storing, into a memory, a key renewal block (KRB) derived from encryption of a renewed node key with at least either a node key unique to each of nodes included in a hierarchical tree structure in which a plurality of different information recorders is included as each of leaves of the tree structure and a leaf key unique to each of the information recorders; and
writing, to the recording medium, the key renewal block (KRB) stored in the memory. - View Dependent Claims (55, 56)
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57. A program serving medium for serving a computer program under which information processing for recording information to a recording medium is conducted in a computer system, the computer program comprising the steps of:
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renewing encryption key generating data to generate an encryption key for encrypting data to be stored into a recording medium with at least either a node key unique to each of nodes included in a hierarchical tree structure in which a plurality of different information recorders is included as each of leaves of the tree structure or a leaf key unique to each of the information recorders; and
generating an encryption key based on the encryption key generating data to encrypt data to be stored into the recording medium.
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58. A program serving medium for serving a computer program under which information stored in a recording medium is played back in a computer system, the computer program comprising the steps of:
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renewing decryption key generating data from which there is generated a decryption key for decryption of encrypted data stored in the recording medium with at least either a node key unique to each of nodes included in a hierarchical tree structure in which a plurality of different information players is included as each of leaves of the tree structure or a leaf key unique to each of the information players; and
generating the decryption key from the decryption key generating data having renewed in the renewing step to decrypt the data stored in the recording medium.
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Specification