Data processing system, data processing method, and program providing medium

A data processing method for executing reproduction of a contents data from a memory device or recording of a contents data into said memory device, said method comprising:

• a step for enciphering an enabling key block distribution key enciphering key by an enabling key block containing enciphered data of renewal keys on such paths for constituting a key tree structure comprising a variety of keys disposed in correspondence with roots, nodes, and leaves on such paths ranging from roots to leaves of said key tree structure comprising a plurality of devices, wherein said enabling key block also contains data of upper-rank key enciphered via lower-rank key;
• and
• a step for storing the key distribution approval data files containing header data consisting of link count key for designating the number of contents data that is enciphered by said enciphering keys in said memory device based on said enabling key block distribution key enciphering key.

A program providing medium which provides such a computer program to enable a computer system to execute a data processing process via reproduction of a contents data from a memory device or via recording of a contents data into a memory device, said process comprising:

• a step for storing said key enciphering key in said memory, wherein said key enciphering key are acquired by way of decode processing said enabling key block distribution key enciphering key contained in a key distribution approval data file containing a greater count number shown by a link-count data present among said key distribution approval data files stored in said memory device;
• and
• a step for executing reading said key distribution approval data files solely in the case where said key enciphering key is identified to be inapplicable, wherein said data processing apparatus judges applicability of said key enciphering key previously stored in said memory device, and then, if it is identified to be applicable, said data processing apparatus utilizes said key enciphering key previously stored in said memory device.

A method for use in recording data to, or reproducing data from, a memory device, the method comprising the steps of:

• enciphering an enabling key block distribution authenticating key by an enabling key block comprising enciphering data for enciphering renewal keys on paths of a hierarchical key tree structure comprising a variety of keys disposed in correspondence with roots, nodes, and leaves of the key tree structure on paths ranging from roots to leaves of the key tree structure, and wherein a device is associated with one of the leaf keys, and wherein said enciphering data further comprises upper-rank keys to be enciphered by lower-rank keys;
• and
• storing, in the memory device, a key distribution approval data file comprising header data, which comprises a link count key for designating a number of contents data that should be enciphered by the enciphering data acquirable from the enabling key block distribution authenticating key.

A computer-readable medium for storing computer-executable software code for the execution of the recording of data to, or the reproduction of data from, a memory device, said code comprising:

• code for enciphering an enabling key block distribution authenticating key by an enabling key block comprising enciphering data for enciphering renewal keys on paths of a hierarchical key tree structure comprising a variety of keys disposed in correspondence with roots, nodes, and leaves of the key tree structure on paths ranging from roots to leaves of the key tree structure, and wherein a device is associated with one of the leaf keys, and wherein said enciphering data further comprises upper-rank keys to be enciphered by lower-rank keys;
• and
• code for storing, in the memory device, a key distribution approval data file comprising header data, which comprises a link count key for designating a number of contents data that should be enciphered by the enciphering data acquirable from the enabling key block distribution authenticating key.