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Information processing system and method for distributing encrypted message data

  • US 7,443,984 B2
  • Filed: 04/02/2001
  • Issued: 10/28/2008
  • Est. Priority Date: 04/06/2000
  • Status: Expired due to Fees
First Claim
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1. An information processing system for distributing encrypted message data, said system comprising:

  • a receiving device, including;

    holding means for holding a key set that is specific to said receiving device and which includes a portion of a plurality of node keys and a corresponding leaf key, the plurality of node keys being associated with a plurality of nodes whereby a given one of the plurality of node keys is associated with a particular one of the plurality of nodes, the plurality of nodes being arranged according to a hierarchical tree structure having a root node and a plurality of leaves, the portion of the plurality of node keys being the node keys associated with the nodes disposed along a particular path from the root node of the hierarchical tree structure to a particular one of the plurality of leaves that is associated with said receiving device and with its corresponding leaf key, andencryption processing means for decrypting encrypted message data distributed to said receiving device by using the key set; and

    a distributing device, including;

    message data generating means for generating an enabling key block (EKB) using one or more keys selected from the group consisting of the portion of the plurality of node keys and the corresponding leaf key, andmessage data distributing means for distributing a storage medium storing first message data that includes data in which first content is encrypted with a first content key, data in which the first content key is encrypted by a content key encryption key, and a link to a location on the storage medium wherein data is stored in which the content key encryption key is encrypted by the enabling key block (EKB), and storing second message data that includes data in which second content is encrypted by a second content key, data in which the second content key is encrypted by the content key encryption key, and another link to the location on the storage medium wherein the data is stored in which the content key encryption key is encrypted by the enabling key block (EKB).

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