Abstract:
The object of the present invention is to provide a data protection system that reduces to a degree the amount of encrypted data that is distributed to a multiplicity of terminals, and that has a structure in which a terminal whose decryption keys are exposed by a dishonest party is made unable to decrypte the data correctly, while other terminals are able to decrypt the data correctly. The present invention is a data protection system that includes a multiplicity of terminals, and an encryption device that encrypts distribution data that is distributed to each terminal. Each terminal is corresponded with one node on a lowest level of 4-ary tree structure or the like that has a plurality of hierarchies. The data protection system, for each node in the tree structure, excluding those on the lowest level, determines a plurality of combination patterns that include combinations of two or more of all four nodes that are reached one level below the node, decides an individual decryption key for each determined combination pattern, further decides an individual decryption key for each node on the lowest level, and has each terminal store all decryption keys decided for the nodes on the path from the node on the lowest level that corresponds to the terminal through to the node on the highest level. The data protection system prescribes nodes reached from the node on the lowest level that corresponds to the terminal through to the node on the highest level that correspond to a terminal that has been dishonestly analyzed as invalid nodes. For invalid nodes, other than invalid nodes on the lowest level, the data protection system designates an encryption key that corresponds to the decryption key decided in correspondence with the combination pattern that combines all nodes, excluding invalid nodes, of the four nodes that are reached one level below the node, and has the encryption device encrypt distribution data that uses each of the designated encryption keys.
Abstract:
A method and apparatus for secure data transmission between a source and a receiver. The method involves generating a first and a second information packet at the source, each packet having an instruction field and a data field. The method then involves sequentially transmitting the packets from the source to the receiver and configuring the receiver in response to the instruction field of the first packet for decoding the data field of the second packet. In response to the instruction field of the first packet, the receiver decodes the instruction field of the second packet.
Abstract:
When an encrypting-decrypting module is being used, there are various methods for determining the key or keys used by said module by analysing the module input or output data. To remedy this inconvenience, the inventive multiple module method is characterised in that the downstream module starts its encrypting-decrypting operations as soon as part of the results of the upstream module is available.
Abstract:
The digital data access and distribution system (100) includes two main components: a data distributor (102) and a user (104). The data distributor (102) takes data (106) and produces packaged data (108) which are provided to the user (104) via the communication channel (105), perhaps in return for some form of payment (110). Corresponding to each of the distributor (102) and the user (104) are the system's authoring mechanism (112) and access mechanism (114). The authoring mechanism (112) of the distributor (102) takes the data (106) to be packaged and produces packaged data (108) which is provided to the user (104) by the distribution mechanism (118).