| 摘要 |
It was not possible to determine a clone source of unauthorized receiver devices. A key distribution system (1) of the present invention comprises a communication path (10), a key issuance center (11), a server (12), and a plurality of receiver devices (13a-13n). The key issuance center (11) distributes, to the server (12), a system private variable group set (SPGS) that is information necessary for distributing a shared key (SK) to the receiver devices (13a-13n), while distributing, to the plurality of receiver devices (13a-13n), an individual information group (EMMG) necessary for receiving the shared key (SK) from the server (12). The server (12) produces the shared key (SK), also produces, based on the shared key (SK) and system private variable group set (SPGS), a common information (ECM), and then distributes the common information (ECM) to the plurality of receiver devices (13a-13n). The receiver devices (13a-13n) acquire, based on the individual information group (EMMG) and common information (ECM), the shared key (SK) and output it to the exterior.
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