Network key update system, server, network key update manner and record media

摘要

The case of update of the network key frequency of communication is decreased, at the same time, without depending on the key tree, degradation of the performance with update is suppressed. The server generates the identifier in order to identify the client with the combination of address with respect to the multiple address spaces, generates the generation impossible network key update key from the address key allotment section which allocates the respective address key, vis-a-vis each address which forms the identifier which is generated and the address key which is allocated to the client of the disconnection target the new network key, encrypting making use of the network key update key, has with the network key encryption section which it transmits to the client.