To prevent leakage of information by limiting file access only in a specific area, so as to disable secret information to be accessed even if the secret information flows out.
In the step of transmitting a decode key request from a client 10 through a network device 20 to an administrative server 30, not the client 10 but the network device 20 adds location information to the decode key request and in the case where the decode key request reaches the administrative server 30, recorded information is compared with the location information relating to the decode key request. If the location information is the same, a decode key is transmitted to the client 10. Upon receipt of the decode key request that becomes a specific packet from the client 10, only in the case where the request is passed through the network device 20 that adds the location information, the decode key is transmitted from the administrative server 30 to the client 10, and access to secret information can be limited within the specific area.
YONEHARA AKIO
IKEDA TAKASHI
KUBOTA AKINORI
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