Patent ID: 7992188

Claim:
A document access control system for determining whether to allow a user of a client device to access a target document file stored in the client device according to a security policy set in a server, the system comprising: a cache timing determination part configured to determine a timing for caching policy determination data corresponding to the target document file stored in the client device, the policy determination data including data indicative of whether access to the target document file is allowed when the client device is in an offline mode and data indicative of a valid period of the policy determination data and a valid count of the policy determination data in a case where access to the target document file is allowed when the client device is in the offline mode; a policy determination data obtaining part configured to obtain the policy determination data from the server according to a report from the cache timing determination part; a policy determination data storage part configured to store, in the client device, the obtained policy determination data in correspondence with the target document file; a file access control part configured to control access to the stored target document file according to the policy determination data stored in the policy determination data storage part in a case where the user of the client device requests access to the target document file when the client device is in the offline mode; a log management part configured to record log data indicating access to the target document file based on the policy determination data during the offline mode; and a log data storing part configured to store the log data in an encrypted state, the log data being encrypted with a user encryption key generated by combining a system encryption key and a user password, the system encryption key being secretly stored in the client device and being inaccessible by the user.