To shorten an authentication period of time in authentication using a plurality of cryptographic keys.
An area 51 is defined as a common area, and data common for providers are stored therein. Only each of corresponding providers can access an area 52. In an area 53, information required for managing the areas 51 and 52 is recorded. The information is block allocation information indicating a number of a provider and an area of the provider, permission information that only reading is possible, a password key and the like. A provider number "00" is common for the providers and in the block allocation information, an address of the area 51 as the common area is written. As the permission information, information for making possible access to the area 51 as the common area is specified. As the cryptographic key and its version, a cryptographic key or the like required for accessing the area 51 as the common area is specified.
ISHIBASHI YOSHITO
TAKADA MASAYUKI
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