Access control technique using cryptographic technology

An access authority management method in a center system, comprising:

• receiving a first digital signature for specific data from a terminal of a user;
• comparing the received first digital signature with a second digital signature, which is registered in a data storage unit so as to correspond to said specific data;
• and
• if it is judged that said first digital signature and said second digital signature are identical, carrying out a setting to grant said user an authority to update said specific data.

A data registration method in a center system, comprising:

• if specific data is received from a user terminal, generate hash data for said specific data;
• transmitting said hash data to said user terminal;
• receiving a digital signature generated from said hash data;
• and
• registering said specific data, said hash data and said digital signature into a data storage unit.

A data access method in a user system, comprising:

• generating a digital signature from hash data, which is stored in a hash storage, for specific data;
• transmitting an access request including said digital signature to a server;
• and
• if said digital signature and a second digital signature, which is registered in said server, for said specific data are identical, receiving and displaying on a display device, said specific data in a state where updating is enabled, from said server.

A computer program embodied on a medium, said computer program comprising:

• receiving a first digital signature for specific data and data concerning a first user to be allowed to read said specific data, from a terminal of a second user;
• comparing the received first digital signature with a second digital signature, which is registered in a data storage unit so as to correspond to said specific data;
• and
• if it is judged that said first signature and said second signature are identical, performing a processing for enabling said first user to read said specific data.

A computer program for an access authority management, said computer program comprising:

• receiving a first digital signature for specific data from a terminal of a user;
• comparing the received first digital signature with a second digital signature, which is registered in a data storage unit so as to correspond to said specific data;
• and
• if it is judged that said first digital signature and said second digital signature are identical, carrying out a setting to grant said user an authority to update said specific data.

A center system, comprising:

• means for receiving a first digital signature for specific data and data concerning a first user to be allowed to read said specific data, from a terminal of a second user;
• means for comparing the received first digital signature with a second digital signature, which is registered in a data storage unit so as to correspond to said specific data;
• and
• means for performing a processing for enabling said first user to read said specific data, if it is judged that said first signature and said second signature are identical.

A center system, comprising:

• means for receiving a first digital signature for specific data from a terminal of a user;
• means for comparing the received first digital signature with a second digital signature, which is registered in a data storage unit so as to correspond to said specific data;
• and
• means for carrying out a setting to grant said user an authority to update said specific data, if it is judged that said first digital signature and said second digital signature are identical.