Collation system, client and server

A collation system comprising:

• a client;
• and
• a server,
• wherein the client includes:
• a random number generation unit which generates a random number;
• and
• a concealed information storage unit which stores concealed information generated by concealing registered information and the generated random number using a concealment key.

A collation system comprising:

• a client;
• and
• a server,
• wherein the client includes a concealed index computation unit which, on the basis of the collation information input for collation with the registered information and concealed information generated by concealing the registered information and a random number using a concealment key, computes a concealed index, generated by concealing an index indicating closeness between the registered information and the collation information, and
• the server includes a determination unit which uses a release key corresponding to the concealment key and the random number transmitted from the client to determine whether or not the index can be acquired from the concealed index transmitted from the client.

A client comprising:

• a random number generation unit which generates a random number;
• a concealed information storage unit which stores concealed information generated by concealing registered information and the generated random number using a concealment key;
• and
• a concealed index computation unit which, on the basis of the collation information input for collation with the registered information and the concealed information, computes a concealed index, generated by concealing an index indicating closeness between the registered information and the collation information.