When a user records confidential data in a communicating object, the user inputs the confidential data which are encoded and transmitted, with a reference of the user, towards a server in order to record the encoded confidential data in association with the reference. When a user searches for a reference of another user of a communicating object in the communicating object, the user inputs a search datum which is encoded and transmitted to the server for comparing therein the encoded search datum transmitted to all of the encoded confidential data recorded in the server. The server transmits a reference associated with an encoded confidential datum corresponding to the encoded search data to the communicating object. In this way, the user of the communicating object is put into contact with the other user without knowing the data of the other user.