Patent ID: 7991694

Claim:
A mobile user terminal for use in an electronic commerce system, said electronic commerce system comprising at least the mobile user terminal, a service providing system and an examination terminal, said mobile user terminal comprising: a remote communication section that communicates with said service providing system via public wireless communication equipment; a local communication section that communicates with said examination terminal by proximity wireless communication equipment; an acquisition section configured to transmit, via said remote communication section, a request for electronic value card information to the service providing system and configured to receive the electronic value card information from the service providing system, said electronic value card information including at least a first key data differing for each type of the electronic value card information and a second key data differing for each type of the electronic value card information; a mutual authentication section configured to exchange messages, via said local communication section, with the examination terminal to execute a first process authenticating the examination terminal and at same time to exchange messages as a part of a second process for authentication by the examination terminal, wherein in the first process authenticating the examination terminal, the mutual authentication section is configured: to encrypt first data with the first key data included in said electronic value card information to transmit a message including said encrypted first data to the examination terminal to receive a first response from the examination terminal to collate the response with said first data, wherein in the second process authenticated by the examination terminal, the mutual authentication section is configured to decrypt encrypted second data received from the examination terminal with the second key data included in said electronic value card information and to transmit a second response including said second data to the examination terminal.