Patent ID: 7726577
Filing Date: 2010-06-01
Classification: G06K

Abstract:
1. A contactless card that communicates with a reader/writer after being supplied with electric power, the contactless card having an identifier that identifies the contactless card, the contactless card comprising: a power detection unit operable to detect that electric power has been supplied for enabling communication to take place between the contactless card and the reader/writer; an identifier determination unit operable to determine an identifier that identifies the contactless card, every time the power detection unit detects that electric power has been supplied for enabling communication to take place between the contactless card and the reader/writer; an identifier storage unit operable to hold the identifier determined by the identifier determination unit; a receiving unit operable to receive, from the reader/writer, a command requesting that the identifier that identifies the contactless card be sent to the reader/writer; a first request judgment unit operable to judge, based on a first request judgment flag, whether the command received by the receiving unit is a first request command or a second or later request command; a sending unit operable to send, to the reader/writer, the identifier that identifies the contactless card; and a mode judgment unit operable to judge an operation mode included in a contactless mode in which the contactless card operates, by judging whether or not a voltage at a predetermined point in the contactless card is a predetermined voltage, wherein the identifier determination unit includes: a random identifier generation unit operable to generate an identifier in a random manner; and a specific identifier generation unit operable to generate a specific identifier, wherein the judged operation mode included in the contactless mode is used to determine, independently of information received by the receiving unit, which one of (i) the random identifier generation unit and (ii) the specific identifier generation unit, is to be used to generate the identifier that identifies the contactless card, and wherein the sending unit is operable to send, to the reader/writer, (i) a new identifier determined by the identifier determination unit in the case where the first request judgment unit judges that the command received by the receiving unit is the first request command, and (ii) the identifier held in the identifier storage unit in the case where the first request judgment unit judges that the command received by the receiving unit is the second or later request command.