| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable simultaneous access to noncontact information storage devices having different encryption keys by a reader/writer device. <P>SOLUTION: The reader/writer device (304) encrypts an information request and a second encryption key (Ke2) with a first encryption key (Ke1) to generate first encrypted data, encrypts the information request with the second encryption key (Ke2) to generate second encrypted data, and periodically repetitively transmits an information request signal of first frequency for alternately carrying the first and second encrypted data. The active noncontact information storage device (202) receives the information request signal, decodes the received encrypted data with one encryption key (Ke) within a memory, and rewrites, when the decoded encrypted data contains the second encryption key (Ke2) different from the one encryption key (Ke), rewrites the one encryption key (Ke) to the second encryption key (Ke2). <P>COPYRIGHT: (C)2008,JPO&INPIT |
