Existence proof system, existence proof method and program

摘要

PROBLEM TO BE SOLVED: To safely certify that two or more portable telephones have been present at the same location at the same time, for a third party.;SOLUTION: A presence certification system includes a plurality of user terminals and a medicator terminal. The plurality of user terminals are grouped, and the mediator terminal certifies the presence of the plurality of user terminals. That is, it is safely certified to the third party that two or more portable telephones have been present at the same location at the same time.;COPYRIGHT: (C)2012,JPO&INPIT