Patent ID: 7941361

Claim:
A quantitative competition method for a system in which a plurality of participant devices send their secret aimed values to a server device and said server device determines which of said plurality of participant devices has offered the maximum or minimum one of said aimed values received, and in which there is provided a conversion table showing the relationships between a sequence of values selectable as said aimed values and a sequence of indexes k of integral values respectively corresponding thereto, and m=1, 2, . . . , M, M being an integer equal to or greater than 2; said method comprising the steps wherein: (a) each of said participant devices processes, with a predetermined one-way function h and through the use of said conversion table, information k(+)b m (k) (+)R m (k) , which contains each index k equal to or larger than an index k m corresponding to said aimed value, select information b m (k) indicating whether said index k corresponds to said aimed value, and a random number R m (k) , to generate at least K−k m +1 pieces of aimed value information h(k(+)b m (k) (+)R m (k) ), and sends these pieces of aimed value information to said server device, A(+)B representing a predetermined arbitrary operation; (b) said server device publishes its received aimed value information on a bulletin board accessible from all of said participant devices; (c) said server device obtains said random number R m corresponding to each of said sequence of indexes k; (d) letting a be a predetermined value with which said select information b m (k) indicates said aimed value, said server device calculates h(k(+)a(+)R m (k) ); (e) said server device checks said aimed values on said bulletin board for matching with said calculated h(k(+)a(+)R m (k) ); and (f) if a match is detected in said step (e), said server device decides that the aimed value of the aimed value information of a participant device having sent said random number R m (k) at that time is the maximum or minimum value.