| 摘要 |
<P>PROBLEM TO BE SOLVED: To keep anonymity concerning a user without imposing burden on the server of a site manager and parties in charge and without allowing the site manager to know the contents. <P>SOLUTION: A cipher information receiving part 32 receives, from the terminal 20 of a bidder, a third kind of cipher data which is obtained by multiplying a first kind of cipher data obtained by enciphering bid information and a random number through the use of a public key of the site by a second kind of cipher data obtained by enciphering private information of the bidder through the use of the public key. An authentication indicating part 33 transmits a fourth kind of cipher data obtained by decoding the third kind of cipher data through the use of a secret key of the site to the terminal 10 of an exhibitor. Then the terminal 10 of the exhibitor authenticates the fourth kind of cipher data, based on random number data which is transmitted from the terminal 20 of the bidder who makes a successful bid. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
