| 摘要 |
PROBLEM TO BE SOLVED: To enable user authentication without storage or input of a password by a user.SOLUTION: Base on information on purchased merchandise which a user has purchased, obtained from a cooperative site, a prescribed number of pieces of choice data including the purchased merchandise information is generated, and based on the user's selection result of the generated choice data, the user authentication is performed. Also, based on preset weighting information for each cooperative site, the number of pieces of the non-purchased merchandise information included in the choice data is adjusted. |
