| 摘要 |
PROBLEM TO BE SOLVED: To rapidly provide a recommendation with a high degree of accuracy while preventing leakage of information.SOLUTION: A server 10 extracts a user identifier for each attribute and encrypts it (a first arithmetic result). A recommendation support device 30 extracts the user identifier for each option and encrypts it (a second arithmetic result). The server 10 encrypts the second arithmetic result (a third arithmetic result). The recommendation support device 30 encrypts the first arithmetic result (a fourth arithmetic result). The recommendation support device 30, with respect to all combinations of attributes and options, obtains a first summary value by tallying the number of code texts coinciding by the third and fourth arithmetic results and generates multiple sets after randomly excluding one or more code texts from the code texts coinciding by the third and fourth arithmetic results, and with respect to each of the sets, it obtains a second summary value by tallying the number of code texts coinciding with the fourth arithmetic result and calculates a parameter for obtaining a product recommendation value on the basis of the first and second summary values. |
