Patent ID: 10992462

Abstract:
A concealed-decision-tree computation system includes a user apparatus and 0th to (n−1)-th server apparatuses, where n is a predetermined positive integer. The user apparatus secret-shares data D into n shares [D]j (j=0, . . . , n−1) and sends the n shares [D]j (j=0, . . . , n−1) to the 0th to (n−1)-th server apparatuses, respectively. The 0th to (n−1)-th server apparatuses use the n shares [D]j (j=0, n−1) to perform secret cooperation computation to obtain n shares [out]0, . . . , [out]n-1 of a value “out” corresponding to the data D in a predetermined decision tree and send the n shares [out]0, . . . , [out]n-1 to the user apparatus. The user apparatus uses at least k shares out of the n received shares [out]0, . . . , [out]n-1 to restore the value “out” corresponding to the data D in the predetermined decision tree, where k is a predetermined integer equal to or smaller than n.