Abstract: A method for performing a secure evaluation of a decision tree, including: receiving, by a processor of a server, an encrypted feature vector x=(x1, . . . , xn) from a client; choosing a random mask ?0; calculating m0 and sending m0 to the client, wherein m0=xi0(0)?t0(0)+?0 and t0(0) is a threshold value in the first node in the first level of a decision tree ?; performing a comparison protocol on m0 and ?0, wherein the server produces a comparison bit b0 and the client produces a comparison bit b?0; choosing a random bit s0?{0,1} and when s0=1 switching a left and right subtrees of ?; sending b0?s0 to the client; and for each level =1, 2, . . . , d?1 of the decision tree ?, where d is the number of levels in the decision tree ?, perform the following steps: receiving from the client yk where k=0, 1, . . .

Abstract: A method for performing a secure comparison between a first secret data and a second secret data, including: receiving, by a processor of a first party, encrypted bits of the second secret data y from a second party, where is an integer; computing the Hamming weight h of first secret data x, wherein x has bits; computing the value of a first comparison bit ?A such that ?A=0 when h>?/2?, ?A=1 when h<?/2?, and ?A is randomly selected when h=/2; forming a set of ?/2? indexes that includes at least the indexes i where xi=?A; selecting random invertible scalars ri for each i in and computing c*i=(1+(1?2?A)xi·yi2?A?1·(xj?yj))ri wherein w denotes the homomorphic encryption of w using a cryptographic key of the second party; selecting random invertible scalars r?1 and computing c*?1=(?A·xj?yj)r?1; transmitting ciphertexts c*i in a random order to the second party.

Abstract: A method for performing a secure comparison between a first secret data and a second secret data, including: receiving, by a processor of a first party, encrypted bits of the second secret data y from a second party, where is an integer; computing the Hamming weight h of first secret data x, wherein x has bits; computing the value of a first comparison bit ?A such that ?A=0 when h>?/2?, ?A=1 when h<?/2?, and ?A is randomly selected when h=/2; forming a set of ?/2? indexes that includes at least the indexes i where xi=?A; selecting random invertible scalars ri for each i in and computing c*i=+(1+(1?2?A)xi·yi2?A?1·(xj?yj))ri wherein w denotes the homomorphic encryption of w using a cryptographic key of the second party; selecting random invertible scalars r?1 and computing c*?1=(?A·xj?yj)r?1; transmitting ciphertexts c*i in a random order to the second party.

Abstract: A method for performing a secure evaluation of a decision tree, including: receiving, by a processor of a server, an encrypted feature vector x=(x1, . . . , xn) from a client; choosing a random mask ?0; calculating m0 and sending m0 to the client, wherein m0=xi0(0)?t0(0)+?0 and t0(0) is a threshold value in the first node in the first level of a decision tree ?; performing a comparison protocol on m0 and ?0, wherein the server produces a comparison bit b0 and the client produces a comparison bit b0?; choosing a random bit s0?{0,1} and when s0=1 switching a left and right subtrees of ?; sending b0?s0 to the client; and for each level =1, 2, . . . , d?1 of the decision tree ?, where d is the number of levels in the decision tree ?, perform the following steps: receiving from the client y0 where k=0, 1, . . .