PRIVATE COMPUTATION ON ENCRYPTED BIOMETRIC DATA USING HOMOMORPHIC ENCRYPTION

摘要

A cryptographic processing device includes a generator that generates a first encrypted polynomial by encrypting a first polynomial that corresponds to a first vector obtained by adding a first random number to a zero vector as a component, a transmitter that transmits, to a terminal, first cryptographic information that represents the first encrypted polynomial, a receiver that receives, from a calculation device, second cryptographic information that represents a fourth encrypted polynomial, and receives, from the calculation device, third cryptographic information that represents a second random number, the fourth encrypted polynomial including a first operation result that is a result of an operation of a fifth vector and a sixth vector that is obtained by adding, to a second vector, a result of a multiplication of the first random number by the second random number as a component, the first operation result being obtained by calculating from a second encrypted polynomial and a third encrypted polynomial, wherein the second encrypted polynomial is obtained by adding a result of a multiplication of the first encrypted polynomial by the second random number to a second polynomial that corresponds to a third vector obtained by adding zero to the second vector as a component, and the third encrypted polynomial is obtained by encrypting a third polynomial that corresponds to the fifth vector obtained by adding zero to a fourth vector as a component, a decryption unit that decrypts the second cryptographic information and the third cryptographic information, and a processing unit that generates a second operation result that is a result of an operation of the second vector and the fourth vector, on the basis of a result of decrypting the second cryptographic information and a result of decrypting the third cryptographic information.