Ciphertext processing device, ciphertext processing method, ciphertext processing program, and information processing device

摘要

A ciphertext processing device (30) acquires a first polynomial into which first text data is converted with a first order and which is encrypted with a first public key and a first square-value polynomial into which square-value vector data of each component of the first text data is converted with the first order and which is encrypted with the first public key. The ciphertext processing device (30) acquires a second polynomial into which second text data is converted with a second order and which is encrypted with the first public key and a second square-value polynomial into which square-value vector data of each component of the second text data is converted with the second order and which is encrypted with the first public key. The ciphertext processing device (30) determines whether the second text data is included in the first text data, using the each polynomial.