encryption device, ciphertext comparison system, ciphertext comparison method, and ciphertext comparison program

摘要

The present invention by performing a magnitude comparison of different numerical data respectively encrypted. A A document as a numerical value with the encryption unit 510 generates encrypted identifier for each encrypted with the document by calculation with an input value above identifier, the document calculates the derived key to the identifier as an input value, derived keys, and and it generates the relative value is the value of a magnitude comparison determination between the plaintext and the other plaintext by performing the calculation by the second hash function to the plaintext as the input value, derived keys, the identifier, and the relative value and an input value the relative value to generate an encrypted relative ciphertext by calculation that was to produce a string of identifiers each ciphertext relative value cryptogram as the document ciphertext, and the identifier for this and other cipher text the calculation by the second hash function when it is entered by performing a magnitude comparison of the relative value to restore the relative values ​​corresponding to different ciphertexts and the comparison to make the size determination of the encrypted different plaintext It was equipped with a section 513. .BACKGROUND