An encrypted data processing system is provided including an encryption device and a server. The encryption device includes an encrypting section that encrypts first information based on a first encryption key and transmits the encrypted information for registration to the server, and encrypts second information based on a second encryption key and transmits the encrypted information to be compared to the server. The server includes a comparison section that employs a cipher comparison function for comparing encrypted information to compare the encrypted information for registration against the encrypted information to be compared, and transmits a comparison result to the encryption device. The encryption device further includes a comparison result decrypting section that employs a decryption function for decrypting the comparison result with the first encryption key and the second encryption key to find a degree of matching between the first information and the second information.