Certified shuffle-decrypting system, certified shuffle-decrypting method and certified shuffle-decryption verifying method

摘要

The present invention provides a certified shuffle-decrypting system, which does not require shuffled encrypted texts to be output, and in which the amounts of calculation and certificates are minimized to allow efficient processing, and the certified shuffle-decrypting system generates shuffle-decryption certificates certifying that multiple encrypted texts have been shuffle-decrypted correctly, and verifies, based on the shuffle-decryption certificates, whether or not the shuffle-decryption has taken place correctly. This system comprises: a certified shuffle-decryption device for shuffle-decrypting the multiple encrypted texts to generate the shuffle-decrypted texts, and for generating the shuffle-decryption certificates; and a shuffle-decryption verification device for verifying whether or not the shuffle-decryption has taken place correctly, by referring to the generated shuffle-decrypted texts and the shuffle-decryption certificates for the shuffle-decrypted texts. The certified shuffle-decryption device: decrypts, with the secret keys, the shuffled encrypted texts obtained by shuffling the order of the encrypted texts and encrypting them with public keys, thereby generating the shuffle decrypted texts; generates responses as a reference for the certifications; generates certificates certifying, based on the responses, the validities of the shuffling of order, the encryption and the decryption for obtaining the shuffle-decrypted texts; and outputs the generated certificates and the responses as shuffle-decryption certificates.