Patent ID: 8005211
Filing Date: 2011-08-23
Classification: H04L

Abstract:
1. A shuffle-decrypting legitimacy certifying apparatus comprising: an input device receiving a plurality of encrypted texts, a public key, a decrypting secret key, and a random number, said plurality being a number greater than one; an output device; a memory; a controller; one or more modules operable to encrypt the encrypted texts with the public key, shuffle the order of the encrypted texts, generate a plurality of decrypted texts produced by decrypting the encrypted texts with the secret key, and certify legitimacy of the encryption, the shuffling of the order, and the decryption to a shuffle-decrypting verifying apparatus; a challenge value generating apparatus waiting for a shuffle-decrypting certifying commitment comprising a substitution certifying commitment including a commitment of a plurality of shuffled encrypted texts and a shuffle commitment, an identical conversion certifying commitment, and a decryption certifying commitment, to be sent from said shuffle-decrypting certifying apparatus, selecting a random number having a given length as a challenge value when said shuffle-decrypting certifying commitment is received, and sending the selected challenge value to said shuffle-decrypting legitimacy certifying apparatus; a substitution verifying apparatus receiving said shuffle commitment, said substitution certifying commitment, a response, and said challenge value, and for generating a verifying result indicating either “legitimate” or “illegitimate” depending on whether the shuffle commitment is a commitment of substitution or a random number for encryption; an identical conversion verifying apparatus receiving said identical conversion certifying commitment, said encrypted texts, the commitment of said shuffled encrypted texts, said public key, said response, and said challenge value, and generating a verifying result indicative of either “legitimate” or “illegitimate” depending on whether the committed shuffled encrypted texts are shuffled using the committed substitution or the committed random number for encryption; and a decryption verifying apparatus receiving said decryption certifying text, commitment of said shuffled encrypted texts, said decrypted texts, said public key, said response, and said challenge value, and generating a verifying result indicative of either “legitimate” or “illegitimate” depending on whether the committed shuffled encrypted texts are decrypted into said decrypted texts, wherein data to communicate with said shuffle-decrypting verifying apparatus includes a number greater than one of shuffled encrypted text commitments, each of which is produced using the random number as an encrypted text by encrypting the encrypted texts with said public key and shuffling the order thereof, and the number of shuffled encrypted text commitments equals the number of encrypted texts received by the input device, and if all the verifying results from said substitution verifying apparatus, said identical conversion verifying apparatus, and said decryption verifying apparatus represent “legitimate”, then a verifying result indicating “legitimate”, that represents that said shuffled decrypted texts are produced by properly shuffle-decrypting said encrypted tests, is output, and if even one of said verifying results represents “illegitimate”, then a verifying result indicative of “illegitimate” is output.