Search

In this paper, the convertible undeniable multi-signature scheme is proposed. An undeniable signature scheme has a property that a verifier can not authenticate the signature of the document without help of the signer. An undeniable multi-signature scheme also has similar property that the signature of the document can not be verified without co-operation of all participating signers. The proposed convertible undeniable multi-signature scheme can convert the undeniable multi-signature to the ordinary multi-signature. The authenticity of confidential document can only be verified with co-operation of all signers. If the document is no longer confidential, it can be opened to public use by converting the undeniable multi-signature on the document to the ordinary one. The proposed scheme satisfies undeniable property and can be applied to copyright protection of digital contents made by many authors.

Voting is an important social activity in democratic society. The realization of electronic democracy is based on the security of electronic voting scheme. Therefore, it is necessary to use the cryptographic technique for secure election. The electronic voting scheme based on undeniable blind signature scheme is proposed for providing anonymity of voters and ensuring that the intermediate voting results do not affect the entire election. In order to make practical voting scheme, we assume that the voting authorization center is trustful and the IP trace between the voting authorization center and a voter is not available. The proposed scheme fully conforms to the requirements of large scale election such as privacy, fairness, unreusability, unforgeability and eligibility.

Election is an important social activity in democratic society. The realization of electronic democracy is based on the security of electronic voting scheme. Therefore, it is necessary to use the cryptographic technique for secure electronic election. In this paper, the electronic voting scheme suitable for large scale election is proposed. The proposed scheme consists of three stages those are preparation stage, voting stage and counting stage. In voting stage, pseudonyms are generated by voters and undeniable blind signature scheme is processed between a voter and the voting center. If the voter wants to vote other candidate after sending the vote, the voter can make up his mistake in the proposed scheme due to the undeniable property. In order to make practical voting scheme, we assume that the voting center is trustful and IP trace between the voting center and a voter is not available. The proposed scheme fully conforms to requirements of large scale election such as privacy, fairness, unreusability, unforgeability and eligibility.