Study And Design Of Universal Designated Verifier Signature Schemes

With the rapid development of computer network and information technology, how to effectively solve the problem of privacy associated with a person in electronic commerce applications has become more and more concerned. Universal designated verifier signature (UDVS) schemes are just the effective technology to solve such problems. In this signature, given a signature from the signer, the privacy of the signature holder is protected by allowing him to convince the designated verifier that he holds a valid signature from the signer without revealing the signature itself. Therefore, our point in this thesis is to study and design universal designated verifier signature schemes with some special properties and verifiably encrypted signature schemes via formalization means of provably security. Our main achievements are as follows:1. An efficient universal designated verifier signature proof scheme is proposed. We firstly give the formal definition and security model and then describe the proposed scheme. Finally, we prove its security in the random oracle model and analyze its performance.2. A restricted universal designated verifier signature scheme is firstly presented which is proved to be secure in the standard model (without random oracles). Our scheme is the integration of Waters signature scheme and (t , n ) threshold idea.3. A designated verifier proxy signature scheme is firstly proposed which is proved to be secure in the standard model. In this scheme, the designed signature which is created by the proxy signer can only be checked the validity by the designated verifier, hence, the privacy of proxy signer can be protected.4. The notion of certificateless universal designated verifier signature is firstly presented by studying certificateless public key cryptosystems. Firstly, we give the formal definition and security model and then describe the proposed concrete scheme. Finally, we prove its security in the random oracle model and analyze its performance. Our scheme can solve the key escrow problem which seems to be inherent in identity-based universal designated verifier signature scheme.5. An efficient verifiably encrypted signature scheme is proposed. Firstly, we give the formal definition and security model and then describe the proposed scheme. Finally, we proven its security in the standard model and analyze its performance. We show that our scheme is the most efficient in the verifiably encrypted signature schemes which are proven to be secure without random oracle. Thus, our scheme is to be applied in the real life.