Study On The Applications Of Undeniable Signature And Proxy Signature

This thesis mainly discusses undeniable signature schemes and proxy signature schemes. The main contents and results that the author obtained are as follows:1. We introduce some basic digital signature schemes and several kinds of attacks the enemy can mount against a digital signature scheme. The security of the signature schemes whose signatures have specific form is discussed in the random oracle model. As an example, we proof the security of Schnorr signature against adaptive chosen message attack in the random oracle model.2. We introduce the notion and model of undeniable signature and show its applications available. Undeniable signature schemes based on the problems of discrete logarithm and RSA are given and their security is analyzed. We then introduce the notion and model of designated confirmer signature. A method to contruct designated confirmer signature scheme is given. Using this method we propose a new secure designated confirmer signature scheme and proof its security.3. We introduce the notion and taxonomy of proxy signature as well as its security properties needed. We specify the schemes of basic proxy signature, strong non-designaed proxy signature and strong proxy signature with proxy signer privacy protection. Their security properties are analyzed. A strong proxy signer protected proxy signature scheme without an authority, which is more reasonable and more efficient, is proposed. We also point out its advantages over original schemes.