Study On Proxy Signature Schemes And Their Applications

This dissertation mainly discusses proxy signature schemes and their applications in digital information socieW The main results that the author obtained are as follo~: By introducing and designing some basic proxy signature schemes, the motivation, significance, and methods of study proxy signature schemes are analyzed. The basic notions are introduced; several basic protocols which can be used to construct proxy signature schemes are given, based on the problem of discrete logarithiw two proxy signature schemes are given, they are based on Fiat-Shamir signature scheme and G-Q signature scheme separately. These protocols or schemes are analyzed carefully. The notion of proxy multi-signature is introduced. Some methods of designing proxy multi-signature schemes is given, and several concrete schemes are designed. To show the value of proxy multi-signature schemes, a fair exchange protocol v~4th fine properties is constn.icted by making use of proxy multi-signature schemes. The notion of blind proxy signature is introduced. Some methods of designing blind proxy signature schemes is given, and some concrete schemes are designed. A electronic voting protocol is constructed by making use of blind proxy signature schemes. The notion of multi-grade proxy signature is introduced. The relationship between multi- grade proxy signature and multi-grade security information systems is discussed. Some basic methods of converting the basic proxy signature schemes to multi-grade proxy signature schemes is proposed. The notion of forward-secure signature schemes is introduced and the possibility of mutual conversion between multi-grade proxy signature schemes and forward secure signature schemes are discussed. As a result, a new multi-grade proxy signature scheme and a new basic proxy signature scheme are obtained.