Forward-secure Signature Research Based On Public Key Cryptosystem

In information ear, how to resolve the secret key exposure is the problem to be solved urgently .Forward-secure signature can guarantee the security of signature be -fore the key exposure, through keeping public key and evoluting secret key,which is a high efficitive way to solve key exposure. Whether viewing from academic or from application , researching forward-secure signature has important academic value and application meaning.In this thesis,we discuss and research forward-secure signature on public key cry- ptosystem through mainline of forward-secure signature development. The main con- tents that the author obtained are as follows:Firstly,we introduce definition of forward -secure, research character of model of forward-secure signature,analyse three charac- teristics, respective character and connection.Secondly,through comparing time-com- plexity and space-complexity of some simple scheme,we find out the bigger in space- complexity,the smaller the scheme is in time-complexity. Thirdly,we discuss a forwa- rd-secure signature and a improved scheme on Fait-Shamir scheme,and analyse their security. Fourthly,making use of three characteristics ,we discuss character of forward -secure signature on discrete logarithm.we analyse wu`s signature scheme,change evo- luting mechod of wu's secret key , propose a new forward secure E1Gamal blind digi- tal signature,and brief signature.Anther,we descrip two different forward signature sc- heme based on blind signature.Lastly,we research a improved forward threshold sche- me, propose a new forward-secure threshold signature based on a probability scheme that has been proved,which security based on diffculty of ellipse curve.