Two Variants Of Transitive Signatures And Their Applications

The graph structure can be used to represent the relationship among enti-ties in a complex environment such as the big data.Among which,in fact,many graphs satisfy the property of "transitive" As a special case of homomorphic sig-natures,transitive signatures can be used to authenticate the dynamically growing and transitive closed graph.It has a broad application prospects in many fields,such as military command system,management domain and e-government.With a transitive signature scheme,anyone without the signer's private key can compute a signature for edge(i,k)by using the given signatures on edges(i,j)and(j,k).This property can reduce the workload of the signer.In this thesis,two secure and efficient transitive signature schemes with special properties are proposed by com-bining the practical application requirements.The research of this thesis mainly includes the following two aspects:1.A proxy transitive signature(PTS)scheme:Delegation of signing right is a common issue in practical applications when the transitive signatures are em-ployed.It is an important issue to delegate the signing right in a safe,feasible and effective way,and it needs to be studied thoroughly.However,no applica-ble scheme has been proposed so far.In view of the above issue,we proposed a secure and efficient PTS scheme,which can meet all the features needed for proxy signatures and transitive signatures.2.A Unive.rsal designated multi-verifier transitive signature(UDMVTS)scheme:Transitive signatures may be leaked by a malicious attacker or verifier,it threat-ens the privacy of the membership relationship in the graph.To solve this prob-lem,the universal designated verifier transitive signature schemes have been designed.Nevertheless,existing schemes cannot be directly employed in the scenarios when multi-verifier are involved,which has some limitations in the background of complex systems such as the big data.Thus,in this thesis,we proposed a secure and efficient UDMVTS scheme,which can not only avoid the leakage of the transitive signature,but also allow a transitive signature holder to designate the signature to multi-verifier.