Decentralized Attribute-based Undeniable Signatures

In addition to fine-grained access control as well as attribute encryption,attribute signature also has the Privacy that is usually not possessed by digital signature,so it has important theoretical significance and wide application prospect.Undeniable signature is a special signature system which can prevent the signature from being abused.Its characteristic is that without the participation of the signer,other people cannot independently verify the signature,nor can they prove the authenticity of the signature to a third party.Decentralization is an increasingly important concept,which can not only prevent the whole system from collapsing due to the corruption of the central authority,but also reduce the burden of the single central authority,so it doesn't form a limit.In order to expand the application scope of attribute signature and undeniable signature,this paper combines the three concepts of attribute,undeniable,decentralization and studies the decentralized attribute-based undeniable signatures.The main work is as follows:1.Give out the formal definition and security model based on decentralized attribute-based(convertible)undeniable signatures.2.Use Cramer et al.evidence of zero knowledge proof protocol,hidden by Hess agreement as the foundation.We use Shamir threshold scheme as a secret sharing scheme,then use the Fiat-Shamir convert to a Identity Based on Threshold Signature scheme(IBTS),then we add undeniable,prevent collusion and decentralization on that scheme of IBTS,construct a decentralized attribute-based convertible undeniable signatures scheme,at the same time prove its security.3.Because the first scheme using bilinear pairings,in order to further promote the efficiency,save expenses.We use Schnorr agreement as its basis,then use the Fiat-Shamir transforme it to a Basic Threshold Signature scheme(BTS).We add undeniable,prevent collusion and decentralization on that scheme of BTS and construct a no-pairing decentralized attribute-based undeniable signatures scheme.Inthe random oracle model we prove its safety.Compared with the existing similar schemes,this scheme has obvious advantages in computation,length and function.