Eecient Convertible Undeniable Signature Schemes Extended Abstract
نویسندگان
چکیده
Undeniable signatures are digital signatures which are not universally veri able but can only be checked with the signer's help. However, the signer cannot deny the validity of a correct signature. An extended concept, convertible undeniable signatures, allows the signer to convert single undeniable signatures or even the whole scheme into universally veri able signatures or into an ordinary digital signature scheme, respectively. In this paper we propose a new convertible undeniable signature scheme and provide proofs for all relevant security properties. The scheme is based on Schnorr's signature scheme and it is e cient. Unlike previous e cient solutions, this new scheme can be used as a basis for an e cient extension to threshold signatures, where the capability of signing (and of verifying signatures) is shared among n parties using a t out of n threshold scheme.
منابع مشابه
Eecient Convertible Undeniable Signature Schemes
Undeniable signatures are digital signatures which are not universally veriiable but can only be checked with the signer's help. However, the signer cannot deny the validity of a correct signature. An extended concept , convertible undeniable signatures, allows the signer to convert single undeniable signatures or even the whole scheme into universally veriiable signatures or into an ordinary d...
متن کاملOff-Line Fair Payment Protocols Using Convertible Signatures
An exchange or payment protocol is considered fair if neither of the two parties exchanging items or payment at any time during the protocol has a signiicant advantage over the other entity. Fairness is an important property for electronic commerce. This paper identiies a design framework based on existing fair protocols which use ooine trusted third parties, but with convertible signatures as ...
متن کاملConvertible Undeniable Signatures
We introduce a new concept called convertible undeniable signature schemes. In these schemes, release of a single bit string by the signer turns all of his signatures, which were originally undeniable signatures, into ordinary digital signatures. We prove that the existence of such schemes is implied by the existence of digital signature schemes. Then, looking at the problem more practically, w...
متن کاملNew Constructions of Convertible Undeniable Signature Schemes without Random Oracles
In Undeniable Signature, a signature’s validity can only be confirmed or disavowed with thehelp of an alleged signer via a confirmation or disavowal protocol. A Convertible undeniablesignature further allows the signer to release some additional information which can make anundeniable signature become publicly verifiable. In this work we introduce a new kind of attacks,called cl...
متن کاملConvertible Undeniable Standard RSA Signatures
A convertible undeniable signature is issued as an undeniable signature which can provide good privacy service in its early lifecycle. Later when necessary, it can be converted into an ordinary signature by a designated party and thereafter assures good accountability just as an ordinary digital signature does. We propose an RSA-based convertible undeniable signature where, in the stage of unde...
متن کامل