Designated verifier signatures were introduced in the middle of the 90’s by Jakobsson, Sako and Impagliazzo, and independenty patended by Chaum as private signatures. In this setting, a signature can only be verified by a unique and specific user. At Crypto’03, Desmedt suggested the problem of generalizing the designated verifier signatures. In this case, a signature should be intended to a spe...

A new concept of society-oriented designated confirmer signatures (SDCS) is introduced in this paper. SDCS is well suited to applications where the capability of the signer and that of the confirmer are both expected to be shared among a group of individuals. The ways to share the signing capability and the confirming capability are different due to the distinct stabilities of the signer group ...

A strong designated verifier signature (SDVS) scheme only allows a designated verifier to validate signer’s signatures for ensuring confidentiality. At the same time, the designated verifier can not transfer the signature to any third party, since he can also generate another computationally indistinguishable SDVS, which is referred to as non-transferability. A proxy signature scheme is a speci...

For many proofs of knowledge it is important that only the verifier designated by the confirmer can obtain any conviction of the correctness of the proof. A good example of such a situation is for undeniable signatures, where the confirmer of a signature wants t o make sure that only the intended verifier(s) in fact can be convinced about the validity or inva1idit)y of the signature. Generally,...

In this paper we propose a new designated verifier signature scheme based on the threshold signature scheme presented [9] by Ghodosi and Pieprzyk. The advantages of the new scheme compared with previously proposed solutions are its computational efficiency and its simple and rational design that allows distributed implementations of the computations and suits the needs of both single individual...

Digital signatures are unsuitable for specific applications that sensitive on a personal or commercial level because they universally verifiable. Jakobsson et al. proposed the Designated Verifier Signature (DVS) system, which only allows intended verifier to validate message’s signature. It prohibits disclosure of conviction third party. This functionality is useful in require both authenticity...

Artin’s braid groups have been recently suggested as a new source for public-key cryptography. In this paper we first propose the designated verifier group signature scheme based on the conjugacy search problem and the root problem in the braid groups which are believed to be hard problems. Furthermore, our scheme can conceal the message to be signed so that it can be applied to E-voting and ca...

In this paper, we provide a new approach to study undeniable signatures by translating secure digital signatures to secure undeniable signatures so that the existing algorithms can be used. Our mechanism is that any verifier without trapdoor information cannot distinguish whether a message is encoded from Diffie-Hellamn resource D or random resource R while a signer with trapdoor information ca...

In this paper, we define an underlying computational problem and its decisional problem. As an application of their problems, we propose an efficient designated verifier signature (DVS) scheme without random oracles (related to symmetric pairings). We formally redefine the (Strong) Privacy of Signature’s Identity, and prove our DVS scheme satisfying security based on the difficulty of the probl...