Non-delegatable Identity-based Designated Verifier Signature

Designated verifier signature is a cryptographic primitive which allows a signer to convince a designated verifier of the validity of a statement but in the meanwhile prevents the verifier from transferring this conviction to any third party. In this work we present the \emph{first} identity-based designated verifier signature scheme that supports non-delegatability, and prove its security in the random oracle model, based on computational Diffie-Hellman assumption. Our scheme is perfectly non-transferable, and its non-delegatability follows the original definition proposed by Lipmaa et al. \cite{LipmaaWaBa05}

On the Security of a Certificateless Strong Designated Verifier Signature Scheme

Recently, Chen et al. proposed the first non-delegatable certificateless strong designated verifier signature scheme and claimed that their scheme achieves all security requirements. However, in this paper, we disprove their claim and present a concrete attack which shows that their proposed scheme is forgeable. More precisely, we show that there exist adversaries who are able to forge any signer\u27s signature for any designated verifier on any message of his choice

A Pairing Based Strong Designated Verifier Signature Scheme without Random Oracles

In this study, a novel strong designated verifier signature scheme based on bilinear pairings with provable security in the standard model is proposed, while the existing ones are secure in the random oracle model. In 2007 and 2011, two strong designated verifier signature schemes in the standard model are proposed by Huang et al. and Zhang et al., respectively; in the former, the property of privacy of the signer’s identity is not proved and the security of the latter is based on the security of a pseudorandom function. Our proposal can deal with the aforementioned drawbacks of the previous schemes. Furthermore, it satisfies non-delegatability for signature verificatio

On Delegatability of Some Strong Designated Verifier Signature Schemes

A strong designated verifier signature scheme makes it possible for a signer to convince a designated verifier that she has signed a message in such a way that the designated verifier cannot transfer the signature to a third party, and no third party can even verify the validity of a designated verifier signature. In 2005, Lipmaa, Wang, and Bao identified a new essential security property, non delegatability, of designated verifier signature schemes. Briefly, in a non delegatability designated verifier signature scheme, neither a signer nor a designated verifier can delegate the signing rights to any third party without revealing their secret keys. However, this paper shows that four recently proposed strong designated verifier signature schemes are delegatable. These schemes do not satisfy non delegatability secure requirement of strong designated verifier signature schemes

A Novel Strong Designated Verifier Signature Scheme without Random Oracles

In this study, a novel pairing based strong designated verifier signature scheme based on non-interactive zero knowledge proofs is proposed. The security of the proposal is presented by sequences of games without random oracles; furthermore, this scheme has a security proof for the property of privacy of the signer’s identity in comparison with the scheme proposed by Zhang et al. in 2007. In addition, this proposal compared to the scheme presented by Huang et al. in 2011 supports non-delegatability. The non-delegatability of our proposal is achieved since we do not use the common secret key shared between the signer and the designated verifier in our construction. Furthermore, if a signer delegates her signing capability which is derived from her secret key on a specific message to a third party, then, the third party cannot generate a valid designated verifier signature due to the relaxed special soundness of the non-interactive zero knowledge proof. To the best of our knowledge, this construction is the first attempt to generate a designated verifier signature scheme with non-delegatability in the standard model, while satisfying of non-delegatability property is loose

Efficient and Provably-secure Certificateless Strong Designated Verifier Signature Scheme without Pairings

Strong designated verifier signature (generally abbreviated to SDVS) allows signers to obtain absolute control over who can verify the signature, while only the designated verifier other than anyone else can verify the validity of a SDVS without being able to transfer the conviction. Certificateless PKC has unique advantages comparing with certificate-based cryptosystems and identity-based PKC, without suffering from key escrow. Motivated by these attractive features, we propose a novel efficient CL-SDVS scheme without bilinear pairings or map-to-point hash operations. The proposed scheme achieves all the required security properties including EUF-CMA, non-transferability, strongness and non-delegatability. We also estimate the computational and communication efficiency. The comparison shows that our scheme outperforms all the previous CL-(S)DVS schemes. Furthermore, the crucial security properties of the CL-SDVS scheme are formally proved based on the intractability of SCDH and ECDL assumptions in random oracle model

Designated-Verifier Linkable Ring Signatures

We introduce Designated-Verifier Linkable Ring Signatures (DVLRS), a novel cryptographic primitive which combines designated-verifier and linkable ring signatures. Our goal is to guarantee signer ambiguity and provide the capability to the designated verifier to add ‘noise’ using simulated signatures that are publicly verifiable. This increases the privacy of the participants, as it does not allow an adversary to bypass the anonymity provided by ring signatures by using the content of a message to identify the signer. We model unforgeability, anonymity, linkability and non-transferability for DVLRS and provide a secure construction in the Random Oracle model. Finally, we explore some first applications for our primitive, which revolve around the use case of an anonymous assessment system that also protects the subject of the evaluation, even if the private key is compromised