Baodian Wei

New receipt-free voting scheme using double-trapdoor commitment

It is considered to be the most suitable solution for large scale elections to design an electronic voting scheme using blind signatures and anonymous channels. Based on this framework, Okamoto first proposed a receipt-free voting scheme [30] for large scale elections. However, in the following paper, Okamoto [31] proved that the scheme [30] was not receipt-free and presented two improved schemes. One scheme requires the help of the parameter registration committee and the other needs a stronger physical assumption of the voting booth. In this paper, we utilize the double-trapdoor commitment to propose a new receipt-free voting scheme based on blind signatures for large scale elections. Neither the parameter registration committee nor the voting booth is required in our scheme. We also present a more efficient zero-knowledge proof for secret permutation. Therefore, our scheme is much more efficient than Okamotos schemes [30,31] with the weaker physical assumptions. Moreover, we prove that our scheme can achieve the desired security properties.

Efficient designated confirmer signature from bilinear pairings

Designated confirmer signature is an important cryptographic primitive, it is widely used in E-commerce. In this paper, we propose a new designated confirmer signature scheme which is transformed from a new signature scheme. The proposed scheme has very simple construction and is much more efficient than the previous ones and does not need any commitment scheme or strong witness hiding proofs.

A systematic method to design strong designated verifier signature without random oracles

Strong designated verifier signature (SDVS) provides secret authentication service to entities in a computing task. The primitive assures that an entity’s signature is verified only by a designated service provider. It also assures that a transcript about a computing task can be produced by both the entity and its service provider independently. Then neither can prove to a third party that an entity is involved in a task. Currently, most SDVS schemes without random oracles have no strong unforgeability and privacy of signer’s identity. This paper proposes a systematic method to design SDVS schemes without random oracles. It provides a basic scheme with unforgeability and non-transferability properties. Then provides it an SDVS scheme with strong unforgeability and privacy of signer’s identity properties and based on standard assumptions. Finally, a more efficient SDVS scheme is shown based on a non-black box assumption.

A non-delegatable strong designated verifier signature in ID-based setting for mobile environment

Abstract Non-delegatability is an interesting property of designated verifier signatures (DVS) as it technically makes a signer responsible for the signer’s actions and protects the privacy of the signer. This property is critical for some financial scenarios when a user is required to do something by itself. As more financial applications are running in a mobile and ubiquitous computing environment, an efficient scheme with a non-delegatability property is desirable. This paper proposes such a scheme in an identity-based setting with detailed proofs. Technically, the scheme combines an identity-based Schnorr style signature and an identification method with an OR proof technique gluing the two parts. It is the second scheme secure in a strict model proposed by Huang et al. And it saves about half the communication and computation costs of the first one.

A lattice-based partially blind signature

Blind signature is a crucial technique to provide anonymity in many information systems such as e-cash, e-voting, and smart grid systems. Partially blind signature is a more applicable extension where the part of the message includes some common information known by the signer and the signature requestor. In the family of lattice-based schemes, blind signatures are given in ASIACRYPT 2010 by Ruckert in the random oracle model, and until now, no partially blind signatures are given. We here design the first scheme based on Lyubashevskys signature scheme in EUROCRYPT 2012 and Abe and Okamotos construction of partially blind signature in CRYPTO 2000 in the random oracle model. The scheme shows an alternative approach to achieve the blindness property without the supports of a commitment scheme and of a final round communication to confirm the validity of a signature. Copyright

Selectively unforgeable but existentially forgeable signature schemes and applications

This paper gives definitions, constructions and applications of signature schemes, which are selectively unforgeable but existentially forgeable (SUEF). We formalize the special notion under conditions of chosen message attack (CMA) and known message attack (KMA). Then two general constructions are presented with two concrete examples. We apply the SUEF secure signature schemes to an elementary authentication mechanism, the challenge-response mechanism, to obtain a basic deniable authentication method. The method is presented as a deniable message transmission (MT) authenticator in the extension framework of Raimondo.

An Efficient Identity-Based Strong Designated Verifier Signature without Delegatability

We propose a non-delegatable identity based strong designated verifier signature scheme. It combines an identity based Schnorr signature and an identification method. An OR proof technique glues the two parts. It is the second scheme secure in a strict model proposed by Huang et al. And it saves about half the communication and computation costs comparing to the first scheme.

ID-based Ring Proxy Signatures

In this paper, by combining the functionalities of proxy signatures and ring signatures, we propose a new concept, named ring proxy signature, which is a proxy signature generated by an anonymous member from a set of potential signers. We construct two ID-based ring proxy signature schemes. The security analysis is provided as well.

Society-oriented Designated Confirmer Signatures

The concept of society-oriented designated confirmer signatures (SDCS) is introduced in this paper. SDCS can be used in the circumstances where the capability of the signer and that of the confirmer are both needed to be shared among groups of individuals. The ways to share the signing capability and the confirming capability are different due to the different stabilities of the signer group and the confirmer group. Based on the techniques of threshold cryptography, a concrete SDCS scheme is proposed and its security is analyzed. Our scheme can also be converted into an ordinary signature scheme or a designated verifier signature scheme.

A rejection sampling algorithm for off-centered discrete Gaussian distributions over the integers

Dear editor, Discrete Gaussian sampling, that is, sampling from a discrete Gaussian distribution DΛ,σ,c with parameter σ > 0 and center c ∈ R over an ndimensional lattice Λ, has been considered by the cryptography research community as one of the fundamental building blocks of lattice-based cryptography [1, 2]. The simplest lattice is the onedimensional integer lattice Z. Sampling from a discrete Gaussian distribution DZ,σ,c over the integers Z, denoted by SampleZ, is an important sub-problem of discrete Gaussian sampling, where parameter σ > 0 and center c ∈ R. The first SampleZ algorithm, which uses rejection sampling and supports a varying center c, was given by Gentry et al. in [1]. This algorithm is not very efficient, because it requires at least about 10 trials on average before providing an integer as the output. Since many lattice-based cryptosystems only involve sampling from centered discrete Gaussian distributions (center c = 0), most of the improved SampleZ algorithms were designed only for centered discrete Gaussian distributions, such as [3,4]. However, they cannot be used in a sampling algorithm for Gaussian distributions over a general lattice, because sampling from DZ,σ,c with a varying center c is usually required as one of the kernel subroutines in a sampling algorithm, for Gaussian distributions over a general n-dimensional lattice Λ. Thus, it is interesting to design more efficient SampleZ algorithms for off-centered discrete Gaussian distributions over the integers, which support arbitrary and varying centers.