Haibo Tian

Identity-based chameleon hash scheme without key exposure

The notion of chameleon hash function without key exposure plays an important role in designing chameleon signatures. However, all of the existing key-exposure free chameleon hash schemes are presented in the setting of certificate-based systems. In 2004, Ateniese and de Medeiros questioned whether there is an efficient construction for identity-based chameleon hashing without key exposure. In this paper, we propose the first identity-based chameleon hash scheme without key exposure based on the three-trapdoor mechanism, which provides an affirmative answer to the open problem.

Identity-based chameleon hashing and signatures without key exposure

The notion of chameleon hash function without key exposure plays an important role in designing secure chameleon signatures. However, all of the existing key-exposure free chameleon hash schemes are presented in the setting of certificate-based systems. In 2004, Ateniese and de Medeiros questioned whether there is an efficient construction for identity-based chameleon hashing without key exposure. In this paper, we propose the first identity-based chameleon hash scheme without key exposure based on the three-trapdoor mechanism, which provides an affirmative answer to the open problem. Moreover, we use the proposed chameleon hash scheme to design an identity-based chameleon signature scheme, which achieves all the desired security properties.

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.

Toward Quantum-Resistant Strong Designated Verifier Signature from Isogenies

This paper proposes a strong designated verifier signature (SDVS) based on a recently proposed mathematical problem. It consists in searching for an isogeny between super singular elliptic curves. The problem is hypothetically strong against a quantum computer. This makes our proposal the first SDVS scheme that may be secure against a quantum computer.

Three-round abuse-free optimistic contract signing with everlasting secrecy

We introduce the novel notion of Verifiable Encryption of Chameleon Signatures (VECS), and then use it to design a three-round abuse-free optimistic contract signing protocol.

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.

Non-interactive deniable authentication protocols

This paper gives a security model for non-interactive deniable authentication (NIDA) protocols. This model captures a session-state-reveal attack and a key-compromise-impersonation attack. We analyze some NIDA protocols in the model, and we find that no one is satisfactory. We give a new paradigm to construct an NIDA protocol, which is provably secure in the model.

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.

Non-delegatable strong designated verifier signature on elliptic curves

We propose a non-delegatable strong designated verifier signature on elliptic curves. The size of the signature is less than 500 bits considering an 80 bits security strength. It provably satisfies the non-delegatability and signer ambiguity properties. The construction method is a combination of the Schnorr signature and the elliptic curve Diffie-Hellman problem.

Comments and improvements on key-exposure free chameleon hashing based on factoring

Chameleon signatures simultaneously provide the properties of non-repudiation and non-transferability for the signed message. However, the initial constructions of chameleon signatures suffer from the key exposure problem of chameleon hashing. This creates a strong disincentive for the recipient to forge signatures, partially undermining the concept of non-transferability. Recently, some specific constructions of key-exposure free chameleon hashing based on various assumptions are presented. In this paper, we present some security flaws of the key-exposure free chameleon hash scheme based on factoring [10]. Besides, we propose an improved chameleon hash scheme without key exposure based on factoring which enjoys all the desired security notions of chameleon hashing.