Blockchain Papers

Qianhong Wu, Yi Mu, Willy Susilo, Fangguo Zhang

No abstract is available for this record.

Cheng Song

Traditional design of authenticated key exchange protocol considers communication security, but seldom takes into account the security threat of server compromises. Whenever an authentication server is captured, the intruder can immediately masquerade as legitimate users to successfully log into the system. Although some zero-knowledge-proof methods were designed to relieve this threat, their computation is relatively high due to computationally heavy modular exponentiations employed. A dynamic-verifier based authenticated key exchange protocol is proposed, where the server stores a dynamically changing password-verifier and no password leakage would occur even when the server’s verifier database is stolen. DV-AKE is especially useful for applications where lightweight client is required or lower server computational load is preferred.

Bo Yang

Committed oblivious transfer is the natural fusion of one-out-of-two oblivious transfer and bit commitment. Unfortunately, the protocols proposed before are not only complicated but also very inefficient. This paper describes a new committed oblivious transfer protocol based on a first two round string oblivious transfer and bit commitment with XOR. With a first two round string oblivious transfer, the protocol can avoid performing a large number of bit oblivious transfers. And with bit commitment with XOR, zero knowledge proofs are very easy. The protocol is conceptually simple and more efficient. The security and complexity of the protocol are also discussed in this paper.

Manshan Lin

Fairness is the vitally necessary for application of electronic transaction.A fair protocol is presented for message transfer in electronic commerce.The protocol is designed to assure when the protocol ends,both parties get the expected messages or nothing.The protocol,based on optimistic approach,uses convertible signature scheme and non-interactive zero-knowledge proof to achieve efficient transparent TTP.Also,the protocol generates standard GDH(gap diffie-hellman) signatures as the final non-repudiation evidences.All these efforts make the protocol efficient and easy to be fitted in existing systems.

Dengguo Feng

New group signature schemes that are secure,effective and shared among different groups are an important direction in re-searching.The group signature scheme based on discrete logarithm problem can be used to share public parameter of the system among different organizations.Further,the main idea of the zero-knowledge proof is used to guarantee the security and efficiency of the scheme.Such sharing represents a high support for a uniform and secure system construction,and is favor to the management and application of the group signature system.

Limin Zhang

A non-interactive publicly verifiable protocol based on the intractable problems of discrete logarithm in elliptic curves cryptography is proposed.A non-interactive publicly verifiable zero knowledge proof protocol is designed.A new non-interactive publicly verifiable electronic voting scheme is established.This scheme enables anybody to verify if the shares are correctly distributed.This scheme can protect against the cheating action and is applicable to elections of smaller scale.

Shundong Li

A new efficient normative signature scheme,based on discrete logarithm assumption and factoring assumption is proposed.A zero knowledge proof protocol between the nominee and a third party to verify the signature is also constructed.This signature can be transformed into an undeniable and fail-stop signature if necessary.The efficiency of different nominative signature schemes is also compared.

Tianqi Yang

An improved confirmer digital signature scheme was presented based on the analysis of the disadvantages of traditional confirmer signature algorithm and the introduction of zero-knowledge proof. In this scheme, signer need not directly provide his signature to the information, he just need to provide a zero-knowledge to prove that he has the information signature. This zero-knowledge proof includes the signer's identity information. Compared with the traditional confirmer signature algorithms, the improved scheme is simpler and more efficient, and has higher security.

Masayuki Abe, Serge Fehr

Abstract The notion of non-interactive zero-knowledge (NIZK) is of fundamental importance incryptography. Despite the vast attention the concept of NIZK has attracted since its introduction, one question has remained very resistant: Is it possible to construct NIZK schemesfor any NP-language with statistical or even perfect ZK? Groth, Ostrovsky and Sahai recently positively answers to the question by presenting a couple of elegant constructions. However,their schemes pose a limitation on the length of the proof statement to achieve adaptive soundness against dishonest provers who may choose the target statement depending on thecommon reference string (CRS). In this work, we first present a very simple and efficient adaptively-sound perfect NIZKargument system for any NP-language. Besides being the first adaptively-sound statistical NIZK argument for all NP that does not pose any restriction on the statements to be proven,it enjoys a number of additional desirable properties: it allows to re-use the CRS, it can handle arithmetic circuits, and the CRS can be set-up very efficiently without the need foran honest party. We then show an application of our techniques in constructing efficient NIZK schemes for proving arithmetic relations among committed secrets, whereas previousmethods required expensive generic NP-reductions. The security of the proposed schemes is based on a strong non-standard assumption,an extended version of the so-called Knowledge-of-Exponent Assumption (KEA) over bilinear groups. We give some justification for using such an assumption by showing that thecommonly-used approach for proving NIZK arguments sound does not allow for adaptivelysound statistical NIZK arguments (unless NP ae P/poly). Furthermore, we show that theassumption used in our construction holds with respect to generic adversaries that do not exploit the specific representation of the group elements. We also discuss how to avoid thenon-standard assumption in a pre-processing model.

Yvo Desmedt, Yongge Wang, Mike Burmester

No abstract is available for this record.

Sungho Maeung

Recent studies argue that traditional voting systems do not encourage increased voter participation due to constraints in time, location, accuracy, and, accessibility. To ensure the rights of a democratic society and to enhance and secure the voting rights of citizens by surpassing all the limitations of the traditional voting system, the development of an electronic voting system is an attractive solution. Research on secure electronic voting systems has been conducted for at least the past two decades. We propose to develop an electronic voting system, called the Rochester Institute of Technology Student Government Election System (SGEES) based on Damgard et al. This voting scheme will use efficient honest-verifier zero-knowledge, which, unlike previous election schemes, are both easy to compute and to verify for both voters and authorities. Our proposed electronic voting system will allow convenient and confident voting while maintaining the accuracy of election results. This project will address the security requirements for electronic voting over the Internet, including privacy, completeness, soundness, receipt-freeness, and universal verifiability. In particular, we will research the feasibility of the voting scheme and protocols by studying three related cryptographical theories: homomorphic encryption, efficient honest-verifier zero-knowledge proofs, and threshold decryption cryptosystem.

Yuen-Yan Chan, Jin Li

No abstract is available for this record.

Serge Abiteboul, Bogdan Cautis, Amos Fiat, T. Milo

The common assumption about digital signatures is that they disallow any kind of modification on signed data. However, a more flexible approach is often needed and has been advocated lately, one in which some restricted modifications may still occur, without invalidating the data. This is made possible by offering signatures which are homomorphic with respect to some operation on the message domain. Starting from the signature(s) of some data instance(s), computed by the data owner, anybody else can derive the signature corresponding to a new data instance, if obtained only via some accepted operation from the previous one(s). More, updated signatures should be indistinguishable from the ones computed by the data owner and this updating step should be applicable as many times as needed. This paper deals with the signing of insert-only collections, in which element insertions are accepted but no removals should occur. Newly inserted elements do not have to be signed or known by the initial signer. We propose two techniques: one which transposes the insert-only problem into a delete-only one (which is already solved), and another technique based on zero-knowledge proofs. We also give performance measures and discuss applications.

Sven Laur, Helger Lipmaa

No abstract is available for this record.

David Wagner

No abstract is available for this record.

Goichiro Hanaoka, Hideki Imai

In this paper, we propose a generic construction of chosen-ciphertext secure cryptosystems against adversaries with a bounded number of decrytion queries from arbitrary semantically secure encryption in a black box manner. Our construction is not only an alternative to the previously known technique, i.e. the Naor-Yung paradigm [37, 19, 42], but also has some interesting properties. Especially, (1) it does not require non-interactive zero-knowledge proof, and (2) its component ciphertexts can be compressed into only one if the underlying encryption has a certain homomorphic property. Consequently, when applying our construction to the ElGamal encryption, ciphertext overhead of the resulting scheme will be only one group element which is considered optimal since it is the same as the original ElGamal. Disadvantages to previous schemes are that the upper bound of the number of decryption queries (e.g. 2 30) has to be known before set-up phase, and the size of public key is large. 1

Alejandro Hevia

No abstract is available for this record.

Hitoshi Asaeda, M. Rahman, Mohammad Hossein Manshaei, Yasuko Fukuzawa

In a mobile ad-hoc network (MANET) architecture, there is no pre-existing fixed network infrastructure, and a mobile node in this network sends data packets to a destination node directly or through its neighbor nodes. This situation is of potential security concern since the neighbor nodes cannot be always trusted. In this paper, we design a group member authentication protocol used in a MANET. It aims to allow a set of nodes to legitimately participate in group communication and then distribute a secret group key to the approved nodes to establish secure communication with group members. Our protocol provides knowledge-based group member authentication, which recognizes a list of secret group keys held in a mobile node as the node's group membership. It employs zero knowledge proof and threshold cryptography. We then introduce our actual implementation and evaluate the behavior to ensure its successful deployment

Boaz Barak

No abstract is available for this record.

Rafail Ostrovsky, Giuseppe Persiano, Ivan Visconti

One of the central questions in Cryptography is to design round-efficient protocols that are secure under man-in-the-middle attacks. In this paper we introduce and study the notion of non-malleable witness indistinguishability (NMWI) and examine its relation with the classic notion of non-malleable zero knowledge (NMZK). Indeed, despite tremendous applicability of witness indistinguishability, while a lot of attention has been given to NMZK, very little attention has been given to witness indistinguishability in case of man-in-the-middle attacks. We initiate this study, with several (perhaps somewhat surprising) results: • We give the first definition of NMWI proof systems. Just like every NMZK proof is a zero-knowledge proof which aims to attain a very strong proof independence property, we require (and formalize) the notion that every NMWI proof is a witness indistinguishable proof system which enjoys a very strong witness independence property against any man-in-the-middle attack. • We show the existence of a constant-round NMWI argument system for NP in the standard model (i.e. without any trusted or any other setup assumptions).

Yan Zhu

Ownership proofs of digital works allow to justify the copyright claim to the buyers without revealing any secret information and prevent the owner from deceiving without the assumption of the trusted individual. This paper proposes an ownership proofs scheme for digital works based on proactive verifiable secret sharing and secure multiparty computation. In the proposed scheme, verifiable secret sharing ensures the correctness of ownership secrets and achieves security against cheating participants. Proactive security provides an automatic recovery feature to maintain the integrity and security of secret throughout the lifetime of the scheme. Furthermore, the ownership verification is implemented by using secure multiparty computation and zero-knowledge proofs with homomorphic commitments. Without the assumption of the existence of a trusted individual, the proposed scheme can provide effective computation and discover the dishonesty if not too many individuals collude.

Jiangtao Li, Ninghui Li

No abstract is available for this record.

Koji Chida, Go Yamamoto

No abstract is available for this record.

Bo Qin, Qianhong Wu, Willy Susilo, Yi Mu · 5 authors

No abstract is available for this record.