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9,005 results · page 349 of 376
Shugong Zhang
We describe matrix-free pivotal algorithms in the XTR+ system.The computation efficiency of the pivotal algorithms is obviously improved.Consequently,the computation efficiency of the provable IND-CCA2 secure cryptosystem,the provable secure digital signature,the provable secure blind signature protocol and zero-knowledge proof protocol by means of XTR+ system is also improved greatly.
Chunming Tang
∑-protocol is an important tool in cryptology field.In this paper,we will prove that any ∑-protocol has the following characters: ①it is a witness hiding protocol if there exist at least two witnesses on R;②there exists a ∑-protocol on any NP statement under the assumption of the existence of one-way permutation;③there exist ∑-protocols with computational zero-knowledge;④∑-protocol can be changed into a zero-knowledge proof.
Федюкович Вадим Евгеньевич
A new protocol is introduced to show knowledge of a Goppa polynomial and of a codeword, as well as that error is of a bounded weight. The protocol is a special honest verifier zero knowledge proof under assumption of the discrete logarithm problem hardness.
Guifang Huang, Dongdai Lin, Yanshuo Zhang
No abstract is available for this record.
Huafei Zhu, Feng Bao
No abstract is available for this record.
Zongyang Zhang, Zhenfu Cao, Rong Ma
No abstract is available for this record.
Anish Arora, Lifeng Sang
Message authentication is a critical task in wireless sensor applications not only because it is a basic building block to ensure the authenticity of information but also a prerequisite for bootstrapping cryptographic secrets. Authentication has been explored extensively in the literature, however, the insecure environment within a fabric where multiple users and applications coexist, and limitations in the hardware pose new challenge for this problem. In this paper, we define a new zero knowledge proof problem in which (1) no memory of neighboring certificates is required; and (2) there is no central verification. We then discuss the properties of any potential solution, and propose a practical scheme that allows zero knowledge proof of the identity of each individual node. A notable merit of this scheme is that even if some nodes are compromised, the rest of the system remains secure. We believe this scheme can satisfy the security requirements in many emerging sensor network applications with proper parameter selection.
Pairat Thorncharoensri, Qiong Huang, Willy Susilo, Man Ho Au · 6 authors
No abstract is available for this record.
Soojin Cho, Manpyo Hong
No abstract is available for this record.
Shlomi Dolev, Marina Kopeetsky
No abstract is available for this record.
Zhengjun Cao, Olivier Markowitch
We put forward the concepts of universal authentication, restrictive authentication and designated authentication. We then revisit a popular signcryption scheme using a technique similar to the one developed in Schnorr's signature, allowing it respects the restrictive authentication property. Comparing with the modification suggested by Baek et al in 2007, which uses a zero-knowledge proof run between the recipient and the third party, our scheme saves about 1/2 cost. Besides, the security of the revisited scheme can be reduced to that of Schnorr's signature.
Matt Smart, Eike Ritter
No abstract is available for this record.
Zhao Yan-meng
Based on information-theoretic hiding commitment scheme and zero-knowledge proof of knowledge,a publicly verifiable secret sharing(PVSS) scheme was constructed.In this scheme,any party could verify the validity of participants' shares in the distribution protocol.Only the receiver could verify validity of these shares gained from the other participants in the reconstruction protocol.This PVSS scheme with information-theoretic security has demostrated that it is more applicable in some cases than any verifiable secrete sharing scheme.
Jianhong Zhang, Hua Chen, Qin Geng
Certificate-based cryptography solves certificate revocation problem and eliminate third-party queries in the traditional PKI and avoid key escrow in the ID-based cryptography. It is a better alternative for the traditional public key system. In this paper, we proposed an efficient certificate based signature scheme based on Schnorr signature and zero-knowledge proof technique. Our proposed scheme doesn't use pairing operator which is the most expensive computation. Then we show that our proposed scheme is proven to be against two forgeable attacks in the random oracles model, and the security is related to that of Schnorr signature.
David Xiao
Learning is a central task in computer science, and there are various formalisms for capturing the notion. One important model studied in computational learning theory is the PAC model of Valiant (CACM 1984). On the other hand, in cryptography the notion of "learning nothing'' is often modelled by the simulation paradigm: in an interactive protocol, a party learns nothing if it can produce a transcript of the protocol by itself that is indistinguishable from what it gets by interacting with other parties. The most famous example of this paradigm is zero knowledge proofs, introduced by Goldwasser, Micali, and Rackoff (SICOMP 1989). Applebaum et al. (FOCS 2008) observed that a theorem of Ostrovsky and Wigderson (ISTCS 1993) combined with the transformation of one-way functions to pseudo-random functions (Hastad et al. SICOMP 1999, Goldreich et al. J. ACM 1986) implies that if there exist non-trivial languages with zero-knowledge arguments, then no efficient algorithm can PAC learn polynomial-size circuits. They also prove a weak reverse implication, that if a certain non-standard learning task is hard, then zero knowledge is non-trivial. This motivates the question we explore here: can one prove that hardness of PAC learning is equivalent to non-triviality of zero-knowledge? We show that this statement cannot be proven via the following techniques: 1. Relativizing techniques: there exists an oracle relative to which learning polynomial-size circuits is hard and yet the class of languages with zero knowledge arguments is trivial. 2. Semi-black-box techniques: if there is a black-box construction of a zero-knowledge argument for an NP-complete language (possibly with a non-black-box security reduction) based on hardness of PAC learning, then NP has statistical zero knowledge proofs, namely NP is contained in SZK. Under the standard conjecture that NP is not contained in SZK, our results imply that most standard techniques do not suffice to prove the equivalence between the non-triviality of zero knowledge and the hardness of PAC learning. Our results hold even when considering non-uniform hardness of PAC learning with membership queries. In addition, our technique relies on a new kind of separating oracle that may be of independent interest.
Jean Monnerat, Sylvain Pasini, Serge Vaudenay
No abstract is available for this record.
Ivan Damgård, Carolin Lunemann
In this paper, we prove classical coin-flipping secure in the presence of quantum adversaries. The proof uses a recent result of Watrous [Wat09] that allows quantum rewinding for protocols of a certain form. We then discuss two applications. First, the combination of coin-flipping with any non-interactive zero-knowledge protocol leads to an easy transformation from non-interactive zero-knowledge to interactive quantum zero-knowledge. Second, we discuss how our protocol can be applied to a recently proposed method for improving the security of quantum protocols [DFL+09], resulting in an implementation without set-up assumptions. Finally, we sketch how to achieve efficient simulation for an extended construction in the common-reference-string model.
Man Ho Au
Digital signatures are fundamental cryptographic primitives. They are useful as a stand-alone application and building blocks of complex cryptographic systems. Accumulators are another useful cryptographic primitive which provide a way to combine a set of values into one short value. They are useful in improving efficiency of cryptographic systems. In particular, these two primitives are key components in privacy-preserving cryptographic systems. In this thesis, we study the use of digital signatures and accumulators in cryptographic applications. We design digital signature schemes and accumulators with different features that are suitable for a wide range of applications. We are interested in privacy-preserving cryptographic applications including anonymous electronic cash systems, anonymous authentication schemes and anonymous credential systems. We construct three different digital signature schemes, each with distinctive features. We also propose two novel constructions of accumulators. Based on our signature schemes and accumulators, we design two compact electronic cash schemes and a divisible electronic cash scheme. All our schemes are truly anonymous, meaning that privacy of the users is well-protected. We also explore other applications of our newly proposed signatures and accumulators. Specifically, we give a construction of k-times anonymous authentication schemes and attribute-based anonymous credential systems. During the course of the development of the thesis, we generalise existing techniques of zero-knowledge proof-of-knowledge protocol of double-discrete logarithms into zero-knowledge proof-of-knowledge protocol of representation of a committed value. Our protocol is compatible with existing zero-knowledge proof-of-knowledge protocols that demonstrate relationship amongst discrete logarithms. We believe that this protocol, together with the newly introduced primitives, are of independent interest.
Sebastiaan de Hoogh, Berry Schoenmakers, Boris Škorić, José Villegas
No abstract is available for this record.
Iftach Haitner, Alon Rosen, Ronen Shaltiel
No abstract is available for this record.
Zecheng Wang, Haifeng Qian, Zhibin Li
We propose a distributed key generation protocol for pairing-based cryptosystems which is adaptively secure in the erasure-free and secure channel model, and at the same time completely avoids the use of interactive zero-knowledge proofs. Utilizing it as the threshold key generation protocol, we present a secure (t,n) threshold signature scheme based on the Waters' signature scheme. We prove that our scheme is unforgeable and robust against any adaptive adversary who can choose players for corruption at any time during the run of the protocols and make adaptive chosen-message attacks. And the security proof of ours is in the standard model (without random oracles). In addition our scheme achieves optimal resilience, that is, the adversary can corrupt any t<n/2 players.
Ying Qiu, Huafei Zhu
This paper studies mobile devices mediated electronic voting system based on the distributed Pailler's encryptions; We apply the standard cut-of-the-choose technique to avoid the computational zero-knowledge proofs and show that the proposed scheme is efficient yet somewhat provably secure in the simulation-based paradigm.
Rafael Dowsley, Jörn Müller‐Quade, Akira Otsuka, Goichiro Hanaoka · 6 authors
Abstract. This paper presents a non-interactive verifiable secret sharing scheme (VSS) tolerating a dishonest majority based on data predistributed by a trusted authority. As an application of this VSS scheme we present very efficient unconditionally secure multiparty protocols based on pre-distributed data which generalize two-party computations based on linear pre-distributed bit commitments. The main results of this paper are a non-interactive VSS where the amount of data which needs to be pre-distributed to each player depends on the number of tolerable cheaters only, a simplified multiplication protocol for shared values based on pre-distributed random products, and non-interactive zero knowledge proofs for arbitrary polynomial relations. The security of the schemes are proved using the UC framework.
Junhua Chen, Peng Wu
Combining the identification characteristics of zero-knowledge proof and blind watermark, an identity verification protocol is proposed. In this protocol, the public key encryption is used to encrypt the watermark and the watermarked data of the watermark embedding locations, and the verification of user's identity watermarking is achieved through estimating the relativity of them. Furthermore, a way which restricts the prover and verifierpsilas communication to a closed situation is put forward, and this way can resist such as brute force cheat-attack.