Blockchain Papers

David Pointcheval

No abstract is available for this record.

Joe Kilian, Erez Petrank

A proof is concurrent zero-knowledge if it remains zero-knowledge when run in an asynchronous environment, such as the Internet. It is known that zero-knowledge is not necessarily preserved in such an environment; Kilian, Petrank and Rackoff have shown that any 4 rounds zero-knowledge interactive proof (for a non-trivial language) is not concurrent zero-knowledge. On the other hand, Richardson and Kilian have shown that there exists a concurrent zero-knowledge argument for all languages in NP, but it requires a polynomial number of rounds. In this paper, we present a concurrent zero-knowledge proof for all languages in NP with a drastically improved complexity: our proof requires only a poly-logarithmic, specifically, ω(log 2 k) number of rounds. Thus, we narrow the huge gap between the known upper and lower bounds on the number of rounds required for a zero-knowledge proof that is robust for asynchronous composition. 1

Guillaume Poupard, Jacques Stern

No abstract is available for this record.

Alon Rosen

No abstract is available for this record.

Ivan Damgård

No abstract is available for this record.

Giovanni Di Crescenzo

No abstract is available for this record.

Danny Gutfreund, Michael Ben-Or

No abstract is available for this record.

Alfredo De Santis, Giovanni Di Crescenzo, Giuseppe Persiano

No abstract is available for this record.

Ronald Cramer, Ivan Damgård, Philip MacKenzie

No abstract is available for this record.

Vijay Varadharajan, Yi Mu

No abstract is available for this record.

Mike Burmester, Yvo Desmedt, Toshiya Itoh, Kouichi Sakurai · 5 authors

No abstract is available for this record.

Josef Pieprzyk, Reihanah Safavi-Naini, Jennifer Seberry

No abstract is available for this record.

Alfredo De Santis, Giovanni Di Crescenzo, Oded Goldreich, Giuseppe Persiano

No abstract is available for this record.

Hyung-Woo Lee, Jung-Eun Kim, Tai-Yun Kim

No abstract is available for this record.

Satoshi Hada, Toshiaki Tanaka

No abstract is available for this record.

Wen‐Chung Kuo, Chi‐Sung Laih, Min-Jea Gau

Measurements of total cholesterol in the field by means of the Reflotron dry-chemistry system (capillary blood) were compared to total cholesterol obtained by a standardized conventional wet-chemistry method in a clinico-chemical laboratory (serum). A total of 1200 people participated in the study. Two identical Reflotron machines were used. In the first period of the study an excellent agreement was found between Reflotron measurements of a reference serum provided by the manufacturer (mean, 4.99 mmol/l; CV, 1.8%) and the stated value (4.97 mmol/l). In the rest of the study higher values and greater variation were found with the Reflotron (mean, 5.32 mmol/l; CV 5.2%). Clearly the Reflotron measurements in the latter period of study were not reliable. In the period with stable instruments most of the values obtained at the two Reflotron machines differed from each other by less than 10%, with a mean difference of 0.08 mmol/l. Reflotron (both machines) and wet-chemistry measurements agreed well for the first 500 participants in the study (mean difference, Reflotron-wet-chemistry, -0.008 mmol/l; 95% confidence interval, -0.035 to 0.019 mmol/l; correlation, 0.967). In this period most Reflotron values differed from wet-chemistry values by less than 9% below to 9% above. With the next 200 participants the Reflotron gave on average slightly higher values than wet-chemistry measurements. The coefficients of variation for measurement variation were higher for Reflotron that for wet-chemistry even in the period with stable instruments. In all parts of the study period a lower HDL-cholesterol level was associated with larger differences between total cholesterol determined by Reflotron and wet-chemistry.

Daniele Micciancio

We describe a general technique to simplify as well as to improve several lattice based cryptographic protocols. The technique is rather straightforward and is easily applied to the protocols, and gives both a simpler analysis and better performance than the original protocols. The improvement is global: the modified protocols are simpler, faster, require less storage, use less bandwidth and need less random bits than the originals. Moreover, the improvement is achieved without any loss in security: we formally prove that the modified protocols are at least as secure as the original ones. In fact, the modified protocols might even be more secure as the adversary gets less information. We exemplify our technique on the Goldreich-Goldwasser zero-knowledge proof systems for lattice problems and the GGH public key cryptosystem. Partially supported by DARPA grant DABT63-96-C-0018 and NTT grant 67627-00. 1 1 Introduction Various cryptographic protocols based on the hardness of la...

Birgit Pfitzmann, Ahmad‐Reza Sadeghi

No abstract is available for this record.

Josep Domingo‐Ferrer

No abstract is available for this record.

Khanh Quoc Nguyen, Vijay Varadharajan, Yi Mu

This paper presents a technique to speed up practical zero-knowledge cryptographic protocols. We introduce a new technique of batching proofs of knowledge. Its security is analysed and its applicability to some cryptographic protocols is described. The use of the batching technique can significantly reduce the number of online computations required in the proofs and consequently helps to lower the costs associated with the corresponding transactions. This technique is particularly useful for e-commerce related cryptographic protocols.

J. Mohajeri

No abstract is available for this record.

Molli Noland

An interactive proof involves two parties, the prover and the verifier. The goal of the proof is for the prover to convince the verifier that some instance of a decision problem is true. A zero-knowledge proof is an interactive proof where the only information learned by the verifier of the proof is the outcome of the proof. This thesis contains a theoretical overview of interactive and zero-knowledge proofs and describes experiments with implementations of some of them. Two examples of interactive proofs from number theory are given, a protocol for quadratic non-residues and a protocol for subgroup non-membership. The third example of an interactive proof is a protocol for determining the truth value of a quantified Boolean formula. This interactive proof was implemented and the details of that implementation, plus a test of the implementation derived from game theory, are included. There is also a discussion of quantum interactive proofs. The two examples of perfect zero-knowledge proofs that are included are protocols for quadratic residues and for subgroup membership. These protocols were also implemented, and those details are included. For each protocol, there is a discussion of the complexity status of the problems addressed by the protocol. There is also a brief discussion of the history and applications of interactive and zero-knowledge proofs.

Markus Jakobsson, Claus-Peter Schnorr

We study the notion of meta-proofs, which, as the name indicates, are proofs about proofs. We employ the notion of meta-proofs to produce a highly efficient oblivous proof of correct exponentiation. It is minimum-knowledge independently of whether the input is valid or not, a property that does not hold for many other protocols (that are zero-knowledge only for valid inputs.) This has direct security implications to multiparty protocols, where the protocols we demonstrate — one interactive and one non-interactive — can be employed to obtain protocol robustness at a low cost. As a result of potential independent interest, we show how to turn any standard discrete log signature scheme into a scheme for proving equality of discrete logarithms. We demonstrate our method using the Schnorr signature scheme.

Alfredo De Santis, Giuseppe Persiano, Giovanni Di Crescenzo

No abstract is available for this record.