An Optimized Implementation of a Succinct Non-Interactive Zero-Knowledge Argument System

Käesolevas töös üritame konstrueerida lakoonilise mitteinteraktiivse nullteadmustõestuste süsteemi implementatsiooni. Mitteinteraktiivne nullteadmustõestuste süsteem on protokoll, milles üks osapool, keda kutsutakse tõestajaks, tõestab teistele osapooltele, keda kutsutakse verifitseerijateks, et mingi verifitseerijale esitatud väide on tõene. Nullteadmusprotokoll peab muuhulgas garanteerima, et vastav tõestus ei lekita väite kohta muud informatsiooni peale väite kehvituse. Antud töös käsitleme tõeväärtusskeemide kehtestatavuse probleemi. Tõeväärtusskeemi kehtestatavuse probleem on küsimus selle kohta, kas leidub sisend, millel antud tõeväärtusskeem saab väljundiks väärtuse tõene. Implementeeritud tõestusskeem põhineb Helger Lipmaa tööl \cite{eprint2013:Lipmaa:NIZKSPECC}, mis kasutab tõestuse konstrueerimiseks lineaarkatte programme \emph{(span program)} ja lineaarseid veaparanduskoode. Töös anname ka kerge ülevaate nullteadmustõestuste üldisest olemusest, et ülejäänud töö olemust paremini selgitada. Me konstrueerime mitteadaptiivse versiooni tõestussüsteemist. Lisaks nullteadmustõestusele iseloomulikele omadustele on see versioon kasulik ka verifitseeritava arvutamise saavutamiseks, nagu käsitletud näiteks artiklis \cite{Pinnochio2013:Parno}. Töö algab ülevaatega mitteinteraktiivsest nullteadmusest ning lineaarkatte programmidest. Edasises kirjeldame, kuidas esitada tõeväärtusskeemi kehtestatavuse probleemi kasutades mainitud lineaarkatte programme. Lõpuks kirjeldame oma implementatsiooni, keskendudes olulistele detailidele ning kasutatud teekidele. Töö kokkuvõtteks on jõudlustulemused ning suunad edasisteks täiendusteks.In this thesis, we construct an implementation of succinct non-interactive zero knowledge argument system. A non-interactive zero knowledge argument system is a protocol for a party (usually known as Prover) to provide a proof of knowledge to the solution of a statement to other parties (usually known as Verifier). The argument system will be able to provide such proof without leaking any other information regarding the solution. The non-interactivity allows such argument system to be done without requiring interaction between the parties involved. The statement that is proven in this work is the circuit satisfiability problem. The circuit satisfiability problem is a problem of deciding whether there exists an input that can make the final output of a circuit to be true. The argument system is based on Lipmaa's work \cite{eprint2013:Lipmaa:NIZKSPECC} which uses span programs and linear error-correcting codes in its construction. We also try to give a very general explanation on zero knowledge argument system along the way in order to provide a simple concept to people encountering the notion for the first time. The argument system we attempt to construct is the non-adaptive version of the argument system. This version is useful for verifiable computation as pointed out by \cite{Pinnochio2013:Parno} apart from its zero knowledge behavior. We begin by giving an overview on non-interactive zero knowledge, followed by span programs. We then proceed to describe on how to represent the circuit satisfiability problem using the mentioned tool. We present our implementation afterwards, listing out the libraries and implementation details that matters. We conclude by providing a speed measurement and possible future improvements of this work

Quantum Limitations on the Storage and Transmission of Information

Information must take up space, must weigh, and its flux must be limited. Quantum limits on communication and information storage leading to these conclusions are here described. Quantum channel capacity theory is reviewed for both steady state and burst communication. An analytic approximation is given for the maximum signal information possible with occupation number signal states as a function of mean signal energy. A theorem guaranteeing that these states are optimal for communication is proved. A heuristic "proof" of the linear bound on communication is given, followed by rigorous proofs for signals with specified mean energy, and for signals with given energy budget. And systems of many parallel quantum channels are shown to obey the linear bound for a natural channel architecture. The time--energy uncertainty principle is reformulated in information language by means of the linear bound. The quantum bound on information storage capacity of quantum mechanical and quantum field devices is reviewed. A simplified version of the analytic proof for the bound is given for the latter case. Solitons as information caches are discussed, as is information storage in one dimensional systems. The influence of signal self--gravitation on communication is considerd. Finally, it is shown that acceleration of a receiver acts to block information transfer.Comment: Published relatively inaccessible review on a perennially interesting subject. Plain TeX, 47 pages, 5 jpg figures (not embedded

A Data Storage and Sharing Scheme for Cyber-Physical-Social Systems

© 2013 IEEE. Cyber-Physical-Social System (CPSS) provides users secure and high-quality mobile service applications to share and exchange data in the cyberspace and physical world. With the explosive growth of data, it is necessary to introduce cloud storage service, which allows devices frequently resort to the cloud for data storage and sharing, into CPSS. In this paper, we propose a data storage and sharing scheme for CPSS with the help of cloud storage service. Since data integrity assurance is an inevitable problem in cloud storage, we first design a secure and efficient data storage scheme based on the technology of public auditing and bilinear map, which also ensures the security of the verification. In order to meet the real-time and reliability requirements of the CPSS, the rewards of timeliness incentive and effectiveness incentive are considered in the scheme. Secondly, based on the proposed storage scheme and ElGamal encryption, we propose a lightweight access model for users to access the final data processed by cloud server. We formally prove the security of the proposed scheme, and conduct performance evaluation to validate its high efficiency. The experimental results show that the proposed scheme has lower overheads in communication and access as compared to the technique CDS

Improved Modeling Of Turbulent Transport: From Noise In Transport Models To The Parareal Algorithm Applied To Full Turbulence Codes

Thesis (Ph.D.) University of Alaska Fairbanks, 2010Turbulence and turbulent transport are ubiquitous in nature and are of fundamental importance in everything from the spread of pollution to confinement in fusion plasmas. In order to study this, turbulence models need to be as realistic as possible and one must also be able to evolve the turbulence and the profiles of the quantities of interest on transport (long) time scales. Improving turbulence simulations by the introduction of new techniques forms the basis of this research. One part of this work involved improving the performance of a 1D transport model by the addition of noise. On a more fundamental level, studying long time dynamics for turbulence simulations is very difficult even with the fastest computers available now or in the near future. To help overcome this difficulty, a new way of simulating turbulence has been presented, namely parallelizing in time. Time parallelization of a fully developed turbulent system is a new application. Parallelizing the space domain to computationally solve partial differential equations has been extensively used and is one of the most common forms of parallelization. In contrast, the Parareal Algorithm parallelizes the time domain and has been found to significantly reduce the computational wall time in many simpler systems. Despite its success in other less complex problems, it has not yet been successfully applied to a turbulent system (to the best of our knowledge). If efficiently applied, this algorithm will allow study of the turbulent transport dynamics on transport time scales - something that has heretofore been very difficult. In this work, the results of applying the Parareal Algorithm to simulations of drift wave turbulence in slab geometry in which the relative dominance of the polarization and E x B nonlinearities are tuned artificially, are presented. These turbulent systems are in many ways similar to neutral fluid turbulence models, so success of the Parareal scheme in them expands the prospect of a broader range of application to many other turbulent problems. This thesis also presents the results of a modification to the algorithm. A model to study and predict the parameters governing the convergence of the scheme is also explored