Blockchain Papers

Jörg Becker, Dominic Breuker, Tobias Heide, Justus Holler · 6 authors

No abstract is available for this record.

Raafat Aburukba

In the Grid/Cloud environment, applications or services and resources belong to different organizations with different objectives. Entities in the Grid/Cloud are autonomous and self-interested; however, they are willing to share their resources and services to achieve their individual and collective goals. In such open environment, the scheduling decision is a challenge given the decentralized nature of the environment. Each entity has specific requirements and objectives that need to achieve. In this thesis, we review the Grid/Cloud computing technologies, environment characteristics and structure and indicate the challenges within the resource scheduling. We capture the Grid/Cloud scheduling model based on the complete requirement of the environment. We further create a mapping between the Grid/Cloud scheduling problem and the combinatorial allocation problem and propose an adequate economic-based optimization model based on the characteristic and the structure nature of the Grid/Cloud. By adequacy, we mean that a comprehensive view of required properties of the Grid/Cloud is captured. We utilize the captured properties and propose a bidding language that is expressive where entities have the ability to specify any set of preferences in the Grid/Cloud and simple as entities have the ability to express structured preferences directly. We propose a winner determination model and mechanism that utilizes the proposed bidding language and finds a scheduling solution. Our proposed approach integrates concepts and principles of mechanism design and classical scheduling theory. Furthermore, we argue that in such open environment privacy concerns by nature is part of the requirement in the Grid/Cloud. Hence, any scheduling decision within the Grid/Cloud computing environment is to incorporate the feasibility of privacy protection of an entity. Each entity has specific requirements in terms of scheduling and privacy preferences. We analyze the privacy problem in the Grid/Cloud computing environment and propose an economic based model and solution architecture that provides a scheduling solution given privacy concerns in the Grid/Cloud. Finally, as a demonstration of the applicability of the approach, we apply our solution by integrating with Globus toolkit (a well adopted tool to enable Grid/Cloud computing environment). We also, created simulation experimental results to capture the economic and time efficiency of the proposed solution.

Clemens H. Cap

No abstract is available for this record.

Mike Small

Blockchain, a continuously growing tamper resistant data structure, was developed as the technology underlying the Bitcoin crypto-currency and it is now being applied to a wide range of problems as a form of ‘Distributed Ledger’. The promise of this technology has been recognised by governments and the financial industry. It also has application to enhance privacy of personal information, to secure the Internet of things and to change electronic identity. This study explains what a Blockchain is and how it works. It describes some actual and the potential applications of this technology together with some of the risks associated with its use.

Vipul Goyal, Abhishek Jain, Rafail Ostrovsky, Silas Richelson · 5 authors

In this paper we put forward the Bounded Player Model for secure computation. In this new model, the number of players that will ever be involved in secure computations is bounded, but the number of computations has no a priori bound. Indeed, while the number of devices and people on this planet can be realistically estimated and bounded, the number of computations these devices will run can not be realistically bounded. We stress that in the Bounded Player model, in addition to no a priori bound on the number of sessions, there is no synchronization barrier, no trusted party, and simulation must be performed in polynomial time. In this setting, we achieve concurrent Zero Knowledge (cZK) with sub-logarithmic round complexity. Our security proof is (necessarily) non-black-box, our simulator is “straight-line” and works as long as the number of rounds is ω(1). We further show that unlike previously studied relaxations of the standard model (e.g., bounded number of sessions, timing assumptions, super-polynomial simulation), concurrent-secure computation is still impossible to achieve in the Bounded Player model. This gives evidence that our model is “closer” to the standard model than previously studied models, and study of this model might shed light on constructing round efficient concurrent zero-knowledge in the standard model as well.

Moshe Babaioff, Shahar Dobzinski, Sigal Oren, Aviv Zohar

Many large decentralized systems rely on information propagation to ensure their proper function. We examine a common scenario in which only participants that are aware of the information can compete for some reward, and thus informed participants have an incentive not to propagate information to others. One recent example in which such tension arises is the 2009 DARPA Network Challenge (finding red balloons). We focus on another prominent example: Bitcoin, a decentralized electronic currency system. Bitcoin represents a radical new approach to monetary systems. It has been getting a large amount of public attention over the last year, both in policy discussions and in the popular press. Its cryptographic fundamentals have largely held up even as its usage has become increasingly widespread. We find, however, that it exhibits a fundamental problem of a different nature, based on how its incentives are structured. We propose a modification to the protocol that can eliminate this problem. Bitcoin relies on a peer-to-peer network to track transactions that are performed with the currency. For this purpose, every transaction a node learns about should be transmitted to its neighbors in the network. The current implemented protocol provides an incentive to nodes to not broadcast transactions they are aware of. Our solution is to augment the protocol with a scheme that rewards information propagation. Since clones are easy to create in the Bitcoin system, an important feature of our scheme is Sybil-proofness. We show that our proposed scheme succeeds in setting the correct incentives, that it is Sybil-proof, and that it requires only a small payment overhead, all this is achieved with iterated elimination of dominated strategies. We complement this result by showing that there are no reward schemes in which information propagation and no self-cloning is a dominant strategy.

Nicola Dragoni, Olga Gadyatskya, Fabio Massacci

If all applications could be loaded at the start this would boil down to information flow analysis for which many solutions exist, but this is precisely what we want to overcome. When applications are not known in advance and can be updated asynchronously and possibly without connection to trusted third parties, we must preserve the security policies of the various owners of the applets during such autonomous evolution. This chapter illustrates the extension of the Security-by-Contract approach from mobile phones to smart cards: Security-by-Contract is based on the loading time application certification on the card that will enable the card to make autonomous decisions on application and policy updates while ensuring the compliance of every change of the platform with the security policy of each application’s owner.

Nikhil Swamy, Juan Chen, Cédric Fournet, Pierre-Yves Strub · 6 authors

Abstract Distributed applications are difficult to program reliably and securely. Dependently typed functional languages promise to prevent broad classes of errors and vulnerabilities, and to enable program verification to proceed side-by-side with development. However, as recursion, effects, and rich libraries are added, using types to reason about programs, specifications, and proofs becomes challenging. We present F*, a full-fledged design and implementation of a new dependently typed language for secure distributed programming. Our language provides arbitrary recursion while maintaining a logically consistent core; it enables modular reasoning about state and other effects using affine types; and it supports proofs of refinement properties using a mixture of cryptographic evidence and logical proof terms. The key mechanism is a new kind system that tracks several sub-languages within F* and controls their interaction. F* subsumes two previous languages, F7 and Fine. We prove type soundness (with proofs mechanized in Coq) and logical consistency for F*. We have implemented a compiler that translates F* to .NET bytecode, based on a prototype for Fine. F* provides access to libraries for concurrency, networking, cryptography, and interoperability with C#, F#, and the other .NET languages. The compiler produces verifiable binaries with 60% code size overhead for proofs and types, as much as a 45x improvement over the Fine compiler, while still enabling efficient bytecode verification. We have programmed and verified nearly 50,000 lines of F* including new schemes for multi-party sessions; a zero-knowledge privacy-preserving payment protocol; a provenance-aware curated database; a suite of web-browser extensions verified for authorization properties; a cloud-hosted multi-tier web application with a verified reference monitor; the core F* typechecker itself; and programs translated to F* from other languages such as F7 and JavaScript.

Shlomi Dolev, Panagiota N. Panagopoulou, Mikaël Rabie, Elad M. Schiller · 5 authors

Players in a game are assumed to be totally rational and absolutely smart. However, in reality all players may act in non-rational ways and may fail to understand and find their best actions. In particular, participants in social interactions, such as lotteries and auctions, cannot be expected to always find by themselves the "best-reply" to any situation. Indeed, agents may consult with others about the possible outcome of their actions. It is then up to the counselee to assure the rationality of the consultant's advice. We present a distributed computer system infrastructure, named rationality authority, that allows safe consultation among (possibly biased) parties. The parties' advices are adapted only after verifying their feasibility and optimality by standard formal proof checkers. The rationality authority design considers computational constraints, as well as privacy and security issues, such as verification methods that do not reveal private preferences. Some of the techniques resembles zero-knowledge proofs. A non-cooperative game is presented by the game inventor along with its (possibly intractable) equilibrium. The game inventor advises playing by this equilibrium and offers a checkable proof for the equilibrium feasibility and optimality. Standard verification procedures, provided by trusted (according to their reputation) verification procedures, are used to verify the proof. Thus, the proposed rationality authority infrastructure facilitates the applications of game theory in several important real-life scenarios by the use of computing systems.

Luis Carlos Coronado-García, Jesus Alejandro Gonzalez-Fuentes, Pedro Josue Hernandez-Torres, Carlos Pérez-Leguízamo

Service Oriented Architecture (SOA) represents a new model in the traditional way of designing systems, this is due to frequent change of requirements and high integration of the applications of organizations around the world. Although the use of SOA has increased, certain features of applications do not allow its use. This is the case of mission critical applications, whose characteristics are high availability, continuous operation, high flexibility, high performance, etc. On the other hand, these features have been covered in Autonomous Decentralized Systems (ADS). This article presents a SOA-ADS modeling novel approach called Autonomous Decentralized Service Oriented Architecture (ADSOA). Additionally it is presented the Loosely Coupling Synchronization and Transactional Delivery Technology that provides consistency and high availability. To show the viability of the proposal a prototype is presented.

Nicola Dragoni, Olga Gadyatskaya, Fabio Massacci

No abstract is available for this record.

Sébastien Canard, Aline Gouget

No abstract is available for this record.

Essam Ghadafi, Nigel P. Smart, Bogdan Warinschi

No abstract is available for this record.

Eric Ayeh

Zero-knowledge proofs protocols are effective interactive methods to prove a node's identity without disclosing any additional information other than the veracity of the proof. They are implementable in several ways. In this thesis, I investigate the graph isomorphism based zero-knowledge proofs protocol. My experiments and analyses suggest that graph isomorphism can easily be solved for many types of graphs and hence is not an ideal solution for implementing ZKP.

Eric Ayeh, Kamesh Namuduri

Abstract : University of North Texas (UNT) is collaborating with the Air Force Research Laboratory (AFRL) in the design and development of ZKP protocol and in investigating its suitability for airborne networks. During this project, we accomplished the following tasks: (1) Implemented a prototype version of graph isomorphism based ZKP protocol. (2) Analyzed the implementation complexity of the ZKP protocol. (3) Investigated the selection of graphs that are suitable for ZKP implementation. Our experiments related to task (3) indicate that the graphs selected for ZKP implementation must possess specific characteristics. While we developed the basic guidelines for this selection, our results are inconclusive and require additional experiments.

Jianwei Ye

In order to prevent the fault wire-key probing attacks from the malicious mobile code generators for enhancing the confidentiality of executors’inputs in Zhong-Yang protocol,a verifiable multiplying subsidiary circuit is proposed and used to extend the garbled circuit in Zhong-Yang protocol.The extended protocol replaces executors’input-wires with the multiplying subsidiary circuits for resisting fault wire-key probing attacks,and ensures the correctness of the construction of the subsidiary circuit by the committed garbled circuit technology of Jarecki and Shmatikov and the third-party challenged zero-knowledge proof protocols.The analyses show that,when more than two-thirds of the third-party servers are honest,the extended protocol can prevent the tampering wire-key attacks of the malicious third-party servers and the fault wire-key probing attacks of the malicious generators simultaneously,meet the non-interactive request of mobile code environment,and add polynomial communication and computation complexity.The extended protocol ensures the complete confidentiality of executors’inputs in malicious mobile code environment.

Rafael Pass, Wei-Lung Dustin Tseng, Douglas Wikström

We show that only languages in BPP have public-coin black-box zero-knowledge protocols that are secure under an unbounded (polynomial) number of parallel repetitions. This result holds both in the plain model (without any setup) and in the bare public key model (where the prover and the verifier have registered public keys). We complement this result by constructing a public-coin black-box zero-knowledge proof based on one-way functions that remains secure under any a priori bounded number of concurrent executions. A key step (of independent interest) in the analysis of our lower bound shows that any public-coin protocol, when repeated sufficiently in parallel, satisfies a notion of “resettable soundness” if the verifier picks its random coins using a pseudorandom function.

Ronald Cramer, Ivan Damgård, Marcel Keller

No abstract is available for this record.

Agostino Forestiero, Carlo Mastroianni, Giandomenico Spezzano

This article presents So-Grid, a set of bio-inspired algorithms tailored to the decentralized construction of a Grid information system that features adaptive and self-organization characteristics. Such algorithms exploit the properties of swarm systems, in which a number of entities/agents perform simple operations at the local level, but together engender an advanced form of swarm intelligence at the global level. In particular, So-Grid provides two main functionalities: logical reorganization of resources, inspired by the behavior of some species of ants and termites that move and collect items within their environment, and resource discovery, inspired by the mechanisms through which ants searching for food sources are able to follow the pheromone traces left by other ants. These functionalities are correlated, since an intelligent dissemination can facilitate discovery. In the Grid environment, a number of ant-like agents autonomously travel the Grid through P2P interconnections and use biased probability functions to: (i) replicate resource descriptors in order to favor resource discovery; (ii) collect resource descriptors with similar characteristics in nearby Grid hosts; (iii) foster the dissemination of descriptors corresponding to fresh (recently updated) resources and to resources having high quality of service (QoS) characteristics. Simulation analysis shows that the So-Grid replication algorithm is capable of reducing the entropy of the system and efficiently disseminating content. Moreover, as descriptors are progressively reorganized and replicated, the So-Grid discovery algorithm allows users to reach Grid hosts that store information about a larger number of useful resources in a shorter amount of time. The proposed approach features characteristics, including self-organization, scalability and adaptivity, which make it useful for a dynamic and partially unreliable distributed system.

Jan Bouda, Paulo Mateus, Nikola Paunković, João Rasga

We show how quantum tamper-proof devices (QTPD's) can be used to attack and to develop security protocols. On one hand, we prove that it is possible to transfer proofs of zero-knowledge protocols using QTPD's. This attack can be extended to other security schemes where privacy is important. On the other hand, we present a fair contract signing protocol using QTPD's where there is no communication with Judge during the exchange phase (which is impossible classically). In the latter case, we make use of decoherence in the quantum state of the QTPD to implement a global clock over the asynchronous network. QTPD's seem to be possible to implement with existing quantum hardware, due to the fact that it is hard to isolate quantum memory from interference. These theoretical results contribute to justify the implementation of QTPD's.

Ali Rezaee, Amir Masoud Rahmani, Saeed P arsa, Sahar Adabi

Grid computing is emerged as a new distributed computing technology that implements flexible and coordinated resource sharing among dynamic, heterogeneous, unpredictable and geographically distributed collections of resources owned by different individuals and organizations. Due to heterogeneous and dynamic nature of the grid, resource management and application scheduling is a complex undertaking. This paper proposed a multi-agent architecture that addressed resource management and application execution with support for Quality of Services (QoS) in grid environment. Five types of collaborative intelligent and mobile agents proposed to manage grid resources and applications in a decentralized, autonomous and intelligent manner. In the proposed architecture, negotiation, advanced reservation and QoS measurements handled by collaborative intelligent agents. Resources and applications are managed independently with respect to their defined policies. The simulation results showed that the multi-agent architecture is practical, flexible and effective.

Jianhua Ge

The private multi-party computation protocol proposed by Claude Crepeau etc.is not only complicated but very inefficient.This paper describes a new protocol with an efficient global commitment transfer sub-protocol.With a first two round string oblivious transfer,the protocol can avoid performing a large mount of bit oblivious transfers.And with bit commitment with XOR,zero knowledge proofs are very easy.This PMPC protocol is conceptually simple and more efficient.The security and complexity of the protocol are also discussed in this paper.

Zbigniew Kotulski, Aneta Zwierko

The recent development in the mobile technology (mobile phones, middleware, wireless networks, etc.) created a need for new methods of protecting the code transmitted through the network. The oldest and the simplest mechanisms concentrate more on integrity of the code itself and on the detection of unauthorized manipulation. The newer solutions not only secure the compiled program, but also the data, that can be gathered during its “journey,” and even the execution state. Some other approaches are based on prevention rather than detection. In this chapter we present a new idea of securing mobile agents. The proposed method protects all components of an agent: the code, the data, and the execution state. The proposal is based on a zero-knowledge proof system and a secure secret sharing scheme, two powerful cryptographic primitives. Next, the chapter includes security analysis of the new method and its comparison to other currently more widespread solutions. Finally, we propose a new direction of securing mobile agents by straightening the methods of protecting integrity of the mobile code with risk analysis and a reputation system that helps avoiding a high-risk behavior.Request access from your librarian to read this chapter's full text.

Sebastian Faust, Emilia Käsper, Stefan Lucks

We present an efficient simultaneous broadcast protocol ν-SimCast that allows n players to announce independently chosen values, even if up to t < n players are corrupt. Independence is guaranteed in the partially syn-2 chronous communication model, where communication is structured into rounds, while each round is asynchronous. The ν-SimCast protocol is more efficient than previous constructions. For repeated executions, we reduce the communication and computation complexity by a factor O(n). Combined with a deterministic extractor, ν-SimCast provides a particularly efficient solution for distributed coin-flipping. The protocol does not require any zero-knowledge proofs and is shown to be secure in the standard model under the Decisional Diffie Hellman assumption.