443 research outputs found

    Raziel: Private and Verifiable Smart Contracts on Blockchains

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    Raziel combines secure multi-party computation and proof-carrying code to provide privacy, correctness and verifiability guarantees for smart contracts on blockchains. Effectively solving DAO and Gyges attacks, this paper describes an implementation and presents examples to demonstrate its practical viability (e.g., private and verifiable crowdfundings and investment funds). Additionally, we show how to use Zero-Knowledge Proofs of Proofs (i.e., Proof-Carrying Code certificates) to prove the validity of smart contracts to third parties before their execution without revealing anything else. Finally, we show how miners could get rewarded for generating pre-processing data for secure multi-party computation.Comment: Support: cothority/ByzCoin/OmniLedge

    Beyond oracles – a critical look at real-world blockchains

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    This thesis intends to provide answers to the following questions: 1) What is the oracle problem, and how do the limitations of oracles affect different real-world applications? 2) What are the characteristics of the portion of the literature that leaves the oracle problem unaddressed? 3) Who are the main contributors to solving the oracle problem, and which issues are they focusing on? 4) How can the oracle problem be overcome in real-world applications? The first chapter aims to answer the first question through a literature review of the most current papers published in the field, bringing clarity to the blockchain oracle problem by discussing its effects in some of the most promising real-world blockchain applications. Thus, the chapter investigates the sectors of Intellectual Property Rights (IPRs), healthcare, supply chains, academic records, resource management, and law. By comparing the different applications, the review reveals that heterogeneous issues arise depending on the sector. The analysis supports the view that the more trusted a system is, the less the oracle problem has an impact. The second chapter presents the results of a systematic review intended to highlight the state-of-the-art of real-world blockchain applications using the oracle problem as a lens of analysis. Academic papers proposing real-world blockchain applications were reviewed to see if the authors considered the oracle’s role in the applications and related issues. The results found that almost 90% of the inspected literature neglected the role of oracles, thereby proposing incomplete or irreproducible projects. Through a bibliometric analysis, the third chapter sheds light on the institutions and authors that are actively contributing to the literature on oracles and promoting progress and cooperation. The study shows that, although there is still a lack of collaboration worldwide, there are dedicated authors and institutions working toward a similar and beneficial cause. The results also make it clear that most areas of oracle research are poorly addressed, with some remaining untouched. The fourth and last chapter focuses on a case study of a dairy company operating in the northeast region of Italy. The company applied blockchain technology to support the traceability of their products worldwide, and the study investigated the benefits of their innovation from the point of view of sustainability. The study also considers the role of oracle management, as it is a critical aspect of a blockchain-based project. Thus, the relationship between the company, the blockchain oracle, and the supervising authority is discussed, offering insight into how sustainable innovations can positively impact supply chain management. This work as a whole aims to shed light on blockchain oracles as an academic area of research, explaining why the study of oracles should be considered the backbone of blockchain literature development

    Storage Solutions for Big Data Systems: A Qualitative Study and Comparison

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    Big data systems development is full of challenges in view of the variety of application areas and domains that this technology promises to serve. Typically, fundamental design decisions involved in big data systems design include choosing appropriate storage and computing infrastructures. In this age of heterogeneous systems that integrate different technologies for optimized solution to a specific real world problem, big data system are not an exception to any such rule. As far as the storage aspect of any big data system is concerned, the primary facet in this regard is a storage infrastructure and NoSQL seems to be the right technology that fulfills its requirements. However, every big data application has variable data characteristics and thus, the corresponding data fits into a different data model. This paper presents feature and use case analysis and comparison of the four main data models namely document oriented, key value, graph and wide column. Moreover, a feature analysis of 80 NoSQL solutions has been provided, elaborating on the criteria and points that a developer must consider while making a possible choice. Typically, big data storage needs to communicate with the execution engine and other processing and visualization technologies to create a comprehensive solution. This brings forth second facet of big data storage, big data file formats, into picture. The second half of the research paper compares the advantages, shortcomings and possible use cases of available big data file formats for Hadoop, which is the foundation for most big data computing technologies. Decentralized storage and blockchain are seen as the next generation of big data storage and its challenges and future prospects have also been discussed
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