TumbleBit: an untrusted Bitcoin-compatible anonymous payment hub

This paper presents TumbleBit, a new unidirectional unlinkable payment hub that is fully compatible with today s Bitcoin protocol. TumbleBit allows parties to make fast, anonymous, off-blockchain payments through an untrusted intermediary called the Tumbler. TumbleBits anonymity properties are similar to classic Chaumian eCash: no one, not even the Tumbler, can link a payment from its payer to its payee. Every payment made via TumbleBit is backed by bitcoins, and comes with a guarantee that Tumbler can neither violate anonymity, nor steal bitcoins, nor print money by issuing payments to itself. We prove the security of TumbleBit using the real/ideal world paradigm and the random oracle model. Security follows from the standard RSA assumption and ECDSA unforgeability. We implement TumbleBit, mix payments from 800 users and show that TumbleBits offblockchain payments can complete in seconds.https://eprint.iacr.org/2016/575.pdfPublished versio

Blockchain and certification for more sustainable coffee Production : how can blockchain complement the sustainability certifications

Blockchain technology is increasingly gaining momentum in the food supply chain, as a technology to shape trust by installing transparency and fairness through assured digital identity, digital traceability, and unchangeable records. The study aimed to evaluate the impacts of sustainability certifications in coffee production, with an objective to assess if blockchain technology, could complement the major applied sustainability certification schemes for more sustainable coffee production. A systematic review of impacts of certifications based on socio-economic and environmental dimensions and existing certifications shortfalls were assessed. Thereafter a theory of change and the Multi-level perspective frameworks were employed to illustrate an intervention matrix, describing how blockchain technology can complement the shortfalls of applied sustainability certifications in coffee production. Simultaneously quantitative and content research methods allowing to answer the research questions were used to analyze dataset including self-reported impacts, from interviews and surveys conducted through self-administered questionnaires to non-random sampled actors from Coffee farmers, farmers cooperatives, coffee processors, exporters, government, Non-governmental organizations in Rwanda, and coffee importers and processors in Sweden, from March to May 2021. Results from the self-reported impacts indicate high training levels and skills connected to certification, have increased the environmental activities, and can lead to price improvement. The thesis reveals an unsustainable certifications structure from the economic perspective, with a high role played by the governments, and NGOs in support of certification compliance costs. In addition, results reveal a larger part of certified coffee being sold as conventional, due to lack of buyers. Consequently, sustainability certifications are failing the existing economic imbalance within the coffee value chain but continue to be an important tool. This implies that blockchain would be an option to complement the existing sustainability certifications shortfalls, for an efficient coffee production chain, to provide transparency, and fairness to enhance the inequitable and unbalanced coffee chain

Contracts Ex Machina

Smart contracts are self-executing digital transactions using decentralized cryptographic mechanisms for enforcement. They were theorized more than twenty years ago, but the recent development of Bitcoin and blockchain technologies has rekindled excitement about their potential among technologists and industry. Startup companies and major enterprises alike are now developing smart contract solutions for an array of markets, purporting to offer a digital bypass around traditional contract law. For legal scholars, smart contracts pose a significant question: Do smart contracts offer a superior solution to the problems that contract law addresses? In this article, we aim to understand both the potential and the limitations of smart contracts. We conclude that smart contracts offer novel possibilities, may significantly alter the commercial world, and will demand new legal responses. But smart contracts will not displace contract law. Understanding why not brings into focus the essential role of contract law as a remedial institution. In this way, smart contracts actually illuminate the role of contract law more than they obviate it

Decentralizing Science: Towards an Interoperable Open Peer Review Ecosystem using Blockchain

Science publication and its Peer Review system strongly rely on a few major industry players controlling most journals (e.g. Elsevier), databases (e.g. Scopus) and metrics (e.g. JCR Impact Factor), while keeping most articles behind paywalls. Critics to such system include concerns about fairness, quality, performance, cost, unpaid labor, transparency, and accuracy of the evaluation process. The Open Access movement has tried to provide free access to the published research articles, but most of the aforementioned issues remain. In such context, decentralized technologies such as blockchain offer an opportunity to experiment with new models for science production and dissemination relying on a decentralized infrastructure, aiming to tackle multiple of the current system shortcomings. This paper makes a proposal for an interoperable decentralized system for an open peer review ecosystem, relying on emerging distributed technologies such as blockchain and IPFS. Such system, named ``Decentralized Science'' (DecSci), aims to enable a decentralized reviewer reputation system, which relies on an Open Access by-design infrastructure, together with transparent governance processes. Two prototypes have been implemented: a proof-of-concept prototype to validate DecSci's technological feasibility, and a Minimum Viable Product (MVP) prototype co-designed with journal editors. In addition, three evaluations have been carried out: an exploratory survey to assess interest on the issues tackled, a set of interviews to confirm the main problems for editors, and another set of interviews to validate the MVP prototype. Additionally, the paper discusses the multiple interoperability challenges such proposal faces, including an architecture to tackle them. This work finishes with a review of some of the open challenges that this ambitious proposal may face

The new ecosystem of the digital age: Impact of blockchain technology on the accounting environment and financial statement fraud detection

The agency theory is an underlying framework for the installation of corporate governance roles in business enterprises. Their function to shield from financial statement fraud remains a shield with lacks that allow the occurrence of unsolved and intrinsic misbehaviour in business conduct. Technological developments have not been able to solve this issue, still waiting for a liberator from these well-known chains. One is seen in the use of Blockchain technology, the framework that builds trust among untrusting participants in networks such as Bitcoin or Ethereum. Since its mainstreaming popularity, researchers, corporations, and advocates foresee a great impact on the accounting industry that stems from the use of Blockchain. Taking this opportunity, this work investigates on these assumptions by reviewing literature on the domain, using case studies of former financial statement frauds to frame the fraudster’s profile, and applying it in the suggested scenario of blockchain-based accounting. By doing so, the use of permissioned blockchains raises doubt in a scenario that is shaped by management override activities, causing severe adversely affections to tiers in an ecosystem that trusts a technology and its “immutable” records.A teoria da agência é um quadro subjacente para a instalação de funções de governação empresarial em empresas comerciais. A sua função de protecção contra a fraude de declarações financeiras continua a ser um escudo com carências que permitem a ocorrência de comportamentos incorrectos não resolvidos e intrínsecos na conduta empresarial. Os desenvolvimentos tecnológicos não foram capazes de resolver esta questão, ainda à espera de um libertador destas bem conhecidas cadeias. Vê-se na utilização da tecnologia Blockchain, a estrutura que gera confiança entre os participantes não confiantes em redes como a Bitcoin ou a Ethereum. Desde a sua popularidade de mainstreaming, investigadores, empresas e defensores prevêem um grande impacto na indústria da contabilidade que resulta da utilização da Blockchain. Aproveitando esta oportunidade, este trabalho investiga estes pressupostos através da revisão da literatura sobre o domínio, utilizando estudos de caso de antigas fraudes em demonstrações financeiras para enquadrar o perfil do fraudador e aplicando-o no cenário sugerido de contabilidade baseada em cadeias de bloqueio. Ao fazê-lo, a utilização sugerida de cadeias de bloqueio autorizadas levanta dúvidas num cenário que é moldado por actividades de substituição da gestão, causando graves afecções negativas a camadas num ecossistema que confia numa tecnologia e nos seus registos "imutáveis"

An architecture for distributed ledger-based M2M auditing for Electric Autonomous Vehicles

Electric Autonomous Vehicles (EAVs) promise to be an effective way to solve transportation issues such as accidents, emissions and congestion, and aim at establishing the foundation of Machine-to-Machine (M2M) economy. For this to be possible, the market should be able to offer appropriate charging services without involving humans. The state-of-the-art mechanisms of charging and billing do not meet this requirement, and often impose service fees for value transactions that may also endanger users and their location privacy. This paper aims at filling this gap and envisions a new charging architecture and a billing framework for EAV which would enable M2M transactions via the use of Distributed Ledger Technology (DLT)