The authors define a notion of adaptive proofs of knowledge (PoKs) in the random oracle model (ROM). These are proofs where the malicious prover can adaptively issue multiple statements and proofs, and where the extractor is supposed to extract a witness for each statement. They begin by studying the traditional notion of zero‐knowledge PoKs in the ROM and then show how to extend it to the case of adaptive adversaries and to simulation soundness, where the adversary can also learn simulated proofs. The authors’ first main result is negative. Under common assumptions, they can show that the well‐known Fiat–Shamir–Schnorr proof system is not adaptively secure. As for the second result, they prove that an existing construction due to Fischlin (Crypto 2005) yields adaptively secure simulation‐sound PoKs in the ROM. Since the purpose of this work is to motivate and introduce adaptive proofs, they only briefly discuss some applications to other areas, for example that adaptive proofs seem to be exactly what one requires to construct chosen‐ciphertext attack‐secure public‐key encryption from indistinguishability under chosen plaintext attack secure schemes.
In recent years the distributed ledger technology (‘DLT’) has been presented as potentially disruptive for financial market applications. Since no reference implementation of such technology has emerged yet, it is not even clear how different it would be from the blockchain technology underlying bitcoin. Blockchain is a sub-optimal data structure if not associated to a virtual currency, i.e. to a native digital asset used to provide the economic incentive to reach distributed consensus on a transaction history. Since the interest for virtual currencies in the financial markets has remained marginal so far, most of the interest for DLT seems to boil down to the cryptographic enhancements of coupling secure messaging with shared databases. Such an evolutionary approach might be relevant, but hardly disruptive; instead, it is the availability for the first time ever in digital realm of a scarce asset, transferable but not replicable, to be groundbreaking. Bitcoin could prove to be digital gold as relevant as physical gold has been in the human history and the development of finance: it has already realized a permissionless transaction network and could play a crucial role in the history of money.
Bitcoin, a fascinating phenomenon of crypto-technology, has emerged in financial markets as a potential alternative to standard fiat currencies. It represents unique sociotechnical \necosystem working outside of any traditional markets, and its economy is still not well understood. Dynamics of Bitcoin price proves to be quite a controversial subject, but there is a strong indication that social factors mainly influence its economy. \n \nTechnical flaws and lack of any central authority issuing and controlling this digital currency make it vulnerable to abuse. It has been associated with controversy due to frequent incidents, namely hacks, theft, scam, and illicit use, which affected its ecosystem ever since it gained popularity. \n \nThis thesis adds to the discussion about social aspects of Bitcoin economy by analysing the changes in its price volatility in the context of incidents occurring in its \necosystem. As empirically proven, those negative events have no impact on the fluctuations of Bitcoin price.
Im Dezember 2015 identifizierte Sir Mark Walport, wissenschaftlicher Berater der Regierung des Vereinigten Königreichs, in seinem Bericht Distributed Ledger Technologie über die Blockchain hinaus massive Vorteile einer Nutzung dezentraler Transaktionssysteme in verschiedenen Geschäftsbereichen der britischen Regierung. Mark Walport sieht vor allem das Potential, die Beziehung zwischen Regierung und Bürger neu zu definieren, wenn es um den Austausch von Daten, um Transparenz und um Aufbau von Vertrauen geht. Ebenso können Betrug, Korruption und Administrationskosten eingedämmt werden. Im Bericht werden u.a. folgende Anwendungsfälle für Blockchain‐Technologien besprochen: Zusammengefasst empfiehlt der Bericht der britischen Regierung, das Thema schnellstmöglich zu adressieren, die Erforschung dezentraler Datenbanken massiv zu fördern und nicht zuletzt ein regulatorisches Rahmenwerk für dezentrale Transaktionssysteme zu entwickeln.
Den Zentralbanken muss vertraut werden, die Währung nicht abzuwerten. Aber die Geschichte des Fiat‐Geldes ist in dieser Hinsicht voller Vertrauensbrüche (Satoshi Nakamoto am 11. Februar 2009 in einem Forum). Durch die immanente Offenheit des Open‐Source‐Bitcoin‐Systems werden die oben beschriebenen Limitationen des Transaktionssystems in der Bitcoin‐Szene heftig diskutiert, wobei diese Limitationen von den einen als Einschränkungen empfunden, von den anderen aber als Stärken des Systems gesehen werden. Ebenso wie die Limitationen des Systems werden die individuellen Lösungsansätze von Beginn an transparent diskutiert und analysiert.
Like how VoIP (Voice over Internet Protocol) disrupted cross‐border telephony, Bitcoin will bring huge savings and improved service in cross‐border payments and will therefore create the MoIP (Money over Internet Protocol) (Pantera Capital). Anhand einiger typischer Gradmesser der Netzwerkökonomie soll in der Folge aufgezeigt werden, welche massive Entwicklung das von Satoshi Nakamoto vorgeschlagene neue kryptografische Transaktionssystem innerhalb einer Zeitspanne von gut sechs Jahren genommen hat.
…the more it is adopted by a mass of users, the more it is secured (Counterparty). Inwieweit, ob und welche Kryptowährung schlussendlich langfristig weltweit akzeptiert wird, ist Thema zahlreicher und vielfältiger Diskussionen. Innerhalb der verschiedenen Kryptowährungen hat das Bitcoin‐System eindeutig einen massiven Vorsprung. Vorstellbar ist jedoch auch analog des Konzepts des freien Wettbewerbs unter den Währungen vom österreichischen Ökonomen Friedrich August von Hayek ein Nebeneinander verschiedenster Kryptowährungen. Jeder dieser Kryptowährungen könnte ein Wert durch eine Gruppe von Menschen, die sich dafür entscheiden, dieser Währung zu vertrauen, beigemessen werden. Diese Gruppe kann durch gemeinsame demografische, geografische oder ethische Interessen definiert werden. Damit Kryptowährungen jedoch von der breiten Öffentlichkeit genutzt werden, bedarf es noch Vor allem aber braucht es Akzeptanz und Nutzung der Kryptowährungen in der breiten Öffentlichkeit und hier liefert die Gratis‐Bitcoin‐Ökosphäre, bestehend aus Hunderten Faucet‐Webseiten, einen großen Beitrag.
Bitcoin offers a sweeping vista of opportunity to reimagine how the financial system can and should work in the Internet era (Marc Andreessen, General Partner at Andreessen Horowitz). Die Vorteile der Nutzung des Bitcoin‐Transaktionssystems als Ersatz für die momentan genutzten elektronischen Zahlungsverkehrssysteme sind offensichtlich, und doch gibt es immer noch viel Diskussion über Sinnhaftigkeit und Nutzbarkeit des Systems. Die Gründe dafür sind vielfältig und sollen das Thema der nächsten Ausführungen sein. Bei der Diskussion der Limitationen des Bitcoin‐Systems ist die relative Neuheit des Systems zu berücksichtigen, sodass es sich bei vielen der im Folgenden im Detail diskutierten Limitationen handelt es sich um Anfangsschwierigkeiten, an deren Lösung intensiv gearbeitet wird.
Darüber hinaus hat Bitcoin jedoch noch zusätzliche Vorteile: So wie im 19. Jahrhundert der Goldstandard eine Welle der Globalisierung losgelöst hat, kann der Bitcoin die Globalisierung von Handel und Dienstleistung auf eine neue Stufe heben. Der Bitcoin macht das Internet zur Währungsunion (Bitcoinblog.de). Die Bitcoin‐Architektur ermöglicht Dieses neue elektronische und weltweit verfügbare Zahlungssystem Die Bitcoin‐Technologie verteilt die Transaktionsverantwortlichkeiten über ein dezentrales Computernetzwerk, wodurch die Notwendigkeit der Involvierung teurer Finanzinstitute und Zahlungsdienstleister zur Authentifizierung und Überprüfung wegfällt und damit die Transaktionskosten und die Transaktionsdauer vermindert werden können.
Talent hits a target others cannot hit, Genius hits a target others cannot see (Arthur Schopenhauer). Bereits 2013 begannen sich neue Kryptowährungsunternehmen zu formieren, die sich von der Wild‐West‐Mentalität der Mt. Gox und der Silk Road abgrenzen wollten. Die entstehenden Kryptowährungsdienstleister – großteils finanziert von US Venture Capital-Gebern – unterwerfen sich teils freiwillig den Know Your Customer (KYC) Bestimmungen der Finanzaufsichtsbehören. Gleichzeitig entstanden Kryptowährungsstartups, deren Gründer die Meinung vertraten, dass eine Kooperation mit den Finanzinstituten bzw. den Fiatwährungen statt Konfrontation wirtschaftlich sinnvoller wäre und damit begannen, neue Kryptotransaktionssysteme mit dieser Zielrichtung zu entwickeln (beispielsweise Ripple Lab vgl. auch Abschn. 14.2.). Zeitgleich – auch hier spielten die Interessen der investierten Venture-Capital-Geber eine wichtige Rolle – begannen Startups intensiv am Einsatz des Bitcoin‐Transaktionssystems für alternative Zwecke zu arbeiten. Dabei wird unterschieden in:
Banks, as they exist now, are obsolete and will not exist as we know them in 10 years. Period. Without a doubt. We’ve seen this movie before. Is anyone using Delphi? CompuServe? AOL? What did they have in common? They tried to retrofit the Internet’s HTTP technology into their systems. They tried to force everyone into their closed loopholes. It worked, temporarily. You had a jump in revenues and profit, and then everybody found out you can deal directly with the source. You don’t need them They’re gone. The banking system is trying to do the same thing (Reggie Middleton, CEO of Veritaseum, designing P2P Smart Contracts through blockchain tech & inventor of UltraCoin). Wie schon oft in diesem Buch aufgezeigt, nutzt die Finanzwirtschaft schon jahrzehntelang Softwaresysteme wie das SWIFT-System, hat es aber bis dato geschafft, sich von der Digitalisierung des Internets abzugrenzen.
Die Möglichkeit der Programmierbarkeit des Bitcoins ist fast ein nachträglicher Einfall, auch wenn Sidechain‐Vorschläge diese Programmierbarkeit ein wenig leichter machen wollen und es bereits Altcoins mit verschiedenen spezifischen Anwendungen gibt. Im Gegensatz dazu wurde das Kryptowährungstechnologieprojekt Ethereum von Vitalik Buterin, seinem Erfinder, von Tag 1 als Software‐Entwicklungsplattform für dezentrale Applikationen konzipiert, und ihre Blockchain wurde speziell entwickelt, um die Ausführung dieser dezentralen Apps (auch Dapps genannt) zu unterstützen. Vitalik Buterin, 1994 in Russland geboren, war vor der Gründung von Ethereum auch involviert in die Entwicklungsprojekte Colored Coins und Mastercoins. Er gewann 2014 den "World Technology Award" und ein Stipendium des Risikokapitalgebers Peter Thiel. In dem Diskussionspapier zu Ethereum skizzierte Buterin vor allem die Grenzen einer Programmierbarkeit der Bitcoin‐Blockchain und schlug die Erstellung einer neuen komplett programmierbaren Blockchain mit einer turing‐vollständigen Programmiersprache vor. Anders als andere Blockchain‐Projekte soll die Ethereum Software nicht nur für einen Zweck nutzbar sein – sondern soll die Basis für die Erarbeitung aller möglichen Arten von Lösungen sein und dabei die Umsetzung intelligenter Verträge (Smart Contracts) ebenso erfassen als auch die Ethereum‐spezifische Idee von dezentralen autonomen Organisationen (DAOs).
We obtain lower tail estimates for the smallest singular value of random\nmatrices with independent but non-identically distributed entries.\nSpecifically, we consider $n\\times n$ matrices with complex entries of the form\n\\[ M = A\\circ X + B = (a_{ij}\\xi_{ij} + b_{ij}) \\] where $X=(\\xi_{ij})$ has iid\ncentered entries of unit variance and $A$ and $B$ are fixed matrices. In our\nmain result we obtain polynomial bounds on the smallest singular value of $M$\nfor the case that $A$ has bounded (possibly zero) entries, and $B= Z\\sqrt{n}$\nwhere $Z$ is a diagonal matrix with entries bounded away from zero. As a\nbyproduct of our methods we can also handle general perturbations $B$ under\nadditional hypotheses on $A$, which translate to connectivity hypotheses on an\nassociated graph. In particular, we extend a result of Rudelson and Zeitouni\nfor Gaussian matrices to allow for general entry distributions satisfying some\nmoment hypotheses. Our proofs make use of tools which (to our knowledge) were\npreviously unexploited in random matrix theory, in particular Szemer\\'edi's\nRegularity Lemma, and a version of the Restricted Invertibility Theorem due to\nSpielman and Srivastava.\n
There has recently been a flood of interest in potential new applications of blockchains, as well as proposals for more generic designs called public ledgers. Most of the novel proposals have been in the financial sector. However, the public ledger is an abstraction that solves several of the fundamental problems in the design of secure distributed systems: global time in the form of a strict linear order of past events, globally consistent and immutable view of the history, and enforcement of some application-specific safety properties. This paper investigates the applications of public ledgers to access control and, more specifically, to group management in distributed systems where entities are represented by their public keys and authorization is encoded into signed certificates. It is particularly difficult to handle negative information, such as revocation of certificates or group membership, in the distributed setting. The linear order of events and global consistency simplify these problems, but the enforcement of internal constraints in the ledger implementation often presents problems. We show that different types of revocation require slightly different properties from the ledger. We compare the requirements with Bitcoin, the best known blockchain, and describe an efficient ledger design for membership revocation that combines ideas from blockchains and from web-PKI monitoring. While we use certificate-based group-membership management as the case study, the same ideas can be applied more widely to rights revocation in distributed systems.
There has recently been a flood of interest in potential new applications of\nblockchains, as well as proposals for more generic designs called public\nledgers. Most of the novel proposals have been in the financial sector.\nHowever, the public ledger is an abstraction that solves several of the\nfundamental problems in the design of secure distributed systems: global time\nin the form of a strict linear order of past events, globally consistent and\nimmutable view of the history, and enforcement of some application-specific\nsafety properties. This paper investigates the applications of public ledgers\nto access control and, more specifically, to group management in distributed\nsystems where entities are represented by their public keys and authorization\nis encoded into signed certificates. It is particularly difficult to handle\nnegative information, such as revocation of certificates or group membership,\nin the distributed setting. The linear order of events and global consistency\nsimplify these problems, but the enforcement of internal constraints in the\nledger implementation often presents problems. We show that different types of\nrevocation require slightly different properties from the ledger. We compare\nthe requirements with Bitcoin, the best known blockchain, and describe an\nefficient ledger design for membership revocation that combines ideas from\nblockchains and from web-PKI monitoring. While we use certificate-based\ngroup-membership management as the case study, the same ideas can be applied\nmore widely to rights revocation in distributed systems.\n
Appearance of Bitcoin raise up evolution in currency. Blockchain database also raise up possibilities to share important data between untrusted peers. In this paper, we propose Arachneum, a decentralized, distributed, and model-view-controller-based web service using blockchain and new privileges model. Therefore, we can enjoy the freedom against censorship of government or organizations, keep transparency of our web services, fork our web services, and create/read/update/delete(CRUD) all model-view-controller(MVC) components dynamically.
We present a novel institutional perspective on the distributed consensus and ledger technology known as blockchain. We discuss the concept of Distributed Autonomous Institutions that are able to facilitate global interactions, contracts, and value transfers, all of which are achieved without the need for the human-based third party trust. We argue that due to its properties and design blockchain technology represents a disruptive change in the modelling paradigms of socio-technical systems. Distributed trust and consensus mechanisms offered by blockchain technology represent a novel, qualitatively different, phenomenon. We present the general design principles, stakeholders, the dynamics between those stakeholders, the incentive models, and the consensus protocols currently used in blockchains, before highlighting the potential of blockchain technology to develop distributed autonomous institutions. We conclude with a discussion of challenges associated with the adoption of blockchain technology.
DT X is building a next generation model from the grassroots of infrastructure Telecommunications 4.0 to IOT, Industry 4.0, Education 4.0 and financial services (Banking 4.0) leveraging Distributed Ledger technology. (Going beyond code and blockchain.)
The aim is to empower and beyond traditional and rational projects by targeting the sore points globally, opposed to the tradition proposals and whitepapers of a target market of 2 billion people who currently don’t have access to banking across the world.
DT X is based over four years of trials and errors of sub projects to evaluate the conditions and possible prospects, which in each and every time fall back to National Infrastructure and resources which varies from country to country: Telecommunications, Energy, Financial Services (Fintech & Regulation), Available Funding, Economic Stimulation, Education and Blockchain adoption & use cases.
Instead of promoting specific problems and identifying alternative underlying issues DT X is targeting the core root of the issue then apply by layers solutions to solve specific requirements.
Western world application will be focused on a similar model of Africa but more evolved around Telecommunication infrastructure merged with Distributed Ledger Technology over its own Network on a national scale thus securing all information and providing Industry 4.0 the infrastructure to grow and create economic growth whilst supporting Fintech, Education and Public or Private services.
The Internet of Things IoT is experiencing exponential growth in research and industry, but it still suffers from privacy and security vulnerabilities. Conventional security and privacy approaches tend to be inapplicable for IoT, mainly due to its decentralized topology and the resource-constraints of the majority of its devices. BlockChain BC that underpin the crypto-currency Bitcoin have been recently used to provide security and privacy in peer-to-peer networks with similar topologies to IoT. However, BCs are computationally expensive and involve high bandwidth overhead and delays, which are not suitable for IoT devices. This position paper proposes a new secure, private, and lightweight architecture for IoT, based on BC technology that eliminates the overhead of BC while maintaining most of its security and privacy benefits. The described method is investigated on a smart home application as a representative case study for broader IoT applications. The proposed architecture is hierarchical, and consists of smart homes, an overlay network and cloud storages coordinating data transactions with BC to provide privacy and security. Our design uses different types of BCs depending on where in the network hierarchy a transaction occurs, and uses distributed trust methods to ensure a decentralized topology. Qualitative evaluation of the architecture under common threat models highlights its effectiveness in providing security and privacy for IoT applications.
Youngbin Kim, Jun Gi Kim, Wook Kim, Jae Ho Im · 7 authors
This paper proposes a method to predict fluctuations in the prices of cryptocurrencies, which are increasingly used for online transactions worldwide. Little research has been conducted on predicting fluctuations in the price and number of transactions of a variety of cryptocurrencies. Moreover, the few methods proposed to predict fluctuation in currency prices are inefficient because they fail to take into account the differences in attributes between real currencies and cryptocurrencies. This paper analyzes user comments in online cryptocurrency communities to predict fluctuations in the prices of cryptocurrencies and the number of transactions. By focusing on three cryptocurrencies, each with a large market size and user base, this paper attempts to predict such fluctuations by using a simple and efficient method.
<em>Blockchain</em> technology has the capacity to make digital goods immutable, transparent, externally provable, decentralized, and distributed. Besides the initial experiment or data acquisition, all remaining parts of the research cycle could take place within a <em>blockchain system</em>. Attribution, data, data postprocessing, publication, research evaluation, incentivisation, and research fund distribution would thereby become comprehensible, open (at will) and provable to the external world. Currently, scientists must be trusted to provide a true and useful representation of their research results in their final publication; <em>blockchain</em> would make much larger parts of the research cycle open to scientific self-correction. This bears the potential to be a technical solution to the current reproducibility crisis in science, and could ‘reduce waste and make more research results true’.
A. B. Ackerman, Anne B. Chang, Nadia Diakun-Thibault, Luca Forni · 7 authors
The President’s Precision Medicine Initiative (PMI) is “enabling a new era of clinical care through research, technology, and policies that empower patients, researchers, and providers to work together toward the development of individualized care”. Its commitment to privacy and security in the setting of responsible data sharing and transparency is articulated in the “Privacy and Trust Principles” and the “Data Security Policy Principles and Framework”, developed by an interagency working groups including the Office of the National Coordinator for Health Information Technology in conjunction with multiple stakeholders.
In this paper, we review the threats to the security, confidentiality, integrity, and availability of PMI data. PMI organizations can mitigate these challenges through a new system architecture in development at MIT -- the OPAL/Enigma project -- which creates a peer-to-peer network that enables parties to jointly store and analyze data with complete privacy, based on highly optimized version of multi-party computation with a secret-sharing. An auditable, tamper-proof distributed ledger (a permissioned blockchain) records and controls access through smart contracts and digital identities. We conclude with an initial use case of OPAL/Enigma that could empower precision medicine clinical trials and research.
MIT’s OPAL/Enigma challenges traditional data security paradigms. Centralized databases cannot assure security and data integrity, regardless de-identification and controlled access requirements. Safe, vetted queries that are distributed to private, encrypted databases assure that organizations and participants can share health care data with cryptographic guarantees of privacy with various stakeholders, assuring momentum for a new era of medical research and practice.
GlaxoSmithKline has joined with Verily Life Sciences to set up Galvani Bioelectronics, which will focus on treating chronic illnesses by controlling electrical impulses in the body. GSK and Verily, the former Google Life Sciences business, will initially invest up to $718 million over seven years to support R&D at Galvani. Having made a concerted push into the bioelectronics area in 2012, GSK will now put its in-house efforts into Galvani for a 55% stake. The start-up will be housed at GSK’s Stevenage, England, R&D site with research also conducted in South San Francisco. Kris Famm, GSK’s vice president of bioelectronics R&D, will become Galvani’s president. Galvani will combine GSK’s capabilities with Verily’s technical expertise in miniaturizing low-power electronics and in developing implantable devices, data analytics, and software for clinical applications. Galvani will initially employ about 30 scientists, engineers, and clinicians. GSK says it has already seen encouraging proof of principle