FastPay: High-Performance Byzantine Fault Tolerant Settlement

FastPay allows a set of distributed authorities, some of which are Byzantine, to maintain a high-integrity and availability settlement system for pre-funded payments. It can be used to settle payments in a native unit of value (crypto-currency), or as a financial side-infrastructure to support retail payments in fiat currencies. FastPay is based on Byzantine Consistent Broadcast as its core primitive, foregoing the expenses of full atomic commit channels (consensus). The resulting system has low-latency for both confirmation and payment finality. Remarkably, each authority can be sharded across many machines to allow unbounded horizontal scalability. Our experiments demonstrate intra-continental confirmation latency of less than 100ms, making FastPay applicable to point of sale payments. In laboratory environments, we achieve over 80,000 transactions per second with 20 authorities---surpassing the requirements of current retail card payment networks, while significantly increasing their robustness

A Byzantine Fault-Tolerant Ordering Service for the Hyperledger Fabric Blockchain Platform

Hyperledger Fabric (HLF) is a flexible permissioned blockchain platform designed for business applications beyond the basic digital coin addressed by Bitcoin and other existing networks. A key property of HLF is its extensibility, and in particular the support for multiple ordering services for building the blockchain. Nonetheless, the version 1.0 was launched in early 2017 without an implementation of a Byzantine fault-tolerant (BFT) ordering service. To overcome this limitation, we designed, implemented, and evaluated a BFT ordering service for HLF on top of the BFT-SMaRt state machine replication/consensus library, implementing also optimizations for wide-area deployment. Our results show that HLF with our ordering service can achieve up to ten thousand transactions per second and write a transaction irrevocably in the blockchain in half a second, even with peers spread in different continents

ARPA Whitepaper

We propose a secure computation solution for blockchain networks. The correctness of computation is verifiable even under malicious majority condition using information-theoretic Message Authentication Code (MAC), and the privacy is preserved using Secret-Sharing. With state-of-the-art multiparty computation protocol and a layer2 solution, our privacy-preserving computation guarantees data security on blockchain, cryptographically, while reducing the heavy-lifting computation job to a few nodes. This breakthrough has several implications on the future of decentralized networks. First, secure computation can be used to support Private Smart Contracts, where consensus is reached without exposing the information in the public contract. Second, it enables data to be shared and used in trustless network, without disclosing the raw data during data-at-use, where data ownership and data usage is safely separated. Last but not least, computation and verification processes are separated, which can be perceived as computational sharding, this effectively makes the transaction processing speed linear to the number of participating nodes. Our objective is to deploy our secure computation network as an layer2 solution to any blockchain system. Smart Contracts\cite{smartcontract} will be used as bridge to link the blockchain and computation networks. Additionally, they will be used as verifier to ensure that outsourced computation is completed correctly. In order to achieve this, we first develop a general MPC network with advanced features, such as: 1) Secure Computation, 2) Off-chain Computation, 3) Verifiable Computation, and 4)Support dApps' needs like privacy-preserving data exchange

Decision Analytics and Decentralized Ledger Technologies for Determination and Preservation of Spare Part Value in Aircraft Maintenance

Aircraft spare parts are used to quickly replace defective parts and ideally avoid expensive aircraft-on-ground situations. Understanding the Fair Market Value of surplus parts is of eminent importance for the competitive advantage of a company. Decisions such as purchase, sale, storage or scrapping are made on the basis of the determined value. Domain experts state that the value of a part depends significantly on its specific characteristics, condition and workshop event history. If the documentation of this history is incomplete, this can lead to a complete loss of value of the part, since, for example, safety-relevant parts may no longer be used without complete documentation. For companies that want to be able to survive in the highly competitive Maintenance Repair and Overhaul market, the use of digital technologies for data-based decision making has become unavoidable. The drowning of data while at the same time thirsting for information affects all market participants who manage their spare parts using digital technologies. The competitive advantage over others is now to use this data efficiently and make decisions based on data rather than experience and instinct. On the other hand, processes still exist in this industry that require documentation in paper form. One such process is the documentation of workshop events for safety-relevant spare parts by means of certificates. Low mutual trust and the heterogeneity of regional requirements in a global market prohibit the establishment of a central instance for data management. The determination of a Fair Market Value was carried out manually for a long time, with great personnel effort and low reliability. The design of an Automated Spare Part Valuation concept provides a basis for data owners to use the amount of data reliably. Similar implementations in industry and with integrated automated evaluation prove the usability. The problem of incomplete certificates of workshop events is addressed and solved by the conception, implementation and evaluation of a Blockchain-based Certification System. The characteristics of a blockchain, in particular its decentralization and persistence, meet the requirements that could not previously be met in an environment with a lack of trust and due to the danger of a single point of failure.Flugzeugersatzteile dienen dem schnellen Austausch von defekten Teilen und vermeiden im Idealfall teure Aircraft-on-Ground-Situationen. Das Verständnis für einen Fair Market Value der überschüssigen Teile ist von eminenter Bedeutung für den Wettbewerbsvorteil eines Unternehmens. Entscheidungen wie Kauf, Verkauf, Einlagerung oder Verschrottung werden auf Basis des ermittelten Werts getroffen. Domänenexperten geben an, dass der Wert eines Teils maßgeblich von seinen spezifischen Charakteristika, seinem Zustand und seiner Werkstattereignishistorie abhängt. Ist der Nachweis dieser Historie lückenhaft, so kann es zum vollständigen Wertverlust des Teils kommen, da etwa sicherheitsrelevante Teile ohne lückenlose Nachweise nicht weiter verwendet werden dürfen. Für Unternehmen, die in der Lage sein wollen im starken Wettbewerb des Maintenance Repair and Overhaul Markts zu bestehen ist der Einsatz digitaler Technologien zur datenbasierten Entscheidungsfindung mittlerweile unumgänglich. Das Ertrinken an Daten bei gleichzeitigem Verdursten an Informationen trifft alle Marktteilnehmer, die ihre Ersatzteile mittels digitaler Technologien verwalten. Der Wettbewerbsvorteil gegenüber anderen besteht nun darin, diese Daten effizient zu nutzen und Entscheidungen weniger nach Erfahrung und Instinkt, sondern datenbasiert zu treffen. Andererseits existieren auch in dieser Branche immer noch Prozesse, die eine Dokumentation in Papierform erfordern. Ein solcher Prozess ist die Dokumentation von Werkstattereignissen für sicherheitsrelevante Ersatzteile durch Zertifikate. Ein geringes Vertrauen untereinander und die Heterogenität regionaler Anforderungen in einem globalen Markt verbieten die Etablierung einer zentralen Instanz zur Verwaltung der Daten. Die Ermittlung eines Fair Market Value erfolgte lange Zeit manuell, unter großem personellen Aufwand und geringer Zuverlässigkeit. Die Konzeption eines Automated Spare Part Valuation Konzepts bildet eine Grundlage für Inhaber von Daten, um die Menge an Daten verlässlich zu nutzen. Ähnliche Umsetzungen in der Industrie und mit integrierter automatisierter Bewertung belegen die Einsatzfähigkeit. Das Problem der lückenhaften Zertifikate von Werkstattereignissen wird durch die Konzeptionierung, Implementierung und Evaluation eines Blockchain-based Certification System adressiert und gelöst. Die Eigenschaften einer Blockchain, insbesondere die Dezentralität und Persistenz, erfüllen die Anforderungen, die in einem Umfeld mit mangelndem Vertrauen und aufgrund der Gefahr eines Single Point of Failure, bisher nicht zu erfüllen waren

FabricCRDT: A Conflict-Free Replicated Datatypes Approach to Permissioned Blockchains

With the increased adaption of blockchain technologies, permissioned blockchains such as Hyperledger Fabric provide a robust ecosystem for developing production-grade decentralized applications. However, the additional latency between executing and committing transactions, due to Fabric's three-phase transaction lifecycle of Execute-Order-Validate (EOV), is a potential scalability bottleneck. The added latency increases the probability of concurrent updates on the same keys by different transactions, leading to transaction failures caused by Fabric's concurrency control mechanism. The transaction failures increase the application development complexity and decrease Fabric's throughput. Conflict-free Replicated Datatypes (CRDTs) provide a solution for merging and resolving conflicts in the presence of concurrent updates. In this work, we introduce FabricCRDT, an approach for integrating CRDTs to Fabric. Our evaluations show that in general, FabricCRDT offers higher throughput of successful transactions than Fabric, while successfully committing and merging all conflicting transactions without any failures.Comment: In Proceedings of the 20th International Middleware Conference (Middleware '19). ACM 201