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

Chainspace: A Sharded Smart Contracts Platform

Chainspace is a decentralized infrastructure, known as a distributed ledger, that supports user defined smart contracts and executes user-supplied transactions on their objects. The correct execution of smart contract transactions is verifiable by all. The system is scalable, by sharding state and the execution of transactions, and using S-BAC, a distributed commit protocol, to guarantee consistency. Chainspace is secure against subsets of nodes trying to compromise its integrity or availability properties through Byzantine Fault Tolerance (BFT), and extremely high-auditability, non-repudiation and `blockchain' techniques. Even when BFT fails, auditing mechanisms are in place to trace malicious participants. We present the design, rationale, and details of Chainspace; we argue through evaluating an implementation of the system about its scaling and other features; we illustrate a number of privacy-friendly smart contracts for smart metering, polling and banking and measure their performance

Performance Testing Bulletin Board Implementations for Online Voting

Internetihääletamine (i-hääletamine) on hääletamisviis, mille puhul hääl liigub valija seadmest urni Interneti vahendusel. I-hääletamise süsteemide sagedaseks komponendiks on avalik teadetetahvel, kuhu registreeritud andmete abil tagatakse valimiste läbipaistvus ja auditeeritavus. Avalik teadetetahvel on komponent, mis võimaldab registreeridaandmeid viisil, mis muudab nende hilisema muutmise või kustutamise keeruliseks.Teadetetahvli puhul on oluline teenuse tagatud kättesaadavus ja toimimine. Sellest tulenevalt on avaliku teadetetahvli implementeerimise tuumküsimuseks korrektne masinate kordistamine, mille muudab keerulisemaks i-hääletamise spetsiifilised lisanõuded. Selle töö käigus käsitletakse kahte olemasolevat tarkvaralahendust, mida saab kasutada teadetetahvli realiseerimisel, uurides nende jõudlust testkeskkonnas, mis imiteerib pärisvalimiste töökoormust.Online voting is an electronic voting method in which the process of casting a vote is done using the Internet as its communication medium. One component of some online voting systems is a public bulletin board (PBB), used to provide election transparency and correctness verifiability. PBB is a component for publishing data in a way that makes modifying or deleting already published data very difficult without leaving evidence of such actions. The security and liveness of this component has to be ensured. This means that implementing PBB is a machine replication problem at its core with some specific requirements inherited from the context of online voting. This work takes a look at two software solutions that can be used for such purpose and analyses their performance in testing environment imitating real election workload