A Byzantine Fault Tolerant Distributed Commit Protocol

In this paper, we present a Byzantine fault tolerant distributed commit protocol for transactions running over untrusted networks. The traditional two-phase commit protocol is enhanced by replicating the coordinator and by running a Byzantine agreement algorithm among the coordinator replicas. Our protocol can tolerate Byzantine faults at the coordinator replicas and a subset of malicious faults at the participants. A decision certificate, which includes a set of registration records and a set of votes from participants, is used to facilitate the coordinator replicas to reach a Byzantine agreement on the outcome of each transaction. The certificate also limits the ways a faulty replica can use towards non-atomic termination of transactions, or semantically incorrect transaction outcomes.Comment: To appear in the proceedings of the 3rd IEEE International Symposium on Dependable, Autonomic and Secure Computing, 200

Study of consensus protocols and improvement of the Federated Byzantine Agreement (FBA) algorithm

At a present time, it has been proven that blockchain technology has influenced to a great extent the way of human interaction in a digital world. The operation of the blockchain systems allows the peers to implement digital transactions in a Peer to Peer (P2P) network in a direct way without the need of third parties. Each blockchain determines different rules for the record of the transactions in the ledger. The transactions are inserted in blocks and each one, in turn, is appended to the chain (ledger) based on different consensus algorithms. Once blocks have been inserted in the chain, the consensus has been reached and the blocks with corresponding transactions are considered immutable. This thesis analyses the main features of the blockchain and how the consensus can be achieved through the different kinds of consensus algorithms. In addition, a detailed reference for Stellar and Federated Byzantine Agreement (FBA) consensus protocols is made in order to explain these algorithms, their limitations as well as their improvement. The development of a reputation mechanism is necessary to the improvement of above algorithms

FairLedger: A Fair Blockchain Protocol for Financial Institutions

Financial institutions are currently looking into technologies for permissioned blockchains. A major effort in this direction is Hyperledger, an open source project hosted by the Linux Foundation and backed by a consortium of over a hundred companies. A key component in permissioned blockchain protocols is a byzantine fault tolerant (BFT) consensus engine that orders transactions. However, currently available BFT solutions in Hyperledger (as well as in the literature at large) are inadequate for financial settings; they are not designed to ensure fairness or to tolerate selfish behavior that arises when financial institutions strive to maximize their own profit. We present FairLedger, a permissioned blockchain BFT protocol, which is fair, designed to deal with rational behavior, and, no less important, easy to understand and implement. The secret sauce of our protocol is a new communication abstraction, called detectable all-to-all (DA2A), which allows us to detect participants (byzantine or rational) that deviate from the protocol, and punish them. We implement FairLedger in the Hyperledger open source project, using Iroha framework, one of the biggest projects therein. To evaluate FairLegder's performance, we also implement it in the PBFT framework and compare the two protocols. Our results show that in failure-free scenarios FairLedger achieves better throughput than both Iroha's implementation and PBFT in wide-area settings

On the Convergence of Blockchain and Internet of Things (IoT) Technologies

The Internet of Things (IoT) technology will soon become an integral part of our daily lives to facilitate the control and monitoring of processes and objects and revolutionize the ways that human interacts with the physical world. For all features of IoT to become fully functional in practice, there are several obstacles on the way to be surmounted and critical challenges to be addressed. These include, but are not limited to cybersecurity, data privacy, energy consumption, and scalability. The Blockchain decentralized nature and its multi-faceted procedures offer a useful mechanism to tackle several of these IoT challenges. However, applying the Blockchain protocols to IoT without considering their tremendous computational loads, delays, and bandwidth overhead can let to a new set of problems. This review evaluates some of the main challenges we face in the integration of Blockchain and IoT technologies and provides insights and high-level solutions that can potentially handle the shortcomings and constraints of both IoT and Blockchain technologies.Comment: Includes 11 Pages, 3 Figures, To publish in Journal of Strategic Innovation and Sustainability for issue JSIS 14(1

Byzantine Fault Tolerant Coordination for Web Services Atomic Transactions

This thesis describes a Byzantine fault tolerant coordination framework for Web services atomic transactions. In the framework, all core services, including transaction activation, registration, completion, and distributed commit, are replicated and protected by Byzantine fault tolerance mechanisms. The traditional two-phase commit protocol is extended by a Byzantine fault tolerant version that can tolerate arbitrary faults on the coordinator and the initiator sides, and some types of malicious faults on the participant side. To achieve Byzantine fault tolerance in an efficient manner, and to limit the types of malicious behaviors of the coordinator, a novel decision certificate is introduced. The decision certificate includes a signed copy of the participants\u27 vote records, and it is piggybacked with all decision notifications to the participants for each participant to verify the legitimacy of the decision. The Byzantine fault tolerance mechanisms, together with the extended two-phase commit protocol, have been incorporated into an open-source framework supporting the standard Web services atomic transactions specification. Performance characterizations of the framework show that the implementation is fairly efficient. Such a Byzantine fault tolerant coordination framework can be useful for many transactional Web services that require a high degree of security and dependabilit