OPODIS 2019 Best Paper Award goes to Sasha Spiegelman and (alumnus) Dahlia Malkhi

Financial institutions nowadays are 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 the selfish behavior that inevitably arises when financial institutions strive to maximize their own profit. We present FairLedger, a permissioned BFT blockchain protocol, which is fair, deigned to deal with rational behavior, and, no less important, easy to understand and implement. Our secret sauce is a new communication abstraction called detectable all-to-all (DA2A), which allows us to detect players (byzantine or rational) that deviate from the protocol and punish them. We implement FairLedger in the Hyperledger open source project using the 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 in wide-area settings, FairLedger achieves better throughput than both Iroha’s implementation and PBFT.