|M.Sc Student||Buchnik Yehonatan|
|Subject||TOY: a Total Ordering Optimistic System for Permissioned|
|Department||Department of Computer Science||Supervisor||Professor Roy Friedman|
Blockchains are distributed secure ledgers to which transactions are issued continuously and each block of transactions is tightly coupled to its predecessors. Permissioned blockchains place special emphasis on transactions throughput. In this dissertation we present TOY, which leverages the iterative nature of blockchains in order to improve their throughput in optimistic execution scenarios. TOY trades latency for throughput in the sense that in TOY the last f
blocks of each node’s blockchain are considered tentative, i.e., they may be rescinded in case one of the last f 1 blocks proposers was Byzantine. Yet, when optimistic assumptions are met, a new block is decided in each communication step, which consists of a proposer that sends only its proposal and all other participants are sending a single bit each. Our performance study demonstrates that in a single Amazon data-center, TOY running on 10 mid-range Amazon
nodes obtains a throughput of up to 160K transactions per second (tps) for (typical Bitcoin size) 512 bytes transactions. In a 10 nodes Amazon geo-distributed setting with 512 bytes transactions, TOY obtains a throughput of 30K tps.