Fair Ordering in Blockchains

Abstract

Blockchains are an emerging paradigm for permissionless distributed computing, that can removedigital intermediaries while at the same time providing trusted computing and storage guarantees. While applications of blockchains beyond cryptocurrencies into generalized digital platforms, are still in their infancy, blockchain technology is expected to create several trillion dollars of value in the next few years, potentially aiding the democratization of trust, data and control in digital platforms. Given the increasing volume of value being exchanged on blockchains, transaction-order-manipulation attacks have become extremely common in public blockchains such as Ethereum, costing hundreds of millions of dollars each year. In these blockchains, a miner can unilaterally determine the order of transactions inside a block, and this ordering is not checked by other users, leaving room for the miner to manipulate the order for its own benefit. Hence, coming up with correct primitives and protocols to achieve those primitives is of paramount importance. Furthermore, even if the miner is honest and includes the transactions in a fair manner, it can be subjected to frontrunning by other users as propagation of transaction takes sometime during which the first transaction can be observed and can be frontrunned. This necessitates fast peer-to-peer propagation. In this thesis, we address the various challenges that are being faced from the point of transactionorder manipulation. This required extensive research across the blockchain stack starting from modifying how messages are communicated across peer-to-peer network to building adapters on byzantine fault tolerant consensus protocols.