We present a simple approach to mitigate transaction-ordering dependent Maximum-Extractable-Value (MEV) opportunities in Ethereum. The approach is built on top of Proposer-Builder-Separation, restricts the freedom to order transactions within a block arbitrarily, and relies primarily on a non-malleable signature scheme and separation of responsibilities. In addition, we generalize the proposed approach to show that the property of unpredictable transaction arrangement can be transferred also to other blockchain systems. We discuss the gain in MEV mitigation, important limitations, and open issues.

Ethereum is a platform for deploying smart contracts, which due to their public nature and the financial value of the assets they manage are attractive targets for attacks. With asset management as a main task of smart contracts, access control aspects are naturally part of the application itself, but also of the functions implemented in a smart contract. Therefore, it is desirable to establish the correctness of smart contracts and their access control on application and single-function level through formal methods. However, there is no established methodology of formalising and verifying correctness properties of smart contracts. In this work, we make an attempt in this direction on the basis of a case study. We choose an existing smart contract application which aims to ascertain the integrity of binary files distributed over the Internet by means of decentralised identity management and access control. We formally specify and verify correctness at the level of single functions as well as temporal properties of the overall application. We demonstrate how to use verified low-level correctness properties for showing correctness at the higher level. In addition, we report on our experience with existing verification tools.

The integrity of executable binaries is essential to the security of any device that runs them. At best, a manipulated binary can leave the system in question open to attack, and at worst, it can compromise the entire system by itself. In recent years, supply-chain attacks have demonstrated that binaries can even be compromised unbeknownst to their creators. This, in turn, leads to the dissemination of supposedly valid binaries that need to be revoked later.