DeFi composability as MEV non-interference
Massimo Bartoletti, Riccardo Marchesin, Roberto Zunino
TL;DR
This paper addresses security in DeFi compositions by reframing from Babel's global, state-wide MEV-based ε-composability to MEV non-interference, a locality-driven security criterion. It introduces local MEV and two adversary wealth models, $MEV$ and $MEV^{\infty}$, to reason about how dependencies influence extractable value and prove that MEV non-interference provides modular, wealth-agnostic security guarantees. The authors develop sufficient conditions (e.g., token independence, sender-agnosticity, and stability) and demonstrate their applicability to common DeFi constructs like AMMs, bets, and arbitrage wrappers, showing that many practical compositions are MEV non-interfering even when they are not ε-composable. They also argue that MEV non-interference offers algorithmic and practical advantages over global MEV-based criteria, enabling more robust and scalable composability verification for smart contracts in DeFi ecosystems.
Abstract
Complex DeFi services are usually constructed by composing a variety of simpler smart contracts. The permissionless nature of the blockchains where these smart contracts are executed makes DeFi services exposed to security risks, since adversaries can target any of the underlying contracts to economically damage the compound service. We introduce a new notion of secure composability of smart contracts, which ensures that adversaries cannot economically harm the compound contract by interfering with its dependencies.