DeFi composability as MEV non-interference

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

Secure compilation of rich smart contracts on poor UTXO blockchains

Most blockchain platforms from Ethereum onwards render smart contracts as stateful reactive objects that update their state and transfer crypto-assets in response to transactions. In this way, they support the development of contracts in the imperative procedural paradigm, familiar to most programmers. A drawback of this design choice is that when a user submits a transaction, they cannot predict in which state it will be executed, exposing them to transaction-ordering attacks. The UTXO model is an alternative blockchain design that thwarts these attacks by requiring new transactions to spend past ones: since transactions have unique identifiers, reordering attacks are ineffective. Currently, the blockchains following the UTXO model either provide contracts with limited expressiveness (Bitcoin), or require complex run-time environments and unfamiliar programming abstractions (Cardano). We present a framework for smart contracts in the UTXO model, that allows expressive contracts to be securely executed by bare-bone UTXO blockchains with loop-free scripts enriched with covenants, and supports the familiar procedural programming style