AC/DC: Adaptive Cutoffs and Disputable Cutoffs for Robust Critical Transactions in Smart-Contracts

Abstract

To guarantee delivery of their intended functionalities in the presence of unresponsive parties, current smartcontracts cut users off from being able to commit their responses after a fixed period of time has elapsed. However, current blockchains have limited transaction processing capacities, so a fixed amount of time will not always be sufficient to receive every critical transaction (C-TX). This paper presents a mechanism for adaptive cutoffs (ACs) which ensures that users retain the opportunity to commit C-TXs despite blockchain congestion, and enables early cutoffs when the number of required C-TXs is low. A non-interactive argument system for setting adaptive cutoffs under the current Ethereum Virtual Machine is described. Additionally, disputable cutoffs (DCs) are presented, which are a more efficient approach used in parallel to ACs based on a bisection-based dispute. Furthermore, it's empirically demonstrated that an AC/DC-enabled smart-contract can receive a larger number of C-TXs than its non-adaptive counterparts when user responsiveness is slowed due to denial of service or congestion.