Mind the Service: What Crypto Wallets Aren't Telling You

Web3 introduces a new paradigm of decentralized services, where users interact with distributed applications and digital assets without centralized intermediaries. Non-custodial wallets, as faithful practitioners of this philosophy, also serve as critical service interfaces, enabling users to store and transact digital assets independently without reliance on third parties. Although prior studies have examined non-custodial wallet design, most focus on generic app issues rather than the service-oriented software challenges unique to wallets, particularly overlooking their core feature - transaction. Since all user actions in the crypto world depend on transactions, the design and implementation of transaction features are critical to wallet usability and trustworthiness, yet remain largely underexplored. To bridge the gap, this paper proposes a five-phase, semi-automated approach that leverages dynamic analysis to thoroughly evaluate the design of transaction features from multiple perspectives. Our study of 77 popular wallets shows that the design of transaction features is often unsatisfactory, potentially undermining the quality and reliability of wallet services and, in some cases, leading to direct financial losses. We identify numerous common design flaws across these wallets and provide targeted recommendations for wallet developers to improve the quality of wallet. This work sheds light on a critical dimension of Web3 services.