Contract Wallet Using Emails

We proposed a new construction for contract wallets, smart contract applications that allow users to control their crypto assets. Users can manipulate their crypto assets by simply sending emails with no need to manage keys. These emails are verified using zero-knowledge proof (ZKP) along with their attached digital signatures that the sender domain server (SDS) generates according to DomainKeys Identified Mail. Unless the SDS forges the emails, the crypto assets remain secure in the proposed system. Moreover, the existing SDSs can be used as is by outsourcing additional work to a third party that is not necessarily trusted. The system supports various functions to manipulate crypto assets. We produced a tool for variable-regex mapping (VRM) that enables developers to build a new function without ZKP skills. For example, using the tool, we built a demo application where users can exchange crypto assets via Uniswap only with emails. The published version of this paper is available at https://doi.org/10.1109/ICBC56567.2023.10174932.