SigVM: Toward Fully Autonomous Smart Contracts

This paper presents SigVM, a novel blockchain virtual machine that supports an event-driven execution model, enabling developers to build fully autonomous smart contracts. SigVM introduces another way for a contract to interact with another. Contracts in SigVM can emit signal events, on which other contracts can listen. Once an event is triggered, corresponding handler functions are automatically executed as signal transactions. We built an end-to-end blockchain platform SigChain and a contract language compiler SigSolid to realize the potential of SigVM. Experimental results show that SigVM enables contracts in our benchmark applications to be reimplemented in a fully autonomous way, eliminating the dependency on unreliable mechanisms like off-chain relay servers. SigVM can significantly simplify the execution flow of our benchmark applications, and can avoid security risks such as front-run attacks.