smart contract security/improvement such as formal verification/analysis,A Smart Contract-based PKI and Identity System,vulnerability detection, machine learning based smart contract security, etc. Just pick one or two topics in the area and let me choose one. These are some papers to look into the area: https://scholar.google.com/scholar?start=10&q=smart+contract+improvement. Please get specific with the topics and the impact . It should have a theoretical and coding component.