Xin Xu developed security hardening features for certificate installation in the EVerest/libocpp repository, focusing on improving maintainability and reducing risk in embedded systems. Using C++ and configuration management techniques, Xin enforced minimum security profiles and introduced policy-driven checks to ensure only eligible certificates could be installed. The work included refactoring security controller logic and configuration naming, which clarified governance and reduced the chance of misconfiguration. By rejecting unsupported certificate types and enhancing code readability, Xin enabled safer certificate management without altering external APIs. The depth of the changes provided a maintainable foundation for future enhancements in OCPP-based security workflows.