During November, Donald Dole developed a configurable Data Encryption Key cache lifetime feature for the mongodb/libmongocrypt repository, focusing on enhancing both performance and security for client-side encryption. He refactored the cache initialization logic to use a default expiration constant, improving maintainability and consistency. Donald also introduced an option to set custom cache expiration in milliseconds, allowing runtime tuning for diverse workloads. Working primarily in C and leveraging skills in caching, configuration, and cryptography, he delivered end-to-end support for cache TTL configuration. The work addressed DEK fetch latency, enabling improved encryption throughput while maintaining robust security guarantees for the library.