Computing systems contain vast amounts of sensitive information, but most systems have numerous layers of abstractions, making it challenging to guarantee high-level security properties. Nathan Dautenhahn's research identifies fundamental abstraction gaps and closes them with cross-layer solutions. He is most interested in building trustworthy systems software, where a single exploit could compromise the whole system. His research in operating system security has applied two key approaches: decompose systems in ways that enhance trustworthiness and harden them to attack.