CMU Ph.D. Student Andy Hammer Earns Prestigious 2025 NSF Graduate Research Fellowship

PITTSBURGH—Andy Hammer, a second-year Ph.D. student in Software Engineering at Carnegie Mellon University's Software and Societal Systems Department (S3D), has received a 2025 National Science Foundation Graduate Research Fellowship. The award is among the nation's most competitive honors for early-career scientists and engineers, providing three years of support that includes a $37,000 annual stipend and a $16,000 cost-of-education allowance. NSF expects to make about 2,300 new fellowships this cycle, typically chosen from a pool that tops 13,000 applicants—an acceptance rate of roughly 17 percent.

Tackling hard problems in secure, resilient software

Hammer's work centers on formal methods—mathematically rigorous techniques for modeling and verifying software—to make critical systems safer and more trustworthy. Their fellowship proposal introduces new ways to validate multi-party computation (MPC) protocols, which let organizations compute over sensitive data without exposing the underlying information. Although MPC unlocks applications from privacy-preserving machine learning to secure joint analytics, the protocols are notoriously tricky to implement correctly.

"Even a subtle coding mistake can undermine the entire security guarantee," Hammer said. Their approach combines model checking with automated reasoning to locate hidden flaws before code is deployed, giving developers a practical safety net as MPC moves from theory to real products.

Hammer has also begun applying similar rigor to the resilience of cyber-physical systems (CPS)—the complex webs of software and hardware that power everything from hospitals to highway-side charging stations. "Consider the healthcare IT domain," explained advisor Eunsuk Kang. "Ideally, a resilient system would ensure that a ransomware attack on a single nurse station does not shut down the entire hospital network; the hospital should continue to provide critical services such as urgent care and patient monitoring."

Hammer recently used their technique in an internal case study of an electric-vehicle charging network, mapping how a single compromised subsystem could ripple outward and interrupt service at multiple stations. "Andy's analysis shows designers exactly where a system is brittle and how to shore it up," Kang said. "Although they have been working on this new direction for just a few months, Andy has already produced some promising results."

From aerospace engineering to software assurance

Hammer arrived at Carnegie Mellon with a bachelor's degree in aerospace engineering from Iowa State University (2023)—an uncommon path for a software-engineering researcher but one that provides a defining perspective. "Both software and aerospace systems share many similarities in terms of their complexity, engineering challenges, and important roles that they play in our society," Kang noted. "Andy's aerospace background trains them to think in failure modes and safety margins, which translates beautifully to secure and resilient software."

That cross-disciplinary outlook first drew Hammer to formal methods as an undergraduate, when they worked with faculty mentor Dr. Kristin Rozier to verify autonomous-flight algorithms. "I realized the same math that keeps a drone stable can also keep your data private or your hospital online," Hammer said. At CMU, they extend that mindset by co-authoring papers on system resilience, mentoring master's students in model-checking techniques, and serving on S3D's Graduate Student Association executive committee.

"Andy has also been actively contributing to the CMU/S3D community, serving on the GSA Executive Committee and helping to mentor multiple Masters and REU students," Kang said, highlighting Hammer's commitment to building community alongside conducting research.

Fellowship bolsters department momentum

Hammer is the first S3D student featured in a news story for winning a GRFP since 2020, when Ph.D. candidate Kyle Liang earned the fellowship for research on safer programming languages. The award reinforces S3D's growing reputation in trustworthy computing—a theme that spans software architecture, cybersecurity, and socio-technical policy.

"NSF's vote of confidence in Andy reflects the department's broader commitment to work that tangibly benefits society," said Nicolas Christin, S3D department head. "We're proud to see our students leading in areas where software reliability and human well-being intersect."

What the fellowship enables

Because the GRFP is awarded to the student rather than a specific grant, Hammer gains unusual flexibility. They plan to deepen collaborations with CMU's CyLab Security and Privacy Institute and to pilot their verification tools with external partners in critical infrastructure. "The fellowship means I can pursue ambitious ideas that don't yet have a funding stream attached," Hammer said. "It lets me focus on the science first."

Long-term, Hammer hopes their research will lower the barrier to adopting privacy-preserving computation and build a stronger engineering culture around resilience. "We shouldn't accept that a single ransomware hit can shut down a hospital or strand EV drivers," they said. "Formal methods give us a playbook to design systems that keep serving people even under stress."