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Lt. Xisen Tian, USN

PhD Candidate, Computer Science '25
MS in Electrical Engineering ‘20

Lt. Xisen Tian is a cyber security expert with a background in information operations, space systems engineering, and program management. He graduated from the U.S. Naval Academy in 2015 with honors in dual majors in Computer Science and Information Technology. During his first tour at Fort Meade, he qualified as a Cryptologic Warfare Officer after being attached to USS CARL VINSON and lead defensive cyber operations at JFHQ-DODIN. In 2020, he graduated NPS with an MS in Electrical Engineering and received the John Wozencraft Academic Honor Award for his work on identifyingcommercial radar vulnerabilities and exploitations using generative AI. After a lateral transfer upon graduation, Tianqualified as an Engineering Duty Officer at the National Reconnaissance Office. He was awarded Information Systems Professional of the Year by Director of National Intelligence for actions as a program officer responsible for the cyber security of space systems. Tian currently studies applied cryptography as a doctoral student in the Computer Science Department at NPS. He will likely work in a technical advisor role for Naval Information Warfare Systems Command(NAVWAR) upon graduation.

As an active NPS Foundation & Alumni Association member, Tian is the president of the NPS Outdoors Club and former president of the NPS Running Club. On a warm sunny day, when he isn’t studying or leading camping trips, Tian can be found on the trails of the Monterey Peninsula biking or running with his dog, Marlie. In colder seasons, he is likely snowboarding down the slopes of Lake Tahoe ski resorts. He and his wife, Sarah, live in Pacific Grove, California.

What has been most impactful about your time so far at NPS both as a master’s student and now as a PhD candidate? How has the academic environment at NPS contributed to your research and overall learning experience?  

As a master’s student, I first became exposed to the unique research opportunities afforded to NPS students through the NPS EEMS Lab where I researched vulnerabilities of ship radars through reverse engineering and machine learning techniques. This whetted my appetite to pursue security research from a more theoretical perspective. As a PhD student studying under Dr. Britta Hale in Applied Cryptographic Engineering (ACE), I’ve traveled to conferences and workshops across the world to research and study cryptography with leading experts in the field. As a result, I’ve collaborated with government, academic, and industry professionals from around the world to conduct research aligned with both DOD priorities and cutting-edge efforts in cryptographic protocol development.

What inspired you to focus your research on security in communication systems for resource constrained operational environments, particularly in the context of near-peer conflicts?

If you ask a junior officer to tell you about the problems facing their job field, they most certainly have a running list in their heads that they can raddle off ad nauseum to you. Two problems from my own list became the basis of my PhD topic. The first came from observations I made during my qualification tour onboard the USS CARL VINSON in 2017 where I witnessed just how challenging normal underway communications could be – even without adversarial disruptions – let alone operating under Emissions control (EMCON). In a near-peer conflict, we should expect successful jamming and/or maximizing EMCON. I struggled to imagine how we could communicate effectively and securely in such a resource starved environment. Next, while working as a space systems program officer during the Russian incursion into Ukraine, the Viasat hack on Ukrainian networks made me especially sensitive to the resiliency of our own satellite networks. In near-peer conflict, we should expect barrages of successful cyber-attacks on our networks: how can we recover/heal our security (possibly continuously)? These questions do not have a silver-bullet answer but as a PhD student at NPS, I’m uniquely resourced to research them with access to space systems experts from across the government, the support of warfare centers, and the intelligence community.  

What are some of the biggest challenges you face in developing cryptographically agile communications systems that can operate effectively in cyber-threatened and resource-constrained environments?

The biggest challenge is narrowing down the focus of the research. You can’t study everything AND expect to be an expert on it all.I narrow my focus on how to apply the latest innovations in delay tolerant networks, key exchange protocols, and quantum-resistant cryptographic algorithms to provide solutions to our problem. It’s a daunting task to familiarize oneself with ‘just enough’ context from each of these fields without getting lost in the weeds.

In what ways do you anticipate your research will impact the Department of the Navy and the greater DOD at both the tactical and strategic levels?

Fundamentally, our research proposes two big concepts: 1) a paradigm shift toward coherent/cohesive security from point-to-point connections and 2) capability for continuous and automatic cryptographic key evolution. On a tactical level, this presents users with new efficient strategies for key management – a sharp departure from manual key refills. On a strategic level, our research provides operational flexibility for leaders in terms of having self-healing cryptographic systems. We also shed light on the looming threat of quantum adversaries and the need to invest immediately into quantum resistant cryptographic systems.

As a participant in the upcoming NPS Innovation in Action Student Showcase, you will have the opportunity to share your research with other students, as well as NPS faculty and partners. What types of connections or collaborations are you hoping to establish during the showcase? Why is it important for students to connect across campus with other students and faculty?

I hope to engender interest and spark collaboration on subproblems in my research area. We need students with strong coding backgrounds to implement and test theories we’ve made in protocol design. In my experience, I think it’s valuable to introduce cross-disciplinary thesis topics to students, so they don’t feel pigeon-holed into a particular research field.  

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