Navy Cyber Expert: Post-Quantum Cryptography is Backbone of Zero Trust The two technologies are converging as War Department officials increasingly prioritize building systems for a quantum era. Zero trust architectures remain effective if the cryptography underlying identity, authentication and communications can withstand future quantum computers, according to cybersecurity expert Steve Defibaugh. Defibaugh, who previously served as command information security officer at Naval Installations Command and as deputy CISO within the Naval Sea Systems Command’s Cyber Engineering and Digital Transformation Directorate, framed the relationship between the two strategies during a July 16 webinar. “Zero trust answers who or what should be trusted right now,” Defibaugh said. “[Post-quantum cryptography] answers the question: Can the cryptographic mechanisms used to establish that trust survive a quantum-capable adversary?” Defibaugh explained that quantum computers could eventually solve certain mathematical problems far faster than classical computers, creating a future risk for today’s public-key encryption standards. While quantum systems are limited by significant technical challenges like temperature sensitivity, he said agencies should begin preparing now for their long-term cybersecurity implications. “Quantum computing can’t replace classic computing at this point in time,” Defibaugh said. “These things are better together rather than separate.” Defibaugh warned that traditional perimeter-based security and static encryption could become obsolete as quantum capability matures. That threat carries particular weight for the Defense Department given how long some fielded combat systems remain in service. “There are fielded combat systems that exist not in the matter of years, but in the matter of decades,” he said, arguing that PQC resistance protects long-lived acquisition, logistics and weapons systems data against future exposure. Zero trust, a reigning priority for DOW, depends heavily on cryptography to perform identity authentication, secure public key infrastructure and digital certificates, issue access tokens and encrypt data and communications through transport layer security. If quantum