"A typical hybrid approach may come by both. If one of the layers is weakened, the other still protects the systems," Cyril Tan said.
Cyril Tan on balancing mathematical and hardware risks
Cyril Tan, identified in the source as a quantum security architect at SpeQtral, framed hybrid cryptography as an explicit balance: post-quantum cryptography (PQC) brings unproven, long-term mathematical assumptions while quantum key distribution (QKD) introduces physical, hardware-dependent risks. That trade-off is central to the hybrid argument Tan made during ISMG's Masterclass Quantum series: using both PQC and QKD together can offset the weaknesses of each, so that a failure in one layer does not automatically yield total compromise.
Kawin Boonyapredee on layered protection and gradual adoption
Kawin Boonyapredee, described in the source as Applied Quantum's representative and an adjunct professor in cybersecurity leadership at Capitol Technology University, characterized hybrid models as layered protection that strengthens resilience. Boonyapredee said the combination of QKD and PQC supports "defense in depth" and permits gradual adoption without major disruption, allowing organizations to move toward quantum-safe communications while retaining existing systems.
How QKD and PQC were mapped to physical and software layers
The Masterclass discussion, as summarized in the source, distinguishes the two technologies by role: PQC is used for authentication and key exchange across existing software systems, while QKD is positioned as a source of high-entropy keys delivered through physical channels. That division assigns cryptographic responsibilities by layer—software-level procedures and protocol compatibilities handled with PQC, and entropy and key generation augmented or replaced by QKD's physical channel outputs.
Hybrid models, crypto agility, and the relationship among key generation, authentication, and encryption
Speakers in the episode addressed how hybrid designs support crypto agility and mitigate risk. The source reports that hybrid approaches pair PQC-based authentication and key exchange with QKD-supplied high-entropy material, letting organizations integrate new protections while preserving operability. The episode also covered how key generation, authentication and encryption function together in hybrid systems—suggesting a multi-layered workflow in which physically generated keys and mathematically based cryptographic algorithms are combined to create resilient communications.
What this means for technologists, organizations, and vendors
- Technologists and security teams: Expect to design hybrid solutions that consciously allocate duties between PQC (authentication and key exchange across software) and QKD (high-entropy key delivery through physical channels), and to validate that the two layers remain protective if one is weakened.
- Organizations and procurement leaders: The speakers recommended gradual adoption to avoid major disruption; procurement decisions will need to weigh both mathematical assumptions behind PQC and hardware risks tied to QKD when specifying solutions.
- Vendors and researchers: The conversation noted complementary roles for QKD and PQC, implying a market and research space for integrated hybrid products and for scrutiny of hardware and mathematical assumptions alike—areas where Applied Quantum, SpeQtral, and contributors to the Masterclass series are already active.
Both experts emphasized that hybrid cryptography is moving beyond theory toward deployment as organizations prepare for quantum-safe communications. Tan's concise formulation—that one layer can backstop the other—and Boonyapredee's emphasis on defense in depth and phased implementation together frame hybrid designs as a pragmatic bridge: combining QKD's physical-channel entropy with PQC's software-layer compatibility to strengthen resilience without abrupt system changes.
