The Engineering of Transition-Period Cryptography
Hybrid cryptography uses classical and post-quantum algorithms together, so the combination is secure as long as either one is unbroken. It is the consensus strategy for the transition. Hybrid implementation is difficult engineering. There are several approaches, each with different security properties, performance characteristics, and operational implications. This course covers the engineering of hybrid cryptography in depth.
Course Outline
Module 1 Hybrid Cryptography Foundations
Why hybrid is the consensus transition approach. The security rationale: a sound combiner keeps the construction secure as long as either component is unbroken. What the combiner has to guarantee for that to be true. The positions of NIST, BSI, ANSSI, and NCSC, what each one’s guidance covers, and why NIST leaves the deployment decision to case-by-case analysis. The different hybrid approaches and how they differ. When hybrid is necessary versus when post-quantum-only is acceptable.
Module 2 Hybrid Key Exchange
Hybrid key exchange in detail. Concatenation approaches (as deployed in TLS 1.3). KDF-based combiners with formal security proofs. Performance and bandwidth implications. Negotiation and fallback handling. Hands-on configuration of hybrid TLS.
Module 3 Hybrid Signatures
Hybrid signature schemes. Nested and composite signature approaches. Dual-certificate strategies. The size and performance implications of hybrid signatures. Use cases where hybrid signatures matter: code signing, document signing, and long-lived trust.
Module 4 Protocol Integration and Exit Planning
Integrating hybrid cryptography into TLS, SSH, IPsec, and application protocols. Performance measurement methodology. Operational considerations for hybrid deployments. Exit planning: how and when to remove the classical algorithm once confidence in post-quantum algorithms is established.
Prerequisites
A working understanding of PQC fundamentals is recommended. Consider Post-Quantum Foundation or PQCS certification for background.
Certificate of Completion
Upon completion, you receive a Quantum Academy certificate of completion. It is separate from our professional certifications and states your CPE credits, one for each 60 minutes of teaching. CISSP, SSCP, CISM and CompTIA SecurityX holders can claim them with their certifying body. The credits also count toward renewing a Quantum Academy certification. Our CPE credits page explains how to claim them.
Who this course is for
Cryptography engineers, protocol implementers, and security architects making hybrid deployment decisions in TLS, SSH, VPN, and code signing. Working familiarity with the protocols is assumed.
For the design principles behind these implementations, take Cryptographic Agility.
What you’ll be able to do afterward
- Implement hybrid key exchange in TLS 1.3 using the concatenation and combiner approaches
- Choose between hybrid signature options and justify the choice based on the maturity of each
- Size the performance and message-length cost of hybrid deployment on your own protocols
- Sequence a hybrid rollout so classical fallback never silently becomes the permanent state
- Plan the exit: the criteria and steps for retiring the classical half later
What you leave with
When you finish, we email you the course handbook, a PDF of every slide with notes that explain it in full. We also include a PDF copy of Quantum Ready. The handbook is yours to keep.
Enrollment includes 180 days of access to the online on-demand course. Where that course is not yet published, the 180 days start on the day it is.
Where this course fits
Post-Quantum Foundation or PQCS Specialist Training provides the background for this course. You can take this course without either. PKI Modernization for Post-Quantum covers certificate infrastructure. Cryptographic Agility covers the underlying design principles.
Why we teach this
The course is built on the Applied Quantum PQC Migration Framework. Its author, Marin Ivezic, is one of the practitioners who teach here. The framework is published openly under Creative Commons at pqcframework.org. The people who teach this course run migration programs inside organizations today. The course covers the problems they meet in that work.
About this program
Quantum Academy credentials are private professional credentials issued by Quantum Academy, a trade name of Post-Quantum Institute. They are not government-issued licenses, accredited degrees, or academic credit, and earning one does not guarantee employment, promotion, regulatory approval, or any other specific outcome.
Quantum Academy programs are educational and informational only, and are not legal, compliance, or engineering advice.
