The Engineering of Transition-Period Cryptography
Hybrid cryptography — running classical and post-quantum algorithms together so that the combination is secure if either remains unbroken — is the consensus transition strategy. But hybrid implementation is genuinely difficult engineering, with multiple approaches that have different security properties, performance characteristics, and operational implications. This course covers the engineering of hybrid cryptography in depth.
Who Should Take This Course
Cryptographic engineers, security engineers, protocol developers, and architects implementing transition-period cryptography.
What You Will Learn
This course provides hands-on technical depth in a specific dimension of PQC migration, aligned with the PQC Migration Framework. You will gain practical, applicable skills you can use immediately in migration work.
Course Outline
Module 1 — Hybrid Cryptography Foundations
Why hybrid is the consensus transition approach. The security rationale: secure if either algorithm holds. Endorsements from NIST, BSI, ANSSI, and NCSC. 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. Some courses assume security engineering experience.
Certificate of Completion
Upon completion, you will receive a Quantum Academy certificate of completion. CPE credits earned may apply toward Quantum Academy certification maintenance.