PQC concepts
What is Hybrid PQC?
Also known as X25519MLKEM768.
Composition of a classical KEM (X25519) and a PQC KEM (ML-KEM-768) where session security holds if either is unbroken. Standard for PQC TLS today - used by QNSI edge-gateway, AWS KMS, Google Cloud KMS, Cloudflare, and the major browsers.
Decision context
Why Hybrid PQC matters
Hybrid composition can preserve compatibility while combining classical and post-quantum key establishment, but it is not the same as a pure PQC trust path. Composition, authentication, transcript binding and failure policy determine whether the intended either-component security property actually holds.
How to evaluate Hybrid PQC
Identify each classical and PQC component and how their secrets are combined. Test failure of either component, downgrade negotiation, transcript binding and peer authentication. Label hybrid external legs separately and prove that an internal PQC-native path does not silently fall back when the PQC operation fails.
PQC concepts
PQC concepts evidence boundary
Post-quantum programmes combine cryptography, architecture, data lifetime, operational ownership, and migration governance. A concept is useful only when it changes a concrete inventory, policy, design, test, or evidence decision. Treat terminology as a decision aid rather than proof that a control exists.
FAQ
Common questions
What is Hybrid PQC?
Composition of a classical KEM (X25519) and a PQC KEM (ML-KEM-768) where session security holds if either is unbroken. Standard for PQC TLS today - used by QNSI edge-gateway, AWS KMS, Google Cloud KMS, Cloudflare, and the major browsers.
Why does Hybrid PQC matter?
Hybrid composition can preserve compatibility while combining classical and post-quantum key establishment, but it is not the same as a pure PQC trust path. Composition, authentication, transcript binding and failure policy determine whether the intended either-component security property actually holds.
How should Hybrid PQC be evaluated?
Identify each classical and PQC component and how their secrets are combined. Test failure of either component, downgrade negotiation, transcript binding and peer authentication. Label hybrid external legs separately and prove that an internal PQC-native path does not silently fall back when the PQC operation fails.
What is Hybrid PQC also known as?
Hybrid PQC is also known as X25519MLKEM768. Composition of a classical KEM (X25519) and a PQC KEM (ML-KEM-768) where session security holds if either is unbroken. Standard for PQC TLS today - used by QNSI edge-gateway, AWS KMS, Google Cloud KMS, Cloudflare, and the major browsers.
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