Demystifying Post-Quantum Cryptography: The Hybrid Approach

The pace at which quantum computing is evolving right now, threats of harvest-now-decrypt-later becoming more relevant. The widely deployed classical cryptographic algorithms such as RSA and ECC face a real risk of being broken by quantum attacks, most notably through Shor’s algorithm. This looming threat makes the transition to Post-Quantum Cryptography (PQC) urgent, not as a future project, but as a present-day migration challenge.
You may have questions whether the transition to PQC is even necessary at the moment. It is true that quantum computers are years away, but it hardly matters because so many governments, telecom, defense entities worldwide are now requiring a transition.
In this talk, we would focus on the practical hybrid transition from classical to quantum-resistant cryptography. We would explore NIST’s PQC standardization efforts through newly selected algorithms particularly ML-KEM (key-exchange), ML-DSA and SLH-DSA (digital signatures) in modern cryptographic infrastructures.
The transition from classical crypto to a hybrid model enable organizations to begin adopting PQC today without breaking interoperability or relying on fully quantum-resistant stacks before they’re ready.
To make this transition concrete, we will demonstrate a TLS connection with hybrid key-exchange and post-quantum signature, showing how post-quantum and classical algorithms can operate together.
https://openssl-foundation.org/post/2025-04-29-ml-kem/index.html

fosdem-2026