FORTRESS Explained #3

FORTRESS Explained #3:

What are Post-Quantum / Traditional hybrid schemes?

Post-Quantum / Traditional (PQ/T) hybrid schemes combine established classical cryptographic algorithms with post-quantum cryptographic mechanisms to support the transition toward quantum-resistant security. Traditional public-key cryptography, such as RSA and elliptic-curve cryptography, is widely deployed and well understood. However, these schemes may become vulnerable once cryptographically relevant quantum computers are capable of running attacks such as Shor’s algorithm.

Post-quantum cryptography is designed to resist attacks from both classical and quantum-capable adversaries. However, many post-quantum algorithms have different performance, memory, bandwidth, and implementation characteristics, which means their deployment must be carefully evaluated. Hybrid schemes address this transition challenge by combining both approaches. Instead of relying on a single cryptographic assumption, a hybrid design can combine a classical algorithm with a post-quantum algorithm, reducing dependency on one algorithm family and supporting a more resilient security architecture.

Why does this matter?

The migration to post-quantum cryptography will not happen instantly. Many embedded systems, industrial devices, edge platforms, and critical infrastructures have long operational lifetimes. Some systems deployed today may still need to remain secure in a future where quantum computers pose a realistic threat to classical public-key cryptography. Hybrid schemes provide a practical bridge between today’s established cryptographic foundations and tomorrow’s quantum-resistant requirements.

In FORTRESS, PQ/T hybrid schemes are explored as part of a scalable and efficient hybrid secure boot architecture, with a flexible Root of Trust that integrates both traditional and post-quantum algorithms while considering security, performance, and cost trade-offs. By integrating PQ/T hybrid cryptography, FORTRESS aims to support secure systems that remain trustworthy against current attack scenarios while preparing for future quantum-enabled threats.