Post-Quantum Cryptography: Overview
Kronos plants are designed to outlive the arrival of cryptographically relevant quantum computers, so long-lived keys and signatures move to quantum-resistant algorithms now.
The harvest-now, decrypt-later threat
A reactor commissioned near 2030 will operate for decades. Data and credentials it produces today may be captured now and decrypted later once a large quantum computer can run Shor's algorithm against RSA and elliptic-curve schemes. For confidentiality of long-lived exported records, and for signatures on firmware and audit anchors that must remain verifiable for the plant's life, Kronos adopts NIST-standardized post-quantum algorithms and treats classical public-key crypto as a legacy fallback.
Where PQC matters most
- Firmware and bitstream signatures that must stay valid for 20+ years - see PQC signatures.
- Key exchange protecting exported telemetry and byproduct-material records - see PQC key exchange.
- Audit-log anchoring signatures whose forgeability would undermine incident reconstruction.
- Long-term identity roots in the OT certificate authority.
Symmetric crypto is largely fine
Grover's algorithm only quadratically speeds up brute force, so AES-256 and SHA-384 retain adequate margin. The urgent migration is in the public-key layer: key establishment and digital signatures. Kronos therefore pairs quantum-safe key exchange and signatures with strong symmetric primitives, and adopts hybrids during transition (see crypto agility).
Standards baseline
The baseline algorithms are the NIST FIPS 203/204/205 families: ML-KEM for key encapsulation, ML-DSA for lattice signatures, and SLH-DSA (hash-based) for the most conservative long-term signatures such as firmware roots. Choosing a hash-based option for the highest-assurance roots hedges against a future break in lattice assumptions.
Design status: PQC primitives are integrated into the twin's transport and signing paths and interoperability-tested. Fielding them on FOAK hardware, including FPGA-side verification cost, is part of the Q2 2027 build; no production reactor is yet running these keys.