To keep devices updatable, implement a flexible bootloader and a replaceable trust anchor that let devices validate signed updates with multiple algorithms; use dual-signed stages and a boot process that can verify both classic and post-quantum signatures, with a fallback if an update fails.

Regulators are setting milestones: deprecate RSA and ECDSA after 2030, disallow classic algorithms after 2035, with the EU aiming to begin transitions by 2026 and finish high‑risk use‑case shifts by 2030, plus the EU CRA adds a post‑sale vulnerability support window starting in December 2027.

Field deployments may rely on gateways using hybrid TLS 1.3 to limit traffic visibility, but long‑term readiness requires planning eight months from algorithm choice to working hardware, so cryptographic requirements must be addressed before design freezes.

Post‑quantum signatures and key exchange (ML‑DSA and ML‑KEM) will require more flash memory and longer boot times; even small parameter sets demand substantial memory and hardware acceleration, impacting flash budgets and radio payloads in threads like Thread/Matter.

Key management should shift signing to hardware security modules (HSMs) at higher security levels and avoid insecure build‑system key storage; organizations must ensure signing systems and HSMs are in place before deploying new signatures.

Decide on post‑quantum readiness for long‑lived IoT devices before design freeze, since flash, bootloader design, and trust anchors fix future security capabilities.

Manufacturers should ask suppliers five critical questions about post‑quantum support: available algorithms and upgrade paths, whether the first boot stage can verify hybrid signatures and replace root keys, hardware acceleration and memory needs, side‑channel protections and certifications, and the ability to guarantee security updates through the CRA period.

Today’s devices rely on RSA and ECDSA, which become vulnerable once a powerful quantum computer exists, risking forged firmware updates and compromised field devices if trust anchors can’t be updated.