Securing OT Systems for the Quantum Era

The Integrity Crisis: Trust Now, Forge Later. 🤓 In my last post, I discussed HNDL (Harvest Now, Decrypt Later)... the threat where attackers hoard encrypted data today to read it tomorrow. That is a crisis of confidentiality. (see link in comments) But there is a second, arguably more dangerous vector emerging in post-quantum security discussions. It targets integrity and authenticity. It is called TNFL: Trust Now, Forge Later. What is the basic mechanism? Current public-key signature algorithms (like RSA and ECDSA) rely on math that a Cryptographically Relevant Quantum Computer (CRQC) will break using Shor’s algorithm. The threat model is simple: ➡️ Trust Now: An attacker records a digitally signed artifact today, a firmware update, a digital identity, or a long-term contract. These are valid and trusted right now. ➡️ Forge Later: Once a quantum computer becomes available (est. 2030s), the attacker uses the public key information from those recorded artifacts to derive the private key. 🤯 The Breached Future: They can now retroactively sign new, malicious artifacts that your systems will accept as authentic. So why this is different (and dangerous)? 🤷♂️ Well... while HNDL reads your diary, TNFL hijacks your car ‼️ HNDL (Confidentiality): Exposes past secrets. The damage is informational. TNFL (Integrity): Allows active compromise. A forged signature on a firmware update in an OT (Operational Technology) environment doesn't just leak data; it could cause physical damage to critical infrastructure. We often mistakenly think signatures are ephemeral, overlooking the significant "long-tail" of trust they actually create. Examples 👩🏫 software/Firmware: Embedded devices often have lifecycles of 15–20 years. A satellite or medical device deployed today with a hard-coded root of trust could be hijacked in 2035 via a forged update. Legal & Finance: Blockchain ledgers and digital contracts signed today must remain immutable for decades. TNFL threatens to rewrite that history. The Fix: Crypto-Agility and Post Quantum Cryptography 🤩 We cannot simply wait for the quantum era to arrive. The mitigation strategy is crypto-agility: building systems today that allow us to swap out cryptographic primitives without rewriting the entire infrastructure. There are good choices of Post Quantum Cryptography already available for implementation. All around the world governments recommend implementing them. It's time to "keep secrets" and "maintain trust". Join Quantum Security Defence for continuous education, business networking and advisory, link in the comments. 💚 🔜 In my next post I will discuss evidence logs as the proof of what happened in the past. #PQC #QuantumSecurity #DigitalTrust #Cybersecurity #TNFL #Integrity #CISO #TechTrends2026 #QSECDEF #QuantumComputing

We’re all bracing for “Harvest Now, Decrypt Later.” The risk that keeps me up at night is its more dangerous twin: “Trust Now, Forge Later.” This isn’t about reading your secrets tomorrow. It’s about forging the signatures and certificates your systems trust today - software updates, firmware, documents, device identities - once quantum computers can break RSA/ECC. When the control plane (signing and verification) fails, attackers can push "validly signed" malware and instructions that our systems accept without a blink. Why this matters - especially in OT and cyber‑physical environments: - Integrity -> safety. In factories, energy, healthcare, and transport, forged signatures can become physical harm. - Long‑lived devices. Roots of trust burned into ROM, narrow maintenance windows, and legacy protocols mean PQC migration in OT is harder (much harder) and slower than in IT. - Evidence and provenance. If signatures become forgeable, non‑repudiation and long‑term legal trust need PQ‑secure timestamping and re‑signing strategies. I lay it out here - including why “Sign Today, Forge Tomorrow / Trust Now, Forge Later” is often a bigger risk than HNDL for OT and critical infrastructure, and why the migration is uniquely complex. #QuantumThreat #QuantumComputing #TrustNowForgeLater #TNFL #QuantumSecurity #PQC #PostQuantum #QuantumReadiness

Quantum in OT: You Can’t Patch Physics. Quantum security in OT isn’t about stronger encryption—it’s about enforcing control where encryption doesn’t exist. PLCs and field devices won’t be upgraded, so the answer isn’t chasing crypto—it’s engineering systems that remain safe even when trust is broken. Wrap the controllers, constrain the commands, and backstop everything with physical and pneumatic controls—because when encryption fails, control must still hold. If you want the full breakdown, I laid it out in the article. #QuantumSecurity #ICS #OTSecurity #CriticalInfrastructure #CyberPhysical #IndustrialCybersecurity #IEC62443 #SCADA #PLCSecurity #ZeroTrustOT #CyberResilience #InfrastructureProtection #NationStateThreats #OperationalTechnology #RiskManagement #EngineeringControls #CyberRisk #OTLeadership #SmartGrid #IndustrialAutomation

Quantum safety in OT protocols There is a lot of interest in “Q-Day” – the day that quantum computers are able to break our current network encryption algorithms and divulge our secrets. So-called “quantum-safe” encryption algorithms have already been developed (they are already in our popular browsers at this very moment). But how about protocols other than HTTPS? I find a lot of documentation about all sorts of cryptographic algorithms, key exchanges, hashes, PKI, authentication, Diffie-Hellman, elliptical curves, etc. But I am not a mathematician (and easily lost in this matter). Instead, I’m a user. I use OT-protocols like Modbus/TCP, DNP3, IEC104 (and many others) and an IT-protocols as well like SMB, Radius and SNMP (and many others too). Are *they* quantum safe? If not, will they be soon? It is difficult to find more details about it without getting drowned in a lot of jargon. That can be made easier! See my article at https://lnkd.in/eHgW-CDK for an alphabetical list of protocols, with comments about their quantum safety at this moment. Good to see there's lots of developments; most of them are based on TLS1.3. NB: I realize the list is far from complete, comments are more than welcome!

I’ve written about the risks GenAI brings - how something theoretical quickly became operational.   Quantum risk is following the same path. But this time, the threat starts before the technology reaches maturity.   Adversaries are already executing “harvest now, decrypt later” strategies by stealing encrypted data today with the intention to break it once quantum computing evolves. That changes the timeline and urgency of cryptographic resilience.   Why it matters: 🔐 OT, IoT, and legacy systems weren’t built with quantum in mind. ⏳ PQC migration takes years, and most organizations haven’t even begun. 🌍 Critical infrastructure is especially exposed.   This isn’t about fear. It’s about getting ahead before the window closes.   To mitigate long-tail risks like data harvesting, security teams should: ✅ Implement forward secrecy to limit future decryption of past traffic ✅ Minimize long-term storage of sensitive data ✅ Strengthen network visibility and segmentation to reduce interception risk   Forescout Technologies Inc. is making this possible right now with: ✅ Complete visibility into all connected devices across IOT, IT, IoT, and IoMT ✅ Automated policy enforcement to respond to cryptographic risk in real time ✅ Crypto agility support to evolve alongside emerging standards - not after they break   👇 Are you thinking about post-quantum risk? Drop your thoughts below.   #QuantumSecurity #PQC #CyberResilience #InfrastructureSecurity