️ Post‑Quantum Cryptography Risk Assessment (PQC‑RA): What, Why & How
22-Sep-2025
Quantum computing is no longer a distant theoretical pursuit; it is rapidly emerging as a genuine disruption to modern cryptography. Algorithms such as RSA and Elliptic Curve Cryptography (ECC)—the foundations of internet security, digital banking, and blockchain networks—will eventually yield to the power of large‑scale quantum machines running Shor’s Algorithm.
This inevitability raises an urgent need for Post‑Quantum Cryptography (PQC) — algorithms engineered to resist quantum attacks. The key question, however, is not only which algorithms to replace, but when and how to replace them
This is where Post‑Quantum Cryptography Risk Assessment (PQC‑RA) becomes central.
🔹 What is PQC‑RA?
PQC‑RA (Post‑Quantum Cryptography Risk Assessment) is a structured process through which organizations:
Identify cryptographic assets in use (from servers to apps to IoT).
Assess their vulnerability against quantum threats.
Score the risks in terms of business impact and urgency.
Compare against emerging standards like NIST PQC and NCSC UK guidance.
Transition towards quantum‑resistant cryptography via a migration roadmap.
Essentially: it is a cryptographic health check for a post‑quantum world.
🔹 Steps in PQC‑RA (Simplified)
Identify Assets — Build a cryptographic inventory (CBOM — Cryptographic Bill of Materials).
Assess Vulnerability — Spot algorithms like RSA, ECC, DH that are quantum breakable.
Initial Risk Score — Rank systems (e.g. 1–10) by criticality and exposure.
Compare vs Standards — Check readiness against NIST PQC winners (Kyber, ML‑DSA, FALCON).
Plan Mitigation — Prioritize high‑value & long‑term secrecy data first.
Recalculate Risk — Show how mitigation reduces threat level (e.g., 9 → 4).
Roadmap Transition — Adopt hybrid crypto now; move fully to PQC by NIST/NCSC deadlines.
PQC Transition: NIST Deprecation Schedule
🔹NCSC (UK) Quantum Timeline
Bottom line: if your data must remain secure beyond 2030, you must act today.
All traditional cryptographic algorithms that lack quantum resistance must be fully replaced with NIST-approved PQC algorithms. Transition now to cutting-edge solutions such as ML-KEM, ML-DSA, and SLH-DSA
Q‑Day and Blockchains: Top 5 at Risk
Blockchains rely almost entirely on elliptic curve cryptography (ECC) for wallet addresses, transaction signatures, and consensus. Once a sufficiently powerful quantum computer exists, Shor’s algorithm could recover private keys from public keys — meaning attackers could steal funds, alter transactions, or even fork chains.
Even worse: adversaries may already be harvesting blockchain transaction data today to decrypt once Q‑Day arrives (the “Harvest Now, Decrypt Later” problem).
🪙 Top 5 Blockchains That Face Quantum Threats
🚨 What This Means for Web3
Without a timely PQC transition, Q‑Day could trigger the largest financial theft event in history:
Bitcoin’s dormant 3+ million coins (~\$150B+) are essentially un-migratable.
Ethereum contracts securing DeFi, NFTs, and DAOs could be trivially altered or drained.
Proof-of-stake systems relying on validator signatures could be hijacked, destroying trust in consensus.
Even post-mitigation, blockchains will face the heritage data problem: everything that’s already on-chain is vulnerable to future decryption unless signatures are made quantum‑safe before Q‑Day.
🔹 Conclusion
PQC‑RA is not optional, it’s mandatory for crypto survival.
NIST standards are set: ML‑DSA + Kyber are tomorrow’s cryptographic backbone.
NCSC is clear: crypto‑agility and PQC rollouts must start this decade.
Blockchains face existential risk if they don’t adopt PQC faster.
Organizations need to inventory, assess, score, and plan their quantum‑safe journey now.
The takeaway is simple: the cost of acting now is far less than the cost of waiting until Q‑Day.
🛡️ Post‑Quantum Cryptography Risk Assessment (PQC‑RA): What, Why & How was originally published in Coinmonks on Medium, where people are continuing the conversation by highlighting and responding to this story.
