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Threat Modeling a Post-Quantum Migration

A post-quantum migration is usually treated as an algorithm swap. It is really a threat-modeling problem: assets whose secrecy must outlive the quantum transition, an adversary with future capability, and a migration that introduces its own attack surface. This series applies threat-modeling discipline to the crypto transition itself. Grounded in NIST IR 8547, SP 1800-38, Mosca, and Shostack.

Murali Chillakuru·5 articles
  1. 1
    Framing the Post-Quantum Threat Model: Assets, Adversaries, and Boundaries

    A post-quantum migration is not an algorithm swap; it is a threat-modeling problem — with assets whose secrecy must outlive the transition, an adversary with future capability, and a migration that adds its own attack surface.

  2. 2
    Harvest-Now-Decrypt-Later as the Anchor Threat: Building a Data-at-Risk Inventory

    The one quantum threat that demands action today is the passive collector recording your encrypted data now to decrypt it later. Defending it starts with an inventory of data ranked by shelf-life against the quantum clock.

  3. 3
    Downgrade, Rollback, and Negotiation Attacks: The Adversary That Strips the PQC

    The active attacker does not need a quantum computer — only your fallback logic. By blocking the post-quantum attempt it forces a dual-stack system back to breakable classical cryptography, re-exposing data to harvest-now-decrypt-later.

  4. 4
    The Migration's Own Attack Surface: Combiners, Dual Stacks, and Key-Management Gaps

    The post-quantum migration is not just a defense; it is a new attack surface. Combiner bugs, dual-stack complexity, handshake bloat as a denial vector, and transitional key-management gaps make the transition period itself the most vulnerable.

  5. 5
    A Post-Quantum Threat-Modeling Playbook: Inventory, Attack Trees, Controls, and a CI Gate

    The whole series assembled into a repeatable method: inventory assets, rank by shelf-life, model the adversary, build attack trees, pair each threat with a control, and gate it all in continuous integration.