Chapter 8 — Quantum and post-quantum security: supervised case analysis
Lesson map
Lesson 08 published. Map, example, EX036.
flowchart TD
N0["Learning outcomes"]
N1["8.1 The case"]
N2["8.2 Analysis"]
N3["8.3 Options"]
N4["8.4 Governance gaps"]
N5["8.5 Recommendation"]
N6["8.7 Practice task"]
N7["8.8 Supervisor review"]
N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> N6 --> N7
N7 --> EX["Worked example"]
EX --> Q["Exercise EX036"]
Logical drawing
flowchart LR
N0["Learning outcomes"]
N1["8.1 The case"]
N2["8.2 Analysis"]
N3["8.3 Options"]
N4["8.4 Governance gaps"]
N5["8.5 Recommendation"]
N6["8.7 Practice task"]
N7["8.8 Supervisor review"]
N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> N6 --> N7 --> Q["EX036"]
[Learning outcomes]
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[8.1 The case]
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[8.2 Analysis]
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[8.3 Options]
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[8.4 Governance gaps]
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[8.5 Recommendation]
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[8.7 Practice task]
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[8.8 Supervisor review]
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[Worked example] --> [Exercise EX036]
Learning outcomes
You will (1) analyse a realistic migration case end to end; (2) apply the workflow under supervision; (3) weigh options with explicit criteria; (4) identify governance gaps; and (5) present a recommendation.
8.1 The case
MTI's life-policy archive (synthetic): 40-year confidentiality and verifiability; documents signed with RSA-2048; transferred nightly from regional offices over IPsec VPNs with ECDH; stored encrypted with AES-256, keys wrapped by an HSM using RSA-OAEP; VPN appliances from a supplier whose firmware supports RFC 9370 from version 7.4, with MTI on 7.1; archive software vendor states "PQC signatures on roadmap".
Notice that the case combines both risks from Chapter 1: classical key exchange on long-lived transfers and classical signatures on long-lived documents. List the facts in a table with their grades before analysing them.
8.2 Analysis
Exposure: transfers are HNDL-exposed now (40-year data). Signatures are forge-later exposed (documents must stay verifiable for decades). AES-256 at rest is adequate; RSA key wrapping matters if wrapped keys ever leave the HSM or are backed up off-site.
Grade each fact before using it. Support from firmware version 7.4 is a supplier statement, so it is grade D until tested; the archive vendor's roadmap claim scores 1 on the questionnaire scale, an undated claim. Note also the HSM backup question, which needs an answer from the owner of the HSM.
8.3 Options
(A) Upgrade VPN firmware to 7.4 and enable hybrid key exchange; (B) interim RFC 8784 PSKs on the archive tunnels until A; (C) reduce transfers by sending documents once at completion instead of nightly re-sync; (D) archive signature plan: require vendor dates for ML-DSA support and plan timestamp renewal. Criteria: protection, time, cost, operational risk, dependency.
Score each option against every criterion and write a short reason for each score. A protects transfers fully but depends on the supplier's firmware; B is quick but adds key management work; C costs little and reduces exposure immediately; D addresses signatures but depends on the vendor.
8.4 Governance gaps
No owner for archive cryptography; no contract clause requiring the archive vendor to support post-quantum signatures; no exception process used for the VPN delay.
Each gap explains part of the risk. Without an owner, nobody chased the archive vendor. Without a clause, MTI has no lever to require dates. Without a registered exception, the VPN delay was accepted by default instead of by decision. Fix the gaps alongside the technical options, or the same problems will recur. Assign each gap an owner.
8.5 Recommendation
A within two quarters, with C immediately and B for the two offices whose appliances cannot be upgraded until hardware refresh; D as a procurement action with a deadline; name Records Management as owner of archive cryptography; register an exception for the two offices with expiry at refresh.
Note that the options are combined, not chosen singly: C and B reduce exposure while A is prepared, and D starts the signature work that has the longest lead time. Each part has an owner and a date.
8.6 Worked example of presentation
"Recommendation: protect archive transfers within six months by upgrading VPN firmware and enabling hybrid post-quantum key exchange, reduce nightly transfers now, and use interim pre-shared keys at two offices. Cost: CU 40–70k (synthetic). Residual: classical document signatures until the archive vendor delivers ML-DSA; we request a contract amendment with dates."
The presentation states the recommendation first, then what it costs, then what remains. It uses plain words rather than option letters, and it ends with the one request the audience can act on.
8.7 Practice task
Analyse the case yourself, score options against criteria, and compare with the recommendation above.
Score each option on protection, time, cost, operational risk and dependency, with a short reason for every score. Grade the facts you rely on, especially the firmware support and the vendor's roadmap claim. Then compare your recommendation with the book's and explain any difference: you may weigh cost or dependency differently, which is acceptable if you say why. Present your scores to a peer and note any changes.
8.8 Supervisor review
Present your analysis to your supervisor before sharing it: they will check whether the facts are graded correctly, whether options were considered fairly and whether the recommendation stays within what the evidence supports. Incorporate comments and record what changed.
For the archive case, expect questions such as why option B applies to two offices only and whether the cost range is supported by quotes. Your supervisor may also ask whether the claim about firmware version 7.4 has been tested. Answer with the evidence you have and say what you do not yet know.
8.9 Common errors and limits
- Ignoring signatures because key exchange is urgent.
- Options without criteria.
- Missing governance gaps.
Each error leaves part of the risk unmanaged. In MTI's archive case, focusing only on transfers would leave decades-old signed documents with no plan. Options without criteria make the recommendation look like preference. Missing governance gaps means the archive vendor stays unchased and the VPN delay stays unrecorded. Check your analysis for all three before presenting it. Revise your analysis where you find any of them. Note each one you fixed.
Exercises
- EX036 — Exposure. List the case's exposures by class. Rubric: 3 = transfers HNDL, signatures forge-later, AES adequate, key wrapping conditional.
- EX037 — Option scoring. Score options A–C on protection and time (1–5). Rubric: 3 = defensible scores with reasons.
- EX038 — Gap. Propose fixes for the three governance gaps. Rubric: 3 = owner, clause, exception.
- EX039 — Recommendation. Rewrite the recommendation for a non-technical board in 60 words. Rubric: 3 = clear, accurate, costs and residual.
- EX040 — Key wrapping. When does RSA-OAEP key wrapping become a quantum concern? Rubric: 3 = when wrapped keys are exposed outside the HSM/recorded.
Synthesis
Supervised case analysis applies the workflow end to end: exposures, options with criteria, governance gaps and a clear, costed recommendation with residual risk.
Continue studying — chapter 08 of 12
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