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Interview question · Cryptography, PKI & TLS

Why is certificate revocation hard, and what do CRLs, OCSP and short-lived certificates each trade off?

Revocation asks every client to check a third party on every connection, and most clients quietly do not. The scored answer explains each mechanism's failure mode and why the industry is moving to short lifetimes.

hardNewPreparation tags: Google, Salesforce, MicrosoftUpdated Nov 2026

Revocation asks every client to check a third party on every connection, and most clients quietly do not. The scored answer explains each mechanism's failure mode and why the industry is moving to short lifetimes.

Make your first attempt

What would you say before reading the answer?

  1. 01 State the assumptions your answer depends on.
  2. 02 Explain the mechanism and choose a control.
  3. 03 Name a condition that would change your decision.

The worked answer includes an approach, scoring criteria and follow-up questions. Compare the reasoning with your own.

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What if · the follow-ups in this answer

The answer works through 6 follow-ups like an interviewer would

A company's TLS private key is stolen and they revoke the certificate, assuming that ends the risk.

  1. What must revocation achieve?
  2. Why are CRLs and OCSP weak?
  3. What do stapling and browser mechanisms add?
  4. What actually limits the damage?
  5. What else should the company do?
  6. What would you tell the company?

Each rung has a nudge, a model answer, the principle that carries over and the weak answer to avoid. Premium opens every answer and ladder.

UP NEXT ON YOUR JOURNEY
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