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CISSP study material: Security engineering

47 questions of the 500 in the CISSP — Certified Information Systems Security Professional quiz. Each opens with its answer, the reasoning and where that is written down.

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The questions

  1. 15. A cloud provider must decommission self-encrypting drives from a multi-tenant storage array inside a two-hour maintenance window far too short for a full-block overwrite of the array. Each drive holds ciphertext belonging to many tenants, and the drives are leased and must be returned to the lessor in working order. Which sanitisation method meets these constraints?
  2. 25. A programme manager claims the systems security engineering principles in SP 800-160 Vol. 1 Rev. 1 suit large defence platforms only, so a small sensor gateway that has already been fielded sits outside their scope. How should the security architect answer?
  3. 27. A payments platform encrypts stored card tokens with AES-128. An architect proposes migrating to AES-256 so that each encrypted block becomes larger, cutting the number of blocks and the padding overhead on every record. How should the security engineer assess this proposal?
  4. 28. A developer encrypts customer records with AES in Cipher Block Chaining (CBC) mode and derives each initialisation vector (IV) from the record's primary key, so that decryption can recompute the IV without storing it. A reviewer objects to the design. Which change should the reviewer require?
  5. 29. A federal agency hardens a public web service and its internal client tooling against NIST SP 800-52 Rev. 2. Both endpoints currently negotiate TLS 1.2 and offer FIPS-approved cipher suites only. The architect asks what further protocol support the guidance obliges the agency to provide.
  6. 30. A protocol team needs a derivation step that emits 512 bits of keying material now and may need 1024 bits for a later revision, produced by a single primitive invocation rather than by concatenating several digests. The design is restricted to functions specified in FIPS 202. Which function meets the requirement?
  7. 31. A vendor tells a procurement team that its hardware security module is "FIPS validated" because its AES implementation passed algorithm testing. The security engineer reviewing the claim explains that cryptographic module validation under FIPS 140-3 examines considerably more than algorithm correctness. Which areas does that validation cover? Choose two.
  8. 35. A procurement team is comparing two IPsec gateways for a site-to-site deployment. One vendor implements Encapsulating Security Payload (ESP) only and calls that sufficient for a conforming implementation, while a reviewer insists Authentication Header (AH) is required so integrity-only protection remains available. Which position is correct?
  9. 36. An engineer is documenting the security associations required for a bidirectional IPsec tunnel carrying ordinary request and response traffic. A colleague proposes one association covering both directions and binding Authentication Header (AH) and Encapsulating Security Payload (ESP) together. How should the engineer describe the actual requirement?
  10. 37. A firewall team operates an IPsec security gateway that terminates site-to-site tunnels and also receives Simple Network Management Protocol (SNMP) polling addressed to the gateway itself. An auditor asserts that every association on the box must use tunnel mode because a security gateway is an endpoint. Which case still permits transport mode?
  11. 39. A team is migrating a payment gateway to TLS 1.3 and asks why its static RSA key exchange and its CBC-mode cipher preferences must be replaced by authenticated encryption with associated data (AEAD) suites. Which statements describe the changes made in TLS 1.3? Choose two.
  12. 40. A vendor is certifying a TLS 1.3 stack for a government customer and must document the minimum algorithm support a conforming implementation owes. To save code space the team proposes shipping ChaCha20-Poly1305 as the only bulk option. Which cipher suite does a conforming implementation have to support?
  13. 42. A telemetry platform holds long-lived TLS 1.3 connections that stream millions of small records per session under AES-GCM, and some clients also send early data on resumption. An engineer asks what an endpoint owes as the record count climbs, and how early data is handled. Which response is correct?
  14. 49. Two research institutes agree to federate under the SP 800-63C-4 federation guidance. They share no common public key infrastructure and neither will join the other's, yet their architects want federation assurance level 3 (FAL3) for a jointly funded data programme. Which binding approach suits this deployment?
  15. 77. An identity team is replacing an unsalted SHA-256 password store for a new consumer application. Policy demands a scheme that resists offline cracking on rented GPUs and lets defenders raise the attacker's cost as hardware improves. Following OWASP's 2025 cryptographic guidance, which choice should the team make?
  16. 225. A procurement specification demands a module validated at FIPS 140-3 Level 3 and states that Level 3 requirements replace the general ones. How are the requirements at a given level actually composed?
  17. 226. Which three of the following are among the requirement areas FIPS 140-3 covers for a cryptographic module? Choose three.
  18. 227. An auditor asks on what basis FIPS 140-3 was written and what it does to its predecessor. Which statement is correct?
  19. 228. A Canadian subsidiary asks whether a module validated by the programme that tests against FIPS 140-3 will be accepted on both sides of the border. What is the position?
  20. 229. A vendor states that its module is FIPS 140-3 compliant on the strength of its own internal testing. Why is that claim insufficient?
  21. 230. An architect specifies FIPS 140-3 Level 4 for every module in a low-impact internal application, arguing that higher is always safer. What does the standard advise?
  22. 231. A buyer finds a module on the validation programme's historical list and proposes to purchase it. What does FIPS 140-3 say about that list?
  23. 232. A module implements a proprietary cipher the vendor considers stronger than any published one. May a FIPS 140-3 conformant module use it?
  24. 233. A key management policy uses the word cryptoperiod without defining it. Which definition matches NIST SP 800-57 Part 1?
  25. 234. A board asks what bounding a key's cryptoperiod actually buys. Which three purposes does NIST SP 800-57 give? Choose three.
  26. 235. A key with three months of its cryptoperiod remaining is found to have been exposed. An administrator proposes leaving it in service until the scheduled rotation. What does NIST SP 800-57 require?
  27. 236. A team is setting cryptoperiods and lists only key length and algorithm as inputs. Which three further factors does NIST SP 800-57 name? Choose three.
  28. 237. A remote site distributes keys by hand, with occasional transcription errors. The security team proposes halving the cryptoperiod to improve safety. What does NIST SP 800-57 caution?
  29. 238. An organisation uses approved algorithms at recommended key sizes. Which consideration does NIST SP 800-57 say usually drives cryptoperiod selection in that situation, and why?
  30. 239. An architect proposes the same cryptoperiod for the keys protecting a message channel and the keys protecting a 40-terabyte archive. Why does NIST SP 800-57 treat these differently?
  31. 240. A control system's availability matters more than anything else, and its re-keying process has a history of failures. The security team wants to shorten cryptoperiods sharply because the data is sensitive. What does NIST SP 800-57 caution?
  32. 241. A signing key pair is issued. Which two statements about the cryptoperiods of the two halves match NIST SP 800-57 Part 1? Choose two.
  33. 242. A certificate is issued with a keyUsage extension present but every bit left unset. Why does RFC 5280 treat this as invalid?
  34. 243. An intermediate certificate asserts keyCertSign but its basic constraints extension leaves the CA boolean unset. What must a conforming relying party do with the certificate's public key?
  35. 244. An engineer must decide which key usage bit to set for an RSA public key that will encrypt a symmetric content-decryption key. Which bit applies, and what does the neighbouring bit mean?
  36. 245. A certificate profile mandates the nonRepudiation bit and a reviewer notes recent editions of X.509 use a different name for it. What is the bit now called, and what does it cover?
  37. 246. A certificate sets encipherOnly but leaves keyAgreement unset. How should a relying party interpret the encipherOnly bit?
  38. 247. A certificate authority certificate carries a path length constraint of zero. What does that permit in a valid certification path?
  39. 248. A certificate authority includes a path length constraint on an end entity certificate that has no CA boolean set. Which two statements from RFC 5280 apply? Choose two.
  40. 249. An authority issues a certificate authority certificate whose key validates signatures on other certificates, and marks the basic constraints extension non-critical. What does RFC 5280 require?
  41. 250. A version 3 certificate carries no basic constraints extension at all. How must its public key be treated?
  42. 251. A certificate authority's signing key will only ever sign certificates and revocation lists. Which practice does RFC 5280 recommend for its keyUsage bits?
  43. 252. An engineer must permit a key to verify signatures on delta certificate revocation lists. Which keyUsage bit governs that?
  44. 253. A supplier states its module either passes or fails FIPS 140-3 validation. How does the standard actually grade modules?
  45. 254. A team wants federal policy and planning obligations for key management rather than general best practice. Which part of NIST SP 800-57 should they read?
  46. 255. A design document states that publication of the SHA-3 standard retired the SHA-2 family. Why is that wrong?
  47. 256. An architect asks how FIPS 140-3 relates to the international standards it is based on, and what adjusts those standards for federal use. Which answer is correct?