Question 200
A backup platform needs fast bulk encryption of multi-terabyte datasets. Which response best addresses the central security requirement with a defensible, risk-based design?
- Use asymmetric encryption on every data block without a hybrid design
- Reuse a nonce under a mode that forbids reuse
- Plan key creation, rotation, escrow/recovery and retirement with old-ciphertext dependency mapping
- Use approved authenticated symmetric encryption with protected key generation and handling
Explanation
Correct Answer
D:Symmetric ciphers are efficient for bulk confidentiality/integrity with shared-secret governance.
Incorrect Answers
A:Public-key operations are inefficient for bulk data.
B:Nonce misuse can destroy confidentiality or authenticity.
C:Deleting needed keys can make retained ciphertext unrecoverable. Use approved authenticated symmetric encryption with protected key generation and handling.
Question 201
A web service wants to exchange session secrets without pre-sharing a symmetric secret with every customer. Which response best addresses the central security requirement with a defensible, risk-based design?
- Use approved authenticated symmetric encryption with protected key generation and handling
- Use approved public-key or key-agreement mechanisms for authenticated session establishment
- Send the server private key to every client
- Treat a public key as a secret password
Explanation
Correct Answer
B:Asymmetric methods enable public distribution of key material and authenticated negotiation.
Incorrect Answers
A:Symmetric ciphers are efficient for bulk confidentiality/integrity with shared-secret governance. Use approved public-key or key-agreement mechanisms for authenticated session establishment.
C:Private key disclosure destroys authentication.
D:Public keys are intended to be shared.
Question 202
An audit needs to detect whether stored firmware binaries have changed. Which response best addresses the central security requirement with a defensible, risk-based design?
- Trust the digest delivered from the same untrusted source as the file
- Use a reversible encoding as an integrity digest
- Use a modern cryptographic hash tied to a trusted reference and secure comparison
- Validate the chain, hostname, validity interval and appropriate revocation status
Explanation
Correct Answer
C:A hash can detect differences but without trusted distribution it does not prove publisher identity.
Incorrect Answers
A:An attacker can replace file and digest together.
B:Encoding does not resist adversarial modification.
D:TLS trust relies on certificate validity and identity mapping, not simply ciphertext. Use a modern cryptographic hash tied to a trusted reference and secure comparison.
Question 203
A regulator requires proof that a vendor released a particular signed firmware artifact. Which response best addresses the central security requirement with a defensible, risk-based design?
- Verify a digital signature against a trusted signer public key and valid trust state
- Use a plain checksum as signer authentication
- Use a shared MAC key and claim which employee signed
- Validate the chain, hostname, validity interval and appropriate revocation status
Explanation
Correct Answer
A:Signatures bind content integrity to a signing identity when private keys stay protected.
Incorrect Answers
B:Checksums lack private-key origin proof.
C:Shared-key MACs generally do not identify one individual signer.
D:TLS trust relies on certificate validity and identity mapping, not simply ciphertext. Verify a digital signature against a trusted signer public key and valid trust state.
Question 204
A browser rejects an otherwise encrypted site connection because the certificate is expired. Which response best addresses the central security requirement with a defensible, risk-based design?
- Validate the chain, hostname, validity interval and appropriate revocation status
- Ignore certificate expiry because the traffic is encrypted
- Use approved authenticated symmetric encryption with protected key generation and handling
- Install any self-signed certificate without trust governance
Explanation
Correct Answer
A:TLS trust relies on certificate validity and identity mapping, not simply ciphertext.
Incorrect Answers
B:Encryption without verified endpoint identity permits impostors.
C:Symmetric ciphers are efficient for bulk confidentiality/integrity with shared-secret governance. Validate the chain, hostname, validity interval and appropriate revocation status.
D:Unmanaged trust can enable MITM.
Question 205
An organization rotates encryption keys but loses access to archival backups after deleting old keys. Which response best addresses the central security requirement with a defensible, risk-based design?
- Verify a digital signature against a trusted signer public key and valid trust state
- Plan key creation, rotation, escrow/recovery and retirement with old-ciphertext dependency mapping
- Grant all developers key-deletion privileges
- Delete old keys immediately when an alias points to a new key
Explanation
Correct Answer
B:Deleting needed keys can make retained ciphertext unrecoverable.
Incorrect Answers
A:Signatures bind content integrity to a signing identity when private keys stay protected. Plan key creation, rotation, escrow/recovery and retirement with old-ciphertext dependency mapping.
C:Broad deletion rights threaten data availability.
D:Alias updates do not decrypt old data.
Question 206
Long-lived confidential records may be harvested now and decrypted after future cryptanalytic advances. Which response best addresses the central security requirement with a defensible, risk-based design?
- Plan cryptographic agility and standards-based migration to approved post-quantum algorithms where justified
- Assume symmetric encryption must be discarded immediately
- Choose an unpublished proprietary algorithm as guaranteed quantum-proof
- Use approved public-key or key-agreement mechanisms for authenticated session establishment
Explanation
Correct Answer
A:Long-retention data can face future quantum risks even if algorithms remain practical today.
Incorrect Answers
B:Quantum impact differs across primitives and key sizes.
C:Unreviewed crypto is not sound assurance.
D:Asymmetric methods enable public distribution of key material and authenticated negotiation. Plan cryptographic agility and standards-based migration to approved post-quantum algorithms where justified.
Question 207
After a prior symmetric keys finding, a regulated financial institution reports that the approved safeguard is implemented: “Use approved authenticated symmetric encryption with protected key generation and handling.” The assurance team must decide whether this measure demonstrably works in operation. Which evidence would MOST directly establish its effectiveness?
- Test decrypt/authentication failures and secure key storage
- Use the completion of this alternative as proof: Use asymmetric encryption on every data block without a hybrid design
- Accept a signed change ticket saying: Use approved authenticated symmetric encryption with protected key generation and handling
- Run this adjacent but different test as the sole proof: Corrupt a signed artifact and verify the signature check fails
Explanation
Correct Answer
A:Correct crypto depends on operational mode and key custody.
Incorrect Answers
B:Public-key operations are inefficient for bulk data. Test decrypt/authentication failures and secure key storage.
C:Test decrypt/authentication failures and secure key storage. Correct crypto depends on operational mode and key custody.
D:Tamper rejection supports integrity and authenticity. It tests digital signatures, while this case requires evidence about symmetric keys.
Question 208
After a prior asymmetric keys finding, a global logistics firm reports that the approved safeguard is implemented: “Use approved public-key or key-agreement mechanisms for authenticated session establishment.” The assurance team must decide whether this measure demonstrably works in operation. Which evidence would MOST directly establish its effectiveness?
- Accept a signed change ticket saying: Use approved public-key or key-agreement mechanisms for authenticated session establishment
- Use the completion of this alternative as proof: Send the server private key to every client
- Verify peer identity and session key establishment with controlled MITM attempts
- Run this adjacent but different test as the sole proof: Inventory cryptographic dependencies and test approved hybrid or migration pathways
Explanation
Correct Answer
C:Handshake authenticity matters more than encryption alone.
Incorrect Answers
A:Verify peer identity and session key establishment with controlled MITM attempts. Handshake authenticity matters more than encryption alone.
B:Private key disclosure destroys authentication. Verify peer identity and session key establishment with controlled MITM attempts.
D:Agility evidence supports a phased transition. It tests postquantum, while this case requires evidence about asymmetric keys.
Question 209
After a prior hash finding, a regional hospital network reports that the approved safeguard is implemented: “Use a modern cryptographic hash tied to a trusted reference and secure comparison.” The assurance team must decide whether this measure demonstrably works in operation. Which evidence would MOST directly establish its effectiveness?
- Accept a signed change ticket saying: Use a modern cryptographic hash tied to a trusted reference and secure comparison
- Use the completion of this alternative as proof: Use a reversible encoding as an integrity digest
- Run this adjacent but different test as the sole proof: Test decrypt/authentication failures and secure key storage
- Compare against an independently authenticated known-good digest
Explanation
Correct Answer
D:Trust provenance is essential for hash evidence.
Incorrect Answers
A:Compare against an independently authenticated known-good digest. Trust provenance is essential for hash evidence.
B:Encoding does not resist adversarial modification. Compare against an independently authenticated known-good digest.
C:Correct crypto depends on operational mode and key custody. It tests symmetric keys, while this case requires evidence about hash.
Question 210
After a prior digital signatures finding, a payment-services company reports that the approved safeguard is implemented: “Verify a digital signature against a trusted signer public key and valid trust state.” The assurance team must decide whether this measure demonstrably works in operation. Which evidence would MOST directly establish its effectiveness?
- Use the completion of this alternative as proof: Use a plain checksum as signer authentication
- Corrupt a signed artifact and verify the signature check fails
- Accept a signed change ticket saying: Verify a digital signature against a trusted signer public key and valid trust state
- Run this adjacent but different test as the sole proof: Inventory cryptographic dependencies and test approved hybrid or migration pathways
Explanation
Correct Answer
B:Tamper rejection supports integrity and authenticity.
Incorrect Answers
A:Checksums lack private-key origin proof. Corrupt a signed artifact and verify the signature check fails.
C:Corrupt a signed artifact and verify the signature check fails. Tamper rejection supports integrity and authenticity.
D:Agility evidence supports a phased transition. It tests postquantum, while this case requires evidence about digital signatures.
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