Advanced Cryptography CAS-005 Practice Questions (Page 3)

Questions 11–15

1. 11foundation · easy

   What does forward secrecy protect against?

   • ACompromise of past session keys even if the long-term private key is later compromised
   • BDenial-of-service attacks on the key exchange
   • CMalware that steals data from the endpoint
   • DCompromise of the long-term private key itself
   Reveal Solution Discussion Select an answer first
2. 12foundation · easy

   Which key exchange mechanism is commonly used to provide forward secrecy in TLS?

   • APre-shared key (PSK) without ephemeral derivation
   • BEphemeral Diffie-Hellman (DHE or ECDHE)
   • CKerberos ticket exchange
   • DStatic RSA key exchange
   Reveal Solution Discussion Select an answer first
4. 13application · medium

   A company is designing a new authentication system that must handle a high volume of login requests. The system will use PBKDF2 for password hashing. The security team is concerned about the CPU load on the application servers. Which approach reduces the CPU load while maintaining the security benefits of key stretching?

   • AOffload PBKDF2 computations to a hardware security module (HSM) or dedicated cryptographic accelerator.
   • BUse a faster hash function like SHA-256 instead of PBKDF2.
   • CReduce the PBKDF2 iteration count to lower CPU usage.
   • DCache the PBKDF2 results for a set of common passwords.
   Reveal Solution Discussion Select an answer first
5. 14application · medium

   A web server handles thousands of TLS connections per second. The administrator notices that the CPU is saturated during the TLS handshake phase. The server uses RSA for key exchange and AES-256 for bulk encryption. Which hardware upgrade would most directly reduce CPU load during the handshake?

   • AUpgrade the CPU to a model with more cores.
   • BInstall a faster network interface card (NIC) to reduce packet processing overhead.
   • CAdd more RAM to the server to cache TLS session keys.
   • DInstall a cryptographic accelerator card that supports RSA operations.
   Reveal Solution Discussion Select an answer first
6. 15expert · hard

   A research organization wants to allow external collaborators to run statistical analysis on its encrypted genomic data. The data is extremely sensitive, and the organization cannot share the decryption key. The collaborators need to compute sums, averages, and standard deviations. Which approach is most practical given current technology?

   • AUse a trusted execution environment (TEE) on the collaborator's server to decrypt and process the data.
   • BUse partially homomorphic encryption (PHE) that supports addition and multiplication, and design the analysis to use only these operations.
   • CUse fully homomorphic encryption (FHE) to allow arbitrary computations on the encrypted data.
   • DShare the decryption key with the collaborators under a non-disclosure agreement.
   Reveal Solution Discussion Select an answer first