Cryptanalysis and Attacks CEH Practice Questions (Page 12)

Questions 56–60

1. 56foundation · easy

   Why does the birthday attack reduce the effort needed to find hash collisions?

   • ABecause it compares pairs of inputs rather than trying to match a specific target
   • BBecause it uses a dictionary of common inputs
   • CBecause it uses precomputed rainbow tables
   • DBecause it exploits the mathematical structure of the hash algorithm
   Reveal Solution Discussion Select an answer first
2. 57foundation · easy

   What is the defining characteristic of a related-key attack?

   • AThe attacker analyzes the frequency of characters
   • BThe attacker uses a list of common passwords
   • CThe attacker intercepts and replays messages
   • DThe attacker knows a mathematical relationship between different keys
   Reveal Solution Discussion Select an answer first
4. 58application · medium

   A security researcher is analyzing a smart card that performs RSA decryption. The researcher notices that the time taken to decrypt a message varies slightly depending on the private key bits. By measuring the decryption time for many chosen ciphertexts, the researcher can infer the private key. Which type of attack is this?

   • AFault injection attack
   • BPower analysis attack
   • CChosen-ciphertext attack
   • DTiming side-channel attack
   Reveal Solution Discussion Select an answer first
5. 59expert · hard

   A network security engineer is designing a VPN tunnel between two sites. The engineer is concerned about an attacker who can intercept and modify packets, and also replay captured packets. Which combination of mechanisms would best protect the VPN?

   • AUse strong mutual authentication during key exchange and include sequence numbers or timestamps in each packet.
   • BUse a longer encryption key and a faster hash algorithm.
   • CUse only symmetric encryption and rely on the encryption to prevent replay.
   • DUse a static pre-shared key and no sequence numbers.
   Reveal Solution Discussion Select an answer first
6. 60expert · hard

   A security researcher is evaluating a smartcard used for authentication. The card performs RSA decryption. The researcher notices that the card's power consumption during decryption correlates with the private key bits. The researcher also has the ability to choose the ciphertexts that the card decrypts. Which combination of attacks would be most effective?

   • AUse a related-key attack by altering the private key.
   • BUse a replay attack to capture and replay decryption operations.
   • CUse a brute-force attack on the RSA key space.
   • DUse a chosen-ciphertext attack to select inputs that amplify the power side-channel, then perform statistical analysis to recover the key.
   Reveal Solution Discussion Select an answer first