Cryptanalysis and Attacks CEH Practice Questions (Page 7)

Questions 31–35

1. 31application · medium

   A network administrator is setting up a secure communication channel between two offices. An attacker is positioned on the network path and can intercept and modify packets. Which attack could the attacker use to compromise the confidentiality of the communication if the protocol lacks proper authentication?

   • ABirthday attack to find a collision in the session keys.
   • BSide-channel attack by measuring network latency.
   • CReplay attack, where the attacker captures and retransmits the entire session.
   • DMan-in-the-middle attack, where the attacker intercepts the key exchange and substitutes their own keys.
   Reveal Solution Discussion Select an answer first
2. 32expert · hard

   A security architect is designing a digital signature scheme for a high-security environment. The architect needs to choose a hash function that resists birthday attacks. The current standard is SHA-256. Which consideration is most important when evaluating the resistance to birthday attacks?

   • AThe use of a salt in the hash function.
   • BThe output size of the hash function, because the birthday attack requires approximately 2^(n/2) operations.
   • CThe speed of the hash function, because faster hashes are more vulnerable to brute-force.
   • DThe block size of the hash function, because larger blocks prevent collisions.
   Reveal Solution Discussion Select an answer first
4. 33foundation · easy

   Which of the following best describes a brute-force attack?

   • AAnalyzing the frequency of characters in ciphertext
   • BUsing a precomputed list of common passwords
   • CTrying every possible key until the correct one is found
   • DExploiting timing differences in the encryption process
   Reveal Solution Discussion Select an answer first
5. 34application · medium

   A cryptanalyst is studying a block cipher that uses a key schedule where each round key is derived from the previous one by a simple XOR with a constant. The analyst notices that if two keys differ by a specific value, the resulting ciphertexts have a predictable relationship. Which type of attack is this?

   • ASide-channel attack
   • BReplay attack
   • CRelated-key attack
   • DMeet-in-the-middle attack
   Reveal Solution Discussion Select an answer first
6. 35foundation · easy

   Which of the following is an example of a side-channel attack?

   • ATrying all possible keys until one works
   • BUsing a precomputed table of hashes to reverse a password
   • CMeasuring the time it takes to decrypt a message to infer the key
   • DIntercepting and modifying messages between two parties
   Reveal Solution Discussion Select an answer first