Certified Ethical Hacker (CEH v10) — Question 166

What is the known plaintext attack used against DES which gives the result that encrypting plaintext with one DES key followed by encrypting it with a second
DES key is no more secure than using a single key?

Answer options

• A. Man-in-the-middle attack
• B. Meet-in-the-middle attack
• C. Replay attack
• D. Traffic analysis attack

Correct answer: B

Explanation

The correct answer is B, Meet-in-the-middle attack, as it specifically refers to a method that shows the vulnerability in using two keys with DES. The other options, such as A (Man-in-the-middle attack), C (Replay attack), and D (Traffic analysis attack), describe different types of security threats that do not relate to the weaknesses of key management in DES.