Certified Ethical Hacker (CEH v11) — Question 375

Tony wants to integrate a 128-bit symmetric block cipher with key sizes of 128, 192, or 256 bits into a software program, which involves 32 rounds of computational operations that include substitution and permutation operations on four 32-bit word blocks using 8-variable S-boxes with 4-bit entry and 4-bit exit.
Which of the following algorithms includes all the above features and can be integrated by Tony into the software program?

Answer options

• A. CAST-128
• B. RC5
• C. TEA
• D. Serpent

Correct answer: D

Explanation

The correct answer is D, Serpent, as it meets all specified requirements, including the 128-bit block size, 32 rounds of operations, and the use of S-boxes. CAST-128, RC5, and TEA do not fulfill all of these criteria, particularly in terms of the number of rounds or the structure of their S-boxes.