Certified Ethical Hacker (CEH v13) — Question 112

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, Serpent, is a symmetric block cipher that meets all the specified criteria, including the use of 32 rounds and 128-bit block size with variable key lengths. The other options, CAST-128, RC5, and TEA, do not incorporate the required number of rounds or do not have the specified structure involving 8-variable S-boxes, making them unsuitable for Tony's integration needs.