Certified Ethical Hacker (CEH v12) — Question 260

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 Serpent, as it is a 128-bit block cipher designed to support key sizes of 128, 192, and 256 bits, and it performs 32 rounds with the specified operations. The other options, CAST-128, RC5, and TEA, do not meet all of the specified requirements, such as the exact number of rounds or the use of 8-variable S-boxes.