A customer using high-speed parallel operations needs to encrypt data in 128-bit blocks with a key
size of up to 256 bits. Which security standard should the customer use?

A.
RC5

B.
DES

C.
AES

D.
SHA

Explanation:

The key size used for an AES cipher specifies the number of repetitions of transformation rounds
that convert the input, called the plaintext, into the final output, called the ciphertext. The number
of cycles of repetition are as follows:
• 10 cycles of repetition for 128-bit keys.
• 12 cycles of repetition for 192-bit keys.
• 14 cycles of repetition for 256-bit keys.
Incorrect:
: RC5 has a variable block size (32, 64 or 128 bits), key size.
: DES is now considered to be insecure for many applications. This is chiefly due to the 56-bit key size
being too small.