An administrator intends to configure an IPSec solution that provides ESP with integrity protection, but not confidentiality protection. Which of the following AES

modes of operation would meet this integrity-only requirement?

A.
GMAC

B.
PCBC

C.
CBC

D.
GCM

E.
CFB

Explanation:
Galois/Counter Mode (GCM) is a mode of operation for symmetric key cryptographic block ciphers that has been widely adopted because of its
efficiency and performance. GCM throughput rates for state of the art, high speed communication channels can be achieved with reasonable hardware resources.
The operation is an authenticated encryption algorithm designed to provide both data authenticity (integrity) and confidentiality.
GCM is defined for block ciphers with a block size of 128 bits.
Galois Message Authentication Code (GMAC) is an authentication-only variant of the GCM which can be used as an incremental message authentication code.
Both GCM and GMAC can accept initialization vectors of arbitrary length.