A security administrator must implement a wireless encryption system to secure mobile devices’
communication. Some users have mobile devices which only support 56-bit encryption. Which of the
following wireless encryption methods should be implemented?

A.
RC4

B.
AES

C.
MD5

D.
TKIP

Explanation:
RC4 is popular with wireless and WEP/WPA encryption. It is a streaming cipher that works with key sizes
between 40 and 2048 bits, and it is used in SSL and TLS.
Incorrect Answers:
B: AES supports key sizes of 128, 192, and 256 bits, with 128 bits being the default.
Advanced Encryption Standard (AES) has replaced DES as the current standard, and it uses the Rijndael
algorithm. It was developed by Joan Daemen and Vincent Rijmen. AES is the current product used by U.S.
governmental agencies.C: The Message Digest Algorithm (MD) creates a hash value and uses a one-way hash. The hash value is
used to help maintain integrity. There are several versions of MD; the most common are MD5, MD4, and
MD2. MD4 was used by NTLM (discussed in a moment) to compute the NT Hash. MD5 is the newest
version of the algorithm. It produces a 128-bit hash.
D: To strengthen WEP encryption, a Temporal Key Integrity Protocol (TKIP) was employed. This placed a
128-bit wrapper around the WEP encryption with a key that is based on things such as the MAC address
of the destination device and the serial number of the packet.

Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, 6th Edition, Sybex, Indianapolis,
2014, pp. 171, 250, 251, 255