A system administrator is setting up a file transfer server. The goal is to encrypt the user authentication
and the files the user is sending using only a user ID and a key pair. Which of the following methods
would achieve this goal?

A.
AES

B.
IPSec

C.
PGP

D.
SSH

Explanation:
With SSH you can use automatically generated public-private key pairs to encrypt a network connection,
and then use password authentication to log on. Or you can use a manually generated public-private key
pair to perform the authentication, allowing users or programs to log in without having to specify a
password.Incorrect Answers:
A: AES is an algorithm used in symmetric key cryptography. Symmetric or secret-key ciphers use the same
key for encrypting and decrypting. This means that there is only one key, not a key pair.
B: IPSec provides secure authentication and encryption of data and headers for LAN-to-LAN connections.
C: Pretty Good Privacy (PGP) is mainly used for message encryption.

Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, 6th Edition, Sybex, Indianapolis,
2014, pp. 91, 272
https://en.wikipedia.org/wiki/Secure_Shell
http://searchsecurity.techtarget.com/definition/Advanced-Encryption-Standard