CompTIA Security Plus Mock Test Q1095

Which of the following BEST describes part of the PKI process?

A. User1 decrypts data with User2’s private key
B. User1 hashes data with User2’s public key
C. User1 hashes data with User2’s private key
D. User1 encrypts data with User2’s public key


Correct Answer: D
Section: Cryptography

Explanation:
In a PKI the sender encrypts the data using the receiver’s public key. The receiver decrypts the data using his own private key.
PKI is a two-key, asymmetric system with four main components: certificate authority (CA), registration authority (RA), RSA (the encryption algorithm), and digital certificates.
Messages are encrypted with a public key and decrypted with a private key.
A PKI example:
You want to send an encrypted message to Jordan, so you request his public key.
Jordan responds by sending you that key.
You use the public key he sends you to encrypt the message.
You send the message to him.
Jordan uses his private key to decrypt the message.

Incorrect Answers:
A: You must use your own private key to decrypt data.
B: In a PKI data is encrypted and decrypted. Data is not hashed.
C: In a PKI data is encrypted and decrypted. Data is not hashed.

References:
Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, 6th Edition, Sybex, Indianapolis, 2014, pp. 279-285