Company A sends a PGP encrypted file to company B. If company A used company B’s public key to encrypt
the file, which of the following should be used to decrypt data at company B?

A.
Registration

B.
Public key

C.
CRLs

D.
Private key

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.