Public Key Infrastructure (PKI) uses asymmetric key encryption between parties. The originator encrypts
information using the intended recipient’s “public” key in order to get confidentiality of the data being sent. The
recipients use their own “private” key to decrypt the information. The “Infrastructure” of this methodology
ensures that:

A.
The sender and recipient have reached a mutual agreement on the encryption key exchange that they will
use.

B.
The channels through which the information flows are secure.

C.
The recipient’s identity can be positively verified by the sender.

D.
The sender of the message is the only other person with access to the recipient’s private key.

Explanation:
When information is encrypted using a public key, it can only be decrypted by using the associated private key.
As the recipient is the only person with the private key, the recipient is the only person who can decrypt the
message. This provides a form of authentication in that the recipient’s identity can be positively verified by the
sender. If the receiver replies to the message, the sender knows that the intended recipient received the
message.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, 2013, pp. 784-785