Which of the following is considered the perfect encryption scheme and is unbreakable?

A.
RSA

B.
IDEA

C.
PKI

D.
One-time pad

Explanation:
One-time pads are considered unbreakable. A pad of random values is
created and used to encrypt the message. The pad is at least as long as the message
itself. The pad is destroyed after it is used and a new pad is created if another
message must be encrypted.