Which of the following is a cryptosystem that uses a session key?

A.
IDEA

B.
PGP

C.
DES

D.
Blowfish

Explanation:
PGP is a free encryption product that uses asymmetric and symmetric
algorithms together in a hybrid approach. It allows users to be able to encrypt,
digitally sign, and determine how much they trust other users. The other answers are
algorithms and not cryptosystems. A cryptosystem is all the necessary software,
algorithms, keys, and protocols needed to carry out cryptographic functions.