Which of the following algorithms is used today for encryption in PGP?

A.
RSA

B.
IDEA

C.
Blowfish

D.
RC5

Explanation:
The Pretty Good Privacy (PGP) email encryption system was developed by Phil Zimmerman. For encrypting
messages, it actually uses AES with up to 256-bit keys, CAST, TripleDES, IDEA and Twofish. RSA is also used
in PGP, but only for symmetric key exchange and for digital signatures, but not for encryption.
ource: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of
Computer Security, John Wiley & Sons, 2001, Chapter 4: Cryptography (pages 154, 169). More info on PGP
can be found on their site at http://www.pgp.com/display.php?pageID=29.