What is a protocol that adds digital signatures and encryption to
Internet MIME (Multipurpose Internet Mail Extensions)?

A.
S/MIME

B.
PGP

C.
SET/MIME

D.
IPSEC

Explanation:
The MIME protocol specifies a structure for the body of an email
message. MIME supports a number of formats in the email body,
including graphic, enhanced text and audio, but does not provide
security services for these messages. S/MIME defines such services
for MIME as digital signatures and encryption based on a standard
syntax.
*Answer IPSEC is incorrect since IPSEC is not an email protocol but
is a standard that provides encryption, access control, nonrepudiation,
and authentication of messages over IP. It is designed to be functionally
compatible with IPv6.
Answer b is incorrect because PGP,
Pretty Good Privacy, brings security to email through the use of a
symmetric cipher, such as IDEA, to encipher the message. RSA is
used for symmetric key exchange and for digital signatures. PGP is
not an augmentation of MIMe. RFC 2440 permits other algorithms to
be used in PGP. In order of preference, they are ElGamal and RSAfor
key distribution; triple DES, IDEAand CAST5 for encryption of messages;
DSA and RSA for digital signatures and SHA-1 or MD5 for
generating hashes of the messages. Answer d is incorrect because
there is no such protocol. There is a protocol called SET for Secure
Electronic Transaction. It was developed by Visa and MasterCard to
secure electronic bankcard transactions. SET requests authorization

for payment and requires certificates binding a person’s public key to
their identity.