When block chaining cryptography is used, what type of code is calculated and appended to the
data to ensure authenticity?

A.
Message authentication code.

B.
Ciphertext authentication code

C.
Cyclic redundancy check

D.
Electronic digital signature

Explanation:
The original Answer was B. This is incorrect as cipthertext is the result not an
authentication code.
“If meaningful plaintext is not automatically recognizable, a message authentication code (MAC)

can be computed and appended to the message. The computation is a function of the entire
message and a secret key; it is practically impossible to find another message with the same
authenticator. The receiver checks the authenticity of the message by computing the MAC using
the same secret key and then verifying that the computed value is the same as the one
transmitted with the message. A MAC can be used to provide authenticity for unencrypted
messages as well as for encrypted ones. The National Institute of Standards and Technology
(NIST) has adopted a standard for computing a MAC. (It is found in Computer Data
Authentication, Federal Information Processing Standards Publication (FIPS PUB) 113.)”
http://www.cccure.org/Documents/HISM/637-639.html from the Handbook of Information Security
Management by Micki Krause