Which of the following can hide confidential or malicious data in the whitespace of other files (e.g.
JPEGs)?

A.
Hashing

B.
Transport encryption

C.
Digital signatures

D.
Steganography

Explanation:
Steganography is the process of concealing a file, message, image, or video within another file, message,
image, or video.
Note: The advantage of steganography over cryptography alone is that the intended secret message does
not attract attention to itself as an object of scrutiny. Plainly visible encrypted messages, no matter how
unbreakable will arouse interest, and may in themselves be incriminating in countries where encryption is
illegal. Thus, whereas cryptography is the practice of protecting the contents of a message alone,
steganography is concerned with concealing the fact that a secret message is being sent, as well as
concealing the contents of the message.
Incorrect Answers:
A: A hash function is used to map digital data of variable size to digital data of fixed length.
B: Transport encryption encrypt the payload data
C: A digital signature is similar in function to a standard signature on a document. It validates the integrity
of the message and the sender.

Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, 6th Edition, Sybex, Indianapolis,
2014, pp. 249, 255, 261, 323
http://en.wikipedia.org/wiki/Steganography