What are the three MOST important functions that Digital Signatures perform?

A.
Integrity, Confidentiality and Authorization

B.
Integrity, Authentication and Nonrepudiation

C.
Authorization, Authentication and Nonrepudiation

D.
Authorization, Detection and Accountability

Explanation:
Digital Signatures can be used to provide Integrity, Authentication and Nonrepudiation.
A digital signature is a hash value that has been encrypted with the sender’s private key.
If Kevin wants to ensure that the message he sends to Maureen is not modified and he wants her to be sure it
came only from him, he can digitally sign the message. This means that a one-way hashing function would be
run on the message, and then Kevin would encrypt that hash value with his private key. When Maureen
receives the message, she will perform the hashing function on the message and come up with her own hash
value. Then she will decrypt the sent hash value (digital signature) with Kevin’s public key. She then compares
the two values, and if they are the same, she can be sure the message was not altered during transmission.
She is also sure the message came from Kevin because the value was encrypted with his private key. The
hashing function ensures the integrity of the message, and the signing of the hash value provides
authentication and nonrepudiation.
Incorrect Answers:
A: Digital signatures do not provide Confidentiality or Authorization.
C: Digital signatures do not provide Authorization.
D: Digital signatures do not provide Authorization, Detection or Accountability.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, 2013, p. 829