Effective CISSP Questions

Alice generated a public/private key pair for asymmetric cryptography. She sent to Bob a document with a message digest encrypted by her private key. Bob then validated the document by computing a new message digest from the document and comparing it with the decrypted message digest. If the comparison matches, Bob can assure that the document comes from Alice while she can not deny it. Which of the following best describes the security principle or objective the process will achieve?
A. Integrity
B. Authenticity
C. Non-repudiation
D. Accountability

Kindly be reminded that the suggested answer is for your reference only. It doesn’t matter whether you have the right or wrong answer. What really matters is your reasoning process and justifications.

My suggested answer is A. Integrity.

CIA as Security Objectives

  • My suggested answer is A. Integrity as this question is designed to remind you that “integrity” includes non-repudiation and authenticity according to the law, the E-Government Act of 2002.
  • The process Alice has completed generates “Digital signature”. Digital signatures provide authenticity protection, integrity protection, and non-repudiation.
  • C. Non-repudiation is not a bad idea as it’s commonly accepted that digital signatures ensure non-repudiation. However, “integrity” as an umbrella term covers more comprehensively in terms of the legal definition.

This post is copied from the second question in CISSP PRACTICE QUESTIONS – 20190906, which has two questions, to serve as the QOTD of 20190907 on 20200816.

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