CISSP Question of the Day – 8-4-2016

Getting You Prepped for the CISSP Exam ...One Question at a Time!

Today’s CISSP question topic: Encryption

Which of the following are valid implementations of 3DES? (Choose 2)

  1. DES-EEE. All 3 keys are unique. Key is effectively 168-bits in length.
  2. DES-EDE. Key1 = Key2. Key3 is unique from Key1. Key is effectively 112-bits in length.
  3. DES-EDE. Key1 = Key3. Key2 is unique from Key1. Key is effectively 112-bits in length.
  4. DES-EED. Key1 = Key2. Key3 is unique from Key1. Key is effectively 112-bits in length.
  5. DES-EEE. All 3 keys are the same. Key is effectively 168-bits in length.



Check Your Answer


  1. DES-EEE. All 3 keys are unique. Key is effectively 168-bits in length.
  2. DES-EDE. Key1 = Key3. Key2 is unique from Key1. Key is effectively 112-bits in length.

Supporting Links:
  1. https://en.wikipedia.org/wiki/Triple_DES#Keying_options
  2. http://www.cs.sjsu.edu/~stamp/CS265/SecurityEngineering/chapter5_SE/tripleDES.html
  3. http://searchsecurity.techtarget.com/tip/Expert-advice-Encryption-101-Triple-DES-explained


Co-workers, friends or colleagues studying for the CISSP exam, too? Share this question with them! Click an icon below to share to your preferred social media platform!
Posted in:
About the Author

Colin Weaver

Colin Weaver is co-owner and lead instructor at ITdojo, Inc., a network security and information assurance training center and consulting firm located in Virginia Beach, VA. His passion for technology, networks, and security has led him to become enthralled with the idea of IPv6 and its implementation. In this blog he will share with you glimpses of what he has learned and a hint at what you’ll learn in his classes.