Cryptographic and network security Essay | Online Homework Help

Chapter 1

1.1 Consider an automated teller machine (ATM) to which users provide a personal identification number (PIN) and a card for account access. Give examples of confidentiality, integrity, and availability requirements associated with the system and, in each case, indicate the degree of importance of the requirement.

Chapter 2

2.2 This problem uses a real-world example of a symmetric cipher, from an old U.S. Special Forces manual (public domain). The document, filename SpecialForces.pdf, is available in the course files.

1. Using the two keys (memory words) cryptographic and network security, encrypt the following message:

Be at the third pillar from the left outside the lyceum theatre tonight at seven. If you are distrustful bring two friends.

Write your reasonable assumptions about how to treat redundant letters and excess letters in the memory words and how to treat spaces and punctuation. Indicate what your assumptions are.

Note: The message is from the Sherlock Holmes novel The Sign of Four.

1. Decrypt the ciphertext. Show your work.
2. Comment on when it would be appropriate to use this technique and what its advantages are.

Chapter 3

3.3 Assume passwords are selected from four-character combinations of 26 alphabetic characters. Assume an adversary can attempt passwords at a rate of one per second.

1. Assuming no feedback to the adversary until each attempt has been completed, what is the expected time to discover the correct password
2. Assuming feedback to the adversary flagging an error as each incorrect character is entered, what is the expected time to discover the correct password?

Chapter 4

4.2 Answer the following questions:

1. Suggest a way of implementing protection domains using access control lists.
2. Suggest a way of implementing protection domains using capability tickets