Assignment 2
Assignment Instructions
For this assignment and any others that require research you must answer in your own words and
cite your references correctly
. A cut-and-paste answer will earn a zero for the entire assignment and may earn a course grade of F for plagiarism.
Part 1: In each of the following scenarios, tell whether there is a violation of confidentiality, integrity, or availability, or some combination of the three. In addition, for each item, write a two- or three-sentence paragraph explaining why your answer is correct.
1. Alex disables Barbara’s router by logging in remotely with the manufacturer’s default password.
2. Mallory builds a WiFi jammer using plans she found on the Internet and jams wireless signals over a large part of her apartment building.
3. Charlene uses a key logger to capture Darla’s banking password.
4. Eve rewrites the magnetic stripe on a gift card to change the amount from $10 to $100.
(Adapted from an exercise in Bishop, Matt,
Introduction to Computer Security.)
Part 2: Using the tool at
, compute the SHA-256 checksum of the MS-Word file that is your work on this assignment so far, or some similar file if you don’t have that one available. Copy the calculated cryptographic hash into Windows Notepad or word processing document to save it temporarily. Now change one character from a capital to a lowercase letter or vice-versa in the original document, re-save, and recompute the the cryptographic hash. Paste the old and new cryptographic hashes into your homework document. Be sure to identify which one is before and which is after.
Do some research and explain in a paragraph or so what a “hash collision” is. Be sure to cite your research.
Part 3: What is a digital signature? And what digital signature algorithm is typically used in cryptocurrencies? Why is it important to always use fresh randomness when computing a digital signature?
Part 4: Generally, a digital signature involves encrypting a cryptographic hash, or digest, generated from the message. What is a hash function? Identify and explain the three properties that make a hash function cryptographic?
Part 5: For each of the following scenarios below, tell what type of encryption is most appropriate and in a sentence, or two explain the reasoning for your choice.
1. Alice wants to send a confidential message to Bill, whom she has never met and who lives in a distant country.
2. Charlie wants to be sure that no one but he can see the financial and medical records he has stored on his computer.
3. David needs a way to check that large computer files stored on corporate servers have not been modified.
4. Eddard uses a “cloud” backup service; he wants to be sure the operators of the service cannot read his files.
5. Frank needs to send a message to George. The message does not need to be confidential, but George must be assured that it actually came from Frank.
