I have a task which has some code writing and explanation

1. What are the properties of hash functions?

2. Write your OWN code of computing SHA1 and compute the following hashes.

1. USF

2. Electrical Engineering

3. Crypto

You can verify the results of your code using: http://www.sha1-online.com/

Submit your code and screenshots of your results.

3. Bob designed a new scheme to detect whether a message is modified by an attacker (protecting data integrity). The scheme is to append to each message a SHA -256 hash of that message. Explain the vulnerability of Bob’s design.

4. Bob designed another new scheme to detect whether a message is modified by an attacker (protecting data integrity). The scheme is to append to each message a SHA – 256 hash of that message, then encrypt the whole appended message using AES with a known key to the public. Explain the vulnerability of Bob’s design.

5. A company is selling an artifact worth millions of dollars. Many interested buyers are in the bidding process, which works as follows. Each buyer sends the information of his/her final number (e.g., $1,000,000.00) to the company to show his/her commitment. And the number must be kept confidential from other buyers and even the company before the deadline. After the deadline, all numbers are released to all buyers and the company, then the buyer with the highest number wins. Design a HASH FUNCTION based scheme to secure the bidding process. Describe steps a buyer and/or the company should do.