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CSCI E-170 Calendar - Fall 2005

Homework #3: Hashing and Crypto

1. Find an English language word which has the MD5 hash of df53ca268240ca76670c8566ee54568a. (2 points)

2. Find a few an English language words in which the first 3 hexadecimal digits of the word's MD5 hash are equal to the first 3 hexadecimal digits of the word's SHA-1 hash. Your professor found 59 such words in the file web2.txt, as well as 2 words where the first 4 hexadecimal digits of each hash were equal. Show the program that you use to find the matches, and report the matches. (2 points)

3. Assuming that hash residues are randomly and evenly distributed, what is the odds that the first four hexadecimal digits for two hash residues will be the same? Do the odds match the findings in problem #2? (2 points)

4. Obtain a free personal email certificate from Thawte, install it on your mail client, and send a digitally signed message to the course staff. The subject line of the message should say 'signed message from ljuser' where ljuser is your LiveJournal username. (2 points)

5. Using OpenSSL, report and explain each of the fields that are in your Thawte certificate. (2 points)

6. Using OpenSSL, connect to two different SSL servers. Report and explain each of the fields in the server's certificates. Are any of the fields in error? Why or why not? (2 points)

Homework is due before the start of class on October 24th.