CSE 505A. Data Security: Homework 4 Due: November 29, Tuesday, 5:30pm 1. Install and use the PGP email system. After reading Section 15.1, do the following: (50pt) a. Find, download, and install a PGP software available online. For example, a package for MS Windows is at: ftp://ftp.pgpi.org/pub/pgp/6.5/6.5.3/PGPfreeware_6.5.3.zip Report the software you used and the steps you followed. b. Generate a key pair for yourself. You may choose your preferred encryption algorithm and key size. DH/DSS algorithm and 2048/1024 key size are recommended. Report your algorithm, key size, and your public key. c. Partner with another student in the class. Email him/her your public key in plain text and have him/her send you a PGP- encrypted email. Decrypt the message using your private key. Report all the steps you have taken in this practice. Compare the size of the message before and after decryption. d. Use PGP to encrypt and sign a large file (>10MB) in your computer. Then decrypt and verify the resulting file. Report the steps you used and the CPU time taken by each step. Also, compare the sizes of the original file, the encrypted and signed file, and the encrypted-then-decrypted file. e. It is known that public-key algorithms are slow and cannot efficiently handle large files. How do you explain the performance of PGP on large files? 2. Study the Kerberos V5 manual available online and answer the following questions, assuming that you are a user in a network domain using the Kerberos V5 login program. (30pt) a. What is the command for obtaining a ticket? What is the default lifetime for a ticket? b. Can you set a different lifetime for a ticket? How? c. Which command can show you all your tickets? From the resulting list of tickets, how can you tell which ones are the ticket-granting tickets? d. Assuming you are on a local host named h1.ker.wustl.edu and you want to use telnet to connect to the host named h2.ker.wustl.edu, and assuming you have no ticket yet, list the sequence of commands your need to use. For each command, list the tickets you have after executing it. 3. Problem 14.4. (20pt) Hint: Taking the normal integer eth root of an integer n is relatively easy.