CSSE/MA479: Cryptography

Homework 2, due on the date listed on the schedule page

• Experiment with the visualization at: http://www.usafa.af.mil/df/dfcs/acis/applets/Vigenere.html
• Decrypt at least 3 of your classmates' discussion forum posts (ones that you don't know already) and submit printouts (5 pts)
• Do the following written problems from Trappe and Washington, section 2.13: (show your work, as discussed in Homework 1): #10, #11, #12, #19, #21, #13, #14 (10 pts each)
• Do the following computer problems from Trappe and Washington, section 2.14: #8 (decrypting Vigenere: 15 pts), and #11 (decrypting LFSR: 10 pts).

  For each, submit a printout of your program (or a transcript of your Matlab/Maple session if you used the Appendix) your results (the decrypted plaintext for #8, and the recurrence for #11).

  Note: you may write a program to do this from scratch (that's what I did for Vigenere), or use the book's code, following the process given in Appendices (e.g, C.2 example 4 in Matlab; that's what I did for LFSR). You reap what you sow: it's harder work to code from scratch, but you get more out of it (that being said, feel free to use the book's code if you get stuck on any details).