CSSE/MA479: Cryptography

Homework 2, due on the date listed on the schedule page (85 points)

• Decrypt at least 3 of your classmates' discussion forum posts (ones that you don't know already) and submit printouts of the plaintext (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, #13, #14 (10 pts each)
• Do the following computer problems from Trappe and Washington, section 2.14: #8 (decrypting Vigenere: 15 pts), #10 (decrypting Hill cipher: 15 pts).

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

  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). 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). On the practical part of Exam 1 (week 3), you'll need to decrypt messages using these various ciphers using this software - doing this homework carefully and documenting it well is the best way to prepare.