CSSE/MA479: Cryptography

Homework 1 (100 pts), due on the date listed on the schedule page.

• Read the syllabus in Angel.
• Familiarize yourself with the schedule that shows daily readings, assignments, topics, etc
• Read the section of the text for today (and continue reading for each class)
• Write a personal statement about yourself and encrypt it using a shift cipher.
• (5 pts) Post the ciphertext on piazza!
• (5 pts) Email a copy of the plaintext to the instructor.
• (5 pts) Decrypt the instructor's posting on the forum to find out about his priorities. Submit the plaintext in writing as part of this assignment.

• Written problems (You must show some kind of work for all written problems in this class. Typically this involves showing your calculations, but if you use a computer program, you must submit your code, so that I could reproduce your answer.) Do the following written problems from Trappe and Washington, section 2.13: #1, #2, #3, #4, #5, #6, #8 (10 pts each)

• The following message was encrypted using an affine cipher. Write a program to decrypt the message using a brute force attack and submit both a printout of your code (10 pts) and the decrypted plaintext (5 pts).

  TKJJKYOMGFEXENYMKGMNERMTKJJKYOMGRMYKUGMNHMWRMYEQMTKGHOEXG

• For fun and pride, not points: solve the substitution cipher from Sherlock Holmes' The Case of the Dancing Men, handed out in class. The backstory is given in the video: http://www.youtube.com/watch?v=ISpuTNxZVck. Key information is given in 12:00 - 13:30, and the woman mentioned in 17:30 - 18:00 and 22:19. Real spoilers start around 24:00, so pause to solve it if you haven't before watching more. Substitution ciphers are discussed in the text in section 1.5.