CSSE/MA479: Cryptography

Homework 5: Using RSA (60 pts) Due at the time listed on the Schedule page

Part (a) Please work with a partner. (Try to complete in-class, but you can finish at home).

• (10 pts) From the middle of p. 167 and the discussions on section 6.2 on "attacking RSA", name at least 5 considerations that you should take in mind when choosing p, q, e, d, and your message.



















• Note that you won't be able to account for all of these reasonably when you do this exercise; that's OK for now.
• Publish your key. Please pick values of n and e using Maple, and send them to your partner, say via email.
• When you have received values of n and e from your partner, encrypt a very short message and send the ciphertext back to your partner.
• When you receive ciphertext from your partner, decrypt it using your value of d and φ(n)



• Write the message here: __________________________
• (20 pts) Please submit a printout of your Maple worksheet (or your alternative program).

Part (b) Written problems. Please work alone (as usual, you may share ideas about problems, but you are to write up your own solutions).

• Trappe and Washington, section 5.5: #1. In (a), the top line of the matrix should be 01100010 (not 01100100). (10 pts)
• Trappe and Washington, section 6.8: #7, #8, #10, #11 (these are all easy; 5 pts each) #1-5 are good warmups as well, but there's no need to turn these in.