Challenges

Before giving the papers to the public, I would say a word to those who may take an interest in them, and give them a little advice, acquired by bitter experience. It is, to devote only such time as can be spared from your legitimate business to the task, and if you can spare no time, let the matter alone. Again, never, as I have done, sacrifice your own and your family's interests to what may prove and illusion; but, as I have already said, when your day's work is done, and you are comfortably seated by your good fire, a short time devoted to the subject can injure no one, and may bring its reward.

From the Beale Papers

Challenge problems are optional, and meant to be somewhere between quite difficult and nearly impossible. Work on them if you find it a fun challenge and can do so without neglecting your responsibilities.

The value of a challenge is initially 100 points (equivalent to one problem set). It may be reduced after a hint is provided.

The bonus points will be given for the first satisfactory solution. Later solutions may receive some credit at my discretion, but only if the significantly improve the first solution. You may work in groups and consult external resources on challenge problems. If N people work together on a challenge problem, each person receives a bonus of value/sqrt(N).

Winners of a challenge problem will also be expected to explain what they did to the class.

Challenge 1: Jefferson Wheel Ciphertext (Open 30 August)
Challenge 2: Hack SDMI (Open 13 September, closed by RIAA, but still open to CS551 students, see SDMI Hacked )
Challenge 3: RC6 decryption (Open 13 September, Closed 14 September - Solution by Vic Ludwig)
Challenge 4: Skeletons in VeriSign's Closet (Open 8 October, Closed 6 November - Solution by Greg Lamm)
Challenge 5 and 6: Voting Protocols - see end of lecture slides. (Open 6 November)

University of Virginia Department of Computer Science CS 551: Security and Privacy on the Internet

David Evans evans@virginia.edu