Assignment 7: Design review for lottery security

Due Tuesday, December 8th, at 11:55 PM

The assignment is to do a design review of another group's solution to Assignment 6. We will email you the names of the students in the group that you will review, along with the solution they submitted for Assignment 6. Your report should discuss the merits of the design in the context of the real world. As a general format, you should include the following:

When discussing potential security flaws (fradulent prizes or underreported tickets), be as specific as possible. Specify the knowledge or physical access that an adversary might need (e.g. root password for tickets database computers, PRF keys, access to a vault, ability to ensconse the lottery terminal in a faraday cage). Consider the real world likelihood of such attacks. Consider how such attacks might be prevented.

If a potential attack relies on some underspecified detail in the design, state any assumptions that might be needed for the attack. For example, if your attack involves stealing a PIN from a central database, and the designers did not specify any details of this database, you should state that an unencrypted PIN could be stolen by a database administrator.

Keep in mind that an adversary might be a courier, a shop owner, the database administrator for the lottery, etc., or any combination of such people.

If you happen to notice any "strict improvements", make sure to note these. A strict improvement, is any change that would improve security, practicality, or cost with no negative impact on the rest of the design.

Similar to our design review last time, you might also consider how removal of the "tamper proof" feature of the terminals might introduce vulnerabilities. Unlike HW5, this is not required.


Your solution should be submitted in either pdf or HTML format. If you're using pdf format, please name your report submit7.pdf. If you're using HTML, please package everything you're submitting into a single zip-file, called You can submit using this link.

If you're using HTML, the report should be an HTML file named index.html. This HTML report may contain images, links to other files, etc. if you include those files in your submission. Though your solution will be graded on content AND presentation, you do not need to design a beautiful document.

For this assignment, you must work in the same group that you worked in for assignment 6. You may not collaborate with anyone outside your group.

Copyright 2000-2012, Edward W. Felten.