Privacy technologies course roundup: Wiki, student projects, HotPETs

May 23, 2013 at 2:14 pm 1 comment

In earlier posts about the privacy technologies course I taught at Princeton during Fall 2012, I described how I refuted privacy myths, and presented an annotated syllabus. In this concluding post I will offer some additional tidbits about the course.

Wiki. I referred to a Wiki a few times in my earlier post, and you might wonder what that was about. The course included an online Wiki discussion component, and this was in fact the centerpiece. Students were required to participate in the online discussion of the day’s readings before coming to class. The in-class discussion would use the Wiki discussion as a starting point.

The advantages of this approach are: 1. it gives the instructor a great degree of control in shaping the discussion of each paper, 2. the instructor can more closely monitor individual students’ progress 3. class discussion can focus on particularly tricky and/or contentious points, instead of rehashing the obvious.

Student projects. Students picked a variety of final projects for the class, and on the whole exceeded my expectations. Here are two very different projects, in brief.

Nora Taranto, a History of Science major, wrote a policy paper about the privacy implications of the shift to electronic medical records. Nora writes:

I wrote a paper about the privacy implications of patient-care institutions (in the United States) using electronic medical record (EMR) systems more and more frequently.  This topic had particular relevance given the huge number of privacy breaches that occurred in 2012 alone.  Meanwhile, there is a simultaneous criticism coming from care providers about the usability of such EMR systems.  As such, many different communities—in the information privacy sphere, in the medical community, in the general public, etc.—have many different things to say.  But, given the several privacy breaches that occurred within a couple of weeks in April 2012 and together implicated over a million individuals, concerns have been raised in particular about how secure EMR systems are.  These concerns are especially worrisome given the federal government’s push for their adoption nationwide beginning in 2009 when the American Recovery and Reinvestment Act granting funds to hospitals explicitly for the purpose of EMR implementation.

So I looked into the benefits and costs of such systems, with a particular slant towards the privacy benefits/costs.  Overall, these systems do have a number of protective mechanisms at their disposal, some preventative and others reactive.  While these protective barriers are all necessary, they are not sufficient to guarantee the patient his or her privacy rights in the modern day.  These protective mechanisms—authentication schemes, encryption, and data logs/anomaly-detection—need to be expanded and further developed to provide an adequate amount of protection for personal health information.  While the government is, at the moment, encouraging the adoption of EMR systems for maximal penetration, medical institutions ought to use caution in considering which systems to implement and ought to hold themselves to a higher standard.  Moreover, greater regulatory oversight of EMR systems on the market would help institutions maintain this cautious approach.

Abu Saparov, Ajay Roopakalu, and Rafi Shamim, also undergraduates, designed an implemented an alternative to centralized key distribution. They write:

Our project for the course was to create and implement a decentralized public key distribution protocol and show how it could be used. One of the initial goals of our project was to experience first-hand some of the things that made the design of a usable and useful privacy application so hard. Early on in the process, we decided to try to build some type of application that used cryptography to enhance the privacy of communication with friends. Some of the reasons that we chose this general topic were the fact that all of us had experience with network programming and that we thought some of the things that cryptography can achieve are uniquely cool. We were also somewhat motivated by the prospect of using our application to talk with each other and our other friends after we graduate. We eventually gravitated towards two ideas: (1) a completely peer-to-peer chat system that is encrypted from end-to-end, and (2) a “dumb” social network that allows users to share posts that only their friends (and not the server) can see. During the semester, our focus shifted to designing and implementing the underlying key distribution mechanism upon which these two systems could be built.

When we began to flesh out the designs for our two ideas, we realized that the act of retrieving a friend’s public cryptographic keys was the first challenge to solve. Certificate authorities are the most common way to obtain public keys, but require a large degree of trust to be placed in a small number of authorities. Web of Trust is another option, and is completely decentralized, but often proves difficult in practice because of the need for manual key signing. We decided to make our own decentralized protocol that exposes an easily usable API for clients to use in order to obtain public keys. Our protocol defines an overlay network that features regular nodes, as well as supernodes that are able to prove their trustworthiness, although the details of this are controllable through a policy delegate. The idea is for supernodes to share the task of remembering and verifying public keys through a majority vote of neighboring supernodes. Users running other nodes can ask the supernodes for a friend’s public key. In order to trick someone, an adversary would have to control over half of the supernodes from which a user requested a key. Our decision to go with an overlay network created a variety of issues such as synchronizing information between supernodes, being able to detect and report malicious supernodes, and getting new nodes incorporated into the network. These and the countless other design problems we faced definitely allowed us to appreciate the difficulty of writing a privacy application, but unfortunately, we were not fully able to test every element of our protocol and its implementation. After creating the protocol, we implemented small, bare-bones applications for our initial ideas of peer-to-peer chat and an encrypted social network.

Master’s students Chris Eubank, Marcela Melara, and Diego Perez-Botero did a project on mobile web tracking which, with some further work, turned into a research paper that Chris will speak about at W2SP tomorrow.

Finally, I’m happy to say that I will be discussing the syllabus and my experiences teaching this class at HotPETs this year, in Bloomington, IN, in July.

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Entry filed under: Uncategorized. Tags: , , .

What Happened to the Crypto Dream? Now in a new and improved paper form! Reidentification as Basic Science

1 Comment Add your own

  • 1. simsong  |  May 24, 2013 at 11:46 am

    Thanks for posting this. I’ve been following the blog closely. I’m glad that things are working out well at Princeton. Students sound great!


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I’m an associate professor of computer science at Princeton. I research (and teach) information privacy and security, and moonlight in technology policy.

This is a blog about my research on breaking data anonymization, and more broadly about information privacy, law and policy.

For an explanation of the blog title and more info, see the About page.

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