Teaching Privacy Enhancing Technologies at UCL
30 June 2015
The course covers principally, and in some detail, engineering aspects of PETs and caters for an audience of CS / engineering students that already understands the basics of information security and cryptography (although these are not hard prerequisites). Students were also provided with a working understanding of legal and compliance aspects of data protection regimes, by guest lecturer Prof. Eleni Kosta (Tilburg); as well as a world class introduction to human aspects of computing and privacy, by Prof. Angela Sasse (UCL). This security & cryptographic engineering focus sets this course apart from related courses.
The taught part of the course runs for 20 hours over 10 weeks, split in 10 topics:
- Introduction and privacy in communication. (01-GA17-IntroComms)
- Anonymous communications & Traffic analysis (02-GA17-Anonymous-Comms)
- Private Computations with homomorphic encryption and secret sharing (03-GA17-Private-Computations)
- Privately checking inputs using Zero-Knowledge Proofs (04-GA17-ZeroKnowlegde)
- Private authorization using selective disclosure credentials (05-GA17-Selective-Disclosure)
- Data anonymization & de-anonymziation attacks (08-GA17-Data-Anonymization)
- Private Storage, queries and lookups (09-GA17-Storage-Retrieval)
- Privacy by design case-studies (10-GA17-Privacy-by-design-case-studies – Copy)
- Guest lectures: Human aspects (Angela Sasse)
- Guest lectures: Data Protection (Eleni Kosta)
Most importantly the course includes 10 hours of labs (20 next year!), split into 5 exercises, that give students (and their teachers!) hands on experience implementing extremely advanced privacy enhancing technologies. More generally the course provides an introduction to solid cryptographic engineering, test-driven development, testing & QA tools and code audits. The programming language used was Python on a Linux environment, with the petlib library that was specially developed for this course.
For each lab exercise students in pairs were provided with a partial code file, and a set of unit tests, and were asked to fill in the remaining code to fulfill the task, and at least make the unit tests pass. The topics of the exercises track the first 5 lecture topics:
- Private communications and basic programming with petlib
- Building a simple mix server and client
- Building a private polling system with homomorphic encryption
- Basics of zero-knowledge proofs of knowledge, equality and linear statement
- A basic selective disclosure authorization credential system
Finally, part of the grading was based on students performing a code review of other groups, looking for code defects leading to security or other bugs.
Overall, I am very proud of the progress everyone made. The course was attended by 16 MSc student and 2 MEng students. Everyone eventually was able to complete all lab assignment — not a given considering the advanced nature of the tasks at hand. It was evident while discussing with student the final exercise, on building a selective disclosure credential, that many had developed an intuitive understanding of how to build solutions based on zero-knowledge protocols, and all had definitely overcome their initial fear of these more advanced concepts in PETs.
I was also very impressed with many students that were able to tackle the hardest questions in the exam. One of those questions, basically asked students to re-invent a variant of the privacy preserving genomic testing protocol we presented at WPES 2014 — and many did successfully. Similarly, they were asked to de-anonymize a mechanism very similar to the 15:15 rule in place in California to “protect” smart meter reading, and again many did so successfully under time constrain and the high pressure environment of exams. As ever, the great engagement from students was the most rewarding part of teaching the course.
All material is available online (see links to slides, and git repositories), and I would be delighted to share / receive any additional exercises by others finding this material relevant to their courses.