I'm a PhD Candidate in Computer Science in the Security Group at Princeton University, which has some history in this area. I sit in the Center for Information Technology Policy where I study security, privacy, and how technology informs policy decisions. I'm currently advised by Ed Felten and Andrew Appel.

The following facts about me may or may not interest you: I'm a National Science Foundation Graduate Research Fellow. For many years, I traveled to Boston each fall to perform Improbable feats of engineering. I got married in 2012. My wife and I have a polydactyl cat named for a William Goldman character.

In the past, I attended a small college near Boston, MA where I spent a lot of time playing with technology and making it accessible to the masses. Prior to that, I grew up in Monterey, CA where I can recommend a good dentist. It was there that I got my start as a Computer Scientist, and experienced the inner workings of government.

I don't always blog, but when I do, I do it on Freedom to Tinker. I can be found on Twitter as @realjoshkroll.


I'm interested in a broad swath of topics in and outside of security (computer and otherwise), privacy (online and otherwise), and related questions in public policy. My current research is on Accountable Algorithms.

For more information, you should contact me.

Peer-reviewed Publications

  • Bonneau, J., Miller, A., Clark, J., Narayanan, A., Kroll, J., and Felten, E., "SoK: Bitcoin and second-generation cryptocurrencies", 36th IEEE Symposium on Security and Privacy, San Jose, CA, May 18-20 [PDF]
  • Kroll, J., Felten, E., and Haldermann, J. A., "Efficiently Auditing Multi-Level Elections", 6th International Conference on Electronic Voting (EVOTE 2014), Lochau, Austria, October 28-31, 2014 [PDF]
  • Edmundsen, A., Simpson, A.K., Kroll, J., and Felten, E., "Security Audit of Safeplug 'Tor in a Box'", 4th USENIX Workshop on Free and Open Communication on the Internet (FOCI 2014), San Diego, CA, August 18, 2014.[PDF]
  • Clark, J., Bonneau, J., Felten, E., Kroll, J., Miller, A., and Narayanan, A., "On Decentralizing Prediction Markets and Order Books", Thirteenth Workshop on the Econpmics of Information Security (WEIS 2014), State College, PA, June 23-24 2014. [PDF]
  • Kroll, J., Stewart, J., and Appel, A. "Portable Software Fault Isolation". Computer Security Foundations, 2014 (CSF 2014), Vienna, Austria, July 19-22 2014. [PDF]
  • Kroll, J., Felten, E., and Boneh, D. "Secure Protocols for Accountable Warrant Execution". Preprint. [PDF]
  • Goldfeder, S., Bonneau, J., Felten, E., Narayanan, A., "Securing Bitcoin Wallets with Threshhold Signatures". Preprint. [PDF]
  • Bonneau, J., Narayanan, A., Miller, A., Clark, J., and Kroll, J. "Mixcoin: Anonymity for Bitcoin with accountable mixes," Financial Cryptography, 2014 (FC 2014), Bridgetown, Barbados, March 3-7 2014. [PDF (full version)]
  • Kroll, J., Davey, I., and Felten, E., "The Economics of Bitcoin Mining, or Bitcoin in the Presence of Adversaries", The Twelfth Workshop on the Economics of Information Security (WEIS 2013), Washington, DC, June 10-11 2013. [PDF]
  • Kroll, J. and D. Dean, “BakerSFIeld: Bringing Software Fault Isolation to the x64,” SRI Computer Science Laboratory Technical Report, 2009. [PDF]
  • Martell, C. and J. Kroll, “Corpus-Based Gesture Analysis: An extension of the FORM dataset for the automatic detection of phases in a gesture”, Int. J. Semantic Computing, 1(4): 521-536 (2007). [PDF] [Journal Page]
  • Martell, C. and J. Kroll, “Using FORM to Predict Phase Labels”, Proceedings of the Language Resources and Evaluation Conference, Workshop on Multimodal Corpora, Genoa, Italy, 27 May 2006. [PDF]

Public Policy Publications and Regulatory Filings

  • Barocas, S., Felten, E., Huey, J., Kroll, J., and Narayanan, A. "Big Data and Consumer Privacy in the Internet Economy". Comment to the NTIA Big Data Request for Comments, 79 Fed. Reg. 32714. August 5, 2014. [PDF]

Other Publications

  • Felten, E., and Kroll J. "Heartbleed Shows Government Must Lead on Internet Security". Scientific American, 16 April 2014. [article]


  • Kroll, J. "Big Data, Fairness, and Nondiscrimination". New Jersey Attorney General's Advocacy Institue In-Service Training, August 7, 2014.
  • Kroll, J. "Accountable Algorithms". Princeton Joint ACM/IEEE Computer Society Chapters Meeting, 17 April 2014 [event]
  • Kroll, J. "The Economics of Bitcoin Mining, or Bitcoin in the Presence of Adversaries". Princeton University Center for Information Technology Policy Luncheon Series, 14 November 2013 [event] [video]
  • Barber, G. and Kroll, J. "Drones: Not Just for Military Use". New Jersey Attorney General's Advocacy Institute In-Service Training, August 8, 2013 (CLE credit course).
  • Felten, E. and Kroll, J. "The State of Electronic Voting". Princeton University Center for Information Technology Policy Luncheon Series, 18 October 2012. [event] [video]
  • Kroll, J. "Seeing Under Sea: Applications of Computer Vision in Underwater Video," Plenary Address, Harvard Undergraduate Research Symposium, Nov. 2006 (Accepted by faculty review; top 3 of 140 papers).



I sincerely enjoy teaching and am always looking for chances to do more of it. I've been fortunate to have many opportunities to be a teacher, a tutor, a docent, a guest speaker, and many other things. Please contact me if you'd like to know more.

I have taught the following university-level courses:

  • Princeton University, Department of Computer Science. Assistant in Instruction, Computer Science 226: Algorithms and Data Structures. Professor Robert Sedgewick, Instructor. Spring 2011.
  • Princeton University, Department of Computer Science. Assistant in Instruction, Computer Science 432: Information Security. Professor Edward Felten, Instructor. Fall 2010.
  • Harvard University, Department of Mathematics. Head Course Assistant (of 6), Mathematics 23a/b: Linear Algebra and Real Analysis I/II. Dr. Paul G. Bamberg, Instructor. 2006-2007.

Please contact me if you have a specific interest and we can talk.


My curriculum vitae. I cannot guarantee that the one on this website is up-to-date.

I occasionally consult for hire via my consulting vehicle Norwegian Blue, LLC. My expertise spans a wide range of topics in computer security and online privacy and previous work involved automated analysis of websites for privacy compliance and work related to Bitcoin.

For more information, it would be best to contact me.

Contact Me

I am most easily contacted via E-mail at .

If you prefer to send mail of the physical variety, please send it to my department:

Joshua Kroll
Computer Science
Princeton University
35 Olden Street Princeton, NJ 08540