Jeffrey Knockel

I'm fighting to bring transparency to Internet censorship and surveillance. I use reverse engineering techniques to reveal how software behavior harms your Internet freedom. Sometimes this behavior is intentional. For instance, some software censors what you say and secretly phones home information about your conversation if you talk about sensitive topics. Sometimes the harm is accidental. For instance, some software communicates your personal information but improperly encrypts it such that someone listening in can easily decrypt it. My graduate research was advised by Jed Crandall and Jared Saia. I'm currently a Postdoctoral Fellow at the Citizen Lab.

📧 Email: jeff ‑ citizenlab.ca
🔑 PGP Key: pgp.txt
🔑 SSH Key: ssh.txt

Selected Publications and Reports

2017

I successfully defended my dissertation in December 2017: Measuring Decentralization of Chinese Censorship in Three Industry Segments. My graduation is May 2018.

Fabian Faessler, Geoffrey Alexander, Masashi Crete-Nishihata, Andrew Hilts, Kelly Kim, and Jeffrey Knockel. Still Safer Without: Another look at Korean Child Monitoring and Filtering Apps. Citizen Lab Report. November 2017. (html)
Jeffrey Knockel, Lotus Ruan, and Masashi Crete-Nishihata. Measuring Decentralization of Chinese Keyword Censorship via Mobile Games. In the 7th USENIX Workshop on Free and Open Communications on the Internet (FOCI 2017). Vancouver, British Columbia. August 2017. (pdf) (slides)
Masashi Crete-Nishihata, Jeffrey Knockel, Blake Miller, Jason Q. Ng, Lotus Ruan, Lokman Tsui, and Ruohan Xiong. Remembering Liu Xiaobo: Analyzing censorship of the death of Liu Xiaobo on WeChat and Weibo. Citizen Lab Report. July 2017. (html)
Oleg Ursu, Jayme Holmes, Jeffrey Knockel, Cristian G. Bologa, Jeremy J. Yang, Stephen L. Mathias, Stuart J. Nelson, and Tudor I. Oprea. DrugCentral: online drug compendium. Nucleic Acids Research (NAR), Volume 45. January 2017. (pdf)

2016

Lotus Ruan, Jeffrey Knockel, Jason Q. Ng, and Masashi Crete-Nishihata. One App, Two Systems: How WeChat uses one censorship policy in China and another internationally. Citizen Lab Report. November 2016. (html)
Xu Zhang, Jeffrey Knockel, and Jedidiah R. Crandall. High Fidelity Off-Path Round-Trip Time Measurement via TCP/IP Side Channels with Duplicate SYNs. In the Proceedings of IEEE GLOBECOM (GLOBECOM 2016). Washington D.C., USA. December 2016. (pdf)
Antonio Espinoza, Jeffrey Knockel, Jedidiah R. Crandall, and Pedro Comesaña. V-DIFT: Vector-Based Dynamic Information Flow Tracking with Application to Locating Cryptographic Keys for Reverse Engineering. In the Proceedings of the International Conference on Availability, Reliability and Security (ARES 2016). Salzburg, Austria. August 2016. (pdf)
Jeffrey Knockel, Adam Senft, and Ron Deibert. Privacy and Security Issues in BAT Web Browsers. In the 6th USENIX Workshop on Free and Open Communications on the Internet (FOCI 2016). Austin, Texas. August 2016. (pdf) (slides)
Jeffrey Knockel, Adam Senft, and Ron Deibert. WUP! There It Is: Privacy and Security Issues in QQ Browser. Citizen Lab Report. March 2016. (html)
Jeffrey Knockel, Sarah McKune, and Adam Senft. Baidu's and Don'ts: Privacy and Security Issues in Baidu Browser. Citizen Lab Report. February 2016. (html)
Andrew Hilts, Christopher Parsons, and Jeffrey Knockel. Every Step You Fake: A Comparative Analysis of Fitness Tracker Privacy and Security. Open Effect Report. February 2016. (pdf)

2015

Jeffrey Knockel, Masashi Crete-Nishihata, Jason Q. Ng, Adam Senft, and Jedidiah R. Crandall. Every Rose Has Its Thorn: Censorship and Surveillance on Social Video Platforms in China. In the Proceedings of the 5th USENIX Workshop on Free and Open Communications on the Internet (FOCI 2015). Washington D.C., USA. August 2015. (pdf) (slides)
Jedidiah R. Crandall, Masashi Crete-Nishihata, and Jeffrey Knockel. Forgive Us Our SYNs: Technical and Ethical Considerations for Measuring Internet Censorship. Workshop on Ethics in Networked Systems Research (co-located with ACM SIGCOMM'15). London, United Kingdom. August 2015. (pdf)
Xu Zhang, Jeffrey Knockel, and Jedidiah R. Crandall. Original SYN: Finding Machines Hidden Behind Firewalls. In the Proceedings of IEEE INFOCOM 2015 (INFOCOM 2015). Hong Kong, China. April 2015. (pdf)

2014

Jeffrey Knockel and Jedidiah R. Crandall. Counting Packets Sent Between Arbitrary Internet Hosts. In the Proceedings of the 4th USENIX Workshop on Free and Open Communications on the Internet (FOCI 2014). San Diego, California. August 2014. (pdf) (slides)
Roya Ensafi, Jeffrey Knockel, Geoffrey Alexander, and Jedidiah R. Crandall. Detecting Intentional Packet Drops on the Internet via TCP/IP Side Channels. In the Proceedings of the 2014 Passive and Active Measurements conference (PAM 2014). Los Angeles, California. March 2014. (pdf)

2013

Jeffrey Knockel, George Saad, and Jared Saia. Self-Healing of Byzantine Faults. In the Proceedings of the 15th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS 2013). Osaka, Japan. November 2013. (pdf)
Jedidiah R. Crandall, Masashi Crete-Nishihata, Jeffrey Knockel, Sarah McKune, Adam Senft, Diana Tseng, and Greg Wiseman. Chat program censorship and surveillance in China: Tracking TOM-Skype and Sina UC. First Monday Volume 18, Number 7. July 2013. (html) (data & visualizations)

2012

Jeffrey Knockel and Jedidiah R. Crandall. Protecting Free and Open Communications on the Internet Against Man-in-the-Middle Attacks on Third-Party Software: We're FOCI'd. In the Proceedings of the 2nd USENIX Workshop on Free and Open Communications on the Internet (FOCI 2012). Bellevue, Washington. August 2012. (pdf) (slides)
Nicholas Aase, Jedidiah R. Crandall, Álvaro Díaz, Jeffrey Knockel, Jorge Ocaña Molinero, Jared Saia, Dan Wallach, and Tao Zhu. Whiskey, Weed, and Wukan on the World Wide Web: On Measuring Censors' Resources and Motivations. In the Proceedings of the 2nd USENIX Workshop on Free and Open Communications on the Internet (FOCI 2012). Bellevue, Washington. August 2012. (pdf)

2011

Jeffrey Knockel, Jedidiah R. Crandall, and Jared Saia. Three Researchers, Five Conjectures: An Empirical Analysis of TOM-Skype Censorship and Surveillance. In the Proceedings of the USENIX Workshop on Free and Open Communications on the Internet (FOCI 2011). San Francisco, California. August 2011. (pdf) (slides) (data)

Selected Talks

Invited talk. Speaking Truth to Power. School of Engineering Convocation, University of New Mexico. Albuquerque, New Mexico. May 2018.
Submitted talk (co-given with Antonio Espinoza). What your apps say about you (and how to find out). Internet Freedom Festival 2016. Valencia, Spain. March 2016. (html)
Submitted talk. Measuring Censorship Everywhere All the Time. Citizen Lab Summer Institute 2014. Toronto, Ontario. July 2014. (slides)
Submitted talk. Running Software in Albuquerque to Measure Censorship Anywhere. Citizen Lab Summer Institute 2013. Toronto, Ontario. July 2013. (slides)
Submitted talk (co-given with Greg Wiseman). Chat Program Censorship and Surveillance in China: Tracking TOM-Skype and Sina UC. Boston Freedom in Online Communications Day. Boston, Massachusetts. March 2013. (slides)
Invited talk. Chinese Keyword Censorship of Instant Messaging Programs (and Work in Progress). CERI Summer Seminar Series, Sandia National Laboratories. Albuquerque, New Mexico. May 2012. (slides)
Invited talk. Jeffrey Knockel. Chinese Keyword Censorship of Instant Messaging Programs. IEEE Annual Computer Communications Workshop. Hyannis, Cape Cod, Massachusetts. October 2011. (slides) (TOM-Skype data) (Sina UC data)

Teaching

CS 357 "Declarative Programming" (Spring 2010)
CS 341 "Computer Architecture" (Fall 2009)

Photo of Jeffrey Knockel atop Wheeler Peak (New Mexico)

Other

What keywords trigger TOM-Skype censorship and surveillance? (~~updated daily~~ TOM-Skype has been discontinued by TOM Online)
What keywords trigger Sina UC censorship? (~~updated daily~~ Sina UC has been discontinued by Sina)
How does SafeConnect network access control (NAC) software open your machine to attacks?
Some old malware analysis tools