NEW: Free and Open Communications on the Internet (FOCI) 2025 call for papers is up, Issue 1 submission deadline: November 8, 2024.
I'm fighting to defend our safety and freedom online.
I use novel techniques to uncover harmful software behavior.
I reveal applications’ secret censorship rules and hidden surveillance activity, and I expose how gaps in applications’ security put the safety and privacy of our data in jeopardy.
I defended my dissertation in Computer Science in 2017, and I'm now a Senior Research Associate at the Citizen Lab.
Jeffrey Knockel, Mona Wang, and Zoë Reichert. The Not-So-Silent Type: Vulnerabilities in Chinese IME Keyboards’ Network Security Protocols. In the Proceedings of the 2024 ACM Conference on Computer and Communications Security (CCS 2024). Salt Lake City, Utah. October 2024.
(paper)(slides)
Mona Wang, Pellaeon Lin, and Jeffrey Knockel. Should We Chat, Too? Security Analysis of WeChat’s MMTLS Encryption Protocol. The Citizen Lab. October 2024.
(report)(The Register)
Benjamin Mixon-Baca, Jeffrey Knockel, Diwen Xue, Tarun Ayyagari, Deepak Kapur, Roya Ensafi, and Jedidiah R. Crandall. Attacking Connection Tracking Frameworks as used by Virtual Private Networks. In the Proceedings on Privacy Enhancing Technologies and at the PETS Symposium (PETS 2024). Bristol, United Kingdom. July, 2024.
(paper)(PC Magazine)
Samuel Ruo, Jeffrey Knockel, and Zoë Reichert. Lost in Translation: Characterizing Automated Censorship in Online Translation Services. In the Proceedings of the 2024 Workshop on Free and Open Communications on the Internet (FOCI 2024).
Bristol, United Kingdom. July 2024.
(paper)(slides)(Rest of World)
Beau Kujath, Jeffrey Knockel, Paul Aguilar, Diego Morabito, Masashi Crete-Nishihata, and Jedidiah R. Crandall. Analyzing Prominent Mobile Apps in Latin America. In the Proceedings of the 2024 Workshop on Free and Open Communications on the Internet (FOCI 2024).
Bristol, United Kingdom. July 2024.
(paper)
Mohamed Ahmed and Jeffrey Knockel. Extended Abstract: The Impact of Online Censorship on LLMs. In the Proceedings of the 2024 Workshop on Free and Open Communications on the Internet (FOCI 2024).
Bristol, United Kingdom. July 2024.
(paper)
Jeffrey Knockel and Emile Dirks. Chinese censorship following the death
of Li Keqiang. The Citizen Lab. November 2023.
(report)(Radio-Canada [2])
Jeffrey Knockel, Zoë Reichert, and Mona Wang. “Please do not
make it public”: Vulnerabilities in Sogou Keyboard encryption expose
keypresses to network eavesdropping. The Citizen Lab. August
2023.
(report)(MIT Tech Review,SCMP,The Record)
Jeffrey Knockel, Jakub Dalek, Levi Meletti, and Ksenia Ermoshina.
Not OK on VK: An Analysis of In-Platform Censorship on Russia’s
VKontakte. The Citizen Lab. July 2023.
(report)(NYTimes,Roskomsvoboda,Gizmodo,Cybernews)
Mona Wang, Pellaeon Lin, and Jeffrey Knockel. Should We Chat?
Privacy in the WeChat Ecosystem. The Citizen Lab. June
2023.
(report)
Jeffrey Knockel, Ken Kato, and Emile Dirks. Missing Links: A
comparison of search censorship in China. The Citizen Lab.
April 2023.
(report)(NYTimes,SCMP,IBT)
2022
Jeffrey Knockel and Lotus Ruan. Bada Bing, Bada Boom:
Microsoft Bing’s Chinese Political Censorship of Autosuggestions in
North America. The Citizen Lab. May 2022.
(report)(WSJ,VICE,Protocol,Bloomberg [2])
Jeffrey Knockel and Lotus Ruan. Engrave Condition: Apple’s
Political Censorship Leaves Taiwan, Remains in Hong Kong.
The Citizen Lab. March 2022.
(report)(The Register)
Jeffrey Knockel and Lotus Ruan. Measuring QQMail’s automated
email censorship in China. In the Proceedings of the 11th Workshop on Free and
Open Communications on the Internet (FOCI 2021).
Virtual Event. August 2021.
(paper,slides)
Nguyen Phong Hoang, Arian Akhavan Niaki, Jakub Dalek, Jeffrey
Knockel, Pellaeon Lin, Bill Marczak, Masashi Crete-Nishihata, Phillipa
Gill, and Michalis Polychronakis. How Great is the Great
Firewall? Measuring China’s DNS Censorship. In the Proceedings of the Proceedings
of the 30th USENIX Security Symposium (USENIX Security
2021). August 2021.
(paper)
In May 2021, I published an interactive Lennon Wall comprised of 5,487 images censored by Tencent relating to the Hong Kong Anti-Extradition Law Protests, which I also have a demo of below. Click or tap a tile in the mosaic below to view the censored image full screen!
Please enable Javascript to try the demo!
2020
Pellaeon Lin, Jeffrey Knockel, Irene Poetranto, Stephanie Tran,
Justin Lau, and Ron Deibert. Unmasked II: An Analysis of
Indonesia and the Philippines’ Government-launched COVID-19
Apps. The Citizen Lab. December 2020.
(report)
Pellaeon Lin, Jeffrey Knockel, Adam Senft, Irene Poetranto, Stephanie
Tran, and Ron Deibert. Unmasked: COVID-KAYA and the Exposure of
Healthcare Worker Data in the Philippines. The Citizen Lab.
November 2020.
(report)(Spiegel,CyberScoop,Manila Bulletin,philstar)
Lotus Ruan, Jeffrey Knockel, and Masashi Crete-Nishihata.
Information control by public punishment: The logic of
signalling repression in China. In China Information 35, no. 2
(2021): 133-157. October 2020.
(paper)
Jeffrey Knockel and Lotus Ruan. Evacuate, capitulate, or
segregate: Classifying how Internet platforms operate in China and the
corresponding consequences to user safety. Presented in the
Borders, Bordering and Sovereignty in Digital Space Symposium (conducted
in lieu of cancelled sessions of RGS 2020). September 2020.
Masashi Crete-Nishihata, Jakub Dalek, Jeffrey Knockel, Nicola Lawford, Caroline Wesley, and Mari Zhou.
Censored Contagion II: A Timeline of Information Control on Chinese Social Media During COVID-19. The Citizen Lab. August 2020.
(report)(NYTimes)
Lotus Ruan, Masashi Crete-Nishihata, Jeffrey Knockel, Ruohan Xiong,
and Jakub Dalek. The Intermingling of State and Private
Companies: Analysing Censorship of the 19th National Communist Party
Congress on WeChat. In the China Quarterly 246 (2021): 497-526.
July 2020.
(paper)
Jeffrey Knockel, Christopher Parsons, Lotus Ruan, Ruohan Xiong,
Jedidiah Crandall, and Ron Deibert. We Chat, They Watch: How
international users unwittingly build up WeChat’s Chinese censorship
apparatus. The Citizen Lab. May 2020.
(report)(WSJ,WaPo [2],SCMP,FT,CBC,NYTimes,AP,Globe and Mail [2])
Lotus Ruan, Jeffrey Knockel, and Masashi Crete-Nishihata.
Censored Contagion: How Information on the Coronavirus is Managed on Chinese Social Media. The Citizen Lab. March 2020.
(report)(Guardian,BBC,Business Insider,Newsweek,FT,The Verge,HKFP)
2019
Ruohan Xiong and Jeffrey Knockel. An Efficient Method to
Determine which Combination of Keywords Triggered Automatic Filtering of
a Message. In the Proceedings of the 9th USENIX Workshop on Free and Open
Communications on the Internet (FOCI 2019). Santa
Clara, California. August 2019.
(paper)
Christopher Parsons, Adam Molnar, Jakub Dalek, Jeffrey Knockel, Miles
Kenyon, Bennett Haselton, Cynthia Khoo, and Ron Deibert. The
Predator in Your Pocket: A Multidisciplinary Assessment of the
Stalkerware Application Industry. The Citizen Lab. June
2019.
(report)
Lotus Ruan, Masashi Crete-Nishihata, Jeffrey Knockel, and Ruohan
Xiong. Censored Commemoration: Chinese Live Streaming Platform
YY Focuses Censorship on June 4 Memorials and Activism in Hong
Kong. The Citizen Lab. June 2019.
(report)
2018
Jeffrey Knockel, Masashi Crete-Nishihata, and Lotus Ruan. The
effect of information controls on developers in China: An analysis of
censorship in Chinese open source projects. In the Proceedings of the Workshop on NLP for Internet Freedom (NLP4IF 2018). Santa Fe, New
Mexico. August 2018.
(paper)
Jeffrey Knockel, Lotus Ruan, and Masashi Crete-Nishihata. An
analysis of automatic image filtering on WeChat Moments. In the Proceedings of the 8th USENIX Workshop on Free and Open Communications on the Internet
(FOCI 2018). Baltimore, Maryland. August 2018.
(paper,slides)
Jeffrey Knockel, Lotus Ruan, Masashi Crete-Nishihata, and Ron
Deibert. (Can’t) Picture This: An Analysis of Image Filtering on
WeChat Moments. The Citizen Lab. August 2018.
(report)(Quartz,Boing Boing [2],ABC,The Verge)
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. The Citizen Lab. November 2017.
(report)
Jeffrey Knockel, Lotus Ruan, and Masashi Crete-Nishihata.
Measuring Decentralization of Chinese Keyword Censorship
via Mobile Games. In the Proceedings of the 7th USENIX
Workshop on Free and Open Communications on the Internet (FOCI
2017). Vancouver, British Columbia. August 2017.
(paper,slides)(Heise)
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. The Citizen Lab. July 2017.
(report)(NYTimes,New Yorker,WSJ,Guardian,Bloomberg [2],AP,CNN,Telegraph,CNBC,SCMP,DW)
Lotus Ruan, Jeffrey Knockel, and Masashi Crete-Nishihata.
We (can’t) Chat: “709 Crackdown” Discussions Blocked on Weibo and WeChat. The Citizen Lab. April 2017.
(report)(Globe and Mail,SCMP,Quartz,The Verge)
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.
(paper)
Masashi Crete-Nishihata, Jeffrey Knockel, and Lotus Ruan.
Tibetans blocked from Kalachakra at borders and on WeChat. The Citizen Lab. January 2017.
(report)(Phayul,VOA Tibetan)
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. The Citizen Lab. November 2016.
(report)(Bloomberg,Reuters,WSJ,Globe and Mail,Quartz,WaPo)
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 the 2016 IEEE Global Communications Conference (GLOBECOM 2016). Washington D.C., USA. December 2016.
(paper)
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.
(paper)
Jeffrey Knockel, Adam Senft, and Ron Deibert. Privacy and Security
Issues in BAT Web Browsers. In the Proceedings of the 6th USENIX
Workshop on Free and Open Communications on the Internet (FOCI
2016). Austin, Texas. August 2016.
(paper,slides)
Jeffrey Knockel, Adam Senft, and Ron Deibert. A Tough Nut to Crack: A Further Look at Privacy and Security Issues in UC Browser. The Citizen Lab. August 2016.
(report)
Jeffrey Knockel, Adam Senft, and Ron Deibert. WUP! There It Is: Privacy and Security Issues in QQ Browser. The Citizen Lab. March 2016.
(report)(WSJ,WaPo,CNN,Fortune,Globe and Mail,IBT,VICE,RCI)
Andrew Hilts, Christopher Parsons, and Jeffrey Knockel. Every Step You Fake: A Comparative Analysis of Fitness Tracker Privacy and Security. Open Effect. February 2016.
(paper)(CBC,Global News,CTV,PC Magazine)
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.
(paper,slides)(Bloomberg [2])
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.
(paper)
Xu Zhang, Jeffrey Knockel, and Jedidiah R. Crandall. Original SYN: Finding Machines Hidden Behind Firewalls. In the Proceedings of the 2015 IEEE Conference on Computer Communications (INFOCOM 2015). Hong Kong, China. April 2015.
(paper)
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.
(paper,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.
(paper)
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.
(paper)
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.
(paper)(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.
(paper,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.
(paper)
Submitted talk. The not-so-silent type:
Breaking network crypto in almost every popular
Chinese keyboard app. HITCON 24. Taipei, Taiwan. August 2024.
(slides)
Submitted talk. The not-so-silent type:
Breaking network crypto in almost every popular
Chinese keyboard app. DEF CON 32. Las Vegas, Nevada. August 2024.
(slides)
Submitted talk. Protecting the network traffic of one billion people:
Reverse-engineering proprietary cryptography in popular
Chinese apps. HOPE XV. New York, New York. July 2024.
(slides)
Submitted talk. Evading geoblocking:
A possible application of QUIC connection migration. CITP Workshop on QUIC and Privacy. Princeton, New Jersey. April 2023.
(slides)
Invited talk. Managing the Message: How information is controlled in Chinese instant messaging apps. NATO Stratcom Center of Excellence. Riga, Latvia. March 2019.
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.
(notes)
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 (CCW 2011). Hyannis, Cape Cod, Massachusetts. October 2011.
(slides)(TOM-Skype data)(Sina UC data)
paper)
(
report)
(
The Register)
PC Magazine)
Rest of World)
DEF CON 32 slides,
HOPE XV slides)
(
MIT Tech Review,
Heise,
IEEE Spectrum,
SOHU)
Radio-Canada [2])
SCMP,
The Record)
NYTimes,
Roskomsvoboda,
Gizmodo,
Cybernews)
IBT)
WSJ,
VICE,
Protocol,
Bloomberg [2])
WaPo,
BBC,
DW,
Reuters,
Globe and Mail,
The Verge,
Business Insider,
Independent)
Spiegel,
CyberScoop,
Manila Bulletin,
philstar)
FT,
AP,
Guardian,
Newsweek,
HKFP)
Quartz,
Boing Boing,
ABC,
New Yorker,
CNN,
Telegraph,
CNBC,
Phayul,
VOA Tibetan)
Fortune,
Slate,
Global News,
CTV,
paper)
(
data & visualizations)
NPR (On the Media),
TechSpot,
Computerworld,
ZDNet)
