Jeffrey Knockel


Engrave Danger: An Analysis of Apple Engraving Censorship across Six Regions

Within mainland China, we found that Apple censors political content including broad references to Chinese leadership and China’s political system, names of dissidents and independent news organizations, and general terms relating to religions, democracy, and human rights. And across all six regions, we found that Apple’s content moderation practices pertaining to derogatory, racist, or sexual content are inconsistently applied and that Apple’s public-facing documents failed to explain how it derives their keyword lists.

Unmasked: COVID-KAYA and the Exposure of Healthcare Worker Data in the Philippines

COVID-KAYA, a platform used by frontline healthcare workers in the Philippines to collect and share COVID-19 cases with the Philippines Department of Health, contained vulnerabilities in both the web and Android apps that allows for unauthorized users to access private data about the app’s users, and potentially patient data.

“未阅先焚” 2: 微信如何实现实时审查用户对话中的敏感图片


(Can’t) Picture This 2: An Analysis of WeChat’s Realtime Image Filtering in Chats

In this work, we study how Tencent implements image filtering on WeChat. We found that Tencent implements realtime, automatic censorship of chat images on WeChat based on what text is in an image and based on an image’s visual similarity to those on a blacklist. Tencent facilitates this realtime filtering by maintaining a hash index of MD5 hashes of sensitive image files.