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.
This report was collaboratively written by researchers from computer science, political science, criminology, law, and journalism studies. As befits their expertise, the report is divided into several parts, with each focusing on specific aspects of the consumer spyware ecosystem, which includes: technical elements associated stalkerware applications, stalkerware companies’ marketing activities and public policies, and these companies’ compliance with Canadian federal commercial privacy legislation.