WeChat communications conducted entirely among non-China-registered accounts are subject to pervasive content surveillance that was previously thought to be exclusively reserved for China-registered accounts.

This document provides a high-level introduction to deep packet inspection, Internet filtering, and targeted intrusion dual-use technologies with the aim of familizaring the reader with their key technical features, the surrounding international human rights law framework, and some of the leading research to date on their deployment.

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.

今年是中国1989年天安门民主运动的30周年纪念。当年，学生自发举行一系列游行示威，呼吁实施民主改革，中共领导人则选择使用武力镇压运动。中国红十字会称有2700名民众在武力镇压中身亡，但有不少研究机构指出死伤人数远不止这个。在2014年解密的一份美国政府机密文件显示，中国内部统计的死亡人数达10,454人。