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.
本报告延续上一篇针对微信朋友圈图片过滤技术的研究，分析微信如何在聊天功能中实现实时图片过滤。微信是中国腾讯控股有限公司旗下的即时通讯应用，目前是中国最受欢迎的聊天软件之一，也是全球排名第四的最流行聊天软件。朋友圈是微信上最常用的功能之一，其中图片是用户最期望看到的内容分享形式。
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.
In the days leading up to the 30th anniversary of June 4 1989, YY, a popular live streaming platform in mainland China, updated its keyword blacklists with content focused on Democracy Movement related memorials and activism in Hong Kong.
加拿大多伦多大学公民实验室（Citizen Lab）研究了微信和微博针对刘晓波逝世的信息审查，初步分析显示，在刘晓波去世後审查力度大幅增加，以至于任何对刘晓波的讨论乃至简单提及也不被允许.
WeChat and Sina Weibo adapted and evolved their censorship efforts in response to the death of Liu Xiaobo.
