Embedding blind watermark in Zhihu response screenshot: experimental function test, has been offline

CTOnews.com, Sept. 8, recently, Zhihu was exposed to embedding blind watermarks in user screenshots on App and web pages. Blind watermarks are difficult to distinguish with the naked eye and can only be seen under specific image display effects. After testing by testing tools, netizens found that blind watermarks suspected to include user UID and other information.

In response, Zhihu said that recently, the station conducted an experimental function test on a small scale, and the experimental function has been offline after a short period of testing, thepaper.cn reported. However, Zhihu did not explain the purpose behind testing the function.

CTOnews.com learned that in February this year, Douban App also sparked a heated discussion by setting a blind watermark for user screenshots. In response, Douban said that this is a new "team content anti-moving function". The team leader can turn on or off "team Management-Group content Anti-removal Settings". When the team content is opened, the encrypted screenshot user ID, screenshot post ID, screenshot time and other information will be automatically generated on the screenshot. For groups that have enabled this feature, you can see the prompt "the content is from the xxx team, which has turned on the anti-handling function" at the bottom of the group post. It is understood that some enterprises will also set screenshot blind watermarks on the intranet to prevent employees from divulging internal information.

According to the 21st Century Economic report, some experts said that the main purpose of using blind watermarking on relevant platforms is to make the information traceable and to facilitate accountability in the event of problems, but the platform should fully protect users' right to know, make corresponding disclosure obligations before launching the function, and take good measures to protect data security and personal information.