Feeds

Gone in 30 minutes: Chinese tweets purged by army of censors

New report claims thousands of censors could be working for Sina Weibo

Securing Web Applications Made Simple and Scalable

The murky world of online self-censorship in China has come under the spotlight again in a new report which estimates that most post deletions on the Twitter-like Sina Weibo occur within the first 30 minutes of appearing.

The Velocity of Censorship: High-Fidelity Detection of Microblog Post Deletions, was researched by academics at Bowdoin College, Rice University and the University of New Mexico alongside independent researcher Tao Zhu(h/t MIT Technology Review).

Sina claims its service has over 500 million users, but for the purposes of this research the team concentrated on the posts of around 3,500 “sensitive” users with a track record of censorship.

Developing a system “which collects removed posts on targeted users in almost real time”, the researchers found that roughly 12 per cent of posts were deleted over the 15 day monitoring period – which amounts to more than 4,500 every day.

The research included the following observation(PDF):

Our research found that deletions happen most heavily in the first hour after a post has been made. Especially for original posts that are not reposts, most deletions occur within 5-30 minutes, accounting for 25 per cent of the total deletions of such posts. Nearly 90 per cent of the deletions of such posts happen within the first 24 hours of the post.

To enable such speedy censorship, the report claims a mixture of technical and non-technical filtering is used, with potentially thousands of staff employed to eyeball content, as per the following hypothesis:

The deletions happen most heavily for a regular post within 5 to 10 minutes of it being posted. Suppose an efficient worker can read 50 posts per minute, including the reposts and figures included in the posts. Then to read Weibo’s full 70,000 new posts in one minute, 1,400 workers working at the same time would be needed. If these workers only worked in 8 hour shifts, 4,200 workers would then be required.

Proactive keyword filtering blocks certain posts before they have gone live, or holds them for human review, while a range of retroactive mechanisms including backwards keyword and repost searches, public timeline filtering and monitoring of specific censorship-prone individuals were also highlighted in the report.

The research also hypothesises that the censors work “relatively independently, in a distributed fashion”, with activity only really dipping between around 1-7am and again slightly at 7pm – which the report authors claim could be due to the national TV news programme broadcast at that time.

Although the report casts new light on the speed and accuracy of China’s web censors, it doesn’t explain why more isn’t done to block potentially illegal content before it is even posted.

One possible answer came from Sina Weibo manager @geniune_Yu_Yang (正版于洋), who – apparently frustrated by user anger directed at the company’s army of censors - wrote an illuminating post of his own back in January.

He effectively argued that Sina is trying to work around the strict regulations forced upon it by government, by at least letting users see and disseminate their content for a few minutes before it is deleted.

He wrote:

You can see the messages before they are deleted, right? You still have your account functioning, right? You are all experienced netizens, you know that the technology allows us to delete messages in a second. Please think carefully on this.

Now, there is no way of proving whether this manager was engaging in a crafty piece of well-timed PR or if there’s some truth to his claims.

Somewhat ironically, his post too was deleted, which illustrates perfectly the central problem with censorship of this kind: there's no way of telling whether a piece of content is deleted because it was true, or because it wasn't. ®

The smart choice: opportunity from uncertainty

More from The Register

next story
Yorkshire cops fail to grasp principle behind BT Fon Wi-Fi network
'Prevent people that are passing by to hook up to your network', pleads plod
UK government officially adopts Open Document Format
Microsoft insurgency fails, earns snarky remark from UK digital services head
Major problems beset UK ISP filth filters: But it's OK, nobody uses them
It's almost as though pr0n was actually rather popular
HP, Microsoft prove it again: Big Business doesn't create jobs
SMEs get lip service - what they need is dinner at the Club
ITC: Seagate and LSI can infringe Realtek patents because Realtek isn't in the US
Land of the (get off scot) free, when it's a foreign owner
MPs wave through Blighty's 'EMERGENCY' surveillance laws
Only 49 politcos voted against DRIP bill
Help yourself to anyone's photos FOR FREE, suggests UK.gov
Copyright law reforms will keep m'learned friends busy
EU's top data cops to meet Google, Microsoft et al over 'right to be forgotten'
Plan to hammer out 'coherent' guidelines. Good luck chaps!
prev story

Whitepapers

Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Reducing security risks from open source software
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.