In an article published on its official WeChat account on Monday, the bureau said forensic firm Beijing Wangshendongjian Technology Co Ltd had “broken through the technical difficulties of tracing anonymous AirDrops”.
The firm “prevented the further spread and potential bad influence of inappropriate speech” on the Beijing subway, when a passenger’s iPhone received an unacceptable video via AirDrop, the bureau said.
The file-sharing service allows Apple device users to share files with nearby users via Wi-fi or Bluetooth without revealing their identity. It was used during protests against strict Covid-19 restrictions in 2022, as well as in Hong Kong’s 2019 unrest.
“Due to the anonymity of AirDrop and the difficulty of tracking it, some netizens have already started to follow this behaviour, so the source of the transmission must be identified as soon as possible to avoid bad influence,” the article said.
Apple’s AirDrop in focus as China moves to restrict ‘short-range’ file-sharing
Apple’s AirDrop in focus as China moves to restrict ‘short-range’ file-sharing
Because the feature could be used without an internet connection, it was difficult for police to regulate “through conventional internet surveillance means”, it said.
The bureau did not specify when the incident occurred, but said Wangshendongjian analysed the iPhone’s logs and found the sender’s mobile number and email address in the form of hash values, some of them hidden.
Wangshendongjian then used a “rainbow table” of cracked passwords to decode enough information from the files to help police “identify several suspects”, according to the article.
The company, a subsidiary of cybersecurity firm Qi An Xin Technology Group Inc (QAX), had handled 850 investigations since its founding in 2020, mostly for “public security clients and criminal cases”, the article said.
The parent company did not immediately respond to a request for comment from the South China Morning Post.
QAX’s website, as well as mainland media reports, indicate that the company provides services to police in several provinces. Wangshendongjian belongs to a division that focuses on research into forensic techniques for electronic devices.
China’s internet watchdog to boost tip-offs to stamp out ‘illegal’ content
China’s internet watchdog to boost tip-offs to stamp out ‘illegal’ content
The parent company had a total revenue of 6.2 billion yuan (US$868 million) in 2022 and “ranks first in the industry in terms of staff size, revenue scale and product coverage”, according to its website.
Apple updated its operating system in November 2022, imposing a 10-minute limit on the sharing of AirDrop content on all iPhones sold in mainland China, weeks after the service was used to share pictures from a protest in Beijing.
The company did not explain the reason for the update, which appeared to be aimed at preventing Chinese iPhone users from bypassing the country’s strict internet censorship rules.
In July 2023, the Cyberspace Administration of China – the top internet watchdog – introduced a draft regulation aimed at further restricting the use of AirDrop to “safeguard national security”.
