Even if a smartphone is offline, in flight mode, encrypted or locked, Chinese authorities could still be able to determine which apps are being used by analysing faint electromagnetic signals emitted as the device operates.
Researchers at the People’s Public Security University of China have developed a method that identifies smartphone applications and user actions through low-frequency electromagnetic radiation.
In their findings published in the peer-reviewed journal Radioengineering on May 22, the researchers described it as a non-contact forensic technique that worked without accessing a phone’s operating system or stored data.
“This technical approach can provide objective technical corroboration for evidence reinforcement in digital forensics and non-contact investigations,” the authors wrote.
According to the paper, the researchers tested the system on three smartphones: an iPhone 15 Pro, Xiaomi 15 Pro and Oppo Reno 13.
