China claims to have cracked AirDrop encryption

China said it had found a way to identify senders who share content that it deems illegal via Apple’s AirDrop.

The government-linked forensics institute has developed a technique to decipher the sender’s device name, email, and phone number, the Beijing Municipal Bureau of Justice said in a statement.

It said the police had identified “multiple suspects” based on its forensics work, which involved analyzing iPhone device logs to understand the underlying principles of AirDrop transmissions.

The institute found that emails and phone numbers were stored as hash values and used a detailed rainbow table to quickly decipher them, the bureau said. Rainbow tables are typically used to crack password hashes by converting them into plain text.

The authorities said that the findings “enhance the efficiency and accuracy of case-solving” and “prevent the further spread of inappropriate content and its potential negative impact.”

The investigation was started after an iPhone user reported to the police they received an unsolicited message via AirDrop while in the Beijing subway, the bureau claimed.

“Due to the anonymity and difficulty in tracing AirDrop, some netizens began imitating this behavior,” it said, which posed a challenge to law enforcement as “regular network monitoring tools cannot effectively regulate this behavior.”

AirDrop does not require an internet connection, and messages can be shared between devices in close proximity using Bluetooth, making it particularly useful in crowded places like subways and malls.

The feature was widely used in the 2019 Hong Kong protests. In 2022, Apple restricted the use of AirDrop in China by putting a 10-minute cap on receiving files from non-contacts, which has to be turned on in advance and automatically reverses back to contacts-only once the time expires.

Apple has been facing mounting pressure in China after government officials were told to stop using iPhones at work despite past efforts of the company to placate Beijing as it seeks total control over the information space in the country.

The company was criticized for removing VPN apps from its Chinese store, and many of its own products, including Apple TV, the iTunes Store, and Apple Books, are not available in China.