A Chinese tech company has been able to crack the encryption around Apple’s Airdrop wireless file sharing function to identify people who used the feature to send “inappropriate information” in the Beijing subway, according to the city’s Justice Bureau.
No shit Sherlock. The encryption uses the phone number of the user for hashing. Building a rainbow table for all phone numbers is childsplay.
They use a weakness in the protocol to identify the senders number. They can’t see what they send, but who sent something and when and to who.
Someone correct me if I’m wrong, but it looks like there are two hashes. A short one based on the iCloud account’s email address or phone number, and a long 2048-bit RSA identity that gets stored on the device after logging into iCloud.
It looks like the short identity is basically just used for that initial airdrop screen where you find available targets to airdrop to, but the actual longer, more secure, hash is required for the actual file transfer.
That might explain why finding airdrop contacts is kind of snappy, but there is a bit of a delay after you initiate a transfer.
https://support.apple.com/guide/security/airdrop-security-sec2261183f4/web
Edit: one more thought. If this really was that easy to crack, wouldn’t China have done this years ago? The CCP has been targeting Airdrop for a long long time.
Thank you, incidentally, for contributing so much to Lemmy. You are great.
Thanks! Right back at ya!
Sounds about right. Might be they have some man in the middle shenannigans going on with permanently installed hardware in the subway, but I doubt it. That would be a race condition that you might win with a lot more signal strength, but still…