Comment by lxgr
8 months ago
How would an open implementation be compatible with this, given that Apple's implementation is based on an Apple-operated PKI?
Note that this is only a conversation about sender identification, which allows sending to a "non-world-visible" receiving device and confirmation-less sending to devices with the same iCloud account on them. Anonymous sending isn't cryptographically gated by Apple, to my knowledge.
Their documentation suggests that is only needed by contacts only mode and they wrote some code to get the needed certificates from macOS:
https://github.com/seemoo-lab/airdrop-keychain-extractor
That still requires you to have (access to) a Mac and an iCloud account.
It might be possible to reimplement the required Apple API, but as demonstrated by the iMessage/Beeper saga, they usually shut such things down pretty quickly.