3 ms·

I get an alert every time I ride my wife’s bicycle. It would be nice to be able to mark her tags as ok to be near me.

closetohome 5y ago
Being able to share AirTags via a family iCloud account seems to be a pretty commonly requested feature. It does seem a little silly that I can track every device attached to the account but not AirTags.
- ssully 5y ago
  Even outside of family. I would buy an airtag for my dog for when my friend watches them. It'd be nice to drop off my dog and "share airtag with this user" so they can have a resource in case my dog got lost.
- dwaite 5y ago
  I suspect they are working on it, but the crypto is privacy-preserving enough to make centralized authorization management hard. Specifically, you get a cryptographic secret when you pair the key, it broadcasts as a bluetooth beacon with encrypted messages based on that secret and current time, that get reported up to an Apple service. When you want to see your accessories, your device will compute the encrypted messages at appropriate times and have apple search for them. However, there's no network push to an AirTag available to tell it to rotate keys. You could grant more people to see a tag by sharing the secret - but you then could not remove that permission without physically resetting the tag. I suspect the solution will eventually be having derived keys from the secret and date, and date-based "leases" for permissions - I share the current key to allowed peers. That would mean revocation might be represented in the UX immediately, and take a day (or some other time period) to actually start to fail cryptographically.
  - olliej 5y ago
    I do think it should be possible to share encryption keys (ignore this MAC alas doesn’t work because the MACs and randomized and rotate fairly frequently when in the vicinity of an owner’s devices)
  - dwaite 5y ago
    sorry I didn't mean the MAC address but rather an HMAC-based key derivation. I suspect they rotate MAC addresses every half hour or so, but the broadcast itself is encrypted such that you can't tell two belong to the same AirTag without knowing the secret. I might have a secret key for the AirTag, and the encrypted messages derive a new key each day based on the current date, then encrypt a check-in message based on the current time. If I share the secret key, its permanent access until a hardware reset of the AirTag. If I want to share "for a while", I just share a bag of those derived keys for the date range. The UX might represent it as not having a date range, and my devices which know the secret just periodically share out the derived keys when online to give out keys, and effectively make it so that any revocation of permission takes a week. The other option is for me to be able to share enough information with Apple's servers that (on permission change) it blocks the AirTag web service query itself. That won't help you with any shared secrets allowing someone to detect its the same tag even after MAC rotation.
- Schiendelman 5y ago
  That feature already exists. If you are sharing your device locations with your iCloud family members you won’t get the complaint notifications.
  - presentation 5y ago
    I get them pretty much everyday for my wife's Airpods despite us being on iCloud Family Sharing. Guess something's buggy.
easton 5y ago
I'd like to be able to mark my own tags as okay. My phone will NFC with the tag in my pocket, and just about every time I pull it out I have a "go to lost.apple.com?" prompt.

Being able to share AirTags via a family iCloud account seems to be a pretty commonly requested feature. It does seem a little silly that I can track every device attached to the account but not AirTags.

ssully 5y ago
Even outside of family. I would buy an airtag for my dog for when my friend watches them. It'd be nice to drop off my dog and "share airtag with this user" so they can have a resource in case my dog got lost.
dwaite 5y ago
I suspect they are working on it, but the crypto is privacy-preserving enough to make centralized authorization management hard. Specifically, you get a cryptographic secret when you pair the key, it broadcasts as a bluetooth beacon with encrypted messages based on that secret and current time, that get reported up to an Apple service. When you want to see your accessories, your device will compute the encrypted messages at appropriate times and have apple search for them. However, there's no network push to an AirTag available to tell it to rotate keys. You could grant more people to see a tag by sharing the secret - but you then could not remove that permission without physically resetting the tag. I suspect the solution will eventually be having derived keys from the secret and date, and date-based "leases" for permissions - I share the current key to allowed peers. That would mean revocation might be represented in the UX immediately, and take a day (or some other time period) to actually start to fail cryptographically.
- olliej 5y ago
  I do think it should be possible to share encryption keys (ignore this MAC alas doesn’t work because the MACs and randomized and rotate fairly frequently when in the vicinity of an owner’s devices)
- dwaite 5y ago
  sorry I didn't mean the MAC address but rather an HMAC-based key derivation. I suspect they rotate MAC addresses every half hour or so, but the broadcast itself is encrypted such that you can't tell two belong to the same AirTag without knowing the secret. I might have a secret key for the AirTag, and the encrypted messages derive a new key each day based on the current date, then encrypt a check-in message based on the current time. If I share the secret key, its permanent access until a hardware reset of the AirTag. If I want to share "for a while", I just share a bag of those derived keys for the date range. The UX might represent it as not having a date range, and my devices which know the secret just periodically share out the derived keys when online to give out keys, and effectively make it so that any revocation of permission takes a week. The other option is for me to be able to share enough information with Apple's servers that (on permission change) it blocks the AirTag web service query itself. That won't help you with any shared secrets allowing someone to detect its the same tag even after MAC rotation.
Schiendelman 5y ago
That feature already exists. If you are sharing your device locations with your iCloud family members you won’t get the complaint notifications.
- presentation 5y ago
  I get them pretty much everyday for my wife's Airpods despite us being on iCloud Family Sharing. Guess something's buggy.

easton 5y ago

I'd like to be able to mark my own tags as okay. My phone will NFC with the tag in my pocket, and just about every time I pull it out I have a "go to lost.apple.com?" prompt.