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Comment by bhauer | Hacker News Reader

> Copy/paste across iPhone and Mac is very useful.

I don't use a Mac or an iPhone, but I applaud this sort of device harmony.

That said, I am worried that it would unnecessarily leverage the cloud. My guess is that instead of the two devices directly communicating with one another—that is, instead of leveraging the fact that they are probably on the same local network and should just work in concert—the clipboard data will be sent via a cloud intermediary. That is, it will be exfiltrated from the local network, sent through Apple, and then back into the local network.

If I am wrong about that, I am happy to hear it.

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Yes, the Hand-off mechanism works without iCloud involvement or even using your active internet connection. I just tried by disabling Wifi on my Mac and opening up message to continue on a semi written message from my iPhone.

Now, there could always be a iCloud fallback that says if there is internet, just use it. Perks of using non-free software is that it will almost always non-verifiable.

> I just tried by disabling Wifi on my Mac and opening up message to continue on a semi written message from my iPhone.

How is this possible? Bluetooth? USB? Or are we talking about a previously synced draft that's still there when you turn your internet off? Sounds like a basic iCloud cache to me.

The original Continuity used bluetooth, p2p wifi (which is also what AirDrop uses), regular wifi and iCloud, some features would depend on a specific substrate but for others it could use several at the same time or switch between them.

Continuity/Handoff works over Bluetooth 4/LE.

In the presentation they said that it used Handoff, which is direct device to device communication.

This enables an interesting new kind of attack.

1. Attach an attack device to someone’s account.

2. ‘Poll’ the clipboard by pasting every ~5 seconds.

3. If the contents of the clipboard appear to be ‘secure’ (looks like shellcode, bitcoin address, url, etc), quickly replace the contents with an attack string with same datatype.

If you have an untrusted device attached to your Apple account, your local clipboard can no longer be trusted.

Indeed, WHATWG is currently considering [1] a related scenario where rogue websites with access to the clipboard will inject formats with dodgy payload to exploit flaws in some app if the user pastes.

[1] https://github.com/whatwg/html/issues/1244

It's unrelated to "apple account" it works over Bluetooth LE.

To my knowledge, existing continuity features already do one better and communicate directly between devices, not even requiring them to be on the same network. (AirDrop is a good example.) But obviously we have no way of knowing if this will be the case here, or if there is a cloud-based fallback.

P2P connections is a place that's generally terrible for mobile. You have to keep connections open to more devices, which is generally bad for battery.

You could imagine a copy/paste that waits for a message from the cloud (because Apple push notifications are pretty solid), then opens the new connection to the local device, so the data never leaves your network. At least to me, that sounds needless complex when the typical use case could just send the entire payload with the "go look for this device" message.

This sort of thing is exactly what Bluetooth Low Energy is for.

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