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Comment by ajross | Hacker News Reader

That does nothing but start an arms race. Fine, audio "works" but do you get noise? Can you read back the sounds you play? No, right? It doesn't work, QED. Now the platform needs to fake the noise.

Likewise for any other hardware access you want, and most of them are harder. How do you fake local storage without storing anything? How do you fake Bluetooth access without virtualizing an entire device? Do you fake the screen dimensions to look like something else? Input latency? Where does it stop?

No, "does this work" is among the easiest questions to answer in technology. We aren't going to win this war.

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> Can you read back the sounds you play?

No, but you also can’t do that if the user approves your app’s permission to play audio, but has the volume permanently turned down to zero.

> local storage

Give the app a temporary, space-constrained store that isn’t shared with other apps.

> bluetooth

Don’t let apps access raw bluetooth signals, but instead ask the platform to display a pairing interface (possibly with a custom stylesheet), ask the platform to call you back when a specific device is in range, etc.

> screen dimensions

Not personal data.

> input latency

Fudge the numbers even when the user grants permission.

This isn’t a war, it’s just engineering for the benefit and autonomy of the user, and not the platforms’ commercial interests.

> This isn’t a war

Fingerprinting and other quasi-malware techniques being used by desirable third party software are absolutely a war, otherwise we wouldn't have this permission structure in place in the first place. And as much as you believe the contrary, Alibaba et. al. are 100% smarter than you about how to exploit these tricks and will win.

> Not personal data.

LOL

I don’t appreciate the personal attack. You don’t know me.

Permissions have nothing to do with preventing fingerprinting, they have to do with user control. Every permission you add that the app can inspect is one extra bit of fingerprint, so it’s actually worse.

In TFA’s case, if the app was simply not hooked up to an actual audio sink, they would still be able to use this mechanism for fingerprinting, since it’s the processing pipeline itself that leaves the fingerprint.

Note that the article isn’t calling out for fingerprinting specifically. I’m sure AliExpress does more fingerprinting than this. The problem is specifically that they’re interfering with multipoint Bluetooth audio.

The best you can do on the modern web is reduce your fingerprint footprint, though it comes at a cost of websites breaking from JS disabling, or local time zone anonymisation.

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