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I'd like to buy a wireless bluetooth headset to not disturbing others by my TV sound but I'm wondering how private the transmission will be?

Can a neighbour with a bluetooth headset hear my TV's bluetooth emission through a wooden wall? If so, how can I avoid it?

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    This depends entirely on the version of Bluetooth being used. Also, even if it is a secure version, some side-channel information leaks due to data transmission sizes and timing. This allows things like simple phrases to be picked up, despite encryption. If you're just worried about them realizing you're watching porn or something, you really have nothing to worry about. – forest Apr 24 at 6:49
  • So which versions of bluetooth ARE scure? And why shouldn't I be worried about being eavesdropped? – Milkyway Apr 24 at 6:54
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    There are multiple versions and each one has different security properties. And why should you be? I'm not trying to imply that privacy is only necessary for people doing something wrong, but that certain threats aren't necessarily realistic. For example, do you worry about your neighbor sticking his ear against the window straining to listen to every conversation you have? That's significantly easier (and more likely) than someone cryptographically attacking Bluetooth just to find out what TV station you're on... – forest Apr 24 at 7:07
  • Are you purely asking about the signals (whether they can reach the neighbor, and how you can stop them from reaching through the wall), or whether your neighbor might be able to decrypt Bluetooth? Because there are a lot of good questions tagged with bluetooth that answer the question of bluetooth security. If it's just about the transmissions, please clarify the title of the question, for example "... my bluetooth headset's radio transmissions?" – Luc Apr 24 at 7:54
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Can a neighbour with a bluetooth headset hear my TV's bluetooth emission through a wooden wall?

If you're asking about if the signal can get through, then the answer is yes. To block a bluetooth signal you'd need very thick and dense walls (something like thick concrete walls) or something that acts as a Faraday cage.

Usually bluetooth transmissions are encrypted by default, the security on this mainly relies on the pairing method.

But as forest commented, you shouldn't be worried about anything. Statistically speaking I think that it's quite unlikely that your neighbour would have the cryptographic expertise to hear your transmissions.

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    -1: You can't know if OPs neighbor is an expert in cryptography. /s – MechMK1 Apr 24 at 8:07
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    I meant statistically speaking it's probably unlikely. Added it to my answer. – AleksanderRas Apr 24 at 8:14
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In August 2019 information about a Key Negotiation of Bluetooth (KNOB) Attack was published.

At this point it's best to assume that all of your Bluetooth devices are unsafe, unless you upgraded firmware in 2019:

After we disclosed our attack to industry in late 2018, some vendors might have implemented workarounds for the vulnerability on their devices. So the short answer is: if your device was not updated after late 2018, it is likely vulnerable. Devices updated afterwards might be fixed.

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