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I've noticed that there are two types of wireless headphones / headsets / earbuds on the market – bluetooth and 2.4 GHz wireless (via proprietary dongles). Good example of headset that has both – bluetooth and 2.4 GHz connectivity are newly made Sony Inzone H7 and H9 models.

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If I understand it correctly, bluetooth headphones use an encrypted protocol which complicates eavesdropping by strangers.

But when it comes to 2.4 GHz wireless headphones they are operating like radio and have no encryption at all? On top of that they often have much longer distance range (100m and further). Does it actually mean that anyone in that huge range can listen to the user's phone calls, hear youtube clips that user is watching etc (occasionally by interfering the same frequency or by doing it on purpose)?

I'm assuming this because I've had Sony MDR-RF895RK wireless headphones that I was using with my TV. And while I was watching TV, there were cases when I was able to hear dialogues of people who use walkie-talkies as well as audio from TVs of my neighbours. Which is quite scary, cause my phone calls can be exposed the same way.

I'm not sure if Inzone headsets (H7 and H9) mentioned above work the same way as Sony MDR-RF895RK that I have experience with, but I found out that they use a Sony Group USB Transceiver YY2965 FCC ID AK8YY2965 dongle. And so far I didn't manage to find any specification of encryption being implemented with this dongle.

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    Bluetooth is encrypted. Proprietary protocols are up to the vendor. Unless someone here did some reversing, nobody but the vendor knows if they are secure. Note that even ordinary wired headsets are vulnerable to radio emission (see: Tempest). Finally, the fact that you can pick up other people's clear signals doesn't mean your signal is in clear. Jan 4, 2023 at 9:56
  • That comment should be reposted as answer, @MargaretBloom
    – vidarlo
    Jan 4, 2023 at 13:59

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Bluetooth MAY be encrypted. There are unencrypted modes of both classic bluetooth and BLE which would expose one's audio streams. Let us also not forget that custom BLE profiles may be used however the OEM intends and with whatever security levels they see fit. So it's possible Sony has implemented a completely insecure way to transmit the audio over Bluetooth or BLE. To end this sky is falling speech, well used BLE is secure against eavesdropping.

Custom 2.4Ghz protocols are an even bigger question mark. Literally anything can be done. It very well might be encrypted but if the keys are common between devices, it's useless. Or if there is some underlying issue in the use of crypto it may be easily circumventable. But I guess that falls under the heading of a skilled attacker and may not be in your threat model.

Only Sony engineers and any independent researchers knows exactly how secure the protocol is. One could relatively easily become one of those researchers with off the shelf tools if one is interested (auditing Bluetooth or BLE modes used using special USB tools).

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