Suppose I have a smartphone and I have disabled all usual de-anonymizing things (e.g., wifi probe requests). My phone sends some data over Bluetooth (or NFC) to device A, and then at a different place and time, sends entirely independent data to device B.

If the owners of device A and B compare these two connections, can they conclude that it was the same device?

1 Answer 1


Not anonymous. Yes, connected devices could compare hardware. Using the Bluetooth Address:

Every single Bluetooth device has a unique 48-bit address, commonly abbreviated BD_ADDR. This will usually be presented in the form of a 12-digit hexadecimal value.

  • It is indeed likely that this could be used to make a comparison to break the anonymity. On the other hand, framing would be possible by spoofing the BD_ADDR, leaving room for plausible deniability. Aug 4 at 18:51
  • Yes, it is possible to break the comparison (the second link suggests that that is true), but it is also possible that without a specific effort on the part of the device user, that the comparison can be made.
    – schroeder
    Aug 5 at 17:36

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