Android 5 static bluetooth MAC address for BLE advertising

Question

Android 5 introduces BLE MAC address rotating for increased privacy. Every time when calling BluetoothLeAdvertiser.startAdvertising(), the MAC-address is changed.

Is it possible to disable address rotating, and just use the same MAC address during the entire lifetime of BluetoothLeAdvertiser?

Answer 1

The MAC Address is a physical address and does not change. In BLE terminology, it is the Public Device Address or BD_ADDR for BR/EDR. I haven't tried it, but reading it with readAddress() should return the same value each time.

What the Android's BLE framework does is NOT use that address when advertising. It rather enables privacy by using Private Resolvable Addresses which may change every few minutes or so but still allow bonded devices to recognize it using the IRK exchanged at bonding.

For obvious privacy reasons, Android's BLE framework does not allow you to set the Controller to use the public address when advertising. So you cannot disable the "address rotating".

Answer 2

You can disable the BLE Privacy Feature to avoid the MAC address rotating, and change the bluedroid source code as follows:

http://androidxref.com/5.1.1_r6/xref/external/bluetooth/bluedroid/include/bt_target.h#1326

    * Toggles support for general LE privacy features such as remote address
    * resolution, local address rotation etc.
    */

    #ifndef BLE_PRIVACY_SPT 
    -#define BLE_PRIVACY_SPT         TRUE
    +#define BLE_PRIVACY_SPT         FLASE
    #endif