RE: nRF connect app's bonding feature and Random address

tesc — Thu, 11 Nov 2021 13:05:30 GMT

Hi,

There are several types of random addresses:

Static address, which must stay the same within the same power cycle. When the device is turned off and on again, it may change address.
Private addresses, of which
- Non-resolvable private adresses changes periodically and cannot be tracked, so you cannot bond with the device and then find it again later
- Resolvable private addresses, which can be resolved by any bonded peer

The nRF Connect smartphone app is compatible with all address types. Please note that if the address of the device changes it will no longer be recognized by other devices. The only exception is if it uses resolvable private addresses, in which case bonded peers (that have stored the Identity Resolving Key (IRK) of the device) will be able to identify the device by resolving the address.

If an address is random, then you can tell what type of address it is by looking at the two most significant bits of the 48 bit address:

Address [47:46]	Sub-Type
0b00	Non-resolvable private address
0b01	Resolvable private address
0b10	Reserved for future use
0b11	Static device address

Regards,
Terje