NimBLE Host Identity Reference


The identity API provides facilities for querying and configuring your device’s addresses. BLE’s addressing scheme is quite involved; the summary that follows is only a brief introduction.

BLE defines four address types:




Configured with


Address assigned by manufacturer; the three most significant bytes form the manufacturer’s OUI.


N/A; read from controller at startup.

Static random

Randomly generated address.



Resolvable private (RPA)

Address randomly generated from an identity address and an identity resolving key (IRK).


N/A; generated by controller periodically.

Non-resolvable private (NRPA)

Randomly generated address.



Identity Addresses

The third column in the above table indicates the identity property of each address type. An identity address never changes, and a device can be identified by one of its unique identity addresses.

Non-identity addresses are used by devices supporting BLE privacy. A device using the privacy feature frequently changes its own address to a newly-generated non-identity address. By cycling its address, the device makes it impossible for eavesdroppers to track its location.

A device can have up to two identity addresses at once: one public and one static random. As indicated in the above table, the public identity address cannot be configured; the static random identity address can be set by calling ble_hs_id_set_rnd().

The address type is selected on a per-GAP-procedure basis. Each time you initiate a GAP procedure, you indicate which address type the device should use for the duration of the procedure.