When privacy is enabled and the local device uses BLE_GAP_ADDR_TYPE_RANDOM_PRIVATE_RESOLVABLE addresses, the device identity list is searched for a matching entry. If the local IRK for that device identity is set, the local IRK for that device will be used to generate the advertiser address field in the advertising packet.
If ble_gap_adv_properties_t::type is directed, this must be set to the targeted scanner or initiator. If the peer address is in the device identity list, the peer IRK for that device will be used to generate BLE_GAP_ADDR_TYPE_RANDOM_PRIVATE_RESOLVABLE target addresses used in the advertising event PDUs.