LE Pairing Responder

The LE Pairing Responder model is a vendor model and you must enable the CONFIG_BT_APP_PASSKEY Kconfig option to use this model. This model can be used to hand over a passkey that will authenticate a Bluetooth LE connection over a mesh network when it is not possible to use other pairing methods.

Before the pairing is initiated, an initiator must send an LE Pairing message with the Passkey Reset sub-opcode. If the passkey has been set by the bt_mesh_le_pair_resp_passkey_set() function, the predefined passkey will be returned in the Passkey Status message. Otherwise, a new passkey will be generated by LE Pairing Responder model and returned in the Passkey Status message. The passkey returned in the LE Pairing message with the Passkey Status sub-opcode should be used for the next pairing.

This model requires an application to only enable the display capability for the LE pairing by setting the bt_conn_auth_cb.passkey_display callback. The application must also set the bt_conn_auth_cb.app_passkey callback to use the passkey generated by LE Pairing Responder model. After every pairing request, the application must invalidate the previously used passkey by calling the bt_mesh_le_pair_resp_passkey_invalidate() function or calling bt_mesh_le_pair_resp_passkey_set() with the BT_PASSKEY_RAND value. Those functions can be called from callbacks bt_conn_auth_info_cb.pairing_complete and bt_conn_auth_info_cb.pairing_failed. See the samples/bluetooth/mesh/common/smp_bt_auth.c file for the reference.

Diagram of interaction between an Initiator and the LE Pairing Responder model

The model supports only LE Secure Connection pairing and requires the CONFIG_BT_SMP_SC_ONLY to be enabled.

Messages

The LE Pairing Request model defines a single message with opcode 0x11, which defines at least 1-byte long sub-opcode field. The supported sub-opcodes are:

Passkey Reset

Sent to instruct a node to generate a new passkey for the next pairing request. The sub-opcode field value is 0x00.

Passkey Status

Sent as a response to the Passkey Reset message. The sub-opcode field value is 0x01. The message contains the 1-byte long request status, and optionally a 3-byte long, 6-digit passkey. If the passkey was generated successfully (the status field is 0x00), the message contains a 3-byte long, 6-digit passkey.

States

None

Extended models

None

Persistent storage

None

API documentation

Header file: include/bluetooth/mesh/vnd/le_pair_resp.h
Source file: subsys/bluetooth/mesh/vnd/le_pair_resp.c
LE Pairing Responder model