RE: Key Distribution Explanation

Kenneth — Tue, 15 May 2018 13:02:47 GMT

Hi,

Answers to most of your questions can found in the BT core spec v5.0. It may be difficult to know where to look to find the relevant information, so this document is useful resource:
https://www.bluetooth.com/~/media/files/specification/bluetooth-low-energy-security.ashx

You can also find the message sequence chart for the softdevice implementation useful, since that show the softdevice api and events triggered by the various security procedures:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s132.api.v6.0.0/group___b_l_e___g_a_p___m_s_c.html

For most part I would say that by including the peer manager in your application, then peer manager will automatically take care of this for you, and the peripheral and central devices will automatically negotiate the highest common security mode and level depending on the features supported. There is no need for the application to consider the LTK or IRK, if however you want to support passkey or OOB, then the application will need to provide the passkey or OOB keyupon request by the softdevice as shown in the message sequence charts.

Best regards,
Kenneth