I am currently new to the world of BLE and I came across this article which mentions ECDH.
In the diagram in part $3$, it generates the DHKey/shared secret (I am assuming this is the correct terminology based on google search) , but then once it's generated the diagram never references it ever again. What exactly is the point of it in this diagram? I know the shared secret is used to encrypt the link.
Is the diagram implying that the shared secret is the LTK? I am utterly stumped on this and would really be happy if someone can explain where the shared secret is exactly used.