I understand BLE secure connection pairing mode is improvement over Legacy Pairing. The issue with legacy pairing was intial TK value can easily be bruteforce by an attacker.
In contrast, in secure connection, both device start by generating ECDH key pair and exchange public key.
Since BLE doesn't use certificate for public key, how would a device know if the public key actually belong to the entity it wants to communicate with.
I know later in pairing, there is confirmation check but that's similar idea to legacy pairing, just sequence is changed.