I am looking at getting the most secure connection between two BLE devices without an I/O capabilities but I am slightly confused by what is going on.
So without I/O capabilities the highest security I can use is Security mode 1 and Security level 'Unauthenticated pairing with encryption'.
However I understand with BLE 4.2 there is the ECDH implementation (LE Secure) to protect against MITM attacks. However I can only see this option with Security mode 1 and 'Authenticated LE Secure Connections pairing with encryption... but this requires I/O capabilities.
However from what I can see implementing the ECDH is specifically for a situation where you have an insecure channel, i.e. no I/O capabilities. Does this mean that with Security mode 1 and security level 'Unauthenticated pairing with encryption' I am using the ECDH with MITM protection?
Any help would be greatly appreciated!