[chmike]

Indeed. So the issue here is to deduce the symetric keys generated with a Cryptographically Secure Psoeudo Random Function (CSPRF) seeded with information exchanged during the initiating handshake and using the respective public and prvate keys, without having any private keys.

Imagine now that with a handfull pseudo random bytes sent in clear with the TLS protcol an eavesdropper could deduce the internal state of the CSPRF and thus the symmetric keys. They could decrypt the channel.