Every time I encounter the concepts of PFS (perfect forward secrecy) and wPFS (weak perfect forward secrecy), I feel uncertain about them.
My understanding is that:
- PFS ensures that, if the parties' long-term keys have compromised in the future by an active adversary, he cannot calculate the session key.
- wPFS ensures that, if a passive adversary has learned the private keys of both peers to the session, and if the session is "clean", he still cannot recover the session key.
I'm not sure whether my understanding is right or not. And I don't know the if these are the correct definitions of PFS and wPFS.
Can you help me understand PFS and wPFS?