4 ms·
PFS protects you if feds get google keys now to not be able to decipher what you told google 3 months ago. But if they have the current keys nothing can protect
by venomsnake 13y ago
PFS protects you if feds get google keys now to not be able to decipher what you told google 3 months ago. But if they have the current keys nothing can protect you.
- mtgx 13y agoWouldn't that mean Google would have to build a system to automatically send each key, for every session, for every user, to the NSA? That would be an insane scenario.
- venomsnake 13y agoUnless I am mistaken the throwaway PFS keys are derived from something. They just have to share it with NSA and they will do the rest. (I am not a serious cryptographer)
- Nursie 13y agoYes, they could share the keys and/or key matter used for every session with the NSA, and the NSA could then decrypt the conversation. Or they could just send the NSA the plaintext logs. There is literally no way to keep a conversation secret if one of the parties involved is compromised, because you're talking to a compromised party!
- phlo 13y agoIn order to provide any forward secrecy, the PFS keys are generated randomly for each session. They are not derived from the certificate holder's RSA keys. A snooping agency holding the private key of, say, Google would still need to intercept each connection and act as a man in the middle. Simply knowing the RSA key (either beforehand or afterwards) is not enough to decrypt PFS sessions. *edit: Google would still be able to collect and hand over all session keys ever used to communicate with them. The NSA might then use those session keys to decrypt any corresponding session.
- patmcc 13y agoWhy? That's perfectly feasible from a technical perspective.