This letter was originally published in our 2024 Annual Report.
The past year at ISRG has been a great one and I couldn’t be more proud of our staff, community, funders, and other partners that made it happen. Let’s Encrypt continues to thrive, serving more websites around the world than ever before with excellent security and stability. Our understanding of what it will take to make more privacy-preserving metrics more mainstream via our Divvi Up project is evolving in important ways.
I’m far from an expert on PKI, but isn’t the keypair used for the cert used for key exchange? Then in theory, if that key was compromised, it could allow an adversary to be able to capture and decrypt full sessions.
Im also not an expert but i believe since there Is still an ephemeral DH key exchange happening an attacker needs to actively MITM while having the certificate private key to decrypt the session. Passive capturing wont work
I’m far from an expert on PKI, but isn’t the keypair used for the cert used for key exchange? Then in theory, if that key was compromised, it could allow an adversary to be able to capture and decrypt full sessions.
No. Perfect Forward Secrecy (ephemeral keys) prevents this type of replay.
Time for a dive, thanks.
Although this only was added in TLS1.2 I think. I had to switch it on manually for my server.
I think it’s default for TLS1.3.
Im also not an expert but i believe since there Is still an ephemeral DH key exchange happening an attacker needs to actively MITM while having the certificate private key to decrypt the session. Passive capturing wont work
Have you read about perfect forward secrecy?