alt Hacker NewsYou could encrypt the handshake that you recieved with the server's certificate and send it back. Then if it doesn't match what the server thought it sent it aborts the handshake. As long as the server's cert isn't broken this would detect a munged handshake, and if the server's cert is broken you have no root of trust to start the connection in the first place.
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dotancohen • 06/16/2025
The fine man in the middle could still intercept that.
How do you agree a protocol to encrypt the message to agree the protocol?
This is the message that returns a list of supported ciphers and key exchange protocols. There’s no data in this first packet.
Alice: I’d like to connect Bob: Sure here is a list of protocols we could use:
You modify bob’s message so that bob only suggests insecure protocols.
You might be proposing that Alice asks Trent for Bob’s public key … But that’s not how TLS works.