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Here's an example of a man-in-the-middle as someone at my ISP, with his laptop plugged into a network switch. He's not blocked by firewalls and he's not missing any IP packets. He's copied all the traffic and stored all the conversations. What can he do with my session?

He can add a load of garbage, but can't hijack my conversation, or inject anything meaningful. he can't even read the requests and responses - the public cipher and symmetric cipher encryption are ridiculously hard to crack. What else is he going to do?