So this video explains how https works. What I don’t get is what if a hacker in the middle pretended to be the server and provided me with the box and the public key. wouldn’t he be able to decrypt the message with his private key? I’m not a tech expert, but just curious and trying to learn.
It is indeed true that some CAs have seriously misbehaved; however, browser builders are rather strict on the presence of the CAs they trust. Misbehaving or even simple errors are reasons for getting kicked out, after which certificates signed by those CAs are now no longer valid.
The certs are still valid.
They are just not implicitly trusted
You are technically correct, best kind of correct
That can be helpful if a transgression is noticed, and it’s not orchestrated by a higher authority (e.g. government), and the damage isn’t already done.
Of course, browser builders are vulnerable to influence, attack, accidents, questionable judgment, and blind spots just as certificate authorities are.
I’m somewhat skeptical. What if LetsEncrypt decided to misbehave tomorrow? Would the browsers have the guts to shut it down and break all sites using it?
Yes, they will. We’ve seen it before in mostly less serious cases: Diginotar, Türktrust, Symantec, etc. As brittle as the CA system can be, when there is real enough trouble, CAs do get revoked.
Not the browser companies. The parent CA would revoke Let’s Encrypt’s certs and publish that revocation in the certificate revocation list. When the browser (software, running on your system) downloads the new CRL, they will automatically stop trusting LE.