My first thought was that broadcasts should never be encrypted; everyone has a license to decrypt the signal and that was a condition of giving them a chunk of the RF spectrum free from interference.
I thought about it some more, and think you need encryption to authenticate the broadcaster to the viewer. For example, without encryption I can drive by the old folks home and broadcast my video of "the world is ending, kill yourself before it's too late" and do a lot of mental damage to people. With encryption, this attack is blocked; I don't have ABC news' key, so I can't pretend to be them.
> For example, without encryption I can drive by the old folks home and broadcast my video of "the world is ending, kill yourself before it's too late" and do a lot of mental damage to people.
I mean, yes, you can take a homebrew transmitter and do that, just like you could have done for decades. But you're still operating an unlicensed transmitter and are performing broadcast signal intrusion.
Is end to end encryption even beneficial in a public broadcast medium? I mean, you’d need to send the encryption key as part of the broadcast. There isn’t an out of band channel to transmit a key, so how could this even work in a secure way? Or will they require an internet connect for key distribution? That seems antithetical to the purpose of broadcast TV.
Signing the signal is all you need to be able to validate that the signal came from the broadcaster. But even this assumes that the public key will be transmitted often and the rogue pirate broadcast a bad key.
Authentication, proving validity, doesn't require encryption. Authentication uses cryptography, but the signal doesn't need to be encrypted since can add a signature to prove who came from and that hasn't been tampered with.
Only the rich and powerful should have the key to broadcasting. We mustn't let those poors tell lies. It's to protect granny! The rich and powerful have never lied to us, so they're the obvious party to hold the only key.
I don't think this invalidates your point, just I would say reduces it significance in the choice to allow encryption.
Additionally, I haven't seen an old folks home that doesn't have cable in many years. OTA signal is more common for the under privileged and rural communities. where a local transmitter wouldn't reach many anyway.
I thought about it some more, and think you need encryption to authenticate the broadcaster to the viewer. For example, without encryption I can drive by the old folks home and broadcast my video of "the world is ending, kill yourself before it's too late" and do a lot of mental damage to people. With encryption, this attack is blocked; I don't have ABC news' key, so I can't pretend to be them.
All in all, I'm not sure what the right public policy decision is here. I guess analog TV worked pretty well. Broadcast intrusions are fun to read about anyway: https://en.wikipedia.org/wiki/Max_Headroom_signal_hijacking