I confess, if I had a modern i5 or i7 processor and appropriate software I'd be tempted to in fact calculate some sort of AES-based HMAC, as I would have hardware assist to do that.
"It's at this point that @Rileyy_69 began lashing out with offensive tweets"
Actually, it isn't. A glance at his history (now, unfortunately, protected) showed that threatening rape, assault on pregnant women, knifing, strangling and the rest was his long-term form. As it happens, Twitter, which is fast becoming a sewer, is full of people talking like that, and it's only because he was foolish enough to get involved in a public figure that it came to attention. But that doesn't make it any less unpleasant. Clearly, he's like that all the time.
And so, Linux desktops...
Why not? The USA's not currently trying to extradite him, but if they did, Ecuador's got an extradition treaty with the USA. Why would Ecuador go out of their way to protect him?
"Assange is apparently on good terms with the president of Ecuador"
Perhaps. But why would he want to risk an international incident for him is a separate question.
Anyway, Ecuador don't have a dog in this fight other than Assange turning up on his doorstep. If their government accepted a fugitive from justice and then exported him from the UK, I'd predict that the UK would break off diplomatic relations and expel their diplomats. Which isn't going to cause the UK any pain; I have no idea what the implications of that for Ecuador are. Other EU states might follow suit if Ecuador announce that they'll provide a route of out jurisdiction for anyone faced with EU arrest.
" criminals are highly unlikely to be able to gather all expended brass"
Because they're too stupid to buy revolvers?
"Certainly there are ways to subvert this,"
By using a revolver?
This has always been possible in theory -- obviously, the computer software has to generate the output so it must have the seed in an accessible form; probably under several layers of obfuscation and encryption
There are some slightly better techniques: McCune's Flicker system leverages TPMs (which any corporate laptop will have) in a way which means you can perform cryptographic operations securely unless the attacker can compromise the hardware in a pretty fundamental way. It would be ideal for implementing soft-tokens.
All from Joe and Sally Sixpack who don't have enough sense to, in affect, close their blinds when they undress for bed at night, or shout all of their telephone conversations, or leave their cars and houses unlocked and the windows down or open. So, what are folks to do when they pass by, plug their ears and close their eyes for 600 feet?
Real-world analogies are always suspect, but even if people are undressing with the curtains open, anyone who films them doing so does so at their legal peril in most jurisdictions. The people undressing with the curtains open may also be committing an offence ("indecent exposure" in UK law) but tu quoque isn't a defence.
The law regarding recording telephone conversations is more variable, but most jurisdictions have a "so long as one party consents" law, which in this case wouldn't be met. It doesn't matter, in UK law at least, whether the recording is done on the electrical or the acoustic side of the proceedings, and I'd be surprised if other legislation draws that distinction: recording phone calls with a sucker mic on the receiver is just as illegal as doing it electrically.
Engineers may like to believe that the burden of enforcing privacy lies with the subject, but law, and social mores, tend to make it an offence to overtly intrude on the privacy of even those unaware they are not maintaining it.