The author references a previous letter that describes what he's doing in jail. Can anyone find that?
Google searches for '"Matthew Bumgardner" arrest' or '"Matthew Bumgardner" truecrypt' were unhelpful. It appears that this story hasn't had any media attention.
Did he forget his TrueCrypt password?
Maybe he was using keyfiles?
In most European countries (that do not have specific crypto laws) you neither need to give the judge any information (except your name and address), nor help the prosecutor (i.e., the judge cannot order you to open a safe, but of course he can try to break the safe hismelf).
To answer your question directly: No, it applies to all methods of communication.
http://en.wikipedia.org/wiki/Right_to_silence#United_States
"...the U.S. District Court for Vermont ruled that because the defendant had already cooperated as far as he had and already potentially incriminated himself, by stating his ownership of his laptop and providing law enforcement with partial access to it prior to his arrest, that he must now surrender complete access to all information on that laptop, even encrypted and potentially self-incriminating or confidential information.[20] Because the defendant had cooperated in part already, the Court ruled that the defendant must continue cooperation and provide the decrypted and potentially harmful information to the government..."
It is. That's what I meant by being in custody (arrested).
or
Ignoring the details of this case, what if the court is ordering you to decrypt something that isn't even encrypted? It's just random data? They assume it is. You assume it isn't.
I suppose in this case, the fact that the someone of authority already saw unencrypted contents gives them enough reason to be confident the drive is encrypted and the defendant has the ability to decrypt it.
But this is why the RECAP project exists - to jail-break the PACER documents you pay for: https://www.recapthelaw.org/
What you're trying to do here is obvious, and I don't like it one bit. Everyone is innocent until proven guilty. You're trying to introduce bias, and shame on you for doing it.
The fact of the matter is that even if the first sentence of his message stated that he was being held on child pornography charges, I would still back his right to not have to reveal his key. That's ridiculously lazy policing.
However, the omission of what his charges are from such a thorough message is extremely conspicuous. I could pretend to be a string parsing robot and only act on what the message itself contained... Or I could use my full brain like a human and make some reasonable assumptions. He's probably been accused of something pretty bad to leave it out like he did.
It's funny that in then contest to appear dispassionate and just people, even in an intelligent community such as this, handicap themselves. We're not better for having done so.
First, the guy could be accused of choking babies to death with child porn and that wouldn't make a damn bit of difference as far as his, and the rest of our, fundamental rights are concerned.
Second, accused (or even indicted) is absolutely different than convicted, which itself bears an indirect relationship to 'true'.
Third, courts typically don't post private proceedings on the internet - you'd be amazed how many things you wouldn't be able to "find anything" about via a google search. If he's being held for contempt in relation to a case that he's not actually a defendant in, I imagine it'd be really bloody difficult to find a whole lot about that online, and in either case I can't imagine any sane lawyer giving him the green light to post on the internet details about a case for which he's already being held in contempt.
But by all means, don't let me stop you from impugning the integrity of a man you admit to knowing nothing at all about.
I can't imagine a lawyer giving him the green light to post on the internet asking people who don't know anything about the case to spam the judge and prosecutor, either.
In fact, he states that he doesn't have a lawyer.
If he expects people to write letters, he needs to explain WHY they need to write letters. That requires telling us what the case is actually about.