[ianremsen]

That assumption is correct, founded deep within the well-tested parts of our current understanding of physics.

When the work required to brute-force a cipher in a sane timeframe doesn't exist (or even couldn't fit) within the bounds of the observable universe, (if the crypto works as intended, which, to be fair, is a big if) brute-forcing is safely axed as an avenue of attack.

Of course, on these scales, if you really want to, you could connive and threaten your way into having a backdoor installed. Or you could spy on the victim and steal their laptop, with the key decrypted and in memory. Or you could beat the key and password out of them. Brute-forcing shouldn't be the most pressing of anyone's cryptographic worries.