> any algorithm that doesn't have general consensus among experts that it is unlikely to be broken in 100 years
Does that algorithm exist and are its performance constraints acceptable to you? If not, you have your answer about why you can't activate "100 year crypto mode".
Well there are plenty of use cases where performance isn't the limiting factor. To encrypt a message to my lover, I would be happy to wait multiple seconds - which at 3 Ghz is tens of billions of math operations for a message perhaps just a few paragraphs long.
Give people the option between "wait 3 seconds" or "the FBI can read your love letter in a decade", I'm pretty sure most people would choose to wait. Yet programmers have already chosen the other option for the user by picking nearly-broken crypto.
No, they haven't. This isn't an accurate framing of how attacks on cryptography work. Ironically: the subject of this thread would probably be pretty helpful in understanding why.
Does that algorithm exist and are its performance constraints acceptable to you? If not, you have your answer about why you can't activate "100 year crypto mode".