It would be interesting to see how some crypto implementations would respond to a quantum attack. I know some implementations that give you back a different mes

It would be interesting to see how some crypto implementations would respond to a quantum attack. I know some implementations that give you back a different message for each key tried, so with a quantum attack there is the possibility of similar-looking messages been shown. So for example, I encrypt a picture of a sunflower, and when running a quantum attack, I get back two different images of a sunflower, and the attacker must then infer which one is the 'encrypted' one and which one is noise. Also why have time horizon solutions/attacks when we already have stego?