4 ms·
From replies it seems my two sentences weren't as clear as I thought. I'll try to refine it: A property of bitwise xoring random variable `x` with a constant (
by ChrisSD 7y ago
From replies it seems my two sentences weren't as clear as I thought. I'll try to refine it:
A property of bitwise xoring random variable `x` with a constant (or otherwise non-random but independent) value is that the entropy of `x` is preserved in the result.
- WAHa_06x36 7y agoHowever, xoring two arbitrary random variables is NOT guaranteed to preserve entropy. Preserving entropy only happens under certain specific conditions.
- deleted 7y ago[deleted]
- ChrisSD 7y agoUnder what circumstances would xoring `x` and `y` not produce a result with entropy at least as great as `x`?
- WAHa_06x36 7y agoIn the very obvious cases where x == y, or x == not y, or x == y + 1, or many other correlations.
- ChrisSD 7y agoOnly if y is known to be dependent on x. If y is random but just so happens to be `not x` or `== x` then that won't make the result any less random. 0 is as random a number as 529890873740477 is.
- WAHa_06x36 7y agoSingle numbers don't really have entropy at all, so that is not something it even makes sense to talk about.