alt Hacker News> Are there other XOR tricks?
Yes, error correction.
You have some packets of data a, b, c. Add one additional packet z that is computed as z = a ^ b ^ c. Now whenever one of a, b or c gets corrupted or lost, it can be reconstructed by computing the XOR of all the others.
So if b is lost: b = a ^ c ^ z. This works for any packet, but only one. If multiple are lost, this will fail.
There are way better error correction algorithms, but I like the simplicity of this one.
Replies
XOR is also great for storing copyrighted works without liability.
a = the bits of some song or movie
b = pure noise
Store c = a^b.
Give b to a friend. Throw away a.
Now both you and your friend have a bit vector of pure noise. Together you can produce the copyrighted work. But nobody is liable.
See also: RAID levels that use one disk for parity. Three disks is simplest, but technically you can do more if you trust that only one will go bad at a time.
A few months ago, I had a rare occasion of trying to explain them to a relative who had just bought a fancy NAS and wanted help setting it up.
https://en.wikipedia.org/wiki/XOR_linked_list