3 ms·
You don't need a copy of the original data, you can simply store your change as a XOR so undoing it mean XORing it again.
by choo-t 2mo ago
You don't need a copy of the original data, you can simply store your change as a XOR so undoing it mean XORing it again.
- Retr0id 2mo agoHowever, if your change involves zeroing something out, you're back to storing the original data again.
- Retr0id 2mo agoSlightly silly idea to solve this: Hash all non-patched areas of the file to produce a key. Use the key to encrypt your XOR value. Thus the key can only be derived by someone who has either the original file, or the patched version.