RE: refunding donations by proving you own one of the private keys that donated: interesting idea! Anybody willing to write code to do that? Could be a fun project... (find all the transactions that donated to EFF, dig out the public keys, come up with a way to sign/verify a message with private key proving you own a public key, then keep track of which donation transactions have already been refunded)
After thinking about this a little bit more, I have reconsidered ... this is a
very bad idea.
During bitcoin's more innocent times, I kept my wallet.dat files unencrypted on my main laptop. I use this laptop to try out new stuff and browse the web with plugins activated, so it has a huge attack surface.
I have long since moved all my bitcoins to offline savings wallets and a spending wallet on a dedicated netbook.
But those old wallet files with zero balance in them should be considered tainted. Even if I move them offline and format my HD it's too late. I am making the assumption that they have been harvested by hackers already. The problem is, my EFF donation happened such a long time ago that it came from one of those wallets.
The last thing we need right now is EFF donations being reclaimed by hackers!