Re: If I'm Satoshi Nakamoto How do I prove it?

In addition to signing a message from an address known to be controlled by him, he could also sign a message using this PGP key, which is the same one he was talking about here:

Quote from: satoshi on July 25, 2010, 10:06:57 PM

For future reference, here's my public key. It's the same one that's been there since the bitcoin.org site first went up in 2008. Grab it now in case you need it later.

http://www.bitcoin.org/Satoshi_Nakamoto.asc

What's interesting is he never actually signed a message with this key, as far as we know. But signing the same message from both bitcoin address and PGP key would certainly be a good start for proving that he was back.