If you want to have a hidden reserve, then is this method the best in imo:
Publish a sha256 hash of the hidden reserve (+ salt) in the beginning of auction.
At the end of the auction then do you reveal your hidden reserve (+salt) and everybody can see
that it matches the hash published in the beginning.
It's a good idea, but the hash can be decrypted at the beginning of the auction, so the reserve price is no longer secret.
Nope, it would be impossible to decrypt (if you add a salt). I will send you a PM how to do it, so we will not derail your auction.
Good luck to everyone, this is a wonderful coin.
Woudn't it suffice to post the signature part of his reserve as signed message?