I don't plan to participate in this auction (even though you have nice sets).
I just want to say that this is the best way reserves should be handled!
. Not too many people do this. Good on you.
"Here is a SHA256 hash of the reserve (in the form xx.xxBTC):
fd5b716af0f5fdbd2d5ce79ebcb556c2ccde8abb4622c2b58ebd7819451c10d1"
While I do like this idea of using a SHA 256 hash to prove what your reserve price is, I think you have given much too much information for it to be kept a secret. Considering that you obviously won't sell for below the face value of the coins (you might as well redeem them if you were willing to do this) and your reserve is at or below your BIN price, and the fact that you have provided the exact format that the reserve price is listed as, there are only 565 possibilities that someone would need to "guess" before figuring out what your reserve is.
Someone would only need to convert 01.85BTC to sha256, and when that doesn't match try 01.86BTC and so on until converting it matches the hash you listed in the OP.
A more secure way to do this would be to either add a salt or simply say that you have posted the hidden reserve and not disclose the format. At the end of the auction you could disclose that your reserve was "one point seven nine bitcoins!! aka 1.79 BTC
" (For example) and someone would be able to easily check to make sure the hash matches the quoted text and the text is clear as to what your reserve is, while it would make it very difficult to brute force your reserve.
