say an organization
friendly wants to take a donation. what they can easily do of course is they post their btc address on their website friendly.org . however, the address can be changed, because the website can be changed. public orgs like greenpeace will probably not do that, but the imagined friendly org is a small org with little trust. the question is how to create a mechanism so that
friendly can prove that the address has not changed.
such a mechanism is wanted, because then the address acts like a fund. that is all inputs and outputs can be tracked. funds can't be misappropriated as easily. with an unproven addresses one can claim that the balance is lower than it actually is. it doesn't have to be 100% secure at first, but reasonably secure.
here is a simple adhoc solution which can serve as a discussion. to my knowledge this has not been done yet.
friendly posts an address in a thread on this board with the title "address proof" with the message
PING addr #1234 tag friendly
1 or several people reply with
PONG addr #1234 tag friendly
This would work for small message loads. Anyone who wants proof can go through the thread and find the post. The PONG message can't be forged by PING unless PING corrupts PONG to change his post. if several people reply he would have to corrupt each of them.
A more involved protocol could be:
PING addr #1234 tag friendly
1 or several people reply with
REQ addr #1234 tag friendly reqaddr #5678 0.01 BTC
If PING sends 0.01 BTC to #5678 the requester will PONG
PONG addr #1234 tag friendly
With this kind of protocol the message load would become to much. it can be done on a separate system for large loads.
Edit: an even simpler solution would be if the message board itself would have a mechanism for a 1:1 relationship between member and btc address, which acts as a central party. I'm not sure what the current protocol is with regards to bitcointalk and the address some members provide.
.
more generally before the blockchain there was no way to prove that things have existed on the internet. the blockchain is not meant to be a record store for arbitrary storage. namecoin comes closer to such a solution as it is build around lookups. the domain system of the internet is a specific lookup mechanism which is not concerned with historic records. there are possible solutions for this discussed mechanism which are not trivial to implement.
see:
http://wikileaks.org/Transcript-Meeting-Assange-Schmidt.html#731https://bitcointalksearch.org/topic/m.642768Edits:
simpler solution
clarify fund aspect
typo