How would this compare to posting the hash in a public and frequently backed up way such that the date would be generally established by archives? For example, you could take out a classified ad with the hash in a newspaper, or post to Usenet so Google Groups archives it, or even submit it as a story to HN. (Or do all of the above and more at once.) Obviously, those aren't as technically sweet, but they seem workable. I'd be interested in knowing if there are more subtle tradeoffs involved.
The Bitcoin blockchain will presumably be around for the foreseeable future, and can't under any circumstance be modified by anyone. That's the main reason you'd want proof there.
Correct me if I am wrong, but I would argue that creating these addresses with tiny leftover cash amounts creates more of a burden on bitcoin nodes than normal transactions.
Every bitcoin node that verifies transactions must at all times be aware of the current balance of all accounts (more precisely all nonredeemed transaction, I think) and hence each of these signatures will necessarily live on all verifying nodes for as long as those coins are considered valid. Pruning strategies are being developed, but they do not prune accounts of balances, they only remove old transactions, so these balances cannot be removed, unless a satoshi stealing strategy is approved which would be a very significant incompatible change.
Personally, I would just include the hash in a comment of a payment to myself (or any payment at all), which is easily done with the current bitcoin client. The signature can easily be viewed on blockchain.info and you can use any hash that you like. Finding it would be harder though, but should not be difficult if I know any of the sending, receiving address or transaction id.
While I applaud novel uses of technology I am a bit uneasy using the bitcoin blockchain for the purpose of something other than transferring financial value. Couldn't you create a new blockchain with the sole purpose you had in mind? I'm sure you considered this, was the widely distribute aspect of the existing bitcoin blockchain the only thing that prevented you from using your own?
I feel opposite. Bitcoin is a proof-of-work scheme to come to an agreement on certain information. Due to the costs of work, any kind of PoW scheme will be used as commodity and traded. Also, people will tend to allocate all their "mining" resources towards most valuable protocol. Which will lead to a single most powerful blockchain while others will be in very tiny minority.
So if you want to create a PoW agreement scheme, you have to create a system of incentives, that is create a currency out of it. Which Bitcoin does. But currency is a secondary part. Primary part is agreement.
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Hey, I'm the author. I'd love to hear your feedback.
How would this compare to posting the hash in a public and frequently backed up way such that the date would be generally established by archives? For example, you could take out a classified ad with the hash in a newspaper, or post to Usenet so Google Groups archives it, or even submit it as a story to HN. (Or do all of the above and more at once.) Obviously, those aren't as technically sweet, but they seem workable. I'd be interested in knowing if there are more subtle tradeoffs involved.
The Bitcoin blockchain will presumably be around for the foreseeable future, and can't under any circumstance be modified by anyone. That's the main reason you'd want proof there.
Correct me if I am wrong, but I would argue that creating these addresses with tiny leftover cash amounts creates more of a burden on bitcoin nodes than normal transactions. Every bitcoin node that verifies transactions must at all times be aware of the current balance of all accounts (more precisely all nonredeemed transaction, I think) and hence each of these signatures will necessarily live on all verifying nodes for as long as those coins are considered valid. Pruning strategies are being developed, but they do not prune accounts of balances, they only remove old transactions, so these balances cannot be removed, unless a satoshi stealing strategy is approved which would be a very significant incompatible change.
Personally, I would just include the hash in a comment of a payment to myself (or any payment at all), which is easily done with the current bitcoin client. The signature can easily be viewed on blockchain.info and you can use any hash that you like. Finding it would be harder though, but should not be difficult if I know any of the sending, receiving address or transaction id.
While I applaud novel uses of technology I am a bit uneasy using the bitcoin blockchain for the purpose of something other than transferring financial value. Couldn't you create a new blockchain with the sole purpose you had in mind? I'm sure you considered this, was the widely distribute aspect of the existing bitcoin blockchain the only thing that prevented you from using your own?
I feel opposite. Bitcoin is a proof-of-work scheme to come to an agreement on certain information. Due to the costs of work, any kind of PoW scheme will be used as commodity and traded. Also, people will tend to allocate all their "mining" resources towards most valuable protocol. Which will lead to a single most powerful blockchain while others will be in very tiny minority.
So if you want to create a PoW agreement scheme, you have to create a system of incentives, that is create a currency out of it. Which Bitcoin does. But currency is a secondary part. Primary part is agreement.
I would suggest this to avoid losing coins.
1. Use SHA256 of your document as a private key.
2. Send some money (e.g. 0.01 BTC) to the address created from that private key.
3. Wait till it is well confirmed and "old enough" (to avoid paying antispam fee).
4. Send that money back to your private address.
5. Reveal your SHA256 to the world.
Have you ever had to use this yourself? Or was this more a technical exercise?
More of a technical exercise, but I could see it coming handy in the future.
How coincident. Not 5 mins ago I was reimplementing trusted timestamping for a document to be opened 3 months in the future.
Yours is infinitely cooler tho