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maraoz / proofofexistence

Prove the existence of files using the bitcoin blockchain.
http://proofofexistence.com/
MIT License
229 stars 78 forks source link

improve explanation of how to verify a document #6

Open maraoz opened 10 years ago

felipecsl commented 10 years ago

I was curious to know more about this. If you were to verify the existence of a document in the blockchain and coinsecrets.org didn't exist, how would you do about it? Do you have to just keep listening to transactions and analyze their contents, looking for OP_RETURN? What about transactions that already happened? Would you have to go backwards to look into every single transaction? BTW cheers for the nice work here!

maraoz commented 10 years ago

Yes, you only need the blockchain to prove the existence of the document once the transaction has been introduced into the blockchain. Services like blockchain.info, insight, and coinsecrets, are an easy way to check data in the blockchain, but you don't need to trust those. You can sync the blockchain from the p2p network and look at the transactions there.

rsvp commented 9 years ago

@maraoz Hi !

I'm working through the API demo where: 15db6dbff590000ea13246e1c166802b690663c4e0635bfca78049d5a8762832 "timestamp":"2015-09-28 18:16:50" "blockstamp":"2015-09-28 19:32:54"

To verify the above, I searched at blockchain.info for "0x444f4350524f4f4615db6dbff590000ea13246e1c166802b690663c4e0635bfca78049d5a8762832" per the instructions:

      Find the transaction in the bitcoin blockchain containing an OP_RETURN
      output with the document's hash prepended by our marker bytes which are
      0x444f4350524f4f46 (or 'DOCPROOF' in ascii).

But nothing matches. Could you please clarify the instructions, and link to a third-party webpage where we can actually see that the transaction has occurred at said time.

Thanks very much.