3 ms·

It's computationally difficult for anyone to forge it. While the operators of archive.org could easily forge an old timestamp.

• hybridsole 11y ago
  Computationally difficult is a bit of an understatement. It is not possible to alter the bitcoin blockchain once a block is added and confirmed. With limitless resources, you could perform a withholding attack to modify the most recent half-hour to one hour's worth of transactions, but that would take tens of millions of dollars in hardware and only be temporarily successful.
  • ikeboy 11y ago
    You could go back in time indefinitely with unlimited resources. Would require a big reorg, but still possible.
    • avar 11y ago
      For the purposes of proving that a document exists no, you really couldn't go back in time, if this were to happen it would be a monumental time for bitcoin, and the old blockchain would be well known & referenced. So for the purposes of proving that you wrote that document it really doesn't matter if that were to happen.
      • ikeboy 11y ago
        Depends who you're proving it to; if you can isolate them, it still works.