Opentimestamps
Basics
- Project by Peter Todd to time stamp files with the Bitcoin blockchain.
- From a paper (Summer 2019) by Andrew Poelstra (Blockstream) and David Vorick (Sia):
"Rather than trying to extend the capabilities and the space available within bitcoin blocks and transactions, much of the innovation in the bitcoin space has been about finding creative ways to avoid using existing technology and just anchor it in a minimal way into the blockchain. The purest example of this is the opentimestamps project. Have people heard of opentimestamps? A smattering. Do people use opentimestamps? You should totally use it. It's open-source and free. I think petertodd is still paying the fees out of his pocket. It's cheap to run. You can commit to data laying around on your hard drive like websites you visited, emails you have received, chat logs, whatever, you produce a cryptographic hash committing to that data. None of your data leaves your system. You send this hash to the opentimestamps server, it aggregates them, it produces a merkle root committing to millions of documents. petertodd was also timestamping the entire contents of the Internet Archive. Then you commit this 32 byte hash to the blockchain, and you can commit to an arbitrary amount of data. A commitment in bitcoin is a proof that the data existed at a certain time. The consensus assumption is that everyone saw the block at roughly the timestamp that the block was labeled with, or that everyone can agree when the block was created so you get a timestamp out of that.
You're anchoring data to the blockchain, not publishing it. Putting data on the blockchain is a so-called proof-of-publication. If you need to prove that some data was available to everyone in the world at some point, you can put it in the blockchain. But typically when people think they need to do this, what they really need to do is anchor their data to the chain. There are some use cases where you really need proof-of-publication but it's much more rare. I'm not aware of a real trustless alternative to using a blockchain for this, but I really wish people wouldn't put all this arbitrary data in the blockchain."
