To convince any skeptics, tell them to substitute the word "blockchain" for "bitcoin" in a lot of discussions about the latter. (It doesn't always work but often enough it does.) . . . Tomorrow, individuals and companies will hash whatever data they need to preserve, use that hash to create a bitcoin address, and then send some fraction of bitcoin to that address. Voila, unalterable proof that their data existed by an exact date and time . . .

We advise, cross out ‘bitcoin’ where you can and put in ‘blockchain.’ It’ll solve most of the problems,” Mr. Selkis said, with a smile. . . Blockchain is a distributed database where bitcoin transactions are recorded. Some startups are trying to use the bitcoin database to record other information.