While this is interesting, is there any concern about over use of the bitcoin blockchain? It's currently 65GB in size[0], which means it's fairly usable, and with a big enough system you could still store the entire thing in memory. What happens when it's 65TB? 65PB? Won't using it for lots and lots of things cause issues long term? Or am I missing something here?

[0] https://blockchain.info/charts/blocks-size?timespan=all

even compressed it was completely untenable space-wise due to the amount of people this would need to support and secondly the amount of transactions the network supports

so........ you're wrong.

I think proofofexistence.com existed at that time as well so why is this even news? bitcoin's been around for a whiiiiiiile

There were a couple other interesting proposals along the same lines as well.

The press releases at the bottom talk about it having potential to be used as a notary service, but even those are lacking detail.

edit: getting downvoted by bitcoin fanboys. should have seen that coming!

   OP_RETURN <hash of document>

You don't have a global getter on bitcoin transactions to get the hash of every document, so querying all the documents persisted on the Bitcoin blockchain you should build a database outside the Bitcoin blockchain to obtain them.

And don't forget the strict buffer limitations in the OP_RETURN that makes difficult to add more data and require to span the buffer within multiple transactions.

I've written up some shell and Git scripts you can use to very easily timestamp stuff: http://www.gwern.net/Timestamping Timestamping has come in handy for me in the past; you rarely need a cryptographically strong timestamp but when you do, it's important.

https://en.wikipedia.org/wiki/Trusted_timestamping

Here's a few companies specializing in it with various tradeoffs:

http://www.surety.com/digital-copyright-protection/prove-own...

http://www.proofspace.com/timestamping/

https://www.digistamp.com/

Here's a paper on fast, decentralized security via witnesses that has timestamping at 120,000 requests a second with 4,000 witnesses:

http://arxiv.org/pdf/1503.08768.pdf

Apart from a tiny group of devs and mining pools engaged in non-stop bickering and infighting

Whereas, with issues you cited, I have no clue what the status or goals of Bitcoin will be in even 5 years.

https://en.wikipedia.org/wiki/Trusted_timestamping

Oh, I did. https://news.ycombinator.com/item?id=6809929

https://www.blocktrail.com/BTC/tx/521f89f9f6980e57c7f3de6072...

First thing I thought of was proactive defense against someone patenting an idea by proving your prior art without necessarily divulging the information (or divulging it, while proving its chronologically prior existence).

After that, my mind jumped to media, such as the ability to be provably certain a given piece of media hasn't been altered after the fact (docs, images, contracts, video, audio, etc.), and that it provably existed when a party claims it did.

A bit on the nefarious side, I thought of being able to prove the existence of certain media a party wishes to use for blackmail or some other purpose.

Maybe applicable to the HN/YC crowd—especially given a certain case that recently made news here about a YC alum—a means of proving the existence of, say, founder agreements when establishing a company, so that protracted legal disputes over ownership could be aided and possibly shortened by irrefutable proof those agreements existed at a particular point in time.

Disclaimer: not a Bitcoin user, and know practically nothing substantial about it.

https://proofofexistence.com/detail/b94d27b9934d3e08a52e52d7...

I was expecting to see someone else's document that had that text.

Tl;dr: myth.

So for the purposes of proving that you wrote that document it really doesn't matter if that were to happen.

1. https://bitcoin.org/bitcoin.pdf