Bitcoin Forum

Blockchain-db.com (http://blockchain-db.com) is a new service that allows you to store text messages or data on the blockchain.

For just 0.001 BTC, you can replicate a 20 byte message to tens of thousands of hard drives around the world. They cannot be pruned, and will be permanently stored on the blockchain. Storage is as cheap as 7897 satoshis per 20 bytes.

Use cases
* Express your love, marriage, or venegeance in a form that will last forever.
* Timestamp a document by publishing its hash, which will be associated to a block and hence timestmap.
* Write a short autobiography and be remembered forever.
* Store your cold storage private keys in encrypted form.
* Publish and distribute an encrypted message, with an associated dead man's switch to release the key.
* Release and immediately distribute sensitive documents, making them uncensorable.
* Leave a time capsule for future historicians, hundreds or thousands of years from now.
* The possibilites are endless.

http://blockchain-db.com/

Is that not classed as hacking, do you have permission to add data to the blockchain?
Just asking.

Nobody owns the blockchain, just like how nobody owns Bitcoin. Anyone is free to use bitcoin and the blockchain. When you make a transaction, you are adding data to the blockchain.

Blockchain-DB.com is similar, except it allows you to add meaningful data to the blockchain - to be distributed among tens of thousands of nodes, forever.

I suppose then it's just the same as when I add a note.
If I know who the transaction is from, I sometimes add a note as reminder.
It's out there for all to see when I do that.
I got ya now.

No, this has been done for ages, even satoshi did it if I'm not mistaken. A good example is the older website cryptograffiti.info (http://www.cryptograffiti.info/). I Just noticed that blockchain-db.com has put a message (http://www.cryptograffiti.info/?txnr=2195) in the Blockchain as well, however cryptograffiti.info works better for me, because it doesn't break the sentences.

You are talking about the notes that you see on Blockchain.info, right? If so, those aren't stored in the blockchain and are useless without Blockchain.info.

I think the unique way to add a "data" to a transaction is to use an "OP_return":

"OP_RETURN and its 40-byte limit represent a compromise between two opposing visions of Bitcoin's future.

One camp sees the block chain as a secure, decentralized data store on which numerous financial and social applications can be built. Promoting the growth of these new applications helps ensure Bitcoin's long-term relevance. Allowing transactions to carry application-specific data in a standard way advances this goal.

The other camp views the Bitcoin block chain exclusively as a medium for recording electronic cash payments. Even so, important scalability issues will need to be addressed sooner or later. Trying to accomodate the data requirements of arbitrary application layers only raises the cost of maintaining the network today, while pushing forward the eventual day of reckoning."

Source: http://bitzuma.com/posts/op-return-and-the-future-of-bitcoin/

No, we do not break sentences. Data is stored via OP_HASH160 exactly the way you enter it, it's not possible for a single bit to be different.

Some sites like cryptograffiti chooses to break up scripts, when there is no accepted standard to do so (it should be joined together). Rather, they invented an arbitrary jigsaw-like format for re-arranging scripts.. that is going to look gibberish if you do it the traditional way (join output scripts).

That's why they're not suitable for archival purposes, you have to rely on their website for their esoteric ordering algo. If you 'cat {the blockchain} | string -n 20', you'll get unsorted gibberish with anything encoded using their service. If you use blockchain-db, you get them in order :)

Furthermore, their service can't force the change address to be at the bottom. There's gibberish in the middle of these messages, and that makes file storage impossible. We've patched our bitcoin core node to always place the change output at the end, and the OP_HASH160 is paddled with terminal 0x00s so you actually know where the file ends.

Also, Blockchain-DB lets you store raw bytes, eg binary files, encrypted files, small images, compressed audio files, etc. :)

As you said, blockchain.info notes are centralised and are not suitable for archival.

TL;DR: Blockchain-DB.com is the only archival-grade service that implements message embedding via OP_HASH160 correctly.