Bitcoin Forum

Would any one kindly tell me how to send a message with a bitcoin transaction please? Either with a trezor or web wallet.

Thank you.

there's no reliable way to send a message with bitcoin transaction. unless you wanna use the OP_return script which have a limit of 80 bytes of hex characters.

edit (someone replied with this but the post is gone.):
there's the blockchain.info transaction note, but those notes can only be seen using bc.i's explorer.

You can use Blockchain.info (web wallet) , while sending transaction go to custom send tab and put any note you want to send and the transaction will be processed with custom note (message) .

you can use OP return scripts , or you can  have a look in this thread : https://bitcointalk.org/index.php?topic=524877.0 (https://bitcointalk.org/index.php?topic=524877.0)

this service is interesting since they have improved their sytsem in the new version , wich is able to upload images too now..  ( not free)

or you can give a try here too : https://stamp.io/  (https://stamp.io/)  where you can upload files form your computer to the blockchain  ( free)

Isn't stamp.io just an upload of a timestamped hash of the document?

yeah , exactly: it's like a Notarization certificate
"This is to certify that the dataset or file referred here under was notarized in the date and time printed down below by the person identified as "signee"

Assuming multiple people (or multiple documents) are using the service, it's not even a timestamped hash of the document if I remember correctly.

I believe they hash all the documents, then they create a hash of the hashes (something like a merkle tree).  It's that hash of the hashes that they then store in the blockchain to establish a proof of existence with the block timestamp.

You would need access to not only the original document, but also to all the other hashes in the set to prove the timestamp on any specific document.  I don't know if stamp.io stores the documents on their servers or makes them publicly available, but I doubt it.

yeah that's correct , as an exemple , here's a sample of one doc uploaded on stamp.io ( this one is about an ometeotl coin COA's  certification) , but you can upload any docs, ie : pictures ...
exemple:
https://stamp.io/stamp/ip8nznz7 (https://stamp.io/stamp/ip8nznz7)

So how do you see this custom note/ message? I presume you cant see it in a normal Bitcoin wallet like multibit etc?

No. There is no mechanism right now for transmitting messages on the Bitcoin network or showing them "in a normal Bitcoin wallet like multibit".

You can't. You need your private key to make a signed message, but if you're meaning embedding a tx into the blockchain, you can use OP_RETURN or something like www.cryptograffiti.info.

So if I send a message with blockchain.info then to read the message you must search for the public key in blockchain.info?

If you send a message with blockchain.info, then to read it you must find the message in the blockchain.info service.  This can be accomplished by searching for the bitcoin address or transaction ID on the blockchain.info website.

Excellent. But this is not stored in the blockchain then? Its just a feature of the blockchain.info site?
Regards,
Matthew

It's just a blockchain.info feature, they're just a company that happens to have the same name as blockchain (technology) which makes the whole thing a bit confusing from time to time.
Your assumption is indeed correct: they (blockchain.info, the company) store your message in their internal database and link it to a transaction (note), or an address (tag).
Blockchain.info (company) parses the blockchain (technology) and stores everything in their own database and lets you link notes and tags  in their internal database.
This process has nothing to do with the blockchain (technology).

If blockchain.info (company) ever goes bancrupt, gets hacked, dissapears,... All notes and tags that were done on blockchain.info will be gone forever.

Hmmm so back to the original question then I guess. For a non tech guy like me what is the best way to send a 6 digit message with a transaction that will be in the block chain forever :)

I don't really have experience in this kind of thing, but if you read this blog for example, things should become pretty clear:
https://www.wlangiewicz.com/2014/10/24/how-to-put-custom-messages-into-bitcoin-blockchain-op_return/

The easyest way to do it seems to be this library: https://github.com/coinspark/php-OP_RETURN
The thing is, you'll need a LAMP (or possibly WAMP) stack + bitcoin daemon to do this...

The other option would be to bloat the blockchain... If you want to send the message "152365" (a six digit message, like you said), you could create a transaction with a very small output to address 1Proof152365ProofD2P2BUH6HoTbuKNWQ The downside is that all the nodes on the network will allways keep the unspent output in their memory. The output of the transaction will always stay unspent, since nobody has the private key to controll 1Proof152365ProofD2P2BUH6HoTbuKNWQ.
The other downside is that each "message" will cost at least a couple cents (fee + couple satoshi's as output), in contrast to the OP_RETURN-method (the output can be used as an input, thus spent again, and it'll only cost you the miner's fee).

Once again: i'm not an expert in this... My explanation might be off on the technical level, or there might be other ways to do this... But this is how i understand it.

This isn't a good idea, because the output will remain in the UTXO set, and thus use some network resources. OP_RETURNs can be sent with a minimal size (one satoshi+fee) from a reasonably-sized input (the remainder can be sent as change back to the sender's wallet) and don't pollute the UTXO set.

That depends on what you are trying to do.

If you just want to embed a message permanently in the blockchain for anyone to go see any time they want as long as Bitcoin continues to exist, then you should use OP_RETURN.  I think there are some services that will help you create an OP_RETURN message, but if you have the ability to sign raw transactions (such as with the Bitcoin Core wallet), then it isn't super difficult to do.

If you want to transmit your message to someone in a way that they can easily see it in their wallet, then you need some other crypto-currency. Bitcoin isn't designed as a messaging system.

then you could use this service called Eternity Wall as well
http://eternitywall.it/

It's also a good way to pass some time when you can since you can find such pearls

http://eternitywall.it/m/d4253deff6eb8ed5fe8ce8c87338fda78d4589a9e329ac380f904e13792d826f

hope it helps

I've been using this online tool:

https://live.blockcypher.com/btc/embed-data/

Which gets retweeted here:

https://twitter.com/op_return_ack

and I have used it here:

(retweeted)

https://twitter.com/op_return_ack/status/728564120404905985
https://twitter.com/op_return_ack/status/728546171895975936
https://twitter.com/op_return_ack/status/728546129139228673
https://twitter.com/op_return_ack/status/728532511312093185 etc

An example:


returns: https://live.blockcypher.com/btc/tx/7dd365ac9a328160d0505ecb1bea5c87c488397b0e423f2c65ccc9b9b61ac3c6/


Hope this helps.

The wallet, which I am using, has this function but I haven't tested it yet. It also has the fuction to get bitcoin from other users which are in this wallet with their permission.