.

[mmeijeri]

You can already encode messages into the blockchain if you want, though the qt client doesn't offer any GUI functionality for this and miners may reject nonstandard transactions.

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[cho]

I've been wondering about messages associated to transactions for a while. It's good to see there might be clever ways to do this without storing them in the blockchains.
One use amongs many : send a message with a tip, gift or donation.

[mmeijeri]

You may also want to take a look at Bitmessage, which is a sort of p2p encrypted e-mail system using proof of work to avoid spamming the network.

[AsymmetricInformation]

You may be interested in an idea that I had, which I actually think is pretty simple:

You use your bitcoin address's private key to generate a Bitmessage identity that can read messages "sent to that bitcoin address" though bitmessage because bitmessage can (probably) reinterpret the bitcoin address as a bitmessage address.

Unfortunately I havent thought through the details at all so there has been zero progress.

https://bitcointalk.org/index.php?topic=128230.120

Cool, I'll take a better look later.

I suppose the problem is that whereas you can (trivially) reinterpret your private key as a bitmessage identity, can you also convert an existing bitcoin address to a bitmessage address that matches that private key (without having the actual private key)?

You are right: the idea/challenge is getting Bitmessage client to say "Ok, with this Bitcoin private key [key A], let me generate the Bitmessage identities such that the user can decrypt bit-messages sent to [bitcoin address A] ("the Bitcoin address associated with the corresponding ECDSA public key of this Bitcoin private key") ."

It should be possible, but its definitely a little stranger than the way it is designed now (would have to be a whole to add-on feature). The developer is brainstorming the idea, I think.

[mmeijeri]

Would there be anything wrong with embedding just a hash of a message to the blockchain, for timestamping purposes?

[arsenische]

Come on, text messages are not that big. If the fee is paid and miners decide to put it in block, then what's the problem?

[mmeijeri]

It's not just the miners who bear the costs, it's everyone who stores the whole blockchain. It might even include people who don't store the whole chain if the messages are difficult to prune by those who don't care about them.

[papa_snurf]

the blockchain is designed to be a ledger, not a place to put your messages. if you want to do that, feel free to create your own "message coin" fork.

Another 'feel free to fork your own shit' reply... it's getting tiresome.

That said we don't want to bloat the blockchain do we?

[arsenische]

I am not sure short paid messages would really bloat the blockchain. Just few additional hundreds bytes per transaction with increased fees. Though it is correct: miners are not the only ones who carry costs. Probably full nodes could prune old messages or messages that are not addressed to them (just to save some disk space).

Update: though probably you are right, it would cause problems (not only blockchain size, but also copyright infringements, propaganda  of racism and other extreme cases of freedom of speech)... Probably better to have messages separate, maybe to integrate with IRC (AFAIK bitcoind had some code to deal with IRC already).

[FlappySocks]

How about something along the line of the new BitTorrent Sync?
http://labs.bittorrent.com/experiments/sync.html

It would be like having a dropbox folder attached to a bitcoin transaction. You could attach anything you wanted, from a simple message to pictures, video, software or any digital content.

[mmeijeri]

Update: though probably you are right, it would cause problems (not only blockchain size, but also copyright infringements, propaganda  of racism and other extreme cases of freedom of speech)... Probably better to have messages separate, maybe to integrate with IRC (AFAIK bitcoind had some code to deal with IRC already).

Perhaps that is a good idea for other reasons as well, but content-related problems would be solved by only embedding a hash, not the whole message.

[roalwe]

I am not sure short paid messages would really bloat the blockchain. Just few additional hundreds bytes per transaction with increased fees. Though it is correct: miners are not the only ones who carry costs. Probably full nodes could prune old messages or messages that are not addressed to them (just to save some disk space).

Update: though probably you are right, it would cause problems (not only blockchain size, but also copyright infringements, propaganda  of racism and other extreme cases of freedom of speech)... Probably better to have messages separate, maybe to integrate with IRC (AFAIK bitcoind had some code to deal with IRC already).

The thing with "pruning" is that, as far as I understand, it deals only with storage, not with bandwidth.

Pruning doesn't really "dislodge" old spent TX from a block (that would screw over the hashes )
It just allows you to discard obviously "spent" stuff after you have recieved it (assuming you follow the "trust no one" doctrine of Satoshi client) - but if the blockchain has bloated to 2 TB due to everyone and their dog putting a message in it, you would still have to download it (somehow).

I believe that Bitcoin should follow its initial design goals, and should not try being everyone's everything (chat client, name resolver, distributed evernote, torrent seeder... )

Just say no to feature bloat.

[FlappySocks]

Attaching messages should defiantly not be part of the block chain IMO, and there is no reason to.  So long as you can tie a message to a transaction, it can be transmitted independently as meta data.

Messages need not be kept in the system indefinitely either.  Once the recipient has received the message, it's their responsibility to archive it (or not). Just like traditional e-mail.

Messages could be limited in size. If you want to attach more, then include URLs to additional content.

[roalwe]

That sounds like a whole lot of fuss for a rather meager goal.

Don't get me wrong, messaging is sweet and all that, but bitcoin devs have finite resources, and I'd very much rather prefer they spend their resources on bitcoin's core functionality.

I am not experiencing a lack of IM software with varying degree of decentralization and anonymity.

[mmeijeri]

I believe that Bitcoin should follow its initial design goals, and should not try being everyone's everything (chat client, name resolver, distributed evernote, torrent seeder... )

Absolutely, but limited encrypted messaging attached to a transaction looks like a core feature of a payment system. Traditional payment systems also have this feature.

In addition, it would be useful to have an application that adds intrinsic value to Bitcoin, as discussed on this page on the bitcoin.it site. The specific application could be something like Bitmessage, but with its PoW scheme replaced by Bitcoin postage.

It would also be nice if the protocol could be layered somehow, with a base layer dealing with generalised notarisation services, and several specialised layers on top of that. Below the notarisation service you could have a generalised message sharing layer and below that a generalised P2P layer that deals with peer discovery and perhaps anonymity. It would also be good to share these layers with other P2P applications like Bittorrent, Tor etc. Sharing the more basic layers with other P2P protocols gives you critical mass, robustness, economies of scale and less duplication of effort.

[runeks]

I believe that Bitcoin should follow its initial design goals, and should not try being everyone's everything (chat client, name resolver, distributed evernote, torrent seeder... )

Absolutely, but limited encrypted messaging attached to a transaction looks like a core feature of a payment system. Traditional payment systems also have this feature.

I disagree. A messaging system should not be in the core part of a decentralized currency.

We have so many ways of sending simple text messages to each other. Why on earth would we want to put this sort of trivial data in the block chain, to be stored for ever and ever?

Every single bitcoin transaction is necessary for the system to work; we need them to figure out if an output has been spent.

Messages like "A no. 5 with extra cheese and mushrooms" is the exact opposite: absolutely irrelevant to the currency itself, and utterly unimportant as soon as the good that the payment was for has been delivered and consumed. Storing this message for eternity in the block chain would be a waste of the scarcest resource in the Bitcoin system: storage space.

[mmeijeri]

I'm not saying the message should be in the deepest Bitcoin-specific layer or stored in the block chain. Nevertheless it would be useful to have standard functionality in the full protocol and in the reference client for specifying things like "A no. 5 with extra cheese and mushrooms".

[Kluge]

I believe that Bitcoin should follow its initial design goals, and should not try being everyone's everything (chat client, name resolver, distributed evernote, torrent seeder... )

Absolutely, but limited encrypted messaging attached to a transaction looks like a core feature of a payment system. Traditional payment systems also have this feature.

I disagree. A messaging system should not be in the core part of a decentralized currency.

We have so many ways of sending simple text messages to each other. Why on earth would we want to put this sort of trivial data in the block chain, to be stored for ever and ever?

Every single bitcoin transaction is necessary for the system to work; we need them to figure out if an output has been spent.

Messages like "A no. 5 with extra cheese and mushrooms" is the exact opposite: absolutely irrelevant to the currency itself, and utterly unimportant as soon as the good that the payment was for has been delivered and consumed. Storing this message for eternity in the block chain would be a waste of the scarcest resource in the Bitcoin system: storage space.

It helps prove intended use of the money (similar to check memo), which might be helpful in law. If the intent is disagreed with, money can be refunded with the memo stating so.

[markm]

I believe that Bitcoin should follow its initial design goals, and should not try being everyone's everything (chat client, name resolver, distributed evernote, torrent seeder... )

Absolutely, but limited encrypted messaging attached to a transaction looks like a core feature of a payment system. Traditional payment systems also have this feature.

And there you have it.

It is NOT a core feature of a currency, in fact although some jurisdictions might not currently prosecute people for writing messages on e.g. dollar bills, I believe there was a time and/or are or have been jurisdictions where "defacing a coin of the realm" was not only offensive but "an offense".

Bitcoin is a currency. Stand by for a payment system, "coming soon". (4 to 6 weeks or so? )

-MarkM-

[mmeijeri]

It is NOT a core feature of a currency, in fact although some jurisdictions might not currently prosecute people for writing messages on e.g. dollar bills, I believe there was a time and/or are or have been jurisdictions where "defacing a coin of the realm" was not only offensive but "an offense".

Is Bitcoin supposed to be only a currency, not a payment system?

Bitcoin is a currency. Stand by for a payment system, "coming soon". (4 to 6 weeks or so? )

You mean Ripple? I'm very enthusiastic about that, but I'd also like to see basic messaging functionality in Bitcoin clients, including the reference client.