Title: An odd looking tx. Post by: CuriousCarl on February 03, 2015, 09:32:31 PM What happened to the tx input in this transaction? The output says "nulldata". What does that mean? Code: C:\Program Files\Bitcoin\daemon>bitcoin-cli.exe getrawtransaction db3cc99eb91533 Blockchain.info also has trouble showing this transaction. I.e. it doesn't have an output address? https://blockchain.info/tx/db3cc99eb91533bf0973b62c572589925df8e1f1501678d54034261b5a4ccfbf?show_adv=true There is btc input, but there doesn't seem to be any output address. How does that work? Title: Re: An odd looking tx. Post by: andytoshi on February 03, 2015, 09:54:33 PM Hi CuriousCarl,
Bitcoin transactions are actually chained together in a more general way than simply "address to address". You might find this overview (https://download.wpsoftware.net/bitcoin/bitcoin-faq.pdf) informative. While ordinary spend-to-address transactions are created such that only the owner of an address[1] can redeem the coins. However, it's possible to create transactions whose outputs can be redeemed given other conditions: some trivial ones are "anybody can spend" and "nobody can spend". What you're seeing here is an example of the latter. Such transactions are used because it is possible to embed other, unrelated data, into such transactions. This is antisocial behaviour because it consumes Bitcoin users' bandwidth and storage (which presumably they are donating for the sake of Bitcoin, not whatever unrelated thing is being stored), but it's technically possible so people do it. Addresses aren't directly part of the Bitcoin protocol; they're just one way of using Bitcoin's scriptable signature system (https://en.bitcoin.it/wiki/Script) to manage asset transfers. blockchain.info uses a broken model of what transactions and addresses are, and therefore gets confused quite easily. Generally if you encounter a weird transaction, checking what bc.i thinks of it is exactly the wrong thing to do. :) [1] By this I mean somebody in possession of a corresponding private key; this often doesn't really correspond to "ownership" on the user level, for example if your coins are stored at an exchange. Then the exchange might own the address even though you own the coins. It is generally true that addresses are a pretty low-level thing and don't correspond well to user expectations, so in a more user-friendly system users would not ever see addresses at all. There is progress in this direction but it's slow. Andrew Title: Re: An odd looking tx. Post by: CuriousCarl on February 04, 2015, 08:21:57 AM Thanks for the explanation. Very clear. It's going to be interesting to see how many of these "not to address" txs there are in the blockchain. I knew about multisig addresses before but not this anyone can spend and nobody can spend, and there seems to be a few more when looking at the core cpp code. Title: Re: An odd looking tx. Post by: Tjopper on February 04, 2015, 01:07:04 PM It looks like some kind of "proof of existence" I think we display it more properly:
https://www.blocktrail.com//tx/db3cc99eb91533bf0973b62c572589925df8e1f1501678d54034261b5a4ccfbf Best Regards, Jop Title: Re: An odd looking tx. Post by: Cryddit on February 07, 2015, 07:53:22 PM I read it as someone publishing some version of a hash on a document. It's getting buried in the blockchain as a proof that he had it at a particular time.
Presumably, at some later time, he asserted (or will assert) that he had the document at that time and offer the blockchain tx as proof. Which as andytoshi pointed out, probably has nothing to do with Bitcoin itself. For all we know the author of this tx is just establishing his copyright on something, or proving that it hasn't been tampered with since that date. Title: Re: An odd looking tx. Post by: unamis76 on February 07, 2015, 08:20:16 PM Are these "nulldata" transfer those composed of "blockchain vandalism" or "blockchain graffiti"?
Title: Re: An odd looking tx. Post by: samson on February 08, 2015, 09:49:23 PM Are these "nulldata" transfer those composed of "blockchain vandalism" or "blockchain graffiti"? That's what some people say, however there are other ways of storing data in the blockchain which use up much more space. Imagine 100's of tiny outputs encoding some data in a single transaction... |