OP RETURN: Difference between revisions
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'''OP_RETURN''' is a [[script]] opcode used to mark a transaction output as invalid. Since any outputs with OP_RETURN are provably unspendable, OP_RETURN outputs can be used to [[Proof of burn|burn]] bitcoins. | '''OP_RETURN''' is a [[script]] opcode used to mark a transaction output as invalid. Since the data after OP_RETURN are irrelevant to Bitcoin payments, arbitrary data can be added into the output after an OP_RETURN. Since any outputs with OP_RETURN are provably unspendable, OP_RETURN outputs can be used to [[Proof of burn|burn]] bitcoins. | ||
Currently, the default Bitcoin client relays OP_RETURN transactions up to 80 bytes [https://github.com/bitcoin/bitcoin/search?utf8=%E2%9C%93&q=MAX_OP_RETURN_RELAY], but does not provide a way for users to create OP_RETURN transactions. | |||
== Is storing data in the blockchain acceptable? == | == Is storing data in the blockchain acceptable? == | ||
Many members of the Bitcoin community believe that use of OP_RETURN is irresponsible in part because Bitcoin was intended to provide a record for financial transactions, not a record for arbitrary data. Additionally, it is trivially obvious that the demand for external, massively-replicated data store is essentially infinite. Despite this, OP_RETURN has the advantage of not creating bogus UTXO entries | Many members of the Bitcoin community believe that use of OP_RETURN is irresponsible in part because Bitcoin was intended to provide a record for financial transactions, not a record for arbitrary data. Additionally, it is trivially obvious that the demand for external, massively-replicated data store is essentially infinite. Despite this, the use of OP_RETURN continues unabated: while there is no global miner consensus to stop people from embedding arbitrary data in the blockchain if they want to, OP_RETURN is somewhat more efficient in terms of [http://i.imgur.com/VAGZWBK.png data bytes stored as a fraction of blockchain space consumed]. Compared to some other ways of storing data in the blockchain, OP_RETURN has the advantage of not creating bogus UTXO entries. [https://github.com/bitcoin/bitcoin/pull/5286 Discussion on GitHub pull request] | ||
The creation of OP_RETURN outputs also destroys Bitcoins used in the outputs of OP_RETURN transactions, which contributes to future deflationary pressures. | |||
From [https://bitcoin.org/en/release/v0.9.0#opreturn-and-data-in-the-block-chain Bitcoin Core release 0.9.0]: | From [https://bitcoin.org/en/release/v0.9.0#opreturn-and-data-in-the-block-chain Bitcoin Core release 0.9.0]: | ||
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== OP_RETURN applications == | == OP_RETURN applications == | ||
OP_RETURN | OP_RETURN is used for writing human-language messages, digital asset proof-of-ownership, and storing data. Its use has been proposed for P2P application discovery. See the "prefixes" table below. | ||
== OP_RETURN prefixes == | == OP_RETURN prefixes == | ||
Often, OP_RETURN transactions include a prefix to identify which "protocol" they belong to. | Often, OP_RETURN transactions include a prefix to identify which "protocol" they belong to. There is no standardized method of claiming OP_RETURN prefixes, and not all OP_RETURN transactions use prefixes. Protocols with no prefix do not use a prefix in OP_RETURN transactions. | ||
== External resources on OP_RETURN == | |||
=== Viewing OP_RETURN === | |||
* [http://coinsecrets.org/ coinsecrets.org]: An OP_RETURN transaction explorer] | |||
* [http://bitcoinstrings.com/ bitcoinstrings.com]: A site showing raw strings in Bitcoin transactions | |||
=== Explaining OP_RETURN === | |||
* [https://github.com/coinspark/python-OP_RETURN python-OP_RETURN] | |||
* [http://bitcoin.stackexchange.com/questions/29554/explanation-of-what-an-op-return-transaction-looks-like StackExchange: Explanation of what an OP_RETURN transaction looks like] | |||
* [http://www.slideshare.net/coinspark/bitcoin-2-and-opreturns-the-blockchain-as-tcpip Metadata in the Blockchain: The OP_RETURN Explosion] | |||
* [http://wlangiewicz.com/blog/2014/10/24/how-to-put-custom-messages-into-bitcoin-blockchain-op-return/ How to Put Custom Messages Into Bitcoin Blockchain - OP_RETURN] | |||
{{DISPLAYTITLE:OP_RETURN}} | {{DISPLAYTITLE:OP_RETURN}} | ||
Revision as of 00:15, 17 July 2018
OP_RETURN is a script opcode used to mark a transaction output as invalid. Since the data after OP_RETURN are irrelevant to Bitcoin payments, arbitrary data can be added into the output after an OP_RETURN. Since any outputs with OP_RETURN are provably unspendable, OP_RETURN outputs can be used to burn bitcoins.
Currently, the default Bitcoin client relays OP_RETURN transactions up to 80 bytes [1], but does not provide a way for users to create OP_RETURN transactions.
Is storing data in the blockchain acceptable?
Many members of the Bitcoin community believe that use of OP_RETURN is irresponsible in part because Bitcoin was intended to provide a record for financial transactions, not a record for arbitrary data. Additionally, it is trivially obvious that the demand for external, massively-replicated data store is essentially infinite. Despite this, the use of OP_RETURN continues unabated: while there is no global miner consensus to stop people from embedding arbitrary data in the blockchain if they want to, OP_RETURN is somewhat more efficient in terms of data bytes stored as a fraction of blockchain space consumed. Compared to some other ways of storing data in the blockchain, OP_RETURN has the advantage of not creating bogus UTXO entries. Discussion on GitHub pull request
The creation of OP_RETURN outputs also destroys Bitcoins used in the outputs of OP_RETURN transactions, which contributes to future deflationary pressures.
From Bitcoin Core release 0.9.0:
This change is not an endorsement of storing data in the blockchain. The OP_RETURN change creates a provably-prunable output, to avoid data storage schemes – some of which were already deployed – that were storing arbitrary data such as images as forever-unspendable TX outputs, bloating bitcoin's UTXO database.
Storing arbitrary data in the blockchain is still a bad idea; it is less costly and far more efficient to store non-currency data elsewhere.
OP_RETURN applications
OP_RETURN is used for writing human-language messages, digital asset proof-of-ownership, and storing data. Its use has been proposed for P2P application discovery. See the "prefixes" table below.
OP_RETURN prefixes
Often, OP_RETURN transactions include a prefix to identify which "protocol" they belong to. There is no standardized method of claiming OP_RETURN prefixes, and not all OP_RETURN transactions use prefixes. Protocols with no prefix do not use a prefix in OP_RETURN transactions.
External resources on OP_RETURN
Viewing OP_RETURN
- coinsecrets.org: An OP_RETURN transaction explorer]
- bitcoinstrings.com: A site showing raw strings in Bitcoin transactions