Difference between revisions of "OP RETURN"

From Bitcoin Wiki
Jump to: navigation, search
(Remove garbage encouraging spam)
(Undo revision 62560 by Luke-jr (talk))
Line 1: Line 1:
'''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, compared to some other ways of storing data in the blockchain.
+
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]:
Line 12: Line 16:
  
 
== OP_RETURN applications ==
 
== OP_RETURN applications ==
OP_RETURN can be used for digital asset proof-of-ownership, and has at times been used to convey additional information needed to send transactions (see [[stealth address]]).
+
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. Protocols wishing to claim OP_RETURN prefixes should use the standard [[Bitcoin Improvement Proposals]] process. Not all OP_RETURN transactions use 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 ===
 +
* [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

Explaining OP_RETURN