OP RETURN: Difference between revisions
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== 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, 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]: | ||
Revision as of 23:31, 6 May 2017
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. At the time of writing, this wiki page is probably the most complete list of OP_RETURN prefixes. Note that this table is an attempt to catalog OP_RETURN prefixes that are already in use, *not* a system for reserving OP_RETURN prefixes! Protocols with no prefix do not use a prefix in OP_RETURN transactions.
| Prefix | Protocol |
|---|---|
| Apekato | |
| SPK | CoinSpark |
| DOCPROOF | Proof of Existence |
| CryptoTests- | Crypto Copyright |
| CryptoProof- | Crypto Copyright |
| BS | BlockSign |
| OA | Open Assets |
| STAMPD## | stampd |
| Factom!! | Factom |
| FACTOM00 | Factom |
| Fa | Factom |
| FA | Factom |
| tradle | Tradle |
| LaPreuve | LaPreuve |
| hex:5888 | Blockstore |
| hex:5808 | Blockstore |
| id | Blockstore |
| BITPROOF | Bitproof |
| S1 | Stampery |
| S2 | Stampery |
| S3 | Stampery |
| S4 | Stampery |
| S5 | Stampery |
| ASCRIBE | Ascribe |
| ProveBit | ProveBit |
| EW | Eternity Wall |
| CC | Colu |
| omni | Omni Layer |
| MG | Monegraph |
| RMBd | Remembr |
| RMBe | Remembr |
| ORIGMY | OriginalMy |
| BID | Identity |
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