[EDU] Hands on OP_RETURN

[promise444c5]

What's OP_RETURN ??
OP_RETURN( an Opcode)  refers  to  a locking script  used for locking data to atrasanction, this data can't exceed 80 Bytes ...

Why do we use OP_RETURN ??
OP_RETURN was meant to be used to store only  important trx related data..you see in the past, there was no usage  of OP_RETURN and some People(with cryptographic Knowledge) were able to embed data in  a way  which will make it remain in the UTXO sets,
This data could be large like(images, tweets...) which could eventually lead to bloated UTXO set , but with OP_RETURN  this  datas were proved to be non-spendable thus, can be pruned by nodes.
Also, to prevent the blockchain from being spammed with large data set, OP_RETURN Limit was introduced..    

Here's a quick Tut on using OP_RETURN on Electrum Testnet

• Open your Electrum and goto send Tab
• On the "Pay to" section, input your Address then followed by  the amount but seperated by delimer " , " comma ( the amount set will be automatically updated on the "Amount section"
• Next, move to the next line in same "Pay to" section and input "OP_RETURN <your data in hex format>" followed by amount to be burned which will be zero(0), also seperated by delimeter " , "  
  
    
  
   

[Update]

The mainnet now uses:

Code:

script(OP_RETURN your_short_msg),0

instead of

Code:

OP_RETURN hex,0

…versions that use the old and new OP_RETURN method in Electrum,

• …version 4.4.6 (2023-Aug-21) or older, it should be the old method.
• …version 4.5.0 (2024-Jan-12) or newer, it should be the new method.

Here's the relevant commit for reference: /spesmilo/electrum/commit/3ff588049e5e9b8f060b853507bf1843b4a918e4

• Now you can add description (if you want for ease identificattoion locally) and then pay , you will be having a transaction like this:
  
     
        you should notice the output with the OP_RETURN script has a balance of zero
  
  Input:             => Sender address
                  
        
  Outputs:           => Receiver address         => Change address
  
      
  

On mempool.space the transaction first-output [zero] will readily have your text attached to it.. and  the hex is still available too, if you use explorer like Blockchair i think it will only show you the hex  and you have to decode it yourself..

the TXID 66f4bd03c03280156d5efeb6965f2b0102c17bd41302c16ab0a089e326b48059

So now you can go through thread like this and understand what's been discussed  

Note: OP_RETURN wasn't created to store all kinds of data.. if you need to store one you can do that on a cloud storage or your local drives but incase you need to store an important messages,data to your transaction, OP_RETURN got you covered.  
Warning:  For the purpose of trying out the Tutorial, use testnet to prevent losing of funds  

Source and useful links:
https://learnmeabitcoin.com/technical/script/return/
https://bitcoin.stackexchange.com/questions/29554/explanation-of-what-an-op-return-transaction-looks-like
https://en.bitcoin.it/wiki/Script
https://learnmeabitcoin.com/technical/general/bytes/
https://learnmeabitcoin.com/technical/general/hexadecimal/

Corrections and suggestions are welcome ..

[Mia Chloe]

Finally a decent technical post. Anyways OP,  a little correction. Actually OP_RETURN isn't technically a locking script. Rather It is an opcode that creates a provably unspendable output (not technically a locking mechanism).  Also, The standard limit is 80 bytes of data but the total output script can actually be up to 83 bytes i.e (including the OP_RETURN opcode + push opcode). I think some implementations allow non-standard larger sizes too. 
Also take note that OP_RETURN outputs are actually prunable and I think nodes discard them from the UTXO set. For this kind of experiment it would be nice to use a testnet so you don't end up burning some coins.

[promise444c5]

Actually OP_RETURN isn't technically a locking script

Yes you're right it's just referred to as OP_RETURN ,it's an opcode used in the locking script (added that) but   just to avoid confusion.. i will edit that
Thanks Mia Chloe

Also take note that OP_RETURN outputs are actually prunable and I think nodes discard them from the UTXO set.

Yeah added that earlier here :

... with OP_RETURN  this  datas were proved to be non-spendable thus, can be pruned by nodes

For this kind of experiment it would be nice to use a testnet so you don't end up burning some coins.

I used Testnet, i should have specified that  but i thought it's more easier to recognise through the adrress ..

[Hatchy]

I used Testnet, i should have specified that  but i thought it's more easier to recognise through the adrress ..

Not everyone would recognise those test net addresses as most people on the local board are just familiar with the normal bitcoin address. But then nice thread but the way op. It nice that we have some technical post here some times to help inform our local board members of many possibilities that can happen in the bitcoin world.

Well op_return was introduced as cleaner way to embed data, allowing nodes to immediately identify and discard these output that would have caused the UTXO set to bloat..

[DubemIfedigbo001]

Nice one promise444c5, it's good that there's a way to exclude these excesses of irrelevant data that the devs have found a way to include and bloat the size of UTXO, leading to higher transaction fees.

Personally, I don't see the need for such extra data being included in the UTXOs, it feels to me that they're deviating from the main focus of Bitcoin, which is sending funds across from one person to another. It might even open door for security threats in the future.

[promise444c5]

Not everyone would recognise those test net addresses as most people on the local board are just familiar with the normal bitcoin address.

Don't mind me, i literally included it "Electrum testnet" right from when i was constructing the post, i think Mia Chloe is just directing the statement to those who might be willing  to give the tutorial  a try , so that  they won't risk their real sats ... i didn’t include that before but i will include it as warning now.

[EarnOnVictor]

Oh, this is lovely! I'm just seeing this post here for the first time, and as a matter of fact, I'm just seeing this kind of technical post on the Naija board, all-time. That's interesting, and nice to see that Bill Gates is now among us. This OP_RETURN of a thing is useful, to be honest, and I will take my time to go through it over again.

[promise444c5]

[Update]
The mainnet now uses:

Code:

script(OP_RETURN your_short_msg),0

instead of

Code:

OP_RETURN hex,0

i couldn’t figure the specific version where it was rolled in but just know with a latest version of Electrum, the previous as specified on the thread won’t work with your mainnet…

Thus, incase anyone already tried it with a newer version and it didn’t work, then the script(….) should work..
i will quote it on the main post to make it visible .

[OgNasty]

OP_RETURN limit in the OP could probably be updated.  

I can see that you wrote, "Bitcoin is great" in your test transaction which is very cool.  I assume ASCII art is put in with the same process so you have to encode the ASCII art using a Hex encoder first in order for it to be submitted as a transaction?

For example, let's say I wanted to put this image into the OP_RETURN...

  ╱|、
(˚ˎ 。7  
 |、˜〵          
じしˍ,)ノ

I would use this for the OP_RETURN, correct?

2020e295b17ce380810a28cb9acb8e20e380823720200a207ce38081cb9ce380b52020202020202 02020200ae38198e38197cb8d2c29e3838e

[promise444c5]

OP_RETURN limit in the OP could probably be updated.  

I can see that you wrote, "Bitcoin is great" in your test transaction which is very cool.  I assume ASCII art is put in with the same process so you have to encode the ASCII art using a Hex encoder first in order for it to be submitted as a transaction?

For example, let's say I wanted to put this image into the OP_RETURN...

  ╱|、
(˚ˎ 。7  
 |、˜〵          
じしˍ,)ノ

I would use this for the OP_RETURN, correct?

2020e295b17ce380810a28cb9acb8e20e380823720200a207ce38081cb9ce380b52020202020202 02020200ae38198e38197cb8d2c29e3838e

Didn’t get a notification..
Yes! you can include that but use the  “script(OP_RETURN hex),0”, it should work same way..Although,not sure Satoshi would like that..
I will update the limit aswell…

[nc50lc]

i couldn’t figure the specific version where it was rolled in but just know with a latest version of Electrum, the previous as specified on the thread won’t work with your mainnet…

Since the thread is in English anyways, I'll post this reply here.
I figured that this is important to narrow-down the versions that use the old and new OP_RETURN method in Electrum,
So here it is:

• If it's version 4.4.6 (2023-Aug-21) or older, it should be the old method.
• If it's version 4.5.0 (2024-Jan-12) or newer, it should be the new method.

Here's the relevant commit for reference: /spesmilo/electrum/commit/3ff588049e5e9b8f060b853507bf1843b4a918e4

[promise444c5]

i couldn’t figure the specific version where it was rolled in but just know with a latest version of Electrum, the previous as specified on the thread won’t work with your mainnet…

Since the thread is in English anyways, I'll post this reply here.
I figured that this is important to narrow-down the versions that use the old and new OP_RETURN method in Electrum,
So here it is:

• If it's version 4.4.6 (2023-Aug-21) or older, it should be the old method.
• If it's version 4.5.0 (2024-Jan-12) or newer, it should be the new method.

Here's the relevant commit for reference: /spesmilo/electrum/commit/3ff588049e5e9b8f060b853507bf1843b4a918e4

Thanks for this. My software was version 4.4.6 when I made the thread, which explains why I didn’t notice it at first.
I tried searching for the specific commit or release back then, but I couldn’t find it..although,I think I only skimmed through the release notes to see if I could spot a related keyword…

I’ll quote it for visibility.