<p>No. This is not possible, although, technically it could be possible by adding <code>n</code> child transaction each formed as a tx out of you original transaction. The child transaction then could each have a OP_RETURN (data only) output. With a OP_RETURN output you can store up to 80 bytes (mind <a href="https://github.com/bitcoin/bitcoin/pull/5286" rel="nofollow">5286</a>). A DER signature will be around <a href="https://github.com/bitcoin/bips/blob/master/bip-0062.mediawiki#der-encoding" rel="nofollow">72 Bytes (71.5 in avg)</a></p>

<p>... so not much to left besides the signature (~8 bytes per OP_RETURN tx as tx out of the original tx). So maybe use OP_RETURN txout <code>0</code> to <code>n-1</code> for the text/data and <code>n</code> for the signature. Obviously this will increase your transaction fee a little because you need at least 2 additional transactions.</p>

<p><strong>Conclusion:</strong>
Not possible unless your are happy to experiment with forging your own custom transactions.</p>

CC BY-SA 3.0
2015-07-27T14:43:31.973Z
Ya looks like OP_RETURN  is the only way to add metadata to a transaction at this point. That's too bad because most wallets don't allow that property to be set, so it would require custom development.
Paul Fryer
CC BY-SA 3.0
2015-07-26T15:30:51.360Z
2015-07-26T15:30:51.360Z
Jonas Schnelli
<p>I know you can use the bitcoin client to sign messages (for which you own the private key) and verify messages from other public addresses. But can you actually embed a signed message into a transaction so its on the blockchain for anyone to verify? When I say "signed message" i'm referring to an arbitrary message like in the attached example.</p>

<p><a href="https://i.sstatic.net/HT1Ux.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/HT1Ux.png" alt="enter image description here"></a></p>

<transactions><signature><message-signing>
Can you include a signature in a bitcoin payment?
Paul Fryer
# Can you include a signature in a bitcoin payment?

(Asked by: username_0 on 2015-07-26)

I know you can use the bitcoin client to sign messages (for which you own the private key) and verify messages from other public addresses. But can you actually embed a signed message into a transaction so its on the blockchain for anyone to verify? When I say "signed message" i'm referring to an arbitrary message like in the attached example.

[![enter image description here](https://i.sstatic.net/HT1Ux.png)](https://i.sstatic.net/HT1Ux.png)

**Tags:** transactions, signature, message-signing


---

## 1 answers

### Answer by username_1 on 2015-07-26. Score: 3 | Accepted answer

No. This is not possible, although, technically it could be possible by adding `n` child transaction each formed as a tx out of you original transaction. The child transaction then could each have a OP\_RETURN (data only) output. With a OP\_RETURN output you can store up to 80 bytes (mind [5286](https://github.com/bitcoin/bitcoin/pull/5286)). A DER signature will be around [72 Bytes (71.5 in avg)](https://github.com/bitcoin/bips/blob/master/bip-0062.mediawiki#der-encoding)

... so not much to left besides the signature (~8 bytes per OP\_RETURN tx as tx out of the original tx). So maybe use OP\_RETURN txout `0` to `n-1` for the text/data and `n` for the signature. Obviously this will increase your transaction fee a little because you need at least 2 additional transactions.

**Conclusion:**
Not possible unless your are happy to experiment with forging your own custom transactions.

> **Comments:**
> **username_0**: Ya looks like OP_RETURN  is the only way to add metadata to a transaction at this point. That's too bad because most wallets don't allow that property to be set, so it would require custom development.  

---

