CPFP: what infos are needed from the payer

[joe1234]

Hello

what infos do I need from the "payer" in order to be able to start a Child-Pays-For-Parent (CPFP)?


Thank you!

[Ever-young]

Full access to the wallet.
Private key or the phrase.

If you have full access to your wallet as stated above, you can initiate the child pay for parent from your own end without even the permission of the sender.

[Findingnemo]

Full access to the wallet.
Private key or the phrase.

He meant the sender.

OP, you don't need anything from the sender, if the transaction appears in your history and I assume you are using Electrum to receive then you can do CPFP. Just select it from the history tab and choose child pays for parent then set the fees then broadcast and its done.

[Zaguru12]

Nothing if you actually control the wallet. If the payer or sender has actually broadcasted the transaction you will definitely see it on your wallet transaction history list as a pending transaction and then you can actually do the CPFP. Also be informed that you need extra funds in the wallet aside the amount coming from the sender so as to cover for the CPFP fee

Full access to the wallet.
Private key or the phrase.

You don’t need this information from the sender.

[Charles-Tim]

Let us say you will need the txid from the payer to easily trace the transaction, especially if you have many unconfirmed transactions.

From your end, you need no information than the private key of your wallet. If you are using a seed phrase wallet (that generates the private key), you will be able to do child-pay-for-parent.

All you have to do is to spend part or all the unconfirmed coins sent to you by the payer. Making sure you have enough fee that can get the two transactions confirmed.

You need a wallet that has coin control feature like Electum or Sparrow.

[Learn Bitcoin]

I didn't get your question. I am kinda confused. If you meant, what info do you need to know from the sender before you use CPFP, The answer is nothing. Make sure they won't use RBF to change the address before you use CPFP. Otherwise, the transaction will disappear from your history and the balance will be deducted as well. I could be wrong BTW.

The mempool is congested. So, You should check how many inputs and outputs the tx has. If it contains too much input and output, you may have to pay a large transaction fee which everyone wants to avoid. I don't know what other security problem you could face.

[Zaguru12]

Make sure they won't use RBF to change the address before you use CPFP. Otherwise, the transaction will disappear from your history and the balance will be deducted as well. I could be wrong BTW.

You are right, if the sender does an RBF on the transaction then it means the first transaction is invalid because nodes will have replaced the transaction with the new one and the receiver can’t do a CPFP on that particular transaction again. As for the balance in don’t understand what you meant but it wasn’t even added at first instance.

The mempool is congested. So, You should check how many inputs and outputs the tx has. If it contains too much input and output, you may have to pay a large transaction fee which everyone wants to avoid. I don't know what other security problem you could face.

CPFP is never advised when there is a multiple output attached like a batch payment that’s paying unnecessary fees for others. As for many inputs it could be worth it depending on the amount and of it’s the only choice available if not first priority should be RBF

[Alphakilo]

what infos do I need from the "payer" in order to be able to start a Child-Pays-For-Parent (CPFP)?

Assuming you haven't done an RBF and you are doing the CPFP for the first time, an important piece of information you would require from the payer is the transaction ID, which would also include some other details such as the outputs, the addresses associated with the wallet and the amount. With the information, you can then go ahead and use it in starting the CPFP

CPFP is never advised when there is a multiple output attached like a batch payment that’s paying unnecessary fees for others. As for many inputs it could be worth it depending on the amount and of it’s the only choice available if not first priority should be RBF

I will help to buttress that unless it is life or death situation where an individual's life depends on the transaction to be confirmed then you can use the CPFP. However where this is not the case, take a chilled beer and relax while you wait for the network to decongest. In summary, it should be your last resort due to the cost-implications and privacy concerns associated with it.

[BitMaxz]

To make it clear if the payer sends you BTC to your wallet you should be able to see the transaction under transaction history as unconfirmed it looks like this below



RBF or non-RBF should be able to do CPFP.

@OP you don't need any info to ask from the payer but to make sure that is the transaction he made you need to ask him the TXID and then follow the guide from the image above.

[khaled0111]

I will help to buttress that unless it is life or death situation where an individual's life depends on the transaction to be confirmed then you can use the CPFP. However where this is not the case, take a chilled beer and relax while you wait for the network to decongest. In summary, it should be your last resort due to the cost-implications and privacy concerns associated with it.

Actually, in case he can't convince the sender to rbf the transaction, accelerating the transaction from his end by performing CPFP is not a bad idea right now.
The mempool is not as congested as it used to be in the past few weeks so it may be the best time for CPFP before we start seeing more and more unconfirmed transactions piling up again.
Another reason is that transactions paying less than ~20sat/vByte are being purged right now while the fee rate for a fast confirmation is only ~30sat/vByte.

[Learn Bitcoin]

You are right, if the sender does an RBF on the transaction then it means the first transaction is invalid because nodes will have replaced the transaction with the new one and the receiver can’t do a CPFP on that particular transaction again. As for the balance in don’t understand what you meant but it wasn’t even added at first instance.

It wasn't added as a confirmed balance. If you use Electrum, as soon as the new transaction shows in your history, the amount also gets added to your balance but it remains unconfirmed. I don't have any unconfirmed transactions at this moment, so, I am unable to show you any screenshots at this moment. But, it adds the amount to your balance even with zero confirmations.

Okay, I did a Google search and found a screenshot that could give you some idea.



In this screenshot, the guy received 0.12807mBTC and it's still unconfirmed. But it is showing in the balance that he can do CPFP if he wants.

[tranthidung]

what infos do I need from the "payer" in order to be able to start a Child-Pays-For-Parent (CPFP)?

If you are the one to make the CPFP, you only need private key of that address but remember using CPFP costs you more transaction fee than RBF so if you can use RBF, do it as your first choice.

• How Replace-By-Fee (RBF) an Child-Pays-For-Parent (CPFP) can speed up confirmation
• [TUTORIAL] Getting a low-fee transaction unstuck by creating a CPFP with electrum
• [Guide] Use CPFP if your stucked transactions from blockchain.com wallet