Benjamin Weintraub [ARCHIVE] on Nostr: 📅 Original date posted:2023-05-02 🗒️ Summary of this message: A user is ...

📅 Original date posted:2023-05-02
🗒️ Summary of this message: A user is seeking help on generating a transaction that spends the to_local and HTLC output after force closing a channel in LND.
📝 Original message:
Thank you, Ken. I have a follow up question as well.

Context: I’m playing around with some failure scenarios in LND. Say Alice is paying Bob, before Bob is able to send the fulfillment (which includes the HTLC preimage), Alice’s node dies and becomes unreachable.

Bob has already received the commitment for the updated balance and already has the preimage, so he force closes the channel.

My understanding is that he will submit the updated commitment to the blockchain as well as the channel closing transaction (after the CSV timeout) which spends his to_local and the HTLC output.

Here is my problem. After using `lncli closechannel --force ...` , I only see the commitment transaction in the mempool, not the subsequent HTLC/to_local spend. How can I generate the transaction that spends the to_local and HTLC output? If there's a way to generate it with lnd, that would be ideal.

Thanks in advance!

Ben
________________________________
From: Ken Sedgwick <ksedgwic at bonsai.com>
Sent: Sunday, April 30, 2023 14:30
To: Benjamin Weintraub <weintraub.b at northeastern.edu>
Cc: Lightning-dev at lists.linuxfoundation.org <lightning-dev at lists.linuxfoundation.org>
Subject: Re: [Lightning-dev] Spending `to_local` output of commitment

Ben,

The necessary witness is described here:
https://github.com/lightning/bolts/blob/master/03-transactions.md#to_local-output

Regards,

Ken

On Sat, Apr 29, 2023 at 7:57 PM Benjamin Weintraub via Lightning-dev <lightning-dev at lists.linuxfoundation.org<mailto:lightning-dev at lists.linuxfoundation.org>> wrote:
Hi all,

I have a question about commitments. If a peer force closes a channel by sending a commitment to the blockchain, what kind of witness script is needed to redeem the `to_local` funds? (assuming the `to_self_delay` has elapsed.) It seems that the transaction described here is for cooperative closures: https://github.com/lightning/bolts/blob/c74a3bbcf890799d343c62cb05fcbcdc952a1cf3/03-transactions.md#closing-transaction. But for force closures, I would think that the txin would need to be the `to_local` txout of the commitment.

Concretely, I have commited the following transaction on a local simnet bitcoin blockchain and mined 500 blocks on top of it. I want to spend vout[2], how can I generate such a transaction?


{
"hash": "47d15337bb3c29c7c2881dd7cd912604b401ed221c66ea6f781b456d4983d451",
"size": 444,
"vsize": 279,
"weight": 1113,
"version": 2,
"locktime": 551351761,
"vin": [
{
"txid": "0248025b9447df8267d02d14c34ab9b269f52cd827132c70159a55cbf27ab3c1",
"vout": 0,
"scriptSig": {
"asm": "",
"hex": ""
},
"txinwitness": [
"",
"3045022100d3f52ca04d6a71587c29592931e542b16a47f3e9e577f1869b416547d00c62dd0220485da35ad31ff71b4263b1a25f0ba9f35990e1c8d5ac848365bbd588c3ce83d701",
"3044022057fc3878e17a865c12d57b7885ed48f0d6122bd9e00511c8eac150180d1508d502205fd1d0674a41b3c0118d0b6c19b1c77d35fc95bb89f929da6478f22e94dbf5ce01",
"5221038acdafe305edd06e91706ee687a091be306f0f29bcbda52dadde084bbaa36c902103d8fd53b9b43638c2255e1abd6f134a0232d2fba65527252c4eb81f926ddf50ad52ae"
],
"sequence": 2161061453
}
],
"vout": [
{
"value": 0.0000033,
"n": 0,
"scriptPubKey": {
"asm": "0 45ec86244376d47000ca6592783ba26f6b2ae619a24c8f5fad249b8c716955d6",
"hex": "002045ec86244376d47000ca6592783ba26f6b2ae619a24c8f5fad249b8c716955d6",
"reqSigs": 1,
"type": "witness_v0_scripthash",
"addresses": [
"sb1qghkgvfzrwm28qqx2vkf8swazda4j4ese5fxg7hadyjdccutf2htqysq3qz"
]
}
},
{
"value": 0.0000033,
"n": 1,
"scriptPubKey": {
"asm": "0 502a17644b334482d0a3f589d9861af6e2105a9b7afd3f5c258efc98bb6aeeed",
"hex": "0020502a17644b334482d0a3f589d9861af6e2105a9b7afd3f5c258efc98bb6aeeed",
"reqSigs": 1,
"type": "witness_v0_scripthash",
"addresses": [
"sb1q2q4pweztxdzg959r7kyanps67m3pqk5m0t7n7hp93m7f3wm2amksa0fysc"
]
}
},
{
"value": 0.0002,
"n": 2,
"scriptPubKey": {
"asm": "0 045553fc789494f16eff4cfa221d0294e140fb79772efeb7d8397d0ac1c4cf85",
"hex": "0020045553fc789494f16eff4cfa221d0294e140fb79772efeb7d8397d0ac1c4cf85",
"reqSigs": 1,
"type": "witness_v0_scripthash",
"addresses": [
"sb1qq3248lrcjj20zmhlfnazy8gzjns5p7mewuh0ad7c897s4swye7zsyrm5pc"
]
}
},
{
"value": 0.009761,
"n": 3,
"scriptPubKey": {
"asm": "0 2d51ca420d0b6ab56c97ca2631d7304c9ad9025252ea71f3af8f97361679042e",
"hex": "00202d51ca420d0b6ab56c97ca2631d7304c9ad9025252ea71f3af8f97361679042e",
"reqSigs": 1,
"type": "witness_v0_scripthash",
"addresses": [
"sb1q94gu5ssdpd4t2myhegnrr4esfjddjqjj2t48rua037tnv9neqshqm4z7yr"
]
}
}
],
"blockhash": "0fa78bc7e9f6e0a60be71bb5fb2eaaf42a97895bb057f09d7cbb2c49120fa61d",
"confirmations": 500,
"time": 1682451410,
"blocktime": 1682451410
}



Thanks in advance,

Ben
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