The Lightning Network FAQ

[DaveF]

Is there a way to choose what inputs you use when opening channel?

Yes. However, I believe that you need to construct the funding transaction manually when using either LND or c-lightning.

c-lightning: lightning-utxopsbt, lightning-openchannel_init, lightning-openchannel_update, lightning-signpsbt, lightning-openchannel_signed

I have never tested it, so you might want to check the documentation more carefully to see if I am correct before trying it out.
...

Did not work, I'll have to check over the weekend when I have time to see what I did wrong.

You would think that a L2 solution that is (1) designed to save people money in tx fees and (2) is supposed to increase privacy would have a simple way to select the UTXOs you want to use.

-Dave

[1715159202]

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[1715159202]

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[1715159202]

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[Rath_]

I mean when one tries to cheat by broadcasting an outdated commitment transaction. As far as I've understood, the cheater needs both signatures to spend from the force-closed multi-sig address.

The sender needs both signatures to spend the output of the funding transaction. That output is spent by every commitment transaction or a transaction that is signed during cooperative close. Commitment transactions lock each output differently.

"to_local":

Code: (https://github.com/lightning/bolts/blob/master/03-transactions.md#to_local-output)

OP_IF
    # Penalty transaction
    <revocationpubkey>
OP_ELSE
    `to_self_delay`
    OP_CHECKSEQUENCEVERIFY
    OP_DROP
    <local_delayedpubkey>
OP_ENDIF
OP_CHECKSIG

If we assume that "to_local" output belongs to A, they can spend it once the CSV timelock expires using "local_delayedprivkey". B can spend this output at any time using their "revocationprivkey". There is no multisig here; just a bunch of conditions.

"to_remote" is usually a simple P2WPKH address.

Commitment transactions can also include HTLC outputs which we haven't talked about yet. They are used while the payment is being routed through a channel. They are also used for direct payments (to keep the protocol simple).

Offered HTLCs:

Code: (https://github.com/lightning/bolts/blob/master/03-transactions.md#offered-htlc-outputs)

# To remote node with revocation key
OP_DUP OP_HASH160 <RIPEMD160(SHA256(revocationpubkey))> OP_EQUAL
OP_IF
    OP_CHECKSIG
OP_ELSE
    <remote_htlcpubkey> OP_SWAP OP_SIZE 32 OP_EQUAL
    OP_NOTIF
        # To local node via HTLC-timeout transaction (timelocked).
        OP_DROP 2 OP_SWAP <local_htlcpubkey> 2 OP_CHECKMULTISIG
    OP_ELSE
        # To remote node with preimage.
        OP_HASH160 <RIPEMD160(payment_hash)> OP_EQUALVERIFY
        OP_CHECKSIG
    OP_ENDIF
OP_ENDIF

In your case, A has this output in their first commitment transaction. This output can be spent using either the payment preimage + B's HTLC signature, or A's and B's HTLC signatures (HTLC-timeout transaction) which it timelocked.

Received HTLCs:

Code: (https://github.com/lightning/bolts/blob/master/03-transactions.md#received-htlc-outputs)

# To remote node with revocation key
OP_DUP OP_HASH160 <RIPEMD160(SHA256(revocationpubkey))> OP_EQUAL
OP_IF
    OP_CHECKSIG
OP_ELSE
    <remote_htlcpubkey> OP_SWAP OP_SIZE 32 OP_EQUAL
    OP_IF
        # To local node via HTLC-success transaction.
        OP_HASH160 <RIPEMD160(payment_hash)> OP_EQUALVERIFY
        2 OP_SWAP <local_htlcpubkey> 2 OP_CHECKMULTISIG
    OP_ELSE
        # To remote node after timeout.
        OP_DROP <cltv_expiry> OP_CHECKLOCKTIMEVERIFY OP_DROP
        OP_CHECKSIG
    OP_ENDIF
OP_ENDIF

In your case, B has this output in their first commitment transaction. It requires either payment preimage and A's and B's HTLC signatures (HTLC-success transaction), or A's HTLC signature once the CSV timelock expires.

A and B include signatures for HTLC-success/timeout transaction in a "commitment_signed" message ("num_htlcs*signature:htlc_signature" field). If you want to learn why these outputs must be spent using another pre-signed transactions, see this answer.

2. Alice wants to send him 0.02 BTC, so she signs a transaction with two outputs: A) to_local (that can be spent by her after x blocks) and B) to_remote that can be spent by Bob instantly.

It's slightly more complicated than that. We have to assume that they have already signed a commitment transaction with HLTC outputs. Every Lightning transaction involves two commitment updates.

Here's an example that I wrote some time ago. I assume that (A)lice wanted to pay (E)ric through B, C, D.

Here's my current understanding of how the system works:

0) Lightning nodes constantly use the gossip protocol (bolt07) to forward/receive "node_announcement", "channel_announcement", "channel_update" messages and maintain a local view of the whole network.
1) Alice receives a payment invoice from Eric which includes information like: Eric node's public key, payment hash, amount, expiry (date) and cltv expiry.
2) Alice constructs a path to Eric using her local map of the network. She tries to find the cheapest and the shortest route. The longer the route, the higher the risk that funds will get stuck during routing.
2a) She prepares "onion_routing_packet" which includes encrypted routing information for each hop.
3) Alice sends "update_add_htlc" message to Bob, which includes the "onion_routing_packet" (which is the same for all peers), the amount, the payment hash and cltv expiry.
4) Alice and Bob sign a new commitment transaction with an HTLC output.
5) Bob sends "update_add_htlc" to Carol with the same "onion_routing_packet".
6) Carol and Diana, Diana and Eric do the same.
7) Eric sends "update_fullfil_htlc" message to Diana, which includes the payment secret.
8) Eric and Diana remove the HTLC output and update balances by signing a new commitment transaction.
9) Diana sends "update_fullfil_htlc" to Carol with the same payment secret and they update the commitment transaction.
10) Carol and Bob, Bob and Alice do the same.

Comments:

3) The amount Alice sends is actually bigger than the one in the invoice as she must account for the fees. Each hop forwards the HTLC with a smaller amount and keeps the difference. If some hop tries to claim higher fees than Alice expected, the next node in the route will fail the payment as the routing instructions say how much one's node is supposed to forward.

If Bob doesn't have enough coins to forward the payment on his side of the channel with Carol, he must send "update_fail_htlc" message and Alice needs to try sending the payment through another route.

All channels use the same payment hash. It is safe because HTLC outputs require both the payment secret and HTLC signatures, which can be produced only by channel partners, to be spent. See this post for explanation.

In your case, A starts with "update_add_htlc" and then everything goes as you described. Afterwards, Bob sends "update_fullfil_hltc" and the commitment transaction is updated again in the same way.

[Wind_FURY]

Today we’re excited to announce Taro, a new Taproot-powered protocol for issuing assets on the bitcoin blockchain that can be transferred over the Lightning Network for instant, high volume, low fee transactions. This announcement marks a big shift to a multi-asset Lightning Network with the potential for the world’s currencies to route through bitcoin liquidity on the network. At its core, Taro taps into the security and stability of the bitcoin network and the speed, scalability, and low fees of Lightning. Together with the new protocol, we're also announcing our Series B fundraise to further build out Lightning Network infrastructure and help Number of People Go Up. 📈

Taro enables bitcoin to serve as a protocol of value by allowing app developers to integrate assets alongside BTC in apps both on-chain and over Lightning. This expands the reach of Lightning Network as a whole, bringing more users to the network who will drive more volume and liquidity in bitcoin, and allowing people to easily transfer fiat for bitcoin in their apps. More network volume means more routing fees for node operators, who will see the benefits of a multi-asset Lightning Network without needing to support any additional assets.

https://lightning.engineering/posts/2022-4-5-taro-launch/

Keep some of your attention on what these developers are trying to build on Bitcoin, and the Lightning Network. Node operators, prepare yourselves for more competition on those routing fees. Plebs accumulate as much Bitcoin as you possibily can during the next bear cycle. Bitcoin/Lightning might be more than a "payment network" during the new bull cycle.

[Carlton Banks]

read the other post about this protocol


Lightning Labs tweaked someone else's protocol, called it their own, and are now using rich backers to promote it.

Laoula Osuntukon/Elizabeth Stark are increasingly looking like a grifter weirdos, who can't seem to find a corporate finance backed protocol development capture scheme they don't like...


don't worry everyone, _every_ corporate backed protocol has always failed since day dot. The smart ones sucked as much money as they could from their dumb customers, then bailed out before the company started circling the drain. Lightning Labs will be no different

[DaveF]

lnd question:

Is there a way to see if peers tried to open a channel to you but could not for some reason?
One one of my nodes only have 2 channels opened by others although there are a lot of peers.

-Dave

[dkbit98]

I don't know if anyone saw that HRF Humans Right Foundation (the real one, not a scam started by Zoltan Konder scammer) is giving everyone 2,100 sats in Lightning Network to everyone who wants it.
All you have to do is, download Muun wallet for your smartphone and fill the form with your email address (use some temp mail) and write explanation why are you interested in Bitcoin?
You obviously can't get rich by doing this, but it's a good way for people to get their first Bitcoin for free and using Lightning.

Check out this cool page on HRF website:

Facing high inflation, frozen bank accounts, or difficulties in sending money?
Bitcoin is a way out.

https://www.getbitcoin.org/#get-btc

[DaveF]

I guess the question is do you really have to use the Muun wallet or will any wallet work?
I didn't check yet, going to later today but was just wondering why that one vs my own running on my own node.

-Dave

[dkbit98]

I guess the question is do you really have to use the Muun wallet or will any wallet work?
I didn't check yet, going to later today but was just wondering why that one vs my own running on my own node.

I think Muun wallet team received some donations before from HRF ($25k back in 2021), they probably like what they are doing and that is the reason to choose them.
Muun wallet have some unique way of storing both regular Bitcoin and Lightning transactions in single multi-signature wallet, so maybe it's something related with that.
You can try receiving sats with other wallet, but there must be a reason for them to say several times to use Muun wallet and not something else.

[LoyceV]

I think Muun wallet team received some donations before from HRF ($25k back in 2021)
~
You can try receiving sats with other wallet, but there must be a reason for them to say several times to use Muun wallet and not something else.

I was expecting this to work the other way: usually "the wallet" would pay someone for promoting their wallet. I wasn't expecting this from Human Rights Foundation, but I guess it makes sense considering those headlines on the site:

Bitcoin Dissidents: Those Who Need It Most
Fighting Monetary Colonialism with Open Source Code
Bitcoin, Authoritarianism, and Human Rights
How Bitcoin Can Help Refugees
How Bitcoin Is Used to Promote Human Rights: Stories From Activists and Refugees
How Bitcoin Is Protecting Human Rights Around the World
Banking The Unbanked: fireside with Jack Dorsey

Update: I've received the email:

Hi,

Congratulations on taking the first step of your Bitcoin journey. If you haven’t already, please download MuunWallet (iOS or Android). This will be the Bitcoin wallet you use to claim your Bitcoin.

Click this link to be redirected to our Bitcoin faucet. Tap “Copy LNURL”.

Open up MuunWallet, and create a new wallet. Tap “Receive”, then tap “Lightning”. Tap the scan button at the top right – it looks like this: [--] – then paste the LNURL link.

Congratulations, you have successfully received your first Bitcoin!

-Human Rights Foundation

BlueWallet says: "Unsupported lnurl".
Phoenix Wallet can't scan the QR-code. Copying it manually shows "legend.lnbits.com returned an error".
Muun Wallet says: "Contacting legend.lnbits.com...", followed by "Something went wrong".
That's not the best promotion for LN

[dkbit98]

BlueWallet says: "Unsupported lnurl".
Phoenix Wallet can't scan the QR-code. Copying it manually shows "legend.lnbits.com returned an error".
Muun Wallet says: "Contacting legend.lnbits.com...", followed by "Something went wrong".
That's not the best promotion for LN

Thanks for testing this for us LoyceV, it's obviously not related with wallet that is used for receiving coins.
They are probably out of funds or they stopped sending sats due to abuse, but if that is the case they should at least add some notification information on their website or disable form submission.

[LoyceV]

They are probably out of funds

That could be the reason. I tried again (by scanning the QR-code in Phoenix Wallet, because I already uninstalled Muun), and it worked now. Funds were received in a few seconds.
I've sent 2100 sat back to HRF.org.

[Wind_FURY]

read the other post about this protocol

What other post?

Lightning Labs tweaked someone else's protocol, called it their own, and are now using rich backers to promote it.

Laoula Osuntukon/Elizabeth Stark are increasingly looking like a grifter weirdos, who can't seem to find a corporate finance backed protocol development capture scheme they don't like...


don't worry everyone, _every_ corporate backed protocol has always failed since day dot. The smart ones sucked as much money as they could from their dumb customers, then bailed out before the company started circling the drain. Lightning Labs will be no different

OK, there's drama behind it. But from a speculator's perspective and if we move away from the drama, and concentrate on the technology of the protocol and what functionality it can bring to Bitcoin, I believe there's a new narrative to build on to push Bitcoin to six digits?

[fillippone]

read the other post about this protocol

What other post?

Lightning Labs tweaked someone else's protocol, called it their own, and are now using rich backers to promote it.

Laoula Osuntukon/Elizabeth Stark are increasingly looking like a grifter weirdos, who can't seem to find a corporate finance backed protocol development capture scheme they don't like...


don't worry everyone, _every_ corporate backed protocol has always failed since day dot. The smart ones sucked as much money as they could from their dumb customers, then bailed out before the company started circling the drain. Lightning Labs will be no different

OK, there's drama behind it. But from a speculator's perspective and if we move away from the drama, and concentrate on the technology of the protocol and what functionality it can bring to Bitcoin, I believe there's a new narrative to build on to push Bitcoin to six digits?

Well, the technology is exactly what TARO stole from an open source project, named RGB.
Technically you cannot steal an open source code, but omitting to credit the original developers for the sake of obtaining funding, well, it's borderline with non ethical behavior.
I already discussed it here and here, not to derail too much this thread.

[n0nce]

OK, there's drama behind it. But from a speculator's perspective and if we move away from the drama, and concentrate on the technology of the protocol and what functionality it can bring to Bitcoin, I believe there's a new narrative to build on to push Bitcoin to six digits?

Well, the technology is exactly what TARO stole from an open source project, named RGB.
Technically you cannot steal an open source code, but omitting to credit the original developers for the sake of obtaining funding, well, it's borderline with non ethical behavior.
I already discussed it here and here, not to derail too much this thread.

Besides this technology being copied without attribution, I don't understand why Wind_FURY is always so focused on dollar-denominated Bitcoin price. Does he believe people work for free to improve Bitcoin just so there is a new narrative to build on to push Bitcoin to six digits? People like those that work on RGB who put in their own free time and money to improve Bitcoin, make it more usable, faster, secure, to add more features like tokens - they don't do it just so some random investor can double his investment. These are genuine attempts to improve Bitcoin as a currency, as a means of payment and much more.
Sure, it can get more valuable if it's got more features, but please let's not always think 'price first' - that's what shitcoiners do. Adding whatever people find fun and cool so they pump their coin, then dump everything. Just about profit, no spirit of anarchistic independent money (often no nodes exist in those projects) or banking the unbanked.

[LoyceV]

BlueWallet says: "Unsupported lnurl".
Phoenix Wallet can't scan the QR-code. Copying it manually shows "legend.lnbits.com returned an error".
Muun Wallet says: "Contacting legend.lnbits.com...", followed by "Something went wrong".
That's not the best promotion for LN

To continue this test: I just found out that 3 days ago, my BlueWallet received 2 times 2100 sat. So it looks like the failed and "Unsupported lnurl" worked a bit later anyway! I can't check if Muun Wallet received something, because I already deleted it (and the seed phrase too).

I assumed a LNURL payment can work only once, but somehow the same QR-code paid me 3 times in total. That seems like a serious bug. I'll donate it back again.

[PrimeNumber7]

BlueWallet says: "Unsupported lnurl".
Phoenix Wallet can't scan the QR-code. Copying it manually shows "legend.lnbits.com returned an error".
Muun Wallet says: "Contacting legend.lnbits.com...", followed by "Something went wrong".
That's not the best promotion for LN

To continue this test: I just found out that 3 days ago, my BlueWallet received 2 times 2100 sat. So it looks like the failed and "Unsupported lnurl" worked a bit later anyway! I can't check if Muun Wallet received something, because I already deleted it (and the seed phrase too).

I assumed a LNURL payment can work only once, but somehow the same QR-code paid me 3 times in total. That seems like a serious bug. I'll donate it back again.

It is only a matter of time before someone takes all the coin intended to be offered to MuunWallet users. The process you described already sounds easy to automate at scale, and simply accessing a LNURL is even easier.

[DaveF]

BlueWallet says: "Unsupported lnurl".
Phoenix Wallet can't scan the QR-code. Copying it manually shows "legend.lnbits.com returned an error".
Muun Wallet says: "Contacting legend.lnbits.com...", followed by "Something went wrong".
That's not the best promotion for LN

To continue this test: I just found out that 3 days ago, my BlueWallet received 2 times 2100 sat. So it looks like the failed and "Unsupported lnurl" worked a bit later anyway! I can't check if Muun Wallet received something, because I already deleted it (and the seed phrase too).

I assumed a LNURL payment can work only once, but somehow the same QR-code paid me 3 times in total. That seems like a serious bug. I'll donate it back again.

It is only a matter of time before someone takes all the coin intended to be offered to MuunWallet users. The process you described already sounds easy to automate at scale, and simply accessing a LNURL is even easier.

And I didn't get anything in any of the wallets I tried.
I guess either they did some really bad coding, or did not put in enough funds, or???
Either way, does not make them look good.

-Dave

[PrimeNumber7]

BlueWallet says: "Unsupported lnurl".
Phoenix Wallet can't scan the QR-code. Copying it manually shows "legend.lnbits.com returned an error".
Muun Wallet says: "Contacting legend.lnbits.com...", followed by "Something went wrong".
That's not the best promotion for LN

To continue this test: I just found out that 3 days ago, my BlueWallet received 2 times 2100 sat. So it looks like the failed and "Unsupported lnurl" worked a bit later anyway! I can't check if Muun Wallet received something, because I already deleted it (and the seed phrase too).

I assumed a LNURL payment can work only once, but somehow the same QR-code paid me 3 times in total. That seems like a serious bug. I'll donate it back again.

It is only a matter of time before someone takes all the coin intended to be offered to MuunWallet users. The process you described already sounds easy to automate at scale, and simply accessing a LNURL is even easier.

And I didn't get anything in any of the wallets I tried.
I guess either they did some really bad coding, or did not put in enough funds, or???
Either way, does not make them look good.

-Dave

Loyce's experience with the error messages is likely (IMO) a result of poor coding and/or the lack of testing (and resolving issues when tests fail). If you are not receiving any funds when Loyce received funds 3x, may mean that someone already took all the funds.

[Wind_FURY]

OK, there's drama behind it. But from a speculator's perspective and if we move away from the drama, and concentrate on the technology of the protocol and what functionality it can bring to Bitcoin, I believe there's a new narrative to build on to push Bitcoin to six digits?

Well, the technology is exactly what TARO stole from an open source project, named RGB.
Technically you cannot steal an open source code, but omitting to credit the original developers for the sake of obtaining funding, well, it's borderline with non ethical behavior.
I already discussed it here and here, not to derail too much this thread.

Besides this technology being copied without attribution, I don't understand why Wind_FURY is always so focused on dollar-denominated Bitcoin price.

Ser, I would be lying if I said that I didn't care about Bitcoin's price. I did buy and HODL them as an investment first and foremost. Didn't anyone?

Plus what's with that tone? Why does it look like that you are always trying to make me look bad? I never had any interactions with you in the forum, nor have I insulted you.

Does he believe people work for free to improve Bitcoin just so there is a new narrative to build on to push Bitcoin to six digits? People like those that work on RGB who put in their own free time and money to improve Bitcoin, make it more usable, faster, secure, to add more features like tokens - they don't do it just so some random investor can double his investment. These are genuine attempts to improve Bitcoin as a currency, as a means of payment and much more.

Sure, it can get more valuable if it's got more features, but please let's not always think 'price first' - that's what shitcoiners do. Adding whatever people find fun and cool so they pump their coin, then dump everything. Just about profit, no spirit of anarchistic independent money (often no nodes exist in those projects) or banking the unbanked.

I was merely suggesting Taro from a technological perspective, without the drama. Will it improve Bitcoin to be more than what it is today? Will it help onboard more users from other cryptocurrencies, from Ethereum perhaps? Will it be the next narrative during the next bull cycle? It was simply a shower-thought.

[n0nce]

Ser, I would be lying if I said that I didn't care about Bitcoin's price. I did buy and HODL them as an investment first and foremost. Didn't anyone?

Plus what's with that tone? Why does it look like that you are always trying to make me look bad? I never had any interactions with you in the forum, nor have I insulted you.

It's just that I want improvements in Bitcoin simply for the sake of having a better payment system and not for the sake of making some investor bags of money. Sure, the value of Bitcoin is that it's such a good payment system, so that's part of the reason it has a high price. But this shouldn't be the main motivation for innovation. That's why a statement like 'this new technology will get btc to the moon' generally rubs me the wrong way.