Skip to main content
8 votes
Accepted

Why aren't 3 party (or more) channels realistically possible in lightning today?

Today's lightning channels use the ln-penalty update mechanism. Each time an HTLC is staged or resolved, the channel owners negotiate new commitment transactions for each side. As part of the ...
Murch's user avatar
  • 76k
7 votes
Accepted

Eltoo: Does the relative locktime on the first UTXO set the lifetime of the channel?

Yes, you’re reading it right. The construction presented here has a limited lifetime since the Settle_0 transaction becomes valid at some point. However, later in the paper, the authors introduce an ...
Murch's user avatar
  • 76k
7 votes
Accepted

Does eltoo require trusting watchtowers not to close channels?

I was intrigued by your question and tried to figure out whether any trustless solutions have been proposed. I found a [Lightning-dev] mailing list thread positing a rough idea by ZmnSCPxj. Z-man ...
Murch's user avatar
  • 76k
7 votes
Accepted

How to emulate SIGHASH_NOINPUT using CHECKSIGFROMSTACKVERIFY?

Eltoo relies on a primitive SIGHASH_ANYPREVOUT or SIGHASH_NOINPUT (hereafter referred as APO) BPI118, constructing Eltoo from APO would be replacing the CHECKSIG figure 4 of Eltoo paper with a ...
sanket1729's user avatar
  • 1,402
5 votes
Accepted

Lightning Network: asymmetry in the information tracked by each participant?

When two channel participants open a channel or update it, they exchange commitment transactions. These commitment transactions allow each party to unilaterally close the channel. The commitment ...
Murch's user avatar
  • 76k
4 votes
Accepted

What are the pitfalls of repurposing the nLocktime field for backward compatability in eltoo?

I was hoping somebody else would answer this, since I am the author of eltoo, I would have preferred an independent answer. To recap: the locktime is used in eltoo to enable a numeric comparison ...
cdecker's user avatar
  • 9,508
4 votes

Is eltoo more memory efficient for watchtowers?

Without eltoo (ie today) a watchtower needs to store a different justice transaction for every channel update in case the channel counterparty broadcasts (deliberately or accidentally) an expired ...
Michael Folkson's user avatar
4 votes

Eltoo: Does the relative locktime on the first UTXO set the lifetime of the channel?

Thanks for the feedback! I replaced "Update: 0" with a "Funding: 0" which is put on-chain when the channel is opened and the channel parties have both signed the first off-chain &...
Richard Myers's user avatar
3 votes
Accepted

How would an adversary increase the required fee to replace a transaction by up to 500 times?

Yes it is, that's why "economical pinning" is also an issue. Requiring a high enough fee increase is comparable to preventing you from replacing altogether. And if you actually replace it, ...
Antoine Poinsot's user avatar
3 votes

How do eltoo channel constructions using ANYPREVOUT compare to those using CTV and CSFS?

The main answer is that we don't really have a fully spec'd Eltoo design for Anyprevout (or CTV+CSFS), and that's something that requires more thorough investigation to make the correct primitives ...
Jeremy Rubin's user avatar
3 votes

Eltoo: Does the relative locktime on the first UTXO set the lifetime of the channel?

Current thinking is (I believe) just to have a funding utxo on chain ("Setup_0") which is always spent by some update transaction ("Update_1" etc; there is no "Settle_0") ...
Anthony Towns's user avatar
2 votes

How do eltoo channel constructions using ANYPREVOUT compare to those using CTV and CSFS?

To add to Jeremy's answer I'll summarize some thoughts from Christian Decker (co-author of BIP 118 for ANYPREVOUT) on the bitcoin-dev mailing list. As Jeremy points out SIGHASH_ANYPREVOUT (APO) has ...
Michael Folkson's user avatar
2 votes
Accepted

Eltoo channel - can opening be off-chain

I think you have answered your question yourself in the last question that you raised. The problem with not publishing Tu0 is that the funder of the channel could double spend the input of Tu0 and in ...
Rene Pickhardt's user avatar
1 vote

How would an adversary increase the required fee to replace a transaction by up to 500 times?

The example given in version3_transactions.md shows how to get a fee rate increase of 100x, but if you assume transaction B is 200vB, instead of 1000vB, you can also demonstrate a 500x increase with ...
Richard Myers's user avatar
1 vote

How could 6 billion people be onboarded to Bitcoin and Lightning today?

The short answer is we’re not quite there yet but almost…the things we need to accomplish this goal however are on the roadmap. I say this to address the common FUD which states that Bitcoin can never ...
Valentino Zertuche's user avatar
1 vote

Can eltoo's no-penalty design be exploited by malicious submissions of old state?

Let's say Alice and Bob have an active eltoo channel. They have transacted 10 times, so there's a history of 10 update txs (as well as 10 accompanying settlement txs, each spending their respective ...
smizzlov's user avatar
  • 350
1 vote
Accepted

Why does the funder send the signed settlement to the counter-party in eltoo?

That step could be skipped for the initial settlement tx of a single-funded channel, but then you would need to implement different behaviour for 1) all subsequent settlement txs of a single-funded ...
smizzlov's user avatar
  • 350
1 vote

BIP118 (SIGHASH_NOINPUT) vs. ANYPREVOUT

The differences between SIGHASH_NOINPUT (BIP 118) and SIGHASH_ANYPREVOUT (proposed update to BIP 118) were discussed at the Sydney Socratic Seminar in July 2020. There is not a real conflict between ...
Michael Folkson's user avatar
1 vote
Accepted

Are both CSV and nLocktime unnecessary in Eltoo?

Anthony Towns' recent draft uses CLTV, which also uses nLocktime.
Janus Troelsen's user avatar
1 vote
Accepted

Does Eltoo eliminate the need to watch the blockchain/implement Watchtowers

With eltoo you can publish old state and the Bitcoin network will accept it. (As every state is a valid and signed transaction.) Let me recall the key idea of eltoo in short (if it's too short read ...
Rene Pickhardt's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible