darosior [ARCHIVE] on Nostr: 📅 Original date posted:2020-01-30 📝 Original message: Sorry I wasn't clear ...

📅 Original date posted:2020-01-30
📝 Original message:
Sorry I wasn't clear enough in the \`(cdecker)\` paragraph.







The funding transaction sig would actually fail verification if tip differs between funder and fundee.







Darosior ( i'll stick with my pseudo, first names definitely don't have enough entropy :-) )
\-------- Original Message --------
On Jan 30, 2020, 19:09, Antoine Riard < antoine.riard at gmail.com> wrote:

>
>
>
> Hey Darosior,
>
>
>
> You don't need a strict synchronization between both peers,
>
>
> just let nLocktime picked up by initiator and announce it at
>
>
> same time than feerate or at \`tx\_complete\`. Worst-case,
>
>
> a slow-block-processing receiver may not be able to get
>
>
> the transaction accepted by its local mempool, but IMO that's
> fine if at least the initiator is able to do so. We are requiring peers
>
>
> to be weakly in sync before operating channel anyway (\`funding\_locked\`
>
>
> exchange).
>
>
>
>
>
> Funding\_tx can already be drop from mempool for others
>
>
> reasons like mempool shrinks or expiry so broadcaster
>
>
> should always be ready to re-send it or bump feerate.
>
>
>
> Or are you describing another issue ?
>
>
>
>
>
> Le jeu. 30 janv. 2020 à 04:06, darosior <[darosior at protonmail.com][darosior_protonmail.com]> a écrit :
>
>
> > Hi Antoine and all,
> >
> >
> >
> >
> >
> >
> >
> > About nLockTime fun thing is Lisa, Cdecker and I had this conversation to integrate it to C-lightning just yesterday.
> >
> >
> >
> >
> >
> >
> >
> > Unfortunately you need to add a "My tip is xxxx" to the openchannel msg, otherwise if you set nLockTime to tip. (cdecker)
> >
> >
> >
> >
> >
> >
> >
> > Moreover in case of reorg the funding tx (now non-final) would be dropped from mempool ? But you could set nLockTime to, say, tip - 6. (niftynei)
> >
> >
> >
> >
> >
> >
> >
> > Antoine
> >
> >
> >
> >
> >
> > \-------- Original Message --------
> > On Jan 30, 2020, 01:21, Antoine Riard < [antoine.riard at gmail.com][antoine.riard_gmail.com]> wrote:
> >
> > >
> > >
> > >
> > > Hey thanks for this proposal!
> > >
> > >
> > >
> > > 2 high-level questions:
> > >
> > >
> > >
> > >
> > >
> > > What about multi-party tx construction ? By multi-party, let's define
> > >
> > > Alice initiate a tx construction to Bob and then Bob announce a
> > >
> > >
> > > construction to Caroll and "bridge" all inputs/outputs additions/substractions
> > >
> > >
> > > in both directions. I think the current proposal hold, if you are a bit more
> > >
> > >
> > > tolerant and bridge peer don't send a tx\_complete before receiving ones
> > >
> > >
> > > from all its peers.
> > >
> > >
> > >
> > >
> > >
> > > What about transactions format ? I think we should coordinate with Coinjoin
> > >
> > >
> > > people to converge to a common one to avoid leaking protocol usage when
> > > we can hinder under Taproot. Like setting the nLocktime or sorting inputs
> > >
> > >
> > > in some protocol-specific fashion. Ideally we should have a BIP for format
> > >
> > >
> > > but every layer 2 protocols its own set of messages concerning the construction.
> > >
> > > > nLocktime is always set to 0x000000
> > > Maybe we can implement anti-fee sniping and mask among wallet core
> > > txn set: [https://github.com/bitcoin/bitcoin/blob/aabec94541e23a67a9f30dc2c80dab3383a01737/src/wallet/wallet.cpp\#L2519][https_github.com_bitcoin_bitcoin_blob_aabec94541e23a67a9f30dc2c80dab3383a01737_src_wallet_wallet.cpp_L2519] ?
> > >
> > > > In the case of a close, a failed collaborative close would result in an error and a uninlateral close"
> > > Or can we do first a mutual closing tx, hold tx broadcast for a bit if "opt\_dual\_fund"
> > > is signaled to see if a tx\_construction + add\_funding\_input for the channel is received
> > > soon ? At least that would be a dual opt-in to know than one party can submit a funding-outpoint
> > > as part of a composed tx ?
> > >
> > >
> > >
> > >
> > > Antoine
> > >
> > >
> > >
> > >
> > >
> > > Le lun. 27 janv. 2020 à 20:51, lisa neigut <[niftynei at gmail.com][niftynei_gmail.com]> a écrit :
> > >
> > >
> > > > Some of the feedback I received from the check-in for the dual-funding proposal this past Monday was along the lines that we look at simplifying for breaking it into smaller, more manageable chunks.
> > > >
> > > >
> > > >
> > > >
> > > > The biggest piece of the dual-funding protocol update is definitely the move from a single peer constructing a transaction to two participants. We're also going to likely want to reuse this portion of the protocol for batched closings and splicing. To that extent, it seemed useful to highlight it in a separate email.
> > > >
> > > >
> > > >
> > > >
> > > > This is a change from the existing proposal in the dual-funding [PR \#524][PR _524] \-- it allows for the removal of inputs and outputs.
> > > >
> > > >
> > > >
> > > >
> > > > The set of messages are as follows.
> > > >
> > > >
> > > >
> > > >
> > > > Note that the 'initiation' of this protocol will be different depending on the case of the transaction (open, close or splice):
> > > >
> > > >
> > > >
> > > >
> > > > 1. type:   440 \`tx\_add\_input\`
> > > >
> > > > 2. data:
> > > >
> > > >     \* \[\`32\*byte\`:\`channel\_identifier\`\]
> > > >
> > > >     \* \[\`u64\`:\`sats\`\]
> > > >
> > > >     \* \[\`sha256\`:\`prevtx\_txid\`\]
> > > >
> > > >     \* \[\`u32\`:\`prevtx\_vout\`\]
> > > >
> > > >     \* \[\`u16\`:\`prevtx\_scriptpubkey\_len\`\]
> > > >
> > > >     \* \[\`prevtx\_scriptpubkey\_len\*byte\`:\`prevtx\_scriptpubkey\`\]
> > > >
> > > >     \* \[\`u16\`:\`max\_witness\_len\`\]
> > > >
> > > >     \* \[\`u16\`:\`scriptlen\`\]
> > > >
> > > >     \* \[\`scriptlen\*byte\`:\`script\`\]
> > > >
> > > >     \* \[\`byte\`:\`signal\_rbf\`\]
> > > >
> > > >
> > > >
> > > >
> > > > 1. type: 442 \`tx\_add\_output\`
> > > >
> > > > 2. data:
> > > >
> > > >     \* \[\`32\*byte\`:\`channel\_identifier\`\]
> > > >
> > > >     \* \[\`u64\`:\`sats\`\]
> > > >
> > > >     \* \[\`u16\`:\`scriptlen\`\]
> > > >
> > > >     \* \[\`scriptlen\*byte\`:\`script\`\]
> > > >
> > > >
> > > >
> > > >
> > > > 1. type: 444 \`tx\_remove\_input\`
> > > >
> > > > 2. data:
> > > >
> > > >     \* \[\`32\*byte\`:\`channel\_identifier\`\]
> > > >
> > > >     \* \[\`sha256\`:\`prevtx\_txid\`\]
> > > >
> > > >     \* \[\`u32\`:\`prevtx\_vout\`\]
> > > >
> > > >
> > > >
> > > >
> > > > 1. type: 446 \`tx\_remove\_output\`
> > > >
> > > > 2. data:
> > > >
> > > >     \* \[\`32\*byte\`:\`channel\_identifier\`\]
> > > >
> > > >     \* \[\`u64\`:\`sats\`\]
> > > >
> > > >     \* \[\`u16\`:\`scriptlen\`\]
> > > >
> > > >     \* \[\`scriptlen\*byte\`:\`script\`\]
> > > >
> > > >
> > > >
> > > >
> > > > 1. type: 448 \`tx\_complete\`
> > > >
> > > > 2. data:
> > > >
> > > >     \* \[\`32\*byte\`:\`channel\_identifier\`\]
> > > >
> > > >     \* \[\`u16\`:\`num\_inputs\`\]
> > > >
> > > >     \* \[\`u16\`:\`num\_outputs\`\]
> > > >
> > > >
> > > >
> > > >
> > > > 1. type:  448 \`tx\_sigs\`
> > > >
> > > > 2. data:
> > > >
> > > >     \* \[\`channel\_id\`:\`channel\_identifier\`\]
> > > >
> > > >     \* \[\`u16\`:\`num\_witnesses\`\]
> > > >
> > > >     \* \[\`num\_witnesses\*witness\_stack\`:\`witness\_stack\`\]
> > > >
> > > >
> > > >
> > > >
> > > > 1. subtype: \`witness\_stack\`
> > > >
> > > > 2. data:
> > > >
> > > >     \* \[\`sha256\`:\`prevtx\_txid\`\]
> > > >
> > > >     \* \[\`u32\`:\`prevtx\_vout\`\]
> > > >
> > > >     \* \[\`u16\`:\`num\_input\_witness\`\]
> > > >
> > > >     \* \[\`num\_input\_witness\*witness\_element\`:\`witness\_element\`\]
> > > >
> > > >
> > > >
> > > >
> > > > 1. subtype: \`witness\_element\`
> > > >
> > > > 2. data:
> > > >
> > > >     \* \[\`u16\`:\`len\`\]
> > > >
> > > >     \* \[\`len\*byte\`:\`witness\`\]
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > \#\# General Notes
> > > >
> > > > \- Validity of inputs/outputs is not checked until both peers have sent consecutive \`tx\_complete\`  messages.
> > > >
> > > > \- Duplicate inputs or outputs is a protocol error.
> > > >
> > > > \- Feerate is set by the initiator, or in the case of a closing transaction, negotiated before the transaction construction is initiated.
> > > >
> > > > \- Every peer pays fees for the inputs + outputs they contribute, plus enough to cover the maximum estimate of their witnesses. Overpayment of fees is permissible.
> > > >
> > > > \- Initiator is responsible for contributing the output/input in question, i.e. the 
> > > >
> > > >   funding output in the case of an opening, or the funding input in the case of a close. 
> > > >
> > > >   (This means that the opener will pay for the opening output). In the case of a splice,
> > > >
> > > >   the initiator of the splice pays for the funding tx's inclusion as an input and the
> > > >
> > > >   new 'funding tx' output.
> > > >
> > > > \- Any contributor may signal that their input is RBF'able. The nSequence for this input should be set to 0xFEFF FFFF, 0xFFFFFFFF otherwise.
> > > >
> > > > \- The initiating peer is understood to be paying the fee for the shared transaction fields (nVersion \[4\], segwit marker + flag \[2\], input + output counts \[2-18\], witness count \[1-9\], nLocktime \[4\]; total \[13-40bytes\])
> > > >
> > > > \- Inputs MUST be segwit compatible (PW\* or P2SH-PW\*)
> > > >
> > > > \- All output scripts must be standard
> > > >
> > > > \- nLocktime is always set to 0x00000000.
> > > >
> > > > \- The \`num\_inputs\` and \`num\_outputs\` in \`tx\_complete\` is a count of that peer’s final input and output contributions, net any removals.
> > > >
> > > >
> > > >
> > > >
> > > > \- Either peer may add or remove inputs and outputs until both peers have successfully
> > > >
> > > >   exchanged a \`tx\_complete\` message in succession.
> > > >
> > > > \- Either peer may only add or remove their own input or output.
> > > >
> > > > \- In the case that a \`tx\_complete\` agreement cannot be reached, either peer may
> > > >
> > > >   fail the channel or open protocol (whatever is reasonable for the particular case)
> > > >
> > > >   - In the case of a splice, this would be a soft error (channel returns to normal operation until      
> > > >
> > > >     otherwise failed or closed.)
> > > >
> > > >   - In the case of an open, this would be a failure to open the channel.
> > > >
> > > >   - In the case of a close, a failed collaborative close would result in an error and a unilateral close.
> > > >
> > > >
> > > >
> > > >
> > > > \#\#\# Considering the Simple Open case (2 parties)
> > > >
> > > > \- Both peers signal \`opt\_dual\_fund\`
> > > >
> > > > \- Opener initiates a channel open with \`open\_channel2\` message, indicating the feerate for the opening transaction
> > > >
> > > > \- Accepter signals acceptance of channel open as proposed, including proposed feerate, via \`accept\_channel2\`
> > > >
> > > > \- Opener sends \`tx\_add\_output\`, with the funding output for the sum of both peer’s funding\_amount
> > > >
> > > > \- Opener sends \`tx\_add\_input\` for each input the wish to add to the funding transaction
> > > >
> > > > \- Opener sends \`tx\_add\_output\` for their change 
> > > >
> > > > \- Opener sends \`tx\_complete\`
> > > >
> > > > \- Accepter sends \`tx\_add\_input\` for each input they wish to add to the funding transaction
> > > >
> > > > \- Accepter sends \`tx\_add\_output\` for their change.
> > > >
> > > > \- Accepter sends \`tx\_complete\`
> > > >
> > > > \- Opener sends \`tx\_complete\`
> > > >
> > > > \- Opener and accepter exchange commitment signatures; etc.
> > > >
> > > >
> > > >
> > > >
> > > > \#\#\# Considering the Splice case:
> > > >
> > > > \- Both peers signal \`opt\_splice\_ok\`
> > > >
> > > > \- One peer initiates a splice, also signaling the feerate for the transaction. Exact protocol unspecified herein.
> > > >
> > > > \- Initiator sends \`tx\_add\_input\` with the original funding output
> > > >
> > > > \- Initiator sends \`tx\_add\_output\` with the new, post-splice funding output
> > > >
> > > > \- Initiator sends \`tx\_add\_input/output\` as needed to add all desired inputs + outputs
> > > >
> > > > \- Initiator sends \`tx\_complete\`
> > > >
> > > > \- Peer sends \`tx\_add\_input/output\` as needed to add all desired inputs + outputs
> > > >
> > > > \- Initiator sends \`tx\_complete\`
> > > >
> > > > \- Peer sends \`tx\_complete\`
> > > >
> > > > \- Initiator + peer exchange commitment signatures, etc.
> > > >
> > > >
> > > >
> > > >
> > > > \#\#\# Considering the Close case:
> > > >
> > > > \- Both peers signal \`opt\_collaborative\_close\` in their \`node\_announcement\`.
> > > >
> > > > \- A peer initiates a close sending a \`shutdown\`, as per usual. 
> > > >
> > > > \- A feerate is negotiated. Out of band for this particular portion of the protocol.
> > > >
> > > > \-The closing initiator (peer which first sent \`shutdown\`), sends \`tx\_add\_input\` to spend the funding output and \`tx\_add\_output\` to add their output for the channel closure.
> > > >
> > > > \- The peer responds with \`tx\_add\_output\`, adding their output to the close transaction.
> > > >
> > > > \- If \`option\_upfront\_shutdown\_script\` is flagged but no such output with a value at or within a reasonable feerate gap of the peer's funding output is present, then the peer must fail the channel. 
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > \#\# Updating a collaborative transaction with RBF:
> > > >
> > > > \- If any input is flagged as RBF’able, then the transaction is considered eligible for RBF
> > > >
> > > > \- RBF can be initiated by either party, and serves as an initiation for another round of transaction composition, as outlined above.
> > > >
> > > > \- Note that this section has been cribbed and re-purposed from the original RBF proposal for splicing, see https://lists.linuxfoundation.org/pipermail/lightning-dev/2018-November/001621.html
> > > >
> > > >
> > > >
> > > >
> > > > 1. type: 45 (\`init\_rbf\`) (\`option\_collaborative\_rbf\`)
> > > >
> > > > 2. data:
> > > >
> > > >    \* \[\`32\`:\`channel\_id\`\]
> > > >
> > > >    \* \[\`4\`:\`fee\_step\`\]
> > > >
> > > >
> > > >
> > > >
> > > > Each \`fee\_step\` adds 1/4 (rounded down) to the initial 
> > > >
> > > > transaction feerate. eg. if the initial feerate was 512 satoshis per kiloweight, \`fee\_step\` 1
> > > >
> > > > is  512 + 512 / 4 = 640, \`fee\_step\` 2 is 640 + 640 / 4 = 800.
> > > >
> > > >
> > > >
> > > >
> > > > The sender:
> > > >
> > > >   - MUST set \`fee\_step\` greater than zero and greater than any prior \`fee\_step\`.
> > > >
> > > >
> > > >
> > > >
> > > > The recipient:
> > > >
> > > >   - if the new fee exceeds the sender's current balance minus reserve
> > > >
> > > >     after it is applied to the splice transaction:
> > > >
> > > >     - MUST error.
> > > >
> > > >   
> > > >
> > > > NOTES:
> > > >
> > > > 1. 1/4 is a reasonable minimal RBF, but as each one requires more
> > > >
> > > >    tracking by the recipient, serves to limit the number you can create.
> > > >
> > > > 2. Rule 4 of BIP125 requires a feerate increase to at least surpass the minimum transaction relay setting. Ratcheting by 25% should satisfy this requirement
> > > >
> > > > 3. An additional rule will be added to the checks of an RBF transaction that it must include at least one identical, replaceable input as the original transaction.
> > > >
> > > >
> > > >
> > > >
> > > > \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
> > > > Lightning-dev mailing list
> > > > [Lightning-dev at lists.linuxfoundation.org][Lightning-dev_lists.linuxfoundation.org]
> > > > https://lists.linuxfoundation.org/mailman/listinfo/lightning-dev
> > > >


[darosior_protonmail.com]: mailto:darosior at protonmail.com
[antoine.riard_gmail.com]: mailto:antoine.riard at gmail.com
[https_github.com_bitcoin_bitcoin_blob_aabec94541e23a67a9f30dc2c80dab3383a01737_src_wallet_wallet.cpp_L2519]: https://github.com/bitcoin/bitcoin/blob/aabec94541e23a67a9f30dc2c80dab3383a01737/src/wallet/wallet.cpp#L2519
[niftynei_gmail.com]: mailto:niftynei at gmail.com
[PR _524]: https://github.com/lightningnetwork/lightning-rfc/pull/524
[Lightning-dev_lists.linuxfoundation.org]: mailto:Lightning-dev at lists.linuxfoundation.org
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