This commit extends the taproot HTLC script generation functions to accept
TaprootScriptOpt parameters, enabling callers to specify whether production
or staging script variants should be generated. The SenderHTLCScriptTaproot
and ReceiverHTLCScriptTaproot functions now accept a variadic opts parameter
that is forwarded to the underlying script tree construction.
This change provides the necessary infrastructure for the wallet and contract
resolution systems to generate the appropriate script trees based on channel
type. Production taproot channels can now pass the WithProdScripts() option
to generate optimized scripts using OP_CHECKSIGVERIFY, while staging channels
continue to use the existing development script structure.
The modification maintains backward compatibility by making the opts parameter
variadic with sensible defaults. Existing callers that do not specify options
will continue to generate staging scripts as before, ensuring no disruption
to current functionality while enabling future production script support.
In this commit, we add an initial cut out to allow us to swap in the
taproot scripts (which changed slightly) once we start using the final
"production" feature bit.
The changes to the scripts are pretty mechanic: we avoid using `OP_DROP`
and instead use a `_VERIFY` earlier in the script to consume the stack
item.
In this commit, we switch to using the new txscript.ScriptTemplate
function. This allows us to write the script in plain text, using some
hidden template operations to swap in items like keys or sigs.
This reduces in less code and boiler plate over all, the code that
defines the script now reads as if it was a comment.
In this commit, we update all the taproot scripts to also accept an
optional aux leaf. This aux leaf can be used to add more redemption
paths for advanced channels, or just as an extra commitment space.
In this commit, we update the channel state machine to use the new
ScriptDescriptor interface. This fixes some subtle issues with the
existing commits, as for p2wsh we always sign the same witness script,
but for p2tr, the witness script differs depending on which branch is
taken.
With the new abstractions, we can treat p2wsh and p2tr as the same
mostly, right up until we need to obtain a control block or a tap tweak.
All tests have been updated accordingly.
In this commit, we update all the taproot scripts spends to optionally
make the control block. This is useful in cases where we've already
created the control block, or may not have the items needed to construct
it in the first place.
We also add the control block to the sign descriptor itself.
In this commit, we modify the to_local script to use a script path for
the revocation scenario. With this change, we ensure that the internal
key is always revealed which means the anchor outputs can still always
be swept.
In this commit, we restore usage of the NUMS key for the to remote
output, as this allows a remote party to scan the chain in order to find
their remote output that in emergency recovery scenarios.
Unlike the old HTLC scripts, we now need to handle the various control
block interactions. As is, we opt to simply re-compute the entire tree
when needed, as the tree only has two leaves.
In this commit, we add GenTaprootFundingScript, which'll return the
taproot pkScript and output for a taproot+musig2 channel. This uses
musig2 key aggregation with sorting activated.
The final key produced uses a bip86 tweak, meaning that the output key
provably doesn't commit to any script path. In the future, we may want
to permit this, as then it allows for a greater degree of
programmability of the funding output.
The default allocation of 500 bytes for the script that is
used in NewScriptBuilder is way too much for most of our scripts.
With the new functional option we can tune the allocation to exactly
what we need.
Because the original dcrec secp256k1 library that is used for the
Schnorr signature primitives uses different hash algorithms than the
btcd secp256k1 library. Therefore pulling in the wrong library can lead
to weird and unexpected errors. We try to make it harder to make the
mistake by not using the library directly in lnd in the first place.
Note that it is still indirectly needed by the btcd secp256k1 library,
therefore the module dependency is still expected to be there, just
moved to the indirect section.
This commit was previously split into the following parts to ease
review:
- 2d746f68: replace imports
- 4008f0fd: use ecdsa.Signature
- 849e33d1: remove btcec.S256()
- b8f6ebbd: use v2 library correctly
- fa80bca9: bump go modules
The new commitment type consists of adding an additional CLTV
requirement to guarantee a leased channel's expiration on any commitment
and HTLC outputs that pay directly to the channel initiator.
This commit updates call-sites to use the proper dust limits for
various script types. This also updates the default dust limit used
in the funding flow to be 354 satoshis instead of 573 satoshis.
