With this commit, the channel is now aware of if it's a musig2 channel, that also has a tapscript root. We'll need to always pass in the tapscript root each time we: make the funding output, sign a new state, and also verify a new state.
In this commit, we modify the musig2 interfaces to instead use an
explicit value for the local nonces. Before this commit, we used the
functional option, but we want to also support specifying this value
over RPC for the remote signer. The functional option pattern is opaque,
so we can't get the nonce value we need. To get around this, we'll just
make this an explicit pointer, then map this to the functional option at
the very last moment.
In this commit, we fix a bug in the `deriveMusig2Shachain` function
where it didn't actually use the passed in revocation root as part of
the hmac invocation.
We also modify the function to be more generally useable as well, as now
the caller can just pass in the revocation root things should be derived
from.
In this commit, we update the genHtlcSigValidationJobs function to be
taproot aware. As we actually need a schnorr signature for the taproot
validation, we need to coerce the entire wire type into a schnorr sig
with the ForceSchnorr() method.
In this commit, we build on all the prior commits and integrate the new
taproot channels into the existing internal funding flow. Along the way,
we do some refactoring to unify things like signing and verifying
incoming commitment transaction signatures.
For our local nonce, we use the existing functional option type to
derive the nonce based on the initial shachain pre-image we'll use as
our revocation.
In this commit, we add a series of abstractions that'll allow us to
easily do funding and also state updates for the new taproot channels. A
partial session is defined by the knowledge of a verification nonce.
Once the remote party sends a signature, we learn of their signing
nonce, and can then complete a session. By using a JIT nonce approach,
we ensure that the signer can generate their nonces randomly and also
at the very last step to avoid having to maintain state.
For our local nonces, we also have an option to use a counter based
nonce derived from the shachain instead of fully random nonces. This
allows us to not have to store ay additional state. Instead, when we
need to go to broadcast, we can just regenerate the nonce then use that
to broadcast.
