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 extract the musig2 session management into a new
module. This allows us to re-use the session logic elsewhere in unit
tests so we don't need to instantiate the entire wallet.
With this commit we bump the github.com/btcd/btcec/v2 library to v2.3.2
which implements the MuSig2 BIP version v1.0.0rc2. With this the
github.com/btcsuite/btcd/btcec/v2/schnorr/musig2 package becomes
v1.0.0rc2 and the github.com/lightningnetwork/lnd/internal/musig2v040
stays at the old v0.4.0 version.
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
