In this commit, we add a new field `TapTweak` to be used for key path
spends. Before this commit, we'd overload the existing `WitnessScript`
field to pass this information to the signing context. This was
confusing as for tapscript spends, this was the leaf script, which
mirrors the other script based spending types.
With this new filed, users need to set this to the script root for
keypath spends where the output key commits to a real merkle root, and
nothing when bip 86 spending is being used.
To make the signing even more explicit, we also add a new field called
sign_method with an enum type that differentiates between the different
segwit v0 and v1 signing methods.
Fixes https://github.com/lightningnetwork/lnd/issues/6446.
Clarification that KeyDescriptor describes the public key in
raw_key_bytes and the key_loc identifies the private key. Helps
clarify responses from calls like DeriveKey and DeriveNextKey from
WalletKit.
Fixes#5899
To make it possible to use a remote signrpc server as a signer for our
wallet, we need to change our main interface to sign the message instead
of the message's digest. Otherwise we'd need to alter the
signrpc.SignMessage RPC to accept a digest instead of only the message
which has security implications.
This is meant to handle a quirk in which key descriptors obtained
through walletrpc.DeriveKey don't result in the derived key being
persisted to the wallet's database, unlike with DeriveNextKey. Due to
this and some fallback logic in the wallet with regards to empty key
locators, if a request only specified the compressed public key, the
signature returned would be over a different key, namely the one derived
from (family=0, index=0).
