To simplify the API surface of a remote signer even more, we refactor
the SignMessage and SignMessageCompact calls to only accept a key
locator as we always know what key we're using for signing anyway.
To make it possible to use a remote lnrpc 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
lnrpc.SignMessage RPC to accept a digest instead of only the message
which has security implications.
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.
In this commit, we start to optimistically use the new private key cache
that was added to btcwallet. As is, btcwallet will cache the decrypted
account keys for each scope in memory. However, the existing methods
to derive a child key from those account keys requires a write database
transaction, and will re-derive the private key using BIP-32 each time.
The newly added `DeriveFromKeyPathCache` lets us skip all this and
directly use a cache assuming the account info is already cached. The
new logic will try to use this method, but if it fails fall back to the
existing `DeriveFromKeyPath` method. All calls after this will use this
new cached key.
Fixes https://github.com/lightningnetwork/lnd/issues/5125.
Basic benchmark before the btcwallet change and after:
```
benchmark old ns/op new ns/op delta
BenchmarkDerivePrivKey-8 22840583 125 -100.00%
benchmark old allocs new allocs delta
BenchmarkDerivePrivKey-8 89 2 -97.75%
benchmark old bytes new bytes delta
BenchmarkDerivePrivKey-8 10225 24 -99.77%
```
In this commit, we extend the DerivePrivKey method to allow callers that
don't know the full KeyLocator information to attempt to derive a
private key via a brute force mechanism. If we don't now the full
KeyLoactor, then given the KeyFamily, we can walk down the derivation
path and compare keys one by one. In order to ensure we don' t enter an
infinite loop when given an unknown public key, we cap the number of
keys derived at 100k.
An upcoming feature to lnd that adds static channel backups will utilize
this feature, as we need to derive the shachain root given only the
public key and key family, as we don't currently store this KeyLocator
on disk.
In this commit, we fix a slight bug in the existing implementation of
DeriveNextKey for btcwallet. Before this commit, we would only set the
public key, and not also the derivation path. It's important that we
also set the path information, as in the near future we'll be using the
KeyDescriptors returned from this method to create static channel back
ups. With these static backups, the key alone may be insufficient to
re-derive the private key as we may need to fallback to brute forcing in
order to re-derive the key as it's possible we add new key families in
the future.
This commit allows for secret keyrings to be initialized
with a specific coin type, which allows us to use
different derivation paths for bitcion and litecoin.
It also provide default constants for Bitcion and
Litecoin BIP 44 coin types.
