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Merge pull request #3280 from Roasbeef/derive-first-empty-key-loc

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lnwallet: fix key derivation for very first key in family
This commit is contained in:
Olaoluwa Osuntokun 2019-07-08 21:53:40 -07:00 committed by GitHub
commit 19ff8f2c1b
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 56 additions and 32 deletions
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88
lnwallet/btcwallet/signer.go
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@ -83,42 +83,49 @@ func (b *BtcWallet) fetchOutputAddr(script []byte) (waddrmgr.ManagedAddress, err
return nil, lnwallet.ErrNotMine
}
// deriveKeyByLocator attempts to derive a key stored in the wallet given a
// valid key locator.
func (b *BtcWallet) deriveKeyByLocator(keyLoc keychain.KeyLocator) (*btcec.PrivateKey, error) {
// We'll assume the special lightning key scope in this case.
scopedMgr, err := b.wallet.Manager.FetchScopedKeyManager(
b.chainKeyScope,
)
if err != nil {
return nil, err
}
var key *btcec.PrivateKey
err = walletdb.View(b.db, func(tx walletdb.ReadTx) error {
addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
path := waddrmgr.DerivationPath{
Account: uint32(keyLoc.Family),
Branch: 0,
Index: uint32(keyLoc.Index),
}
addr, err := scopedMgr.DeriveFromKeyPath(addrmgrNs, path)
if err != nil {
return err
}
key, err = addr.(waddrmgr.ManagedPubKeyAddress).PrivKey()
return err
})
if err != nil {
return nil, err
}
return key, nil
}
// fetchPrivKey attempts to retrieve the raw private key corresponding to the
// passed public key if populated, or the key descriptor path (if non-empty).
func (b *BtcWallet) fetchPrivKey(keyDesc *keychain.KeyDescriptor) (*btcec.PrivateKey, error) {
// If the key locator within the descriptor *isn't* empty, then we can
// directly derive the keys raw.
if !keyDesc.KeyLocator.IsEmpty() {
// We'll assume the special lightning key scope in this case.
scopedMgr, err := b.wallet.Manager.FetchScopedKeyManager(
b.chainKeyScope,
)
if err != nil {
return nil, err
}
var key *btcec.PrivateKey
err = walletdb.View(b.db, func(tx walletdb.ReadTx) error {
addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
path := waddrmgr.DerivationPath{
Account: uint32(keyDesc.Family),
Branch: 0,
Index: uint32(keyDesc.Index),
}
addr, err := scopedMgr.DeriveFromKeyPath(addrmgrNs, path)
if err != nil {
return err
}
key, err = addr.(waddrmgr.ManagedPubKeyAddress).PrivKey()
return err
})
if err != nil {
return nil, err
}
return key, nil
emptyLocator := keyDesc.KeyLocator.IsEmpty()
if !emptyLocator {
return b.deriveKeyByLocator(keyDesc.KeyLocator)
}
hash160 := btcutil.Hash160(keyDesc.PubKey.SerializeCompressed())
@ -127,7 +134,24 @@ func (b *BtcWallet) fetchPrivKey(keyDesc *keychain.KeyDescriptor) (*btcec.Privat
return nil, err
}
return b.wallet.PrivKeyForAddress(addr)
// Otherwise, we'll attempt to derive the key based on the address.
// This will only work if we've already derived this address in the
// past, since the wallet relies on a mapping of addr -> key.
key, err := b.wallet.PrivKeyForAddress(addr)
switch {
// If we didn't find this key in the wallet, then there's a chance that
// this is actually an "empty" key locator. The legacy KeyLocator
// format failed to properly distinguish an empty key locator from the
// very first in the index (0, 0).IsEmpty() == true.
case waddrmgr.IsError(err, waddrmgr.ErrAddressNotFound) && emptyLocator:
return b.deriveKeyByLocator(keyDesc.KeyLocator)
case err != nil:
return nil, err
default:
return key, nil
}
}
// maybeTweakPrivKey examines the single and double tweak parameters on the