9915780197

Committed 13 Jul 2024 12:30AM UTC coverage: 49.268% (-9.1%) from 58.413%

Build # 9915780197

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Merge pull request #8653 from ProofOfKeags/fn-prim

DynComms [0/n]: `fn` package additions

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76.13

/lnwallet/btcwallet/signer.go

package btcwallet

import (
        "fmt"

        "github.com/btcsuite/btcd/btcec/v2"
        "github.com/btcsuite/btcd/btcec/v2/ecdsa"
        "github.com/btcsuite/btcd/btcec/v2/schnorr"
        "github.com/btcsuite/btcd/btcutil"
        "github.com/btcsuite/btcd/btcutil/hdkeychain"
        "github.com/btcsuite/btcd/chaincfg/chainhash"
        "github.com/btcsuite/btcd/txscript"
        "github.com/btcsuite/btcd/wire"
        "github.com/btcsuite/btcwallet/waddrmgr"
        "github.com/btcsuite/btcwallet/walletdb"
        "github.com/lightningnetwork/lnd/input"
        "github.com/lightningnetwork/lnd/keychain"
        "github.com/lightningnetwork/lnd/lnwallet"
)

// FetchInputInfo queries for the WalletController's knowledge of the passed
// outpoint. If the base wallet determines this output is under its control,
// then the original txout should be returned. Otherwise, a non-nil error value
// of ErrNotMine should be returned instead.
//
// This is a part of the WalletController interface.
func (b *BtcWallet) FetchInputInfo(prevOut *wire.OutPoint) (*lnwallet.Utxo,
        error) {

        prevTx, txOut, bip32, confirmations, err := b.wallet.FetchInputInfo(
                prevOut,
        )
        if err != nil {
                return nil, err
        }

        // Then, we'll populate all of the information required by the struct.
        addressType := lnwallet.UnknownAddressType
        switch {
        case txscript.IsPayToWitnessPubKeyHash(txOut.PkScript):
                addressType = lnwallet.WitnessPubKey
        case txscript.IsPayToScriptHash(txOut.PkScript):
                addressType = lnwallet.NestedWitnessPubKey
        case txscript.IsPayToTaproot(txOut.PkScript):
                addressType = lnwallet.TaprootPubkey
        }

        return &lnwallet.Utxo{
                AddressType:   addressType,
                Value:         btcutil.Amount(txOut.Value),
                PkScript:      txOut.PkScript,
                Confirmations: confirmations,
                OutPoint:      *prevOut,
                Derivation:    bip32,
                PrevTx:        prevTx,
        }, nil
}

// ScriptForOutput returns the address, witness program and redeem script for a
// given UTXO. An error is returned if the UTXO does not belong to our wallet or
// it is not a managed pubKey address.
func (b *BtcWallet) ScriptForOutput(output *wire.TxOut) (
        waddrmgr.ManagedPubKeyAddress, []byte, []byte, error) {

        return b.wallet.ScriptForOutput(output)
}

// deriveFromKeyLoc attempts to derive a private key using a fully specified
// KeyLocator.
func deriveFromKeyLoc(scopedMgr *waddrmgr.ScopedKeyManager,
        addrmgrNs walletdb.ReadWriteBucket,
        keyLoc keychain.KeyLocator) (*btcec.PrivateKey, error) {

        path := waddrmgr.DerivationPath{
                InternalAccount: uint32(keyLoc.Family),
                Account:         uint32(keyLoc.Family),
                Branch:          0,
                Index:           keyLoc.Index,
        }
        addr, err := scopedMgr.DeriveFromKeyPath(addrmgrNs, path)
        if err != nil {
                return nil, err
        }

        return addr.(waddrmgr.ManagedPubKeyAddress).PrivKey()
}

// deriveKeyByBIP32Path derives a key described by a BIP32 path. We expect the
// first three elements of the path to be hardened according to BIP44, so they
// must be a number >= 2^31.
func (b *BtcWallet) deriveKeyByBIP32Path(path []uint32) (*btcec.PrivateKey,
        error) {

        // Make sure we get a full path with exactly 5 elements. A path is
        // either custom purpose one with 4 dynamic and one static elements:
        //    m/1017'/coinType'/keyFamily'/0/index
        // Or a default BIP49/89 one with 5 elements:
        //    m/purpose'/coinType'/account'/change/index
        const expectedDerivationPathDepth = 5
        if len(path) != expectedDerivationPathDepth {
                return nil, fmt.Errorf("invalid BIP32 derivation path, "+
                        "expected path length %d, instead was %d",
                        expectedDerivationPathDepth, len(path))
        }

        // Assert that the first three parts of the path are actually hardened
        // to avoid under-flowing the uint32 type.
        if err := assertHardened(path[0], path[1], path[2]); err != nil {
                return nil, fmt.Errorf("invalid BIP32 derivation path, "+
                        "expected first three elements to be hardened: %w", err)
        }

        purpose := path[0] - hdkeychain.HardenedKeyStart
        coinType := path[1] - hdkeychain.HardenedKeyStart
        account := path[2] - hdkeychain.HardenedKeyStart
        change, index := path[3], path[4]

        // Is this a custom lnd internal purpose key?
        switch purpose {
        case keychain.BIP0043Purpose:
                // Make sure it's for the same coin type as our wallet's
                // keychain scope.
                if coinType != b.chainKeyScope.Coin {
                        return nil, fmt.Errorf("invalid BIP32 derivation "+
                                "path, expected coin type %d, instead was %d",
                                b.chainKeyScope.Coin, coinType)
                }

                return b.deriveKeyByLocator(keychain.KeyLocator{
                        Family: keychain.KeyFamily(account),
                        Index:  index,
                })

        // Is it a standard, BIP defined purpose that the wallet understands?
        case waddrmgr.KeyScopeBIP0044.Purpose,
                waddrmgr.KeyScopeBIP0049Plus.Purpose,
                waddrmgr.KeyScopeBIP0084.Purpose,
                waddrmgr.KeyScopeBIP0086.Purpose:

                // We're going to continue below the switch statement to avoid
                // unnecessary indentation for this default case.

        // Currently, there is no way to import any other key scopes than the
        // one custom purpose or three standard ones into lnd's wallet. So we
        // shouldn't accept any other scopes to sign for.
        default:
                return nil, fmt.Errorf("invalid BIP32 derivation path, "+
                        "unknown purpose %d", purpose)
        }

        // Okay, we made sure it's a BIP49/84 key, so we need to derive it now.
        // Interestingly, the btcwallet never actually uses a coin type other
        // than 0 for those keys, so we need to make sure this behavior is
        // replicated here.
        if coinType != 0 {
                return nil, fmt.Errorf("invalid BIP32 derivation path, coin " +
                        "type must be 0 for BIP49/84 btcwallet keys")
        }

        // We only expect to be asked to sign with key scopes that we know
        // about. So if the scope doesn't exist, we don't create it.
        scope := waddrmgr.KeyScope{
                Purpose: purpose,
                Coin:    coinType,
        }
        scopedMgr, err := b.wallet.Manager.FetchScopedKeyManager(scope)
        if err != nil {
                return nil, fmt.Errorf("error fetching manager for scope %v: "+
                        "%w", scope, err)
        }

        // Let's see if we can hit the private key cache.
        keyPath := waddrmgr.DerivationPath{
                InternalAccount: account,
                Account:         account,
                Branch:          change,
                Index:           index,
        }
        privKey, err := scopedMgr.DeriveFromKeyPathCache(keyPath)
        if err == nil {
                return privKey, nil
        }

        // The key wasn't in the cache, let's fully derive it now.
        err = walletdb.View(b.db, func(tx walletdb.ReadTx) error {
                addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)

                addr, err := scopedMgr.DeriveFromKeyPath(addrmgrNs, keyPath)
                if err != nil {
                        return fmt.Errorf("error deriving private key: %w", err)
                }

                privKey, err = addr.(waddrmgr.ManagedPubKeyAddress).PrivKey()
                return err
        })
        if err != nil {
                return nil, fmt.Errorf("error deriving key from path %#v: %w",
                        keyPath, err)
        }

        return privKey, nil
}

// assertHardened makes sure each given element is >= 2^31.
func assertHardened(elements ...uint32) error {
        for idx, element := range elements {
                if element < hdkeychain.HardenedKeyStart {
                        return fmt.Errorf("element at index %d is not hardened",
                                idx)
                }
        }

        return nil
}

// 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
        }

        // First try to read the key from the cached store, if this fails, then
        // we'll fall through to the method below that requires a database
        // transaction.
        path := waddrmgr.DerivationPath{
                InternalAccount: uint32(keyLoc.Family),
                Account:         uint32(keyLoc.Family),
                Branch:          0,
                Index:           keyLoc.Index,
        }
        privKey, err := scopedMgr.DeriveFromKeyPathCache(path)
        if err == nil {
                return privKey, nil
        }

        var key *btcec.PrivateKey
        err = walletdb.Update(b.db, func(tx walletdb.ReadWriteTx) error {
                addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)

                key, err = deriveFromKeyLoc(scopedMgr, addrmgrNs, keyLoc)
                if waddrmgr.IsError(err, waddrmgr.ErrAccountNotFound) {
                        // If we've reached this point, then the account
                        // doesn't yet exist, so we'll create it now to ensure
                        // we can sign.
                        acctErr := scopedMgr.NewRawAccount(
                                addrmgrNs, uint32(keyLoc.Family),
                        )
                        if acctErr != nil {
                                return acctErr
                        }

                        // Now that we know the account exists, we'll attempt
                        // to re-derive the private key.
                        key, err = deriveFromKeyLoc(
                                scopedMgr, addrmgrNs, keyLoc,
                        )
                        if err != nil {
                                return err
                        }
                }

                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.
        emptyLocator := keyDesc.KeyLocator.IsEmpty()
        if !emptyLocator || keyDesc.PubKey == nil {
                return b.deriveKeyByLocator(keyDesc.KeyLocator)
        }

        hash160 := btcutil.Hash160(keyDesc.PubKey.SerializeCompressed())
        addr, err := btcutil.NewAddressWitnessPubKeyHash(hash160, b.netParams)
        if err != nil {
                return nil, err
        }

        // 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
// passed sign descriptor and may perform a mapping on the passed private key
// in order to utilize the tweaks, if populated.
func maybeTweakPrivKey(signDesc *input.SignDescriptor,
        privKey *btcec.PrivateKey) (*btcec.PrivateKey, error) {

        var retPriv *btcec.PrivateKey
        switch {

        case signDesc.SingleTweak != nil:
                retPriv = input.TweakPrivKey(privKey,
                        signDesc.SingleTweak)

        case signDesc.DoubleTweak != nil:
                retPriv = input.DeriveRevocationPrivKey(privKey,
                        signDesc.DoubleTweak)

        default:
                retPriv = privKey
        }

        return retPriv, nil
}

// SignOutputRaw generates a signature for the passed transaction according to
// the data within the passed SignDescriptor.
//
// This is a part of the WalletController interface.
func (b *BtcWallet) SignOutputRaw(tx *wire.MsgTx,
        signDesc *input.SignDescriptor) (input.Signature, error) {

        witnessScript := signDesc.WitnessScript

        // First attempt to fetch the private key which corresponds to the
        // specified public key.
        privKey, err := b.fetchPrivKey(&signDesc.KeyDesc)
        if err != nil {
                return nil, err
        }

        // If a tweak (single or double) is specified, then we'll need to use
        // this tweak to derive the final private key to be used for signing
        // this output.
        privKey, err = maybeTweakPrivKey(signDesc, privKey)
        if err != nil {
                return nil, err
        }

        // In case of a taproot output any signature is always a Schnorr
        // signature, based on the new tapscript sighash algorithm.
        if txscript.IsPayToTaproot(signDesc.Output.PkScript) {
                sigHashes := txscript.NewTxSigHashes(
                        tx, signDesc.PrevOutputFetcher,
                )

                // Are we spending a script path or the key path? The API is
                // slightly different, so we need to account for that to get the
                // raw signature.
                var rawSig []byte
                switch signDesc.SignMethod {
                case input.TaprootKeySpendBIP0086SignMethod,
                        input.TaprootKeySpendSignMethod:

                        // This function tweaks the private key using the tap
                        // root key supplied as the tweak.
                        rawSig, err = txscript.RawTxInTaprootSignature(
                                tx, sigHashes, signDesc.InputIndex,
                                signDesc.Output.Value, signDesc.Output.PkScript,
                                signDesc.TapTweak, signDesc.HashType,
                                privKey,
                        )
                        if err != nil {
                                return nil, err
                        }

                case input.TaprootScriptSpendSignMethod:
                        leaf := txscript.TapLeaf{
                                LeafVersion: txscript.BaseLeafVersion,
                                Script:      witnessScript,
                        }
                        rawSig, err = txscript.RawTxInTapscriptSignature(
                                tx, sigHashes, signDesc.InputIndex,
                                signDesc.Output.Value, signDesc.Output.PkScript,
                                leaf, signDesc.HashType, privKey,
                        )
                        if err != nil {
                                return nil, err
                        }

                default:
                        return nil, fmt.Errorf("unknown sign method: %v",
                                signDesc.SignMethod)
                }

                // The signature returned above might have a sighash flag
                // attached if a non-default type was used. We'll slice this
                // off if it exists to ensure we can properly parse the raw
                // signature.
                sig, err := schnorr.ParseSignature(
                        rawSig[:schnorr.SignatureSize],
                )
                if err != nil {
                        return nil, err
                }

                return sig, nil
        }

        // TODO(roasbeef): generate sighash midstate if not present?

        amt := signDesc.Output.Value
        sig, err := txscript.RawTxInWitnessSignature(
                tx, signDesc.SigHashes, signDesc.InputIndex, amt,
                witnessScript, signDesc.HashType, privKey,
        )
        if err != nil {
                return nil, err
        }

        // Chop off the sighash flag at the end of the signature.
        return ecdsa.ParseDERSignature(sig[:len(sig)-1])
}

// ComputeInputScript generates a complete InputScript for the passed
// transaction with the signature as defined within the passed SignDescriptor.
// This method is capable of generating the proper input script for both
// regular p2wkh output and p2wkh outputs nested within a regular p2sh output.
//
// This is a part of the WalletController interface.
func (b *BtcWallet) ComputeInputScript(tx *wire.MsgTx,
        signDesc *input.SignDescriptor) (*input.Script, error) {

        // If a tweak (single or double) is specified, then we'll need to use
        // this tweak to derive the final private key to be used for signing
        // this output.
        privKeyTweaker := func(k *btcec.PrivateKey) (*btcec.PrivateKey, error) {
                return maybeTweakPrivKey(signDesc, k)
        }

        // Let the wallet compute the input script now.
        witness, sigScript, err := b.wallet.ComputeInputScript(
                tx, signDesc.Output, signDesc.InputIndex, signDesc.SigHashes,
                signDesc.HashType, privKeyTweaker,
        )
        if err != nil {
                return nil, err
        }

        return &input.Script{
                Witness:   witness,
                SigScript: sigScript,
        }, nil
}

// A compile time check to ensure that BtcWallet implements the Signer
// interface.
var _ input.Signer = (*BtcWallet)(nil)

// SignMessage attempts to sign a target message with the private key that
// corresponds to the passed key locator. If the target private key is unable to
// be found, then an error will be returned. The actual digest signed is the
// double SHA-256 of the passed message.
//
// NOTE: This is a part of the MessageSigner interface.
func (b *BtcWallet) SignMessage(keyLoc keychain.KeyLocator,
        msg []byte, doubleHash bool) (*ecdsa.Signature, error) {

        // First attempt to fetch the private key which corresponds to the
        // specified public key.
        privKey, err := b.fetchPrivKey(&keychain.KeyDescriptor{
                KeyLocator: keyLoc,
        })
        if err != nil {
                return nil, err
        }

        // Double hash and sign the data.
        var msgDigest []byte
        if doubleHash {
                msgDigest = chainhash.DoubleHashB(msg)
        } else {
                msgDigest = chainhash.HashB(msg)
        }
        return ecdsa.Sign(privKey, msgDigest), nil
}

// A compile time check to ensure that BtcWallet implements the MessageSigner
// interface.
var _ lnwallet.MessageSigner = (*BtcWallet)(nil)

1	package btcwallet
2
3	import (
4	"fmt"
5
6	"github.com/btcsuite/btcd/btcec/v2"
7	"github.com/btcsuite/btcd/btcec/v2/ecdsa"
8	"github.com/btcsuite/btcd/btcec/v2/schnorr"
9	"github.com/btcsuite/btcd/btcutil"
10	"github.com/btcsuite/btcd/btcutil/hdkeychain"
11	"github.com/btcsuite/btcd/chaincfg/chainhash"
12	"github.com/btcsuite/btcd/txscript"
13	"github.com/btcsuite/btcd/wire"
14	"github.com/btcsuite/btcwallet/waddrmgr"
15	"github.com/btcsuite/btcwallet/walletdb"
16	"github.com/lightningnetwork/lnd/input"
17	"github.com/lightningnetwork/lnd/keychain"
18	"github.com/lightningnetwork/lnd/lnwallet"
19	)
20
21	// FetchInputInfo queries for the WalletController's knowledge of the passed
22	// outpoint. If the base wallet determines this output is under its control,
23	// then the original txout should be returned. Otherwise, a non-nil error value
24	// of ErrNotMine should be returned instead.
25	//
26	// This is a part of the WalletController interface.
27	func (b BtcWallet) FetchInputInfo(prevOut wire.OutPoint) (*lnwallet.Utxo,
28	error) {	3✔
29		3✔
30	prevTx, txOut, bip32, confirmations, err := b.wallet.FetchInputInfo(	3✔
31	prevOut,	3✔
32	)	3✔
33	if err != nil {	6✔
34	return nil, err	3✔
35	}	3✔
36
37	// Then, we'll populate all of the information required by the struct.
38	addressType := lnwallet.UnknownAddressType	3✔
39	switch {	3✔
40	case txscript.IsPayToWitnessPubKeyHash(txOut.PkScript):	3✔
41	addressType = lnwallet.WitnessPubKey	3✔
42	case txscript.IsPayToScriptHash(txOut.PkScript):	3✔
43	addressType = lnwallet.NestedWitnessPubKey	3✔
44	case txscript.IsPayToTaproot(txOut.PkScript):	3✔
45	addressType = lnwallet.TaprootPubkey	3✔
46	}
47
48	return &lnwallet.Utxo{	3✔
49	AddressType: addressType,	3✔
50	Value: btcutil.Amount(txOut.Value),	3✔
51	PkScript: txOut.PkScript,	3✔
52	Confirmations: confirmations,	3✔
53	OutPoint: *prevOut,	3✔
54	Derivation: bip32,	3✔
55	PrevTx: prevTx,	3✔
56	}, nil	3✔
57	}
58
59	// ScriptForOutput returns the address, witness program and redeem script for a
60	// given UTXO. An error is returned if the UTXO does not belong to our wallet or
61	// it is not a managed pubKey address.
62	func (b BtcWallet) ScriptForOutput(output wire.TxOut) (
63	waddrmgr.ManagedPubKeyAddress, []byte, []byte, error) {	3✔
64		3✔
65	return b.wallet.ScriptForOutput(output)	3✔
66	}	3✔
67
68	// deriveFromKeyLoc attempts to derive a private key using a fully specified
69	// KeyLocator.
70	func deriveFromKeyLoc(scopedMgr *waddrmgr.ScopedKeyManager,
71	addrmgrNs walletdb.ReadWriteBucket,
72	keyLoc keychain.KeyLocator) (*btcec.PrivateKey, error) {	3✔
73		3✔
74	path := waddrmgr.DerivationPath{	3✔
75	InternalAccount: uint32(keyLoc.Family),	3✔
76	Account: uint32(keyLoc.Family),	3✔
77	Branch: 0,	3✔
78	Index: keyLoc.Index,	3✔
79	}	3✔
80	addr, err := scopedMgr.DeriveFromKeyPath(addrmgrNs, path)	3✔
81	if err != nil {	3✔
82	return nil, err	×
83	}	×
84
85	return addr.(waddrmgr.ManagedPubKeyAddress).PrivKey()	3✔
86	}
87
88	// deriveKeyByBIP32Path derives a key described by a BIP32 path. We expect the
89	// first three elements of the path to be hardened according to BIP44, so they
90	// must be a number >= 2^31.
91	func (b BtcWallet) deriveKeyByBIP32Path(path []uint32) (btcec.PrivateKey,
92	error) {	3✔
93		3✔
94	// Make sure we get a full path with exactly 5 elements. A path is	3✔
95	// either custom purpose one with 4 dynamic and one static elements:	3✔
96	// m/1017'/coinType'/keyFamily'/0/index	3✔
97	// Or a default BIP49/89 one with 5 elements:	3✔
98	// m/purpose'/coinType'/account'/change/index	3✔
99	const expectedDerivationPathDepth = 5	3✔
100	if len(path) != expectedDerivationPathDepth {	3✔
101	return nil, fmt.Errorf("invalid BIP32 derivation path, "+	×
102	"expected path length %d, instead was %d",	×
103	expectedDerivationPathDepth, len(path))	×
104	}	×
105
106	// Assert that the first three parts of the path are actually hardened
107	// to avoid under-flowing the uint32 type.
108	if err := assertHardened(path[0], path[1], path[2]); err != nil {	3✔
109	return nil, fmt.Errorf("invalid BIP32 derivation path, "+	×
110	"expected first three elements to be hardened: %w", err)	×
111	}	×
112
113	purpose := path[0] - hdkeychain.HardenedKeyStart	3✔
114	coinType := path[1] - hdkeychain.HardenedKeyStart	3✔
115	account := path[2] - hdkeychain.HardenedKeyStart	3✔
116	change, index := path[3], path[4]	3✔
117		3✔
118	// Is this a custom lnd internal purpose key?	3✔
119	switch purpose {	3✔
120	case keychain.BIP0043Purpose:	3✔
121	// Make sure it's for the same coin type as our wallet's	3✔
122	// keychain scope.	3✔
123	if coinType != b.chainKeyScope.Coin {	3✔
124	return nil, fmt.Errorf("invalid BIP32 derivation "+	×
125	"path, expected coin type %d, instead was %d",	×
126	b.chainKeyScope.Coin, coinType)	×
127	}	×
128
129	return b.deriveKeyByLocator(keychain.KeyLocator{	3✔
130	Family: keychain.KeyFamily(account),	3✔
131	Index: index,	3✔
132	})	3✔
133
134	// Is it a standard, BIP defined purpose that the wallet understands?
135	case waddrmgr.KeyScopeBIP0044.Purpose,
136	waddrmgr.KeyScopeBIP0049Plus.Purpose,
137	waddrmgr.KeyScopeBIP0084.Purpose,
138	waddrmgr.KeyScopeBIP0086.Purpose:	3✔
139
140	// We're going to continue below the switch statement to avoid
141	// unnecessary indentation for this default case.
142
143	// Currently, there is no way to import any other key scopes than the
144	// one custom purpose or three standard ones into lnd's wallet. So we
145	// shouldn't accept any other scopes to sign for.
146	default:	×
147	return nil, fmt.Errorf("invalid BIP32 derivation path, "+	×
148	"unknown purpose %d", purpose)	×
149	}
150
151	// Okay, we made sure it's a BIP49/84 key, so we need to derive it now.
152	// Interestingly, the btcwallet never actually uses a coin type other
153	// than 0 for those keys, so we need to make sure this behavior is
154	// replicated here.
155	if coinType != 0 {	3✔
156	return nil, fmt.Errorf("invalid BIP32 derivation path, coin " +	×
157	"type must be 0 for BIP49/84 btcwallet keys")	×
158	}	×
159
160	// We only expect to be asked to sign with key scopes that we know
161	// about. So if the scope doesn't exist, we don't create it.
162	scope := waddrmgr.KeyScope{	3✔
163	Purpose: purpose,	3✔
164	Coin: coinType,	3✔
165	}	3✔
166	scopedMgr, err := b.wallet.Manager.FetchScopedKeyManager(scope)	3✔
167	if err != nil {	3✔
168	return nil, fmt.Errorf("error fetching manager for scope %v: "+	×
169	"%w", scope, err)	×
170	}	×
171
172	// Let's see if we can hit the private key cache.
173	keyPath := waddrmgr.DerivationPath{	3✔
174	InternalAccount: account,	3✔
175	Account: account,	3✔
176	Branch: change,	3✔
177	Index: index,	3✔
178	}	3✔
179	privKey, err := scopedMgr.DeriveFromKeyPathCache(keyPath)	3✔
180	if err == nil {	6✔
181	return privKey, nil	3✔
182	}	3✔
183
184	// The key wasn't in the cache, let's fully derive it now.
185	err = walletdb.View(b.db, func(tx walletdb.ReadTx) error {	6✔
186	addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)	3✔
187		3✔
188	addr, err := scopedMgr.DeriveFromKeyPath(addrmgrNs, keyPath)	3✔
189	if err != nil {	3✔
190	return fmt.Errorf("error deriving private key: %w", err)	×
191	}	×
192
193	privKey, err = addr.(waddrmgr.ManagedPubKeyAddress).PrivKey()	3✔
194	return err	3✔
195	})
196	if err != nil {	3✔
197	return nil, fmt.Errorf("error deriving key from path %#v: %w",	×
198	keyPath, err)	×
199	}	×
200
201	return privKey, nil	3✔
202	}
203
204	// assertHardened makes sure each given element is >= 2^31.
205	func assertHardened(elements ...uint32) error {	3✔
206	for idx, element := range elements {	6✔
207	if element < hdkeychain.HardenedKeyStart {	3✔
208	return fmt.Errorf("element at index %d is not hardened",	×
209	idx)	×
210	}	×
211	}
212
213	return nil	3✔
214	}
215
216	// deriveKeyByLocator attempts to derive a key stored in the wallet given a
217	// valid key locator.
218	func (b *BtcWallet) deriveKeyByLocator(
219	keyLoc keychain.KeyLocator) (*btcec.PrivateKey, error) {	3✔
220		3✔
221	// We'll assume the special lightning key scope in this case.	3✔
222	scopedMgr, err := b.wallet.Manager.FetchScopedKeyManager(	3✔
223	b.chainKeyScope,	3✔
224	)	3✔
225	if err != nil {	3✔
226	return nil, err	×
227	}	×
228
229	// First try to read the key from the cached store, if this fails, then
230	// we'll fall through to the method below that requires a database
231	// transaction.
232	path := waddrmgr.DerivationPath{	3✔
233	InternalAccount: uint32(keyLoc.Family),	3✔
234	Account: uint32(keyLoc.Family),	3✔
235	Branch: 0,	3✔
236	Index: keyLoc.Index,	3✔
237	}	3✔
238	privKey, err := scopedMgr.DeriveFromKeyPathCache(path)	3✔
239	if err == nil {	6✔
240	return privKey, nil	3✔
241	}	3✔
242
243	var key *btcec.PrivateKey	3✔
244	err = walletdb.Update(b.db, func(tx walletdb.ReadWriteTx) error {	6✔
245	addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)	3✔
246		3✔
247	key, err = deriveFromKeyLoc(scopedMgr, addrmgrNs, keyLoc)	3✔
248	if waddrmgr.IsError(err, waddrmgr.ErrAccountNotFound) {	3✔
249	// If we've reached this point, then the account	×
250	// doesn't yet exist, so we'll create it now to ensure	×
251	// we can sign.	×
252	acctErr := scopedMgr.NewRawAccount(	×
253	addrmgrNs, uint32(keyLoc.Family),	×
254	)	×
255	if acctErr != nil {	×
256	return acctErr	×
257	}	×
258
259	// Now that we know the account exists, we'll attempt
260	// to re-derive the private key.
261	key, err = deriveFromKeyLoc(	×
262	scopedMgr, addrmgrNs, keyLoc,	×
263	)	×
264	if err != nil {	×
265	return err	×
266	}	×
267	}
268
269	return err	3✔
270	})
271	if err != nil {	3✔
272	return nil, err	×
273	}	×
274
275	return key, nil	3✔
276	}
277
278	// fetchPrivKey attempts to retrieve the raw private key corresponding to the
279	// passed public key if populated, or the key descriptor path (if non-empty).
280	func (b *BtcWallet) fetchPrivKey(
281	keyDesc keychain.KeyDescriptor) (btcec.PrivateKey, error) {	3✔
282		3✔
283	// If the key locator within the descriptor isn't empty, then we can	3✔
284	// directly derive the keys raw.	3✔
285	emptyLocator := keyDesc.KeyLocator.IsEmpty()	3✔
286	if !emptyLocator \|\| keyDesc.PubKey == nil {	6✔
287	return b.deriveKeyByLocator(keyDesc.KeyLocator)	3✔
288	}	3✔
289
290	hash160 := btcutil.Hash160(keyDesc.PubKey.SerializeCompressed())	3✔
291	addr, err := btcutil.NewAddressWitnessPubKeyHash(hash160, b.netParams)	3✔
292	if err != nil {	3✔
293	return nil, err	×
294	}	×
295
296	// Otherwise, we'll attempt to derive the key based on the address.
297	// This will only work if we've already derived this address in the
298	// past, since the wallet relies on a mapping of addr -> key.
299	key, err := b.wallet.PrivKeyForAddress(addr)	3✔
300	switch {	3✔
301	// If we didn't find this key in the wallet, then there's a chance that
302	// this is actually an "empty" key locator. The legacy KeyLocator
303	// format failed to properly distinguish an empty key locator from the
304	// very first in the index (0, 0).IsEmpty() == true.
305	case waddrmgr.IsError(err, waddrmgr.ErrAddressNotFound) && emptyLocator:	3✔
306	return b.deriveKeyByLocator(keyDesc.KeyLocator)	3✔
307
308	case err != nil:	×
309	return nil, err	×
310
311	default:	3✔
312	return key, nil	3✔
313	}
314	}
315
316	// maybeTweakPrivKey examines the single and double tweak parameters on the
317	// passed sign descriptor and may perform a mapping on the passed private key
318	// in order to utilize the tweaks, if populated.
319	func maybeTweakPrivKey(signDesc *input.SignDescriptor,
320	privKey btcec.PrivateKey) (btcec.PrivateKey, error) {	3✔
321		3✔
322	var retPriv *btcec.PrivateKey	3✔
323	switch {	3✔
324
325	case signDesc.SingleTweak != nil:	3✔
326	retPriv = input.TweakPrivKey(privKey,	3✔
327	signDesc.SingleTweak)	3✔
328
329	case signDesc.DoubleTweak != nil:	3✔
330	retPriv = input.DeriveRevocationPrivKey(privKey,	3✔
331	signDesc.DoubleTweak)	3✔
332
333	default:	3✔
334	retPriv = privKey	3✔
335	}
336
337	return retPriv, nil	3✔
338	}
339
340	// SignOutputRaw generates a signature for the passed transaction according to
341	// the data within the passed SignDescriptor.
342	//
343	// This is a part of the WalletController interface.
344	func (b BtcWallet) SignOutputRaw(tx wire.MsgTx,
345	signDesc *input.SignDescriptor) (input.Signature, error) {	3✔
346		3✔
347	witnessScript := signDesc.WitnessScript	3✔
348		3✔
349	// First attempt to fetch the private key which corresponds to the	3✔
350	// specified public key.	3✔
351	privKey, err := b.fetchPrivKey(&signDesc.KeyDesc)	3✔
352	if err != nil {	3✔
353	return nil, err	×
354	}	×
355
356	// If a tweak (single or double) is specified, then we'll need to use
357	// this tweak to derive the final private key to be used for signing
358	// this output.
359	privKey, err = maybeTweakPrivKey(signDesc, privKey)	3✔
360	if err != nil {	3✔
361	return nil, err	×
362	}	×
363
364	// In case of a taproot output any signature is always a Schnorr
365	// signature, based on the new tapscript sighash algorithm.
366	if txscript.IsPayToTaproot(signDesc.Output.PkScript) {	6✔
367	sigHashes := txscript.NewTxSigHashes(	3✔
368	tx, signDesc.PrevOutputFetcher,	3✔
369	)	3✔
370		3✔
371	// Are we spending a script path or the key path? The API is	3✔
372	// slightly different, so we need to account for that to get the	3✔
373	// raw signature.	3✔
374	var rawSig []byte	3✔
375	switch signDesc.SignMethod {	3✔
376	case input.TaprootKeySpendBIP0086SignMethod,
377	input.TaprootKeySpendSignMethod:	3✔
378		3✔
379	// This function tweaks the private key using the tap	3✔
380	// root key supplied as the tweak.	3✔
381	rawSig, err = txscript.RawTxInTaprootSignature(	3✔
382	tx, sigHashes, signDesc.InputIndex,	3✔
383	signDesc.Output.Value, signDesc.Output.PkScript,	3✔
384	signDesc.TapTweak, signDesc.HashType,	3✔
385	privKey,	3✔
386	)	3✔
387	if err != nil {	3✔
388	return nil, err	×
389	}	×
390
391	case input.TaprootScriptSpendSignMethod:	3✔
392	leaf := txscript.TapLeaf{	3✔
393	LeafVersion: txscript.BaseLeafVersion,	3✔
394	Script: witnessScript,	3✔
395	}	3✔
396	rawSig, err = txscript.RawTxInTapscriptSignature(	3✔
397	tx, sigHashes, signDesc.InputIndex,	3✔
398	signDesc.Output.Value, signDesc.Output.PkScript,	3✔
399	leaf, signDesc.HashType, privKey,	3✔
400	)	3✔
401	if err != nil {	3✔
402	return nil, err	×
403	}	×
404
405	default:	×
406	return nil, fmt.Errorf("unknown sign method: %v",	×
407	signDesc.SignMethod)	×
408	}
409
410	// The signature returned above might have a sighash flag
411	// attached if a non-default type was used. We'll slice this
412	// off if it exists to ensure we can properly parse the raw
413	// signature.
414	sig, err := schnorr.ParseSignature(	3✔
415	rawSig[:schnorr.SignatureSize],	3✔
416	)	3✔
417	if err != nil {	3✔
418	return nil, err	×
419	}	×
420
421	return sig, nil	3✔
422	}
423
424	// TODO(roasbeef): generate sighash midstate if not present?
425
426	amt := signDesc.Output.Value	3✔
427	sig, err := txscript.RawTxInWitnessSignature(	3✔
428	tx, signDesc.SigHashes, signDesc.InputIndex, amt,	3✔
429	witnessScript, signDesc.HashType, privKey,	3✔
430	)	3✔
431	if err != nil {	3✔
432	return nil, err	×
433	}	×
434
435	// Chop off the sighash flag at the end of the signature.
436	return ecdsa.ParseDERSignature(sig[:len(sig)-1])	3✔
437	}
438
439	// ComputeInputScript generates a complete InputScript for the passed
440	// transaction with the signature as defined within the passed SignDescriptor.
441	// This method is capable of generating the proper input script for both
442	// regular p2wkh output and p2wkh outputs nested within a regular p2sh output.
443	//
444	// This is a part of the WalletController interface.
445	func (b BtcWallet) ComputeInputScript(tx wire.MsgTx,
446	signDesc input.SignDescriptor) (input.Script, error) {	3✔
447		3✔
448	// If a tweak (single or double) is specified, then we'll need to use	3✔
449	// this tweak to derive the final private key to be used for signing	3✔
450	// this output.	3✔
451	privKeyTweaker := func(k btcec.PrivateKey) (btcec.PrivateKey, error) {	6✔
452	return maybeTweakPrivKey(signDesc, k)	3✔
453	}	3✔
454
455	// Let the wallet compute the input script now.
456	witness, sigScript, err := b.wallet.ComputeInputScript(	3✔
457	tx, signDesc.Output, signDesc.InputIndex, signDesc.SigHashes,	3✔
458	signDesc.HashType, privKeyTweaker,	3✔
459	)	3✔
460	if err != nil {	3✔
461	return nil, err	×
462	}	×
463
464	return &input.Script{	3✔
465	Witness: witness,	3✔
466	SigScript: sigScript,	3✔
467	}, nil	3✔
468	}
469
470	// A compile time check to ensure that BtcWallet implements the Signer
471	// interface.
472	var _ input.Signer = (*BtcWallet)(nil)
473
474	// SignMessage attempts to sign a target message with the private key that
475	// corresponds to the passed key locator. If the target private key is unable to
476	// be found, then an error will be returned. The actual digest signed is the
477	// double SHA-256 of the passed message.
478	//
479	// NOTE: This is a part of the MessageSigner interface.
480	func (b *BtcWallet) SignMessage(keyLoc keychain.KeyLocator,
481	msg []byte, doubleHash bool) (*ecdsa.Signature, error) {	3✔
482		3✔
483	// First attempt to fetch the private key which corresponds to the	3✔
484	// specified public key.	3✔
485	privKey, err := b.fetchPrivKey(&keychain.KeyDescriptor{	3✔
486	KeyLocator: keyLoc,	3✔
487	})	3✔
488	if err != nil {	3✔
489	return nil, err	×
490	}	×
491
492	// Double hash and sign the data.
493	var msgDigest []byte	3✔
494	if doubleHash {	6✔
495	msgDigest = chainhash.DoubleHashB(msg)	3✔
496	} else {	3✔
497	msgDigest = chainhash.HashB(msg)	×
498	}	×
499	return ecdsa.Sign(privKey, msgDigest), nil	3✔
500	}
501
502	// A compile time check to ensure that BtcWallet implements the MessageSigner
503	// interface.
504	var _ lnwallet.MessageSigner = (*BtcWallet)(nil)

lightningnetwork / lnd / 9915780197

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