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78 lines
2.0 KiB
Go
78 lines
2.0 KiB
Go
package lnd
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import (
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"fmt"
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"github.com/btcsuite/btcd/btcec"
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"github.com/btcsuite/btcd/chaincfg"
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"github.com/btcsuite/btcd/txscript"
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"github.com/btcsuite/btcd/wire"
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"github.com/btcsuite/btcutil/hdkeychain"
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"github.com/lightningnetwork/lnd/input"
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"github.com/lightningnetwork/lnd/keychain"
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)
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type Signer struct {
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ExtendedKey *hdkeychain.ExtendedKey
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ChainParams *chaincfg.Params
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}
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func (s *Signer) SignOutputRaw(tx *wire.MsgTx,
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signDesc *input.SignDescriptor) ([]byte, error) {
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witnessScript := signDesc.WitnessScript
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// First attempt to fetch the private key which corresponds to the
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// specified public key.
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privKey, err := s.FetchPrivKey(&signDesc.KeyDesc)
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if err != nil {
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return nil, err
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}
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privKey = maybeTweakPrivKey(signDesc, privKey)
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amt := signDesc.Output.Value
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sig, err := txscript.RawTxInWitnessSignature(
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tx, signDesc.SigHashes, signDesc.InputIndex, amt,
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witnessScript, signDesc.HashType, privKey,
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)
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if err != nil {
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return nil, err
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}
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// Chop off the sighash flag at the end of the signature.
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return sig[:len(sig)-1], nil
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}
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func (s *Signer) ComputeInputScript(_ *wire.MsgTx, _ *input.SignDescriptor) (
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*input.Script, error) {
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return nil, fmt.Errorf("unimplemented")
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}
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func (s *Signer) FetchPrivKey(descriptor *keychain.KeyDescriptor) (
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*btcec.PrivateKey, error) {
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key, err := DeriveChildren(s.ExtendedKey, []uint32{
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HardenedKeyStart + uint32(keychain.BIP0043Purpose),
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HardenedKeyStart + s.ChainParams.HDCoinType,
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HardenedKeyStart + uint32(descriptor.Family),
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0,
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descriptor.Index,
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})
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if err != nil {
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return nil, err
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}
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return key.ECPrivKey()
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}
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// maybeTweakPrivKey examines the single tweak parameters on the passed sign
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// descriptor and may perform a mapping on the passed private key in order to
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// utilize the tweaks, if populated.
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func maybeTweakPrivKey(signDesc *input.SignDescriptor,
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privKey *btcec.PrivateKey) *btcec.PrivateKey {
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if signDesc.SingleTweak != nil {
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return input.TweakPrivKey(privKey, signDesc.SingleTweak)
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}
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return privKey
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}
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