如何簽署 PSBT 交易？

我有一個 PSBT（Base64 格式），我需要使用 GoLang 進行簽名，但我不知道我需要執行哪些步驟。我發現了這一點，但我對比特幣和 Python 並不是很有信心，所以我沒有完全理解簽名者算法。我該怎麼辦？

正如我評論的那樣，使用它的psbt包btcsuite/btcutil是可能的。

我已經創建了一個如何使用它的範例。我不知道這是否是最好/最有效的方法。但我希望這能給你一個模板和例子來使用。但它相對較低級，如果對比特幣沒有更深入的技術了解，可能很難理解。

它將此交易的第二個（0 索引）輸出用於測試網上。

package main

import (
   "bytes"
   "encoding/hex"
   "fmt"

   "github.com/btcsuite/btcd/chaincfg"
   "github.com/btcsuite/btcd/chaincfg/chainhash"
   "github.com/btcsuite/btcd/txscript"
   "github.com/btcsuite/btcd/wire"
   "github.com/btcsuite/btcutil"
   "github.com/btcsuite/btcutil/hdkeychain"
   "github.com/btcsuite/btcutil/psbt"
)

const (
   // Provided PSBT with one P2PKH input. Created in part 1 below.
   psbtBase64 = "cHNidP8BAFIBAAAAAX7Mj1abZbFtfUYFYBIFRKxCOxs8wfMRu3NhVBHTbnFfAQAAAAAAAAAAAayEAQAAAAAAFgAU8yFPpRndMpAJ7aO+RtRN4Nh3mbYAAAAAAAEBH6CGAQAAAAAAFgAUJw/E3xSMUU+8VVGHXk7Dc4vGNjkiBgOoVLKI2rj2DMlswSDkSf0KR7jQHULLPOWS/x3q8b3MqQyj8e/WAAAAAAMAAAAAAA=="

   // Extended Private Key.
   extPrivateKeyStr = "vprv9GpFMh8VMAXKgdZVFGXFvsexjr25MHKvtCY7vKHbRr8A6xCm4bQYbQrJmLz6h3F9MGf5edwxQuZR7DCLFVvjMxgfJ9so9mcN2SHGR3QFr3S"
)

// Part 1: Creating the PSBT (will be returned as base64)
func part1() string {
   // The extended private key was generated with Electrum and we derive the
   // specific key used.
   // `keyC` contains the private key that _contains_ the coins to be spend.
   keyC, _ := hdkeychain.NewKeyFromString(extPrivateKeyStr)
   fingerprint := keyC.ParentFingerprint()
   keyC, _ = keyC.Child(0)
   keyC, _ = keyC.Child(3) // Electrum derivation of the 4th address.
   pubKeyC, _ := keyC.ECPubKey()

   // Create a brand new PSBT spending the following outpoint.
   txhash, _ := chainhash.NewHashFromStr("5f716ed311546173bb11f3c13c1b3b42ac4405126005467d6db1659b568fcc7e")
   outpoint := wire.NewOutPoint(txhash, 1)
   inputs := []*wire.OutPoint{outpoint}
   pubkeyScript, _ := hex.DecodeString("0014270fc4df148c514fbc5551875e4ec3738bc63639")
   spendTxOut := wire.NewTxOut(100000, pubkeyScript)

   // The address and amount to send funds to.
   outAddress, err := btcutil.DecodeAddress("tb1q7vs5lfgem5efqz0d5wlyd4zdurv80xdkfkf3cn", &chaincfg.TestNet3Params)
   // The witnessScript consists of a `0x00`, followed by the size of the
   // pubkey-hash `0x20` and the pubkey-hash itself.
   witnessScript := append([]byte{0, 20}, outAddress.ScriptAddress()...)
   outputs := []*wire.TxOut{wire.NewTxOut(99500, witnessScript)}

   // Create the psbt instance.
   pC, err := psbt.New(inputs, outputs, wire.TxVersion, 0, []uint32{0}) // Note: typically the sequence is `0xffffffff`!
   if err != nil {
       panic(err)
   }

   // Use the Updater to add information to the input.
   u, err := psbt.NewUpdater(pC)
   if err != nil {
       panic(err)
   }

   u.AddInBip32Derivation(fingerprint, []uint32{0, 3}, pubKeyC.SerializeCompressed(), 0)
   u.AddInWitnessUtxo(spendTxOut, 0)
   u.AddInSighashType(0, 0)

   // Show the base64 encoding of the unsigned PSBT.
   b64, _ := pC.B64Encode()
   return b64

}

// Part 2: Sign the PSBT in base64 encoding and return it.
func part2(psbtBase64 string) string {
   // Reader for the PSBT.
   psbtBytes := []byte(psbtBase64)
   r := bytes.NewReader(psbtBytes)

   // Create instance of a PSBT.
   p, err := psbt.NewFromRawBytes(r, true)
   if err != nil {
       panic(err)
   }

   // Load the extended private key.
   bip32Key, err := hdkeychain.NewKeyFromString(extPrivateKeyStr)
   if err != nil {
       panic(err)
   }

   // Derivation path should be read from PSBT.
   // Note: We ignore checking the fingerprint, etc.
   path := p.Inputs[0].Bip32Derivation[0]
   for _, d := range path.Bip32Path {
       bip32Key, _ = bip32Key.Child(d)
   }

   pubKey, err := bip32Key.ECPubKey()
   if err != nil {
       panic(err)
   }

   privKey, err := bip32Key.ECPrivKey()
   if err != nil {
       panic(err)
   }

   // Manually creating the signature.
   sigHashes := txscript.NewTxSigHashes(p.UnsignedTx)
   sig, err := txscript.RawTxInWitnessSignature(p.UnsignedTx, sigHashes, 0,
       p.Inputs[0].WitnessUtxo.Value, p.Inputs[0].WitnessUtxo.PkScript,
       txscript.SigHashAll, privKey)

   // Use the Updater to add the signature to the input.
   u, err := psbt.NewUpdater(p)
   if err != nil {
       panic(err)
   }
   sucess, err := u.Sign(0, sig, pubKey.SerializeCompressed(), nil, nil)
   if err != nil {
       panic(err)
   }
   if sucess != psbt.SignSuccesful {
       panic("could not sucessfully sign for some reason")
   }

   // Finalize PSBT.
   err = psbt.Finalize(p, 0)
   tx, err := psbt.Extract(p)

   var buf bytes.Buffer
   tx.Serialize(&buf)
   return hex.EncodeToString(buf.Bytes())
}

func main() {
   fmt.Println("Base64 PSBT: ", part1())

   fmt.Println("Signed tx: ", part2(psbtBase64))
}

引用自：https://bitcoin.stackexchange.com/questions/96283