How to use btcd/txscript to build a custom locking and unlocking script.

[iamgamelover]

1. First, generate a P2SH multisig address including some custom content.

     script := txscript.NewScriptBuilder()
   
     // custom content
   

   script.AddOp(txscript.OP_HASH160)
   script.AddData(Hash_Preimage_R)
   script.AddOp(txscript.OP_EQUALVERIFY)

     // standard content
   

   script.AddOp(txscript.OP_2)
   script.AddData(aPubKey)
   script.AddData(bPubKey)
   script.AddOp(txscript.OP_2)
   script.AddOp(txscript.OP_CHECKMULTISIG)
   return script.Script()

Then got an address like 2Mv12R1VNdiSzeFiDxs2WVxeBZzTScrs8Q6

2. Sent some test bitcoin to the address above.
3. Construct a transaction with btcd/txscript and btcd/wire to spend a UTXO of the address above.

4. How to write the unlocking script?
Currently, I'm using txscript.SignTxOutput reference from https://sourcegraph.com/github.com/btcsuite/btcd/-/blob/txscript/sign_test.go#L344

     // signature ...
sigScript, err := txscript.SignTxOutput(&chaincfg.TestNet3Params,
	tx, 0, scriptPkScript, txscript.SigHashAll,
	mkGetKey(map[string]addressToKey{
		address1.EncodeAddress(): {key1.PrivKey, true},
		address2.EncodeAddress(): {key2.PrivKey, true},
	 }), mkGetScript(map[string][]byte{
		scriptAddr.EncodeAddress(): custom_pkScript,
	}), nil)

if err != nil {
	fmt.Println("Sign has wrong : ", err)
	return
}

tx.TxIn[0].SignatureScript = sigScript

5. But got a error: Sign has wrong : can't sign unknown transactions

Anybody have some idea? Thank you very much!

[mahdiidarabi]

read https://developer.bitcoin.org/devguide/transactions.html#p2pkh-script-validation to get the idea behind bitcoin script language, you should provide some op-codes result in true on stack after completely be doen.

[neocarmack]

import(
    "github.com/btcsuite/btcd/txscript"
    "github.com/btcsuite/btcd/wire"
)

tx := wire.NewMsgTx(2)
tx.AddTxOut(wire.NewTxOut(int64(*outputvalueFlag*1e8), script()))

func script() ([]byte) {
    script := txscript.NewScriptBuilder()
    script.AddInt64(1)
    script.AddData(bytes[0:65])
    script.AddInt64(1)
    script.AddOp(txscript.OP_CHECKMULTISIG)
    return script.Script()
}