mirror of
https://github.com/aljazceru/ark.git
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Congestion tree validation (#84)
* add common/pkg/tree validation * update noah go.mod * cleaning and fixes * fix builder_test.go * Fix deferred func * fix even number of vtxos in congestion tree --------- Co-authored-by: altafan <18440657+altafan@users.noreply.github.com>
This commit is contained in:
Louis Singer
260
common/tree/script.go
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260
common/tree/script.go
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@@ -0,0 +1,260 @@
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package tree
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import (
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"bytes"
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"encoding/binary"
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"github.com/ark-network/ark/common"
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"github.com/btcsuite/btcd/btcec/v2/schnorr"
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"github.com/btcsuite/btcd/txscript"
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"github.com/decred/dcrd/dcrec/secp256k1/v4"
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"github.com/vulpemventures/go-elements/taproot"
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)
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const (
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OP_INSPECTOUTPUTSCRIPTPUBKEY = 0xd1
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OP_INSPECTOUTPUTVALUE = 0xcf
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OP_PUSHCURRENTINPUTINDEX = 0xcd
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)
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// VtxoScript returns a simple checksig script for a given pubkey
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func VtxoScript(pubkey *secp256k1.PublicKey) (*taproot.TapElementsLeaf, error) {
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script, err := checksigScript(pubkey)
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if err != nil {
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return nil, err
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}
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tapLeaf := taproot.NewBaseTapElementsLeaf(script)
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return &tapLeaf, nil
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}
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// SweepScript returns a taproot leaf letting the owner of the key to spend the output after a given timeDelta
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func SweepScript(sweepKey *secp256k1.PublicKey, seconds uint) (*taproot.TapElementsLeaf, error) {
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sweepScript, err := csvChecksigScript(sweepKey, seconds)
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if err != nil {
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return nil, err
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}
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tapLeaf := taproot.NewBaseTapElementsLeaf(sweepScript)
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return &tapLeaf, nil
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}
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// BranchScript returns a taproot leaf that will split the coin in two outputs
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// each output (left and right) will have the given amount and the given taproot key as witness program
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func BranchScript(
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leftKey, rightKey *secp256k1.PublicKey, leftAmount, rightAmount uint64,
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) taproot.TapElementsLeaf {
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nextScriptLeft := withOutput(txscript.OP_0, schnorr.SerializePubKey(leftKey), leftAmount, rightKey != nil)
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branchScript := append([]byte{}, nextScriptLeft...)
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if rightKey != nil {
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nextScriptRight := withOutput(txscript.OP_1, schnorr.SerializePubKey(rightKey), rightAmount, false)
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branchScript = append(branchScript, nextScriptRight...)
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}
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return taproot.NewBaseTapElementsLeaf(branchScript)
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}
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func decodeBranchScript(script []byte) (valid bool, leftKey, rightKey *secp256k1.PublicKey, leftAmount, rightAmount uint64, err error) {
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if len(script) != 52 && len(script) != 104 {
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return false, nil, nil, 0, 0, nil
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}
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isLeftOnly := len(script) == 52
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validLeft, leftKey, leftAmount, err := decodeWithOutputScript(script[:52], txscript.OP_0, !isLeftOnly)
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if err != nil {
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return false, nil, nil, 0, 0, err
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}
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if !validLeft {
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return false, nil, nil, 0, 0, nil
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}
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if isLeftOnly {
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return true, leftKey, nil, leftAmount, 0, nil
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}
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validRight, rightKey, rightAmount, err := decodeWithOutputScript(script[52:], txscript.OP_1, false)
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if err != nil {
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return false, nil, nil, 0, 0, err
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}
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if !validRight {
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return false, nil, nil, 0, 0, nil
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}
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rebuilt := BranchScript(leftKey, rightKey, leftAmount, rightAmount)
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if !bytes.Equal(rebuilt.Script, script) {
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return false, nil, nil, 0, 0, nil
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}
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return true, leftKey, rightKey, leftAmount, rightAmount, nil
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}
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func decodeWithOutputScript(script []byte, expectedIndex byte, isVerify bool) (valid bool, pubkey *secp256k1.PublicKey, amount uint64, err error) {
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if len(script) != 52 {
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return false, nil, 0, nil
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}
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if script[0] != expectedIndex {
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return false, nil, 0, nil
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}
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// 32 bytes for the witness program
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pubkey, err = schnorr.ParsePubKey(script[5 : 5+32])
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if err != nil {
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return false, nil, 0, err
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}
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inspectOutputValueIndex := bytes.IndexByte(script, OP_INSPECTOUTPUTVALUE)
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if inspectOutputValueIndex == -1 {
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return false, nil, 0, nil
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}
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if script[inspectOutputValueIndex-1] != expectedIndex {
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return false, nil, 0, nil
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}
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// 8 bytes for the amount
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amountBytes := script[len(script)-9 : len(script)-1]
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amount = binary.LittleEndian.Uint64(amountBytes)
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rebuilt := withOutput(expectedIndex, schnorr.SerializePubKey(pubkey), amount, isVerify)
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if !bytes.Equal(rebuilt, script) {
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return false, nil, 0, nil
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}
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return true, pubkey, amount, nil
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}
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func decodeChecksigScript(script []byte) (valid bool, pubkey *secp256k1.PublicKey, err error) {
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checksigIndex := bytes.Index(script, []byte{txscript.OP_CHECKSIG})
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if checksigIndex == -1 || checksigIndex == 0 {
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return false, nil, nil
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}
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key := script[1:checksigIndex]
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if len(key) != 32 {
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return false, nil, nil
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}
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pubkey, err = schnorr.ParsePubKey(key)
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if err != nil {
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return false, nil, err
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}
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rebuilt, err := checksigScript(pubkey)
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if err != nil {
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return false, nil, err
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}
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if !bytes.Equal(rebuilt, script) {
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return false, nil, nil
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}
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return true, pubkey, nil
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}
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func decodeSweepScript(script []byte) (valid bool, aspPubKey *secp256k1.PublicKey, seconds uint, err error) {
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csvIndex := bytes.Index(script, []byte{txscript.OP_CHECKSEQUENCEVERIFY, txscript.OP_DROP})
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if csvIndex == -1 || csvIndex == 0 {
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return false, nil, 0, nil
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}
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sequence := script[:csvIndex]
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seconds, err = common.BIP68Decode(sequence)
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if err != nil {
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return false, nil, 0, err
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}
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checksigScript := script[csvIndex+2:]
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valid, aspPubKey, err = decodeChecksigScript(checksigScript)
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if err != nil {
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return false, nil, 0, err
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}
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rebuilt, err := csvChecksigScript(aspPubKey, seconds)
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if err != nil {
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return false, nil, 0, err
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}
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if !bytes.Equal(rebuilt, script) {
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return false, nil, 0, nil
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}
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return valid, aspPubKey, seconds, nil
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}
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// checkSequenceVerifyScript without checksig
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func checkSequenceVerifyScript(seconds uint) ([]byte, error) {
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sequence, err := common.BIP68Encode(seconds)
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if err != nil {
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return nil, err
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}
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return append(sequence, []byte{
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txscript.OP_CHECKSEQUENCEVERIFY,
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txscript.OP_DROP,
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}...), nil
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}
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// checkSequenceVerifyScript + checksig
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func csvChecksigScript(pubkey *secp256k1.PublicKey, seconds uint) ([]byte, error) {
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script, err := checksigScript(pubkey)
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if err != nil {
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return nil, err
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}
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csvScript, err := checkSequenceVerifyScript(seconds)
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if err != nil {
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return nil, err
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}
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return append(csvScript, script...), nil
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}
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func checksigScript(pubkey *secp256k1.PublicKey) ([]byte, error) {
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key := schnorr.SerializePubKey(pubkey)
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return txscript.NewScriptBuilder().AddData(key).AddOp(txscript.OP_CHECKSIG).Script()
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}
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// withOutput returns an introspection script that checks the script and the amount of the output at the given index
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// verify will add an OP_EQUALVERIFY at the end of the script, otherwise it will add an OP_EQUAL
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// length = 52 bytes
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func withOutput(index byte, taprootWitnessProgram []byte, amount uint64, verify bool) []byte {
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amountBuffer := make([]byte, 8)
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binary.LittleEndian.PutUint64(amountBuffer, amount)
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script := []byte{
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index,
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OP_INSPECTOUTPUTSCRIPTPUBKEY,
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txscript.OP_1,
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txscript.OP_EQUALVERIFY,
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txscript.OP_DATA_32,
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}
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script = append(script, taprootWitnessProgram...)
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script = append(script, []byte{
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txscript.OP_EQUALVERIFY,
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}...)
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script = append(script, index)
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script = append(script, []byte{
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OP_INSPECTOUTPUTVALUE,
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txscript.OP_1,
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txscript.OP_EQUALVERIFY,
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txscript.OP_DATA_8,
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}...)
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script = append(script, amountBuffer...)
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if verify {
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script = append(script, []byte{
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txscript.OP_EQUALVERIFY,
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}...)
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} else {
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script = append(script, []byte{
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txscript.OP_EQUAL,
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}...)
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}
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return script
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}
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