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https://github.com/aljazceru/ark.git
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Covenant-less TxBuilder (#178)
* initial commit * wip * add bitcointree pkg in common * add bitcoin txbuilder * fix BuildPoolTx test * fix sweeper * v0 musig2 congestion tree * bitcointree: add signatures support * add Makefile in common * fix lint * fix go.mod and TxBuilder * go mod tidy * rename "pset" --> "psbt" * add GetSweepInput method in TxBuilder * fix extractSweepLeaf (bitcoin tx builder)
This commit is contained in:
Louis Singer
375
common/bitcointree/builder.go
Normal file
375
common/bitcointree/builder.go
Normal file
@@ -0,0 +1,375 @@
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package bitcointree
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import (
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"encoding/hex"
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"fmt"
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"github.com/ark-network/ark/common/tree"
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"github.com/btcsuite/btcd/btcec/v2/schnorr"
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"github.com/btcsuite/btcd/btcec/v2/schnorr/musig2"
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"github.com/btcsuite/btcd/btcutil/psbt"
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"github.com/btcsuite/btcd/chaincfg/chainhash"
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"github.com/btcsuite/btcd/txscript"
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"github.com/btcsuite/btcd/wire"
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"github.com/decred/dcrd/dcrec/secp256k1/v4"
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)
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// CraftSharedOutput returns the taproot script and the amount of the initial root output
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func CraftSharedOutput(
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cosigners []*secp256k1.PublicKey, aspPubkey *secp256k1.PublicKey, receivers []Receiver,
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feeSatsPerNode uint64, roundLifetime, unilateralExitDelay int64,
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) ([]byte, int64, error) {
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aggregatedKey, _, err := createAggregatedKeyWithSweep(
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cosigners, aspPubkey, roundLifetime,
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)
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if err != nil {
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return nil, 0, err
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}
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root, err := createRootNode(aggregatedKey, aspPubkey, receivers, feeSatsPerNode, unilateralExitDelay)
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if err != nil {
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return nil, 0, err
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}
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amount := root.getAmount() + int64(feeSatsPerNode)
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scriptPubKey, err := taprootOutputScript(aggregatedKey.FinalKey)
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if err != nil {
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return nil, 0, err
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}
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return scriptPubKey, amount, err
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}
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// CraftCongestionTree creates all the tree's transactions
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func CraftCongestionTree(
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initialInput *wire.OutPoint, cosigners []*secp256k1.PublicKey, aspPubkey *secp256k1.PublicKey, receivers []Receiver,
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feeSatsPerNode uint64, roundLifetime, unilateralExitDelay int64,
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) (tree.CongestionTree, error) {
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aggregatedKey, sweepTapLeaf, err := createAggregatedKeyWithSweep(
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cosigners, aspPubkey, roundLifetime,
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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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root, err := createRootNode(aggregatedKey, aspPubkey, receivers, feeSatsPerNode, unilateralExitDelay)
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if err != nil {
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return nil, err
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}
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congestionTree := make(tree.CongestionTree, 0)
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ins := []*wire.OutPoint{initialInput}
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nodes := []node{root}
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for len(nodes) > 0 {
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nextNodes := make([]node, 0)
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nextInputsArgs := make([]*wire.OutPoint, 0)
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treeLevel := make([]tree.Node, 0)
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for i, node := range nodes {
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treeNode, err := getTreeNode(node, ins[i], schnorr.SerializePubKey(aggregatedKey.PreTweakedKey), sweepTapLeaf)
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if err != nil {
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return nil, err
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}
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nodeTxHash, err := chainhash.NewHashFromStr(treeNode.Txid)
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if err != nil {
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return nil, err
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}
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treeLevel = append(treeLevel, treeNode)
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children := node.getChildren()
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for i, child := range children {
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nextNodes = append(nextNodes, child)
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nextInputsArgs = append(nextInputsArgs, &wire.OutPoint{
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Hash: *nodeTxHash,
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Index: uint32(i),
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})
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}
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}
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congestionTree = append(congestionTree, treeLevel)
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nodes = append([]node{}, nextNodes...)
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ins = append([]*wire.OutPoint{}, nextInputsArgs...)
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}
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return congestionTree, nil
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}
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type node interface {
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getAmount() int64 // returns the input amount of the node = sum of all receivers' amounts + fees
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getOutputs() ([]*wire.TxOut, error)
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getChildren() []node
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}
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type leaf struct {
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aspKey *secp256k1.PublicKey
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vtxoKey *secp256k1.PublicKey
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exitDelay int64
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amount int64
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}
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type branch struct {
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aggregatedKey *musig2.AggregateKey
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children []node
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feeAmount int64
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}
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func (b *branch) getChildren() []node {
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return b.children
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}
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func (l *leaf) getChildren() []node {
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return []node{}
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}
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func (b *branch) getAmount() int64 {
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amount := int64(0)
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for _, child := range b.children {
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amount += child.getAmount()
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amount += b.feeAmount
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}
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return amount
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}
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func (l *leaf) getAmount() int64 {
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return l.amount
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}
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func (l *leaf) getOutputs() ([]*wire.TxOut, error) {
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redeemClosure := &CSVSigClosure{
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Pubkey: l.vtxoKey,
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Seconds: uint(l.exitDelay),
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}
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redeemLeaf, err := redeemClosure.Leaf()
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if err != nil {
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return nil, err
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}
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forfeitClosure := &ForfeitClosure{
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Pubkey: l.vtxoKey,
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AspPubkey: l.aspKey,
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}
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forfeitLeaf, err := forfeitClosure.Leaf()
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if err != nil {
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return nil, err
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}
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leafTaprootTree := txscript.AssembleTaprootScriptTree(
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*redeemLeaf, *forfeitLeaf,
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)
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root := leafTaprootTree.RootNode.TapHash()
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taprootKey := txscript.ComputeTaprootOutputKey(
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UnspendableKey(),
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root[:],
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)
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script, err := taprootOutputScript(taprootKey)
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if err != nil {
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return nil, err
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}
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output := &wire.TxOut{
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Value: l.amount,
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PkScript: script,
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}
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return []*wire.TxOut{output}, nil
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}
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func (b *branch) getOutputs() ([]*wire.TxOut, error) {
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sharedOutputScript, err := taprootOutputScript(b.aggregatedKey.FinalKey)
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if err != nil {
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return nil, err
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}
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outputs := make([]*wire.TxOut, 0)
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for _, child := range b.children {
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outputs = append(outputs, &wire.TxOut{
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Value: child.getAmount() + b.feeAmount,
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PkScript: sharedOutputScript,
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})
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}
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return outputs, nil
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}
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func getTreeNode(
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n node,
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input *wire.OutPoint,
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inputTapInternalKey []byte,
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inputSweepTapLeaf *psbt.TaprootTapLeafScript,
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) (tree.Node, error) {
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partialTx, err := getTx(n, input, inputTapInternalKey, inputSweepTapLeaf)
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if err != nil {
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return tree.Node{}, err
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}
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txid := partialTx.UnsignedTx.TxHash().String()
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tx, err := partialTx.B64Encode()
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if err != nil {
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return tree.Node{}, err
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}
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return tree.Node{
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Txid: txid,
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Tx: tx,
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ParentTxid: input.Hash.String(),
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Leaf: len(n.getChildren()) == 0,
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}, nil
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}
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func getTx(
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n node,
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input *wire.OutPoint,
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inputTapInternalKey []byte,
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inputSweepTapLeaf *psbt.TaprootTapLeafScript,
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) (*psbt.Packet, error) {
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outputs, err := n.getOutputs()
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if err != nil {
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return nil, err
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}
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tx, err := psbt.New([]*wire.OutPoint{input}, outputs, 2, 0, []uint32{wire.MaxTxInSequenceNum})
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if err != nil {
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return nil, err
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}
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updater, err := psbt.NewUpdater(tx)
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if err != nil {
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return nil, err
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}
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if err := updater.AddInSighashType(0, int(txscript.SigHashDefault)); err != nil {
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return nil, err
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}
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tx.Inputs[0].TaprootInternalKey = inputTapInternalKey
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tx.Inputs[0].TaprootLeafScript = []*psbt.TaprootTapLeafScript{inputSweepTapLeaf}
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return tx, nil
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}
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func createRootNode(
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aggregatedKey *musig2.AggregateKey, aspPubkey *secp256k1.PublicKey, receivers []Receiver,
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feeSatsPerNode uint64, unilateralExitDelay int64,
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) (root node, err error) {
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if len(receivers) == 0 {
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return nil, fmt.Errorf("no receivers provided")
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}
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nodes := make([]node, 0, len(receivers))
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for _, r := range receivers {
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pubkeyBytes, err := hex.DecodeString(r.Pubkey)
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if err != nil {
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return nil, err
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}
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receiverKey, err := secp256k1.ParsePubKey(pubkeyBytes)
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if err != nil {
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return nil, err
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}
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leafNode := &leaf{
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aspKey: aspPubkey,
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vtxoKey: receiverKey,
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exitDelay: unilateralExitDelay,
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amount: int64(r.Amount),
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}
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nodes = append(nodes, leafNode)
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}
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for len(nodes) > 1 {
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nodes, err = createUpperLevel(nodes, aggregatedKey, int64(feeSatsPerNode))
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if err != nil {
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return
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}
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}
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return nodes[0], nil
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}
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func createAggregatedKeyWithSweep(
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cosigners []*secp256k1.PublicKey, aspPubkey *secp256k1.PublicKey, roundLifetime int64,
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) (*musig2.AggregateKey, *psbt.TaprootTapLeafScript, error) {
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sweepClosure := &CSVSigClosure{
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Pubkey: aspPubkey,
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Seconds: uint(roundLifetime),
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}
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sweepLeaf, err := sweepClosure.Leaf()
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if err != nil {
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return nil, nil, err
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}
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tapTree := txscript.AssembleTaprootScriptTree(*sweepLeaf)
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tapTreeRoot := tapTree.RootNode.TapHash()
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aggregatedKey, err := AggregateKeys(
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cosigners, tapTreeRoot[:],
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)
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if err != nil {
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return nil, nil, err
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}
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index := tapTree.LeafProofIndex[sweepLeaf.TapHash()]
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proof := tapTree.LeafMerkleProofs[index]
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controlBlock := proof.ToControlBlock(aggregatedKey.PreTweakedKey)
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controlBlockBytes, err := controlBlock.ToBytes()
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if err != nil {
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return nil, nil, err
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}
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tapLeaf := &psbt.TaprootTapLeafScript{
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ControlBlock: controlBlockBytes,
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Script: sweepLeaf.Script,
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LeafVersion: sweepLeaf.LeafVersion,
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}
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return aggregatedKey, tapLeaf, nil
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}
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func createUpperLevel(nodes []node, aggregatedKey *musig2.AggregateKey, feeAmount int64) ([]node, error) {
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if len(nodes)%2 != 0 {
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last := nodes[len(nodes)-1]
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pairs, err := createUpperLevel(nodes[:len(nodes)-1], aggregatedKey, feeAmount)
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if err != nil {
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return nil, err
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}
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return append(pairs, last), nil
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}
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pairs := make([]node, 0, len(nodes)/2)
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for i := 0; i < len(nodes); i += 2 {
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left := nodes[i]
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right := nodes[i+1]
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branchNode := &branch{
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aggregatedKey: aggregatedKey,
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feeAmount: feeAmount,
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children: []node{left, right},
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}
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pairs = append(pairs, branchNode)
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}
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return pairs, nil
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}
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func taprootOutputScript(taprootKey *secp256k1.PublicKey) ([]byte, error) {
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return txscript.NewScriptBuilder().AddOp(txscript.OP_1).AddData(
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schnorr.SerializePubKey(taprootKey),
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).Script()
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}
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