Update project structure and build process

libwallet/V2.go

@@ -0,0 +1,115 @@
+package libwallet
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/btcsuite/btcd/txscript"
+	"github.com/muun/libwallet/addresses"
+
+	"github.com/btcsuite/btcd/wire"
+)
+
+func CreateAddressV2(userKey, muunKey *HDPublicKey) (MuunAddress, error) {
+	// TODO: check both paths match?
+	return addresses.CreateAddressV2(&userKey.key, &muunKey.key, userKey.Path, userKey.Network.network)
+}
+
+type coinV2 struct {
+	Network       *chaincfg.Params
+	OutPoint      wire.OutPoint
+	KeyPath       string
+	MuunSignature []byte
+}
+
+func (c *coinV2) SignInput(index int, tx *wire.MsgTx, userKey *HDPrivateKey, muunKey *HDPublicKey) error {
+	userKey, err := userKey.DeriveTo(c.KeyPath)
+	if err != nil {
+		return fmt.Errorf("failed to derive user key: %w", err)
+	}
+
+	muunKey, err = muunKey.DeriveTo(c.KeyPath)
+	if err != nil {
+		return fmt.Errorf("failed to derive muun key: %w", err)
+	}
+
+	if len(c.MuunSignature) == 0 {
+		return errors.New("muun signature must be present")
+	}
+
+	txInput := tx.TxIn[index]
+
+	redeemScript, err := createRedeemScriptV2(userKey.PublicKey(), muunKey)
+	if err != nil {
+		return fmt.Errorf("failed to build reedem script for signing: %w", err)
+	}
+
+	sig, err := c.signature(index, tx, userKey.PublicKey(), muunKey, userKey)
+	if err != nil {
+		return err
+	}
+
+	// This is a standard 2 of 2 multisig script
+	// 0 because of a bug in bitcoind
+	// Then the 2 sigs: first the users and then muuns
+	// Last, the script that contains the two pub keys and OP_CHECKMULTISIG
+	builder := txscript.NewScriptBuilder()
+	builder.AddInt64(0)
+	builder.AddData(sig)
+	builder.AddData(c.MuunSignature)
+	builder.AddData(redeemScript)
+	script, err := builder.Script()
+	if err != nil {
+		return fmt.Errorf("failed to generate signing script: %w", err)
+	}
+
+	txInput.SignatureScript = script
+
+	return nil
+}
+
+func (c *coinV2) FullySignInput(index int, tx *wire.MsgTx, userKey, muunKey *HDPrivateKey) error {
+
+	derivedUserKey, err := userKey.DeriveTo(c.KeyPath)
+	if err != nil {
+		return fmt.Errorf("failed to derive user key: %w", err)
+	}
+
+	derivedMuunKey, err := muunKey.DeriveTo(c.KeyPath)
+	if err != nil {
+		return fmt.Errorf("failed to derive muun key: %w", err)
+	}
+
+	muunSignature, err := c.signature(index, tx, derivedUserKey.PublicKey(), derivedMuunKey.PublicKey(), derivedMuunKey)
+	if err != nil {
+		return err
+	}
+	c.MuunSignature = muunSignature
+	return c.SignInput(index, tx, userKey, muunKey.PublicKey())
+}
+
+func (c *coinV2) signature(index int, tx *wire.MsgTx, userKey, muunKey *HDPublicKey,
+	signingKey *HDPrivateKey) ([]byte, error) {
+
+	redeemScript, err := createRedeemScriptV2(userKey, muunKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to build reedem script for signing: %w", err)
+	}
+
+	privKey, err := signingKey.key.ECPrivKey()
+	if err != nil {
+		return nil, fmt.Errorf("failed to produce EC priv key for signing: %w", err)
+	}
+
+	sig, err := txscript.RawTxInSignature(tx, index, redeemScript, txscript.SigHashAll, privKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to sign V2 output: %w", err)
+	}
+
+	return sig, nil
+}
+
+func createRedeemScriptV2(userKey, muunKey *HDPublicKey) ([]byte, error) {
+	return addresses.CreateRedeemScriptV2(&userKey.key, &muunKey.key, userKey.Network.network)
+}