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psbt: add global XPubs to packet
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Adds support for the PSBT_GLOBAL_XPUB type as defined in BIP-0174.
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@guggero
guggero committed Dec 26, 2024
1 parent bdb0b3d commit f863d97
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Showing 3 changed files with 125 additions and 8 deletions.
69 changes: 69 additions & 0 deletions btcutil/psbt/bip32.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,10 @@ package psbt
import (
"bytes"
"encoding/binary"

"github.com/btcsuite/btcd/btcutil/base58"
"github.com/btcsuite/btcd/btcutil/hdkeychain"
"github.com/btcsuite/btcd/chaincfg/chainhash"
)

const (
Expand Down Expand Up @@ -85,3 +89,68 @@ func SerializeBIP32Derivation(masterKeyFingerprint uint32,

return derivationPath
}

// XPub is a struct that encapsulates an extended public key, as defined in
// BIP-0032.
type XPub struct {
// ExtendedKey is the serialized extended public key as defined in
// BIP-0032.
ExtendedKey []byte

// MasterFingerprint is the fingerprint of the master pubkey.
MasterKeyFingerprint uint32

// Bip32Path is the derivation path of the key, with hardened elements
// having the 0x80000000 offset added, as defined in BIP-0032. The
// number of path elements must match the depth provided in the extended
// public key.
Bip32Path []uint32
}

// ReadXPub deserializes a byte slice containing an extended public key and a
// BIP-0032 derivation path.
func ReadXPub(keyData []byte, path []byte) (*XPub, error) {
xPub, err := DecodeExtendedKey(keyData)
if err != nil {
return nil, ErrInvalidPsbtFormat
}
numPathElements := xPub.Depth()

// The path also contains the master key fingerprint,
expectedSize := int(uint32Size * (numPathElements + 1))
if len(path) != expectedSize {
return nil, ErrInvalidPsbtFormat
}

masterKeyFingerprint, bip32Path, err := ReadBip32Derivation(path)
if err != nil {
return nil, err
}

return &XPub{
ExtendedKey: keyData,
MasterKeyFingerprint: masterKeyFingerprint,
Bip32Path: bip32Path,
}, nil
}

// EncodeExtendedKey serializes an extended key to a byte slice, without the
// checksum.
func EncodeExtendedKey(key *hdkeychain.ExtendedKey) []byte {
serializedKey := key.String()
decodedKey := base58.Decode(serializedKey)
return decodedKey[:len(decodedKey)-uint32Size]
}

// DecodeExtendedKey deserializes an extended key from a byte slice that does
// not contain the checksum.
func DecodeExtendedKey(encodedKey []byte) (*hdkeychain.ExtendedKey, error) {
checkSum := chainhash.DoubleHashB(encodedKey)[:uint32Size]
serializedBytes := append(encodedKey, checkSum...)
xPub, err := hdkeychain.NewKeyFromString(base58.Encode(serializedBytes))
if err != nil {
return nil, err
}

return xPub, nil
}
60 changes: 52 additions & 8 deletions btcutil/psbt/psbt.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,13 @@ type Packet struct {
// produced by this PSBT.
Outputs []POutput

// XPubs is a list of extended public keys that can be used to derive
// public keys used in the inputs and outputs of this transaction. It
// should be the public key at the highest hardened derivation index so
// that the unhardened child keys used in the transaction can be
// derived.
XPubs []XPub

// Unknowns are the set of custom types (global only) within this PSBT.
Unknowns []*Unknown
}
Expand All @@ -161,12 +168,14 @@ func NewFromUnsignedTx(tx *wire.MsgTx) (*Packet, error) {

inSlice := make([]PInput, len(tx.TxIn))
outSlice := make([]POutput, len(tx.TxOut))
xPubSlice := make([]XPub, 0)
unknownSlice := make([]*Unknown, 0)

return &Packet{
UnsignedTx: tx,
Inputs: inSlice,
Outputs: outSlice,
XPubs: xPubSlice,
Unknowns: unknownSlice,
}, nil
}
Expand Down Expand Up @@ -230,7 +239,10 @@ func NewFromRawBytes(r io.Reader, b64 bool) (*Packet, error) {

// Next we parse any unknowns that may be present, making sure that we
// break at the separator.
var unknownSlice []*Unknown
var (
xPubSlice []XPub
unknownSlice []*Unknown
)
for {
keyint, keydata, err := getKey(r)
if err != nil {
Expand All @@ -247,14 +259,32 @@ func NewFromRawBytes(r io.Reader, b64 bool) (*Packet, error) {
return nil, err
}

keyintanddata := []byte{byte(keyint)}
keyintanddata = append(keyintanddata, keydata...)

newUnknown := &Unknown{
Key: keyintanddata,
Value: value,
switch GlobalType(keyint) {
case XPubType:
xPub, err := ReadXPub(keydata, value)
if err != nil {
return nil, err
}

// Duplicate keys are not allowed
for _, x := range xPubSlice {
if bytes.Equal(x.ExtendedKey, keyData) {
return nil, ErrDuplicateKey
}
}

xPubSlice = append(xPubSlice, *xPub)

default:
keyintanddata := []byte{byte(keyint)}
keyintanddata = append(keyintanddata, keydata...)

newUnknown := &Unknown{
Key: keyintanddata,
Value: value,
}
unknownSlice = append(unknownSlice, newUnknown)
}
unknownSlice = append(unknownSlice, newUnknown)
}

// Next we parse the INPUT section.
Expand Down Expand Up @@ -286,6 +316,7 @@ func NewFromRawBytes(r io.Reader, b64 bool) (*Packet, error) {
UnsignedTx: msgTx,
Inputs: inSlice,
Outputs: outSlice,
XPubs: xPubSlice,
Unknowns: unknownSlice,
}

Expand Down Expand Up @@ -325,6 +356,19 @@ func (p *Packet) Serialize(w io.Writer) error {
return err
}

// Serialize the global xPubs.
for _, xPub := range p.XPubs {
pathBytes := SerializeBIP32Derivation(
xPub.MasterKeyFingerprint, xPub.Bip32Path,
)
err := serializeKVPairWithType(
w, uint8(XPubType), xPub.ExtendedKey, pathBytes,
)
if err != nil {
return err
}
}

// Unknown is a special case; we don't have a key type, only a key and
// a value field
for _, kv := range p.Unknowns {
Expand Down
4 changes: 4 additions & 0 deletions btcutil/psbt/psbt_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,8 @@ var validPsbtHex = map[int]string{
5: "70736274ff01003f0200000001ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff0000000000ffffffff010000000000000000036a010000000000000a0f0102030405060708090f0102030405060708090a0b0c0d0e0f0000",
6: "70736274ff01003f0200000001ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff0000000000ffffffff010000000000000000036a010000000000002206030d097466b7f59162ac4d90bf65f2a31a8bad82fcd22e98138dcf279401939bd104ffffffff0a0f0102030405060708090f0102030405060708090a0b0c0d0e0f0000",
7: "70736274ff01002001000000000100000000000000000d6a0b68656c6c6f20776f726c64000000000000",
8: "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",
9: "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",
}

// These are additional valid PSBTs encoded as base64.
Expand All @@ -78,6 +80,8 @@ var validPsbtBase64 = map[int]string{
4: "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",
5: "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",
6: "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",
7: "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",
8: "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",
}

// These are all invalid PSBTs for the indicated reasons.
Expand Down

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