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jmwallet.wallet.psbt

jmwallet.wallet.psbt

Strict BIP174 PSBT v0 parsing and record-preserving updates.

Attributes

PSBT_GLOBAL_UNSIGNED_TX = 0 module-attribute

PSBT_GLOBAL_VERSION = 251 module-attribute

PSBT_GLOBAL_XPUB = 1 module-attribute

PSBT_IN_BIP32_DERIVATION = 6 module-attribute

PSBT_IN_FINAL_SCRIPTSIG = 7 module-attribute

PSBT_IN_FINAL_SCRIPTWITNESS = 8 module-attribute

PSBT_IN_NON_WITNESS_UTXO = 0 module-attribute

PSBT_IN_PARTIAL_SIG = 2 module-attribute

PSBT_IN_PROPRIETARY = 252 module-attribute

PSBT_IN_REDEEM_SCRIPT = 4 module-attribute

PSBT_IN_SIGHASH_TYPE = 3 module-attribute

PSBT_IN_WITNESS_SCRIPT = 5 module-attribute

PSBT_IN_WITNESS_UTXO = 1 module-attribute

PSBT_MAGIC = b'psbt\xff' module-attribute

PSBT_OUT_BIP32_DERIVATION = 2 module-attribute

PSBT_OUT_PROPRIETARY = 252 module-attribute

PSBT_OUT_REDEEM_SCRIPT = 0 module-attribute

PSBT_OUT_WITNESS_SCRIPT = 1 module-attribute

Classes

BIP32KeyOrigin dataclass

A BIP32 public key and its master fingerprint and derivation path.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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@dataclass(frozen=True)
class BIP32KeyOrigin:
    """A BIP32 public key and its master fingerprint and derivation path."""

    pubkey: bytes
    fingerprint: bytes
    path: tuple[int, ...]
Attributes
fingerprint: bytes instance-attribute
path: tuple[int, ...] instance-attribute
pubkey: bytes instance-attribute

PSBTError

Bases: ValueError

Raised when a PSBT violates BIP174 serialization requirements.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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class PSBTError(ValueError):
    """Raised when a PSBT violates BIP174 serialization requirements."""

PSBTKeyValue dataclass

An ordered raw PSBT key/value record.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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@dataclass(frozen=True)
class PSBTKeyValue:
    """An ordered raw PSBT key/value record."""

    key: bytes
    value: bytes
Attributes
key: bytes instance-attribute
value: bytes instance-attribute

PSBTMap dataclass

A PSBT map retaining record order and unknown records.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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@dataclass
class PSBTMap:
    """A PSBT map retaining record order and unknown records."""

    records: list[PSBTKeyValue] = field(default_factory=list)

    def append(self, key: bytes, value: bytes) -> None:
        """Append a unique, nonempty raw record to this map."""
        if not key:
            raise PSBTError("PSBT map keys must not be empty")
        if any(record.key == key for record in self.records):
            raise PSBTError(f"Duplicate PSBT key: {key.hex()}")
        self.records.append(PSBTKeyValue(key=key, value=value))

    def serialize(self) -> bytes:
        """Serialize this map with canonical CompactSize lengths."""
        result = bytearray()
        for record in self.records:
            result.extend(encode_varint(len(record.key)))
            result.extend(record.key)
            result.extend(encode_varint(len(record.value)))
            result.extend(record.value)
        result.append(0)
        return bytes(result)
Attributes
records: list[PSBTKeyValue] = field(default_factory=list) class-attribute instance-attribute
Methods:
append(key: bytes, value: bytes) -> None

Append a unique, nonempty raw record to this map.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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def append(self, key: bytes, value: bytes) -> None:
    """Append a unique, nonempty raw record to this map."""
    if not key:
        raise PSBTError("PSBT map keys must not be empty")
    if any(record.key == key for record in self.records):
        raise PSBTError(f"Duplicate PSBT key: {key.hex()}")
    self.records.append(PSBTKeyValue(key=key, value=value))
serialize() -> bytes

Serialize this map with canonical CompactSize lengths.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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def serialize(self) -> bytes:
    """Serialize this map with canonical CompactSize lengths."""
    result = bytearray()
    for record in self.records:
        result.extend(encode_varint(len(record.key)))
        result.extend(record.key)
        result.extend(encode_varint(len(record.value)))
        result.extend(record.value)
    result.append(0)
    return bytes(result)

ParsedPSBT dataclass

A parsed BIP174 PSBT v0, retaining all raw map records.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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@dataclass
class ParsedPSBT:
    """A parsed BIP174 PSBT v0, retaining all raw map records."""

    unsigned_tx: bytes
    transaction: ParsedTransaction
    global_map: PSBTMap
    input_maps: list[PSBTMap]
    output_maps: list[PSBTMap]

    def serialize(self) -> bytes:
        """Serialize the PSBT while preserving all map record order."""
        result = bytearray(PSBT_MAGIC)
        result.extend(self.global_map.serialize())
        for input_map in self.input_maps:
            result.extend(input_map.serialize())
        for output_map in self.output_maps:
            result.extend(output_map.serialize())
        return bytes(result)

    def append_input_key_value(self, input_index: int, key: bytes, value: bytes) -> None:
        """Append a valid unique record to an input map."""
        if input_index < 0:
            raise PSBTError(f"PSBT input index out of range: {input_index}")
        try:
            input_map = self.input_maps[input_index]
        except IndexError as error:
            raise PSBTError(f"PSBT input index out of range: {input_index}") from error
        _validate_key("input", key)
        _validate_map_records("input", PSBTMap(records=[PSBTKeyValue(key=key, value=value)]))
        input_map.append(key, value)
Attributes
global_map: PSBTMap instance-attribute
input_maps: list[PSBTMap] instance-attribute
output_maps: list[PSBTMap] instance-attribute
transaction: ParsedTransaction instance-attribute
unsigned_tx: bytes instance-attribute
Methods:
append_input_key_value(input_index: int, key: bytes, value: bytes) -> None

Append a valid unique record to an input map.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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def append_input_key_value(self, input_index: int, key: bytes, value: bytes) -> None:
    """Append a valid unique record to an input map."""
    if input_index < 0:
        raise PSBTError(f"PSBT input index out of range: {input_index}")
    try:
        input_map = self.input_maps[input_index]
    except IndexError as error:
        raise PSBTError(f"PSBT input index out of range: {input_index}") from error
    _validate_key("input", key)
    _validate_map_records("input", PSBTMap(records=[PSBTKeyValue(key=key, value=value)]))
    input_map.append(key, value)
serialize() -> bytes

Serialize the PSBT while preserving all map record order.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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def serialize(self) -> bytes:
    """Serialize the PSBT while preserving all map record order."""
    result = bytearray(PSBT_MAGIC)
    result.extend(self.global_map.serialize())
    for input_map in self.input_maps:
        result.extend(input_map.serialize())
    for output_map in self.output_maps:
        result.extend(output_map.serialize())
    return bytes(result)

WitnessUTXO dataclass

The amount and scriptPubKey contained in a PSBT witness UTXO record.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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@dataclass(frozen=True)
class WitnessUTXO:
    """The amount and scriptPubKey contained in a PSBT witness UTXO record."""

    value: int
    script_pubkey: bytes
Attributes
script_pubkey: bytes instance-attribute
value: int instance-attribute

Functions:

parse_bip32_derivation(key: bytes, value: bytes) -> BIP32KeyOrigin

Parse a BIP174 BIP32 derivation key/value pair.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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def parse_bip32_derivation(key: bytes, value: bytes) -> BIP32KeyOrigin:
    """Parse a BIP174 BIP32 derivation key/value pair."""
    if len(key) != 34:
        raise PSBTError("BIP32 derivation key must contain a type byte and 33-byte public key")
    pubkey = key[1:]
    if pubkey[0] not in (0x02, 0x03):
        raise PSBTError("BIP32 derivation key must contain a compressed public key")
    _validate_key_origin_value(value, "BIP32 derivation")
    path = tuple(
        int.from_bytes(value[offset : offset + 4], "little", signed=False)
        for offset in range(4, len(value), 4)
    )
    return BIP32KeyOrigin(pubkey=pubkey, fingerprint=value[:4], path=path)

parse_psbt(data: bytes) -> ParsedPSBT

Parse a strict, complete BIP174 PSBT v0 binary payload.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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def parse_psbt(data: bytes) -> ParsedPSBT:
    """Parse a strict, complete BIP174 PSBT v0 binary payload."""
    if not data.startswith(PSBT_MAGIC):
        raise PSBTError("Invalid PSBT magic bytes")

    offset = len(PSBT_MAGIC)
    global_map, offset = _read_map(data, offset, "global")
    _validate_map_records("global", global_map)
    unsigned_tx = _get_unsigned_transaction(global_map)
    _validate_version(global_map)

    try:
        transaction = parse_transaction_bytes(unsigned_tx)
    except Exception as error:
        raise PSBTError(f"Invalid PSBT unsigned transaction: {error}") from error
    if transaction.has_witness:
        raise PSBTError("PSBT unsigned transaction must not contain witness data")
    if any(tx_input.scriptsig for tx_input in transaction.inputs):
        raise PSBTError("PSBT unsigned transaction must have empty scriptSigs")

    input_maps, offset = _read_expected_maps(data, offset, len(transaction.inputs), "input")
    output_maps, offset = _read_expected_maps(data, offset, len(transaction.outputs), "output")
    for input_map in input_maps:
        _validate_map_records("input", input_map)
    for output_map in output_maps:
        _validate_map_records("output", output_map)
    if offset != len(data):
        raise PSBTError("Trailing data after PSBT maps")

    return ParsedPSBT(
        unsigned_tx=unsigned_tx,
        transaction=transaction,
        global_map=global_map,
        input_maps=input_maps,
        output_maps=output_maps,
    )

parse_witness_utxo(value: bytes) -> WitnessUTXO

Parse a BIP174 witness UTXO value with exact consumption.

Source code in jmwallet/src/jmwallet/wallet/psbt.py 
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def parse_witness_utxo(value: bytes) -> WitnessUTXO:
    """Parse a BIP174 witness UTXO value with exact consumption."""
    if len(value) < 8:
        raise PSBTError("Truncated witness UTXO value")
    amount = int.from_bytes(value[:8], "little", signed=False)
    if amount > MAX_MONEY:
        raise PSBTError("Witness UTXO amount exceeds Bitcoin MAX_MONEY")
    script_length, offset = _read_compact_size(value, 8, "witness UTXO script length")
    remaining = len(value) - offset
    if script_length > remaining:
        raise PSBTError("Truncated witness UTXO scriptPubKey")
    if script_length != remaining:
        raise PSBTError("Trailing data after witness UTXO scriptPubKey")
    return WitnessUTXO(value=amount, script_pubkey=value[offset:])