transaction: rm hardcoded sighash magic numbers

electrum/lnchannel.py

@@ -39,7 +39,7 @@ from .util import bfh, bh2u, chunks, TxMinedInfo
 from .invoices import PR_PAID
 from .bitcoin import redeem_script_to_address
 from .crypto import sha256, sha256d
-from .transaction import Transaction, PartialTransaction, TxInput
+from .transaction import Transaction, PartialTransaction, TxInput, Sighash
 from .logging import Logger
 from .lnonion import decode_onion_error, OnionFailureCode, OnionRoutingFailure
 from . import lnutil
@@ -1101,7 +1101,7 @@ class Channel(AbstractChannel):
         data = self.config[LOCAL].current_htlc_signatures
         htlc_sigs = list(chunks(data, 64))
         htlc_sig = htlc_sigs[htlc_relative_idx]
-        remote_htlc_sig = ecc.der_sig_from_sig_string(htlc_sig) + b'\x01'
+        remote_htlc_sig = ecc.der_sig_from_sig_string(htlc_sig) + Sighash.to_sigbytes(Sighash.ALL)
         return remote_htlc_sig
 
     def revoke_current_commitment(self):
@@ -1554,7 +1554,7 @@ class Channel(AbstractChannel):
         assert self.signature_fits(tx)
         tx.sign({bh2u(self.config[LOCAL].multisig_key.pubkey): (self.config[LOCAL].multisig_key.privkey, True)})
         remote_sig = self.config[LOCAL].current_commitment_signature
-        remote_sig = ecc.der_sig_from_sig_string(remote_sig) + b"\x01"
+        remote_sig = ecc.der_sig_from_sig_string(remote_sig) + Sighash.to_sigbytes(Sighash.ALL)
         tx.add_signature_to_txin(txin_idx=0,
                                  signing_pubkey=self.config[REMOTE].multisig_key.pubkey.hex(),
                                  sig=remote_sig.hex())

electrum/lnpeer.py

@@ -25,7 +25,7 @@ from .util import (bh2u, bfh, log_exceptions, ignore_exceptions, chunks, OldTask
                    UnrelatedTransactionException)
 from . import transaction
 from .bitcoin import make_op_return
-from .transaction import PartialTxOutput, match_script_against_template
+from .transaction import PartialTxOutput, match_script_against_template, Sighash
 from .logging import Logger
 from .lnonion import (new_onion_packet, OnionFailureCode, calc_hops_data_for_payment,
                       process_onion_packet, OnionPacket, construct_onion_error, OnionRoutingFailure,
@@ -2039,8 +2039,8 @@ class Peer(Logger):
         assert our_scriptpubkey
         # estimate fee of closing tx
         dummy_sig, dummy_tx = chan.make_closing_tx(our_scriptpubkey, their_scriptpubkey, fee_sat=0)
-        our_sig = None
-        closing_tx = None
+        our_sig = None  # type: Optional[bytes]
+        closing_tx = None  # type: Optional[PartialTransaction]
         is_initiator = chan.constraints.is_initiator
         our_fee, our_fee_range = self.get_shutdown_fee_range(chan, dummy_tx, is_local)
 
@@ -2185,11 +2185,11 @@ class Peer(Logger):
         closing_tx.add_signature_to_txin(
             txin_idx=0,
             signing_pubkey=chan.config[LOCAL].multisig_key.pubkey.hex(),
-            sig=bh2u(der_sig_from_sig_string(our_sig) + b'\x01'))
+            sig=bh2u(der_sig_from_sig_string(our_sig) + Sighash.to_sigbytes(Sighash.ALL)))
         closing_tx.add_signature_to_txin(
             txin_idx=0,
             signing_pubkey=chan.config[REMOTE].multisig_key.pubkey.hex(),
-            sig=bh2u(der_sig_from_sig_string(their_sig) + b'\x01'))
+            sig=bh2u(der_sig_from_sig_string(their_sig) + Sighash.to_sigbytes(Sighash.ALL)))
         # save local transaction and set state
         try:
             self.lnworker.wallet.adb.add_transaction(closing_tx)

electrum/plugins/bitbox02/bitbox02.py

@@ -8,7 +8,7 @@ from typing import TYPE_CHECKING, Dict, Tuple, Optional, List, Any, Callable
 from electrum import bip32, constants
 from electrum.i18n import _
 from electrum.keystore import Hardware_KeyStore
-from electrum.transaction import PartialTransaction
+from electrum.transaction import PartialTransaction, Sighash
 from electrum.wallet import Standard_Wallet, Multisig_Wallet, Deterministic_Wallet
 from electrum.util import bh2u, UserFacingException
 from electrum.base_wizard import ScriptTypeNotSupported, BaseWizard
@@ -523,7 +523,8 @@ class BitBox02Client(HardwareClientBase):
         # Fill signatures
         if len(sigs) != len(tx.inputs()):
             raise Exception("Incorrect number of inputs signed.")  # Should never occur
-        signatures = [bh2u(ecc.der_sig_from_sig_string(x[1])) + "01" for x in sigs]
+        sighash = Sighash.to_sigbytes(Sighash.ALL).hex()
+        signatures = [bh2u(ecc.der_sig_from_sig_string(x[1])) + sighash for x in sigs]
         tx.update_signatures(signatures)
 
     def sign_message(self, keypath: str, message: bytes, script_type: str) -> bytes:

electrum/plugins/digitalbitbox/digitalbitbox.py

@@ -23,7 +23,7 @@ from electrum import ecc
 from electrum.ecc import msg_magic
 from electrum.wallet import Standard_Wallet
 from electrum import constants
-from electrum.transaction import Transaction, PartialTransaction, PartialTxInput
+from electrum.transaction import Transaction, PartialTransaction, PartialTxInput, Sighash
 from electrum.i18n import _
 from electrum.keystore import Hardware_KeyStore
 from electrum.util import to_string, UserCancelled, UserFacingException, bfh
@@ -645,7 +645,7 @@ class DigitalBitbox_KeyStore(Hardware_KeyStore):
                     sig_r = int(signed['sig'][:64], 16)
                     sig_s = int(signed['sig'][64:], 16)
                     sig = ecc.der_sig_from_r_and_s(sig_r, sig_s)
-                    sig = to_hexstr(sig) + '01'
+                    sig = to_hexstr(sig) + Sighash.to_sigbytes(Sighash.ALL).hex()
                     tx.add_signature_to_txin(txin_idx=i, signing_pubkey=pubkey_bytes.hex(), sig=sig)
         except UserCancelled:
             raise

electrum/plugins/keepkey/keepkey.py

@@ -7,7 +7,7 @@ from electrum.util import bfh, bh2u, UserCancelled, UserFacingException
 from electrum.bip32 import BIP32Node
 from electrum import constants
 from electrum.i18n import _
-from electrum.transaction import Transaction, PartialTransaction, PartialTxInput, PartialTxOutput
+from electrum.transaction import Transaction, PartialTransaction, PartialTxInput, PartialTxOutput, Sighash
 from electrum.keystore import Hardware_KeyStore
 from electrum.plugin import Device, runs_in_hwd_thread
 from electrum.base_wizard import ScriptTypeNotSupported
@@ -330,7 +330,8 @@ class KeepKeyPlugin(HW_PluginBase):
         outputs = self.tx_outputs(tx, keystore=keystore)
         signatures = client.sign_tx(self.get_coin_name(), inputs, outputs,
                                     lock_time=tx.locktime, version=tx.version)[0]
-        signatures = [(bh2u(x) + '01') for x in signatures]
+        sighash = Sighash.to_sigbytes(Sighash.ALL).hex()
+        signatures = [(bh2u(x) + sighash) for x in signatures]
         tx.update_signatures(signatures)
 
     @runs_in_hwd_thread

electrum/plugins/safe_t/safe_t.py

@@ -8,7 +8,7 @@ from electrum.bip32 import BIP32Node
 from electrum import constants
 from electrum.i18n import _
 from electrum.plugin import Device, runs_in_hwd_thread
-from electrum.transaction import Transaction, PartialTransaction, PartialTxInput, PartialTxOutput
+from electrum.transaction import Transaction, PartialTransaction, PartialTxInput, PartialTxOutput, Sighash
 from electrum.keystore import Hardware_KeyStore
 from electrum.base_wizard import ScriptTypeNotSupported
 
@@ -300,7 +300,8 @@ class SafeTPlugin(HW_PluginBase):
         outputs = self.tx_outputs(tx, keystore=keystore)
         signatures = client.sign_tx(self.get_coin_name(), inputs, outputs,
                                     lock_time=tx.locktime, version=tx.version)[0]
-        signatures = [(bh2u(x) + '01') for x in signatures]
+        sighash = Sighash.to_sigbytes(Sighash.ALL).hex()
+        signatures = [(bh2u(x) + sighash) for x in signatures]
         tx.update_signatures(signatures)
 
     @runs_in_hwd_thread

electrum/plugins/trezor/trezor.py

@@ -7,7 +7,7 @@ from electrum.bip32 import BIP32Node, convert_bip32_path_to_list_of_uint32 as pa
 from electrum import constants
 from electrum.i18n import _
 from electrum.plugin import Device, runs_in_hwd_thread
-from electrum.transaction import Transaction, PartialTransaction, PartialTxInput, PartialTxOutput
+from electrum.transaction import Transaction, PartialTransaction, PartialTxInput, PartialTxOutput, Sighash
 from electrum.keystore import Hardware_KeyStore
 from electrum.base_wizard import ScriptTypeNotSupported, HWD_SETUP_NEW_WALLET
 from electrum.logging import get_logger
@@ -370,7 +370,8 @@ class TrezorPlugin(HW_PluginBase):
                                        amount_unit=self.get_trezor_amount_unit(),
                                        serialize=False,
                                        prev_txes=prev_tx)
-        signatures = [(bh2u(x) + '01') for x in signatures]
+        sighash = Sighash.to_sigbytes(Sighash.ALL).hex()
+        signatures = [(bh2u(x) + sighash) for x in signatures]
         tx.update_signatures(signatures)
 
     @runs_in_hwd_thread

electrum/tests/test_lnutil.py

@@ -11,7 +11,7 @@ from electrum.lnutil import (RevocationStore, get_per_commitment_secret_from_see
                              ScriptHtlc, extract_nodeid, calc_fees_for_commitment_tx, UpdateAddHtlc, LnFeatures,
                              ln_compare_features, IncompatibleLightningFeatures, ChannelType)
 from electrum.util import bh2u, bfh, MyEncoder
-from electrum.transaction import Transaction, PartialTransaction
+from electrum.transaction import Transaction, PartialTransaction, Sighash
 from electrum.lnworker import LNWallet
 
 from . import ElectrumTestCase
@@ -725,7 +725,8 @@ class TestLNUtil(ElectrumTestCase):
         assert len(pubkey) == 33
         assert len(privkey) == 33
         tx.sign({bh2u(pubkey): (privkey[:-1], True)})
-        tx.add_signature_to_txin(txin_idx=0, signing_pubkey=remote_pubkey.hex(), sig=remote_signature + "01")
+        sighash = Sighash.to_sigbytes(Sighash.ALL).hex()
+        tx.add_signature_to_txin(txin_idx=0, signing_pubkey=remote_pubkey.hex(), sig=remote_signature + sighash)
 
     def test_get_compressed_pubkey_from_bech32(self):
         self.assertEqual(b'\x03\x84\xef\x87\xd9d\xa2\xaaa7=\xff\xb8\xfe=t8[}>;\n\x13\xa8e\x8eo:\xf5Mi\xb5H',

electrum/transaction.py

@@ -90,19 +90,25 @@ class MissingTxInputAmount(Exception):
 
 
 class Sighash(IntEnum):
+    # note: this is not an IntFlag, as ALL|NONE != SINGLE
+
     ALL = 1
     NONE = 2
     SINGLE = 3
     ANYONECANPAY = 0x80
 
     @classmethod
-    def is_valid(cls, sighash) -> bool:
+    def is_valid(cls, sighash: int) -> bool:
         for flag in Sighash:
             for base_flag in [Sighash.ALL, Sighash.NONE, Sighash.SINGLE]:
                 if (flag & ~0x1f | base_flag) == sighash:
                     return True
         return False
 
+    @classmethod
+    def to_sigbytes(cls, sighash: int) -> bytes:
+        return sighash.to_bytes(length=1, byteorder="big")
+
 
 class TxOutput:
     scriptpubkey: bytes
@@ -1940,7 +1946,7 @@ class PartialTransaction(Transaction):
         txin = inputs[txin_index]
         sighash = txin.sighash if txin.sighash is not None else Sighash.ALL
         if not Sighash.is_valid(sighash):
-            raise Exception("SIGHASH_FLAG not supported!")
+            raise Exception(f"SIGHASH_FLAG ({sighash}) not supported!")
         nHashType = int_to_hex(sighash, 4)
         preimage_script = self.get_preimage_script(txin)
         if txin.is_segwit():
@@ -1966,6 +1972,8 @@ class PartialTransaction(Transaction):
             nSequence = int_to_hex(txin.nsequence, 4)
             preimage = nVersion + hashPrevouts + hashSequence + outpoint + scriptCode + amount + nSequence + hashOutputs + nLocktime + nHashType
         else:
+            if sighash != Sighash.ALL:
+                raise Exception(f"SIGHASH_FLAG ({sighash}) not supported! (for legacy sighash)")
             txins = var_int(len(inputs)) + ''.join(txin.serialize_to_network(script_sig=bfh(preimage_script) if txin_index==k else b"").hex()
                                                    for k, txin in enumerate(inputs))
             txouts = var_int(len(outputs)) + ''.join(o.serialize_to_network().hex() for o in outputs)
@@ -1994,12 +2002,11 @@ class PartialTransaction(Transaction):
         txin = self.inputs()[txin_index]
         txin.validate_data(for_signing=True)
         sighash = txin.sighash if txin.sighash is not None else Sighash.ALL
-        sighash_type = sighash.to_bytes(length=1, byteorder="big").hex()
         pre_hash = sha256d(bfh(self.serialize_preimage(txin_index,
                                                        bip143_shared_txdigest_fields=bip143_shared_txdigest_fields)))
         privkey = ecc.ECPrivkey(privkey_bytes)
         sig = privkey.sign_transaction(pre_hash)
-        sig = bh2u(sig) + sighash_type
+        sig = bh2u(sig) + Sighash.to_sigbytes(sighash).hex()
         return sig
 
     def is_complete(self) -> bool: