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wallet: tx weight exact calculator
This commit is contained in:
Tomas Susanka
Jan Pochyla
parent
c5cd844bef
commit
272d64b9e8
109
src/apps/wallet/sign_tx/tx_weight_calculator.py
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109
src/apps/wallet/sign_tx/tx_weight_calculator.py
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@ -0,0 +1,109 @@
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# It assumes largest possible signature size for all inputs. For segwit
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# multisig it can be .25 bytes off due to difference between segwit
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# encoding (varint) vs. non-segwit encoding (op_push) of the multisig script.
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#
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# Heavily inspired by:
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# https://github.com/trezor/trezor-mcu/commit/e1fa7af1da79e86ccaae5f3cd2a6c4644f546f8a
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from micropython import const
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from trezor.messages import InputScriptType
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from trezor.messages.TxInputType import TxInputType
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# transaction header size: 4 byte version
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_TXSIZE_HEADER = const(4)
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# transaction footer size: 4 byte lock time
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_TXSIZE_FOOTER = const(4)
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# transaction segwit overhead 2 (marker, flag)
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_TXSIZE_SEGWIT_OVERHEAD = const(2)
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# transaction input size (without script): 32 prevhash, 4 idx, 4 sequence
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_TXSIZE_INPUT = const(40)
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# transaction output size (without script): 8 amount
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_TXSIZE_OUTPUT = const(8)
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# size of a pubkey
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_TXSIZE_PUBKEY = const(33)
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# size of a DER signature (3 type bytes, 3 len bytes, 33 R, 32 S, 1 sighash
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_TXSIZE_SIGNATURE = const(72)
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# size of a multiscript without pubkey (1 M, 1 N, 1 checksig)
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_TXSIZE_MULTISIGSCRIPT = const(3)
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# size of a p2wpkh script (1 version, 1 push, 20 hash)
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_TXSIZE_WITNESSPKHASH = const(22)
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# size of a p2wsh script (1 version, 1 push, 32 hash)
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_TXSIZE_WITNESSSCRIPT = const(34)
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class TxWeightCalculator:
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def __init__(self, inputs_count: int, outputs_count: int):
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self.inputs_count = inputs_count
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self.counter = 4 * (
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_TXSIZE_HEADER
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+ _TXSIZE_FOOTER
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+ self.ser_length_size(inputs_count)
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+ self.ser_length_size(outputs_count))
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self.segwit = False
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def add_witness_header(self):
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if not self.segwit:
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self.counter += _TXSIZE_SEGWIT_OVERHEAD
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self.counter += self.ser_length_size(self.inputs_count)
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self.segwit = True
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def add_input(self, i: TxInputType):
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if i.multisig:
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multisig_script_size = (
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_TXSIZE_MULTISIGSCRIPT
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+ i.multisig.pubkeys_count * (1 + _TXSIZE_PUBKEY))
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input_script_size = (
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1 # the OP_FALSE bug in multisig
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+ i.multisig.m * (1 + _TXSIZE_SIGNATURE)
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+ self.op_push_size(multisig_script_size)
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+ multisig_script_size)
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else:
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input_script_size = 1 + _TXSIZE_SIGNATURE + 1 + _TXSIZE_PUBKEY
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self.counter += 4 * _TXSIZE_INPUT
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if (i.script_type == InputScriptType.SPENDADDRESS
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or i.script_type == InputScriptType.SPENDMULTISIG):
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input_script_size += self.ser_length_size(input_script_size)
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self.counter += 4 * input_script_size
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elif (i.script_type == InputScriptType.SPENDWITNESS
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or i.script_type == InputScriptType.SPENDP2SHWITNESS):
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self.add_witness_header()
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if i.script_type == InputScriptType.SPENDP2SHWITNESS:
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if i.multisig:
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self.counter += 4 * (2 + _TXSIZE_WITNESSSCRIPT)
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else:
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self.counter += 4 * (2 + _TXSIZE_WITNESSPKHASH)
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else:
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self.counter += 4 # empty
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self.counter += input_script_size # discounted witness
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def add_output(self, script: bytes):
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size = len(script) + self.ser_length_size(len(script))
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self.counter += 4 * (_TXSIZE_OUTPUT + size)
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def get_total(self) -> int:
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return self.counter
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@staticmethod
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def ser_length_size(length: int):
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if length < 253:
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return 1
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if length < 0x10000:
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return 3
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return 5
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@staticmethod
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def op_push_size(length: int):
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if length < 0x4c:
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return 1
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if length < 0x100:
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return 2
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if length < 0x10000:
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return 3
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return 5
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@ -41,7 +41,7 @@ class TestSignSegwitTxNativeP2WPKH(unittest.TestCase):
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address='2N4Q5FhU2497BryFfUgbqkAJE87aKHUhXMp',
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amount=5000000,
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script_type=OutputScriptType.PAYTOADDRESS,
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address_n=None, # @todo ask honza about sanitizing
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address_n=None,
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)
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out2 = TxOutputType(
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address='tb1q694ccp5qcc0udmfwgp692u2s2hjpq5h407urtu',
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131
tests/test_apps.wallet.txweight.py
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131
tests/test_apps.wallet.txweight.py
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@ -0,0 +1,131 @@
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from common import *
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from trezor.messages.TxOutputType import TxOutputType
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from trezor.messages import OutputScriptType
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from trezor.crypto import bip32, bip39
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from apps.common import coins
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from apps.wallet.sign_tx.tx_weight_calculator import *
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from apps.wallet.sign_tx import signing
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class TestCalculateTxWeight(unittest.TestCase):
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# pylint: disable=C0301
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def test_p2pkh_txweight(self):
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coin = coins.by_name('Bitcoin')
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seed = bip39.seed(' '.join(['all'] * 12), '')
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root = bip32.from_seed(seed, 'secp256k1')
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inp1 = TxInputType(address_n=[0], # 14LmW5k4ssUrtbAB4255zdqv3b4w1TuX9e
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# amount=390000,
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prev_hash=unhexlify('d5f65ee80147b4bcc70b75e4bbf2d7382021b871bd8867ef8fa525ef50864882'),
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prev_index=0,
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amount=None,
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script_type=InputScriptType.SPENDADDRESS,
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sequence=None,
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multisig=None)
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out1 = TxOutputType(address='1MJ2tj2ThBE62zXbBYA5ZaN3fdve5CPAz1',
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amount=390000 - 10000,
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script_type=OutputScriptType.PAYTOADDRESS,
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address_n=None,
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multisig=None)
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calculator = TxWeightCalculator(1, 1)
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calculator.add_input(inp1)
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calculator.add_output(signing.output_derive_script(out1, coin, root))
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serialized_tx = '010000000182488650ef25a58fef6788bd71b8212038d7f2bbe4750bc7bcb44701e85ef6d5000000006b4830450221009a0b7be0d4ed3146ee262b42202841834698bb3ee39c24e7437df208b8b7077102202b79ab1e7736219387dffe8d615bbdba87e11477104b867ef47afed1a5ede7810121023230848585885f63803a0a8aecdd6538792d5c539215c91698e315bf0253b43dffffffff0160cc0500000000001976a914de9b2a8da088824e8fe51debea566617d851537888ac00000000'
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tx_weight = len(serialized_tx) / 2 * 4 # non-segwit tx's weight is simple length*4
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self.assertEqual(calculator.get_total(), tx_weight)
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def test_p2wpkh_in_p2sh_txweight(self):
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coin = coins.by_name('Testnet')
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seed = bip39.seed(' '.join(['all'] * 12), '')
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root = bip32.from_seed(seed, 'secp256k1')
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inp1 = TxInputType(
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# 49'/1'/0'/1/0" - 2N1LGaGg836mqSQqiuUBLfcyGBhyZbremDX
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address_n=[49 | 0x80000000, 1 | 0x80000000, 0 | 0x80000000, 1, 0],
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amount=123456789,
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prev_hash=unhexlify('20912f98ea3ed849042efed0fdac8cb4fc301961c5988cba56902d8ffb61c337'),
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prev_index=0,
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script_type=InputScriptType.SPENDP2SHWITNESS,
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sequence=0xffffffff,
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multisig=None,
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)
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out1 = TxOutputType(
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address='mhRx1CeVfaayqRwq5zgRQmD7W5aWBfD5mC',
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amount=12300000,
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script_type=OutputScriptType.PAYTOADDRESS,
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address_n=None,
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multisig=None,
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)
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out2 = TxOutputType(
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address='2N1LGaGg836mqSQqiuUBLfcyGBhyZbremDX',
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script_type=OutputScriptType.PAYTOADDRESS,
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amount=123456789 - 11000 - 12300000,
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address_n=None,
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multisig=None,
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)
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calculator = TxWeightCalculator(1, 2)
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calculator.add_input(inp1)
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calculator.add_output(signing.output_derive_script(out1, coin, root))
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calculator.add_output(signing.output_derive_script(out2, coin, root))
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self.assertEqual(calculator.get_total(), 670)
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# non-segwit: header, inputs, outputs, locktime 4*(4+65+67+4) = 560
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# segwit: segwit header, witness count, 2x witness 1*(2+1+107) = 110
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# total 670
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def test_native_p2wpkh_txweight(self):
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coin = coins.by_name('Testnet')
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seed = bip39.seed(' '.join(['all'] * 12), '')
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root = bip32.from_seed(seed, 'secp256k1')
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inp1 = TxInputType(
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# 49'/1'/0'/0/0" - tb1qqzv60m9ajw8drqulta4ld4gfx0rdh82un5s65s
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address_n=[49 | 0x80000000, 1 | 0x80000000, 0 | 0x80000000, 0, 0],
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amount=12300000,
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prev_hash=unhexlify('09144602765ce3dd8f4329445b20e3684e948709c5cdcaf12da3bb079c99448a'),
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prev_index=0,
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script_type=InputScriptType.SPENDWITNESS,
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sequence=0xffffffff,
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multisig=None,
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)
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out1 = TxOutputType(
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address='2N4Q5FhU2497BryFfUgbqkAJE87aKHUhXMp',
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amount=5000000,
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script_type=OutputScriptType.PAYTOADDRESS,
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address_n=None,
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multisig=None,
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)
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out2 = TxOutputType(
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address='tb1q694ccp5qcc0udmfwgp692u2s2hjpq5h407urtu',
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script_type=OutputScriptType.PAYTOADDRESS,
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amount=12300000 - 11000 - 5000000,
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address_n=None,
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multisig=None,
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)
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calculator = TxWeightCalculator(1, 2)
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calculator.add_input(inp1)
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calculator.add_output(signing.output_derive_script(out1, coin, root))
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calculator.add_output(signing.output_derive_script(out2, coin, root))
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self.assertEqual(calculator.get_total(), 566)
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# non-segwit: header, inputs, outputs, locktime 4*(4+42+64+4) = 456
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# segwit: segwit header, witness count, 2x witness 1*(2+1+107) = 110
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# total 566
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if __name__ == '__main__':
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unittest.main()
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