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#!/usr/bin/env python3
# Copyright (c) 2019-2022 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Useful Script constants and utils."""
import unittest
from test_framework.script import (
CScript,
OP_0,
OP_15,
OP_16,
OP_CHECKMULTISIG,
OP_CHECKSIG,
OP_DUP,
OP_EQUAL,
OP_EQUALVERIFY,
OP_HASH160,
OP_RETURN,
hash160,
sha256,
)
# To prevent a "tx-size-small" policy rule error, a transaction has to have a
# non-witness size of at least 65 bytes (MIN_STANDARD_TX_NONWITNESS_SIZE in
# src/policy/policy.h). Considering a Tx with the smallest possible single
# input (blank, empty scriptSig), and with an output omitting the scriptPubKey,
# we get to a minimum size of 60 bytes:
#
# Tx Skeleton: 4 [Version] + 1 [InCount] + 1 [OutCount] + 4 [LockTime] = 10 bytes
# Blank Input: 32 [PrevTxHash] + 4 [Index] + 1 [scriptSigLen] + 4 [SeqNo] = 41 bytes
# Output: 8 [Amount] + 1 [scriptPubKeyLen] = 9 bytes
#
# Hence, the scriptPubKey of the single output has to have a size of at
# least 5 bytes.
MIN_STANDARD_TX_NONWITNESS_SIZE = 65
MIN_PADDING = MIN_STANDARD_TX_NONWITNESS_SIZE - 10 - 41 - 9
assert MIN_PADDING == 5
# This script cannot be spent, allowing dust output values under
# standardness checks
DUMMY_MIN_OP_RETURN_SCRIPT = CScript([OP_RETURN] + ([OP_0] * (MIN_PADDING - 1)))
assert len(DUMMY_MIN_OP_RETURN_SCRIPT) == MIN_PADDING
def key_to_p2pk_script(key):
key = check_key(key)
return CScript([key, OP_CHECKSIG])
def keys_to_multisig_script(keys, *, k=None):
n = len(keys)
if k is None: # n-of-n multisig by default
k = n
assert k <= n
checked_keys = [check_key(key) for key in keys]
return CScript([k] + checked_keys + [n, OP_CHECKMULTISIG])
def keyhash_to_p2pkh_script(hash):
assert len(hash) == 20
return CScript([OP_DUP, OP_HASH160, hash, OP_EQUALVERIFY, OP_CHECKSIG])
def scripthash_to_p2sh_script(hash):
assert len(hash) == 20
return CScript([OP_HASH160, hash, OP_EQUAL])
def key_to_p2pkh_script(key):
key = check_key(key)
return keyhash_to_p2pkh_script(hash160(key))
def script_to_p2sh_script(script):
script = check_script(script)
return scripthash_to_p2sh_script(hash160(script))
def key_to_p2sh_p2wpkh_script(key):
key = check_key(key)
p2shscript = CScript([OP_0, hash160(key)])
return script_to_p2sh_script(p2shscript)
def program_to_witness_script(version, program):
if isinstance(program, str):
program = bytes.fromhex(program)
assert 0 <= version <= 16
assert 2 <= len(program) <= 40
assert version > 0 or len(program) in [20, 32]
return CScript([version, program])
def script_to_p2wsh_script(script):
script = check_script(script)
return program_to_witness_script(0, sha256(script))
def key_to_p2wpkh_script(key):
key = check_key(key)
return program_to_witness_script(0, hash160(key))
def script_to_p2sh_p2wsh_script(script):
script = check_script(script)
p2shscript = CScript([OP_0, sha256(script)])
return script_to_p2sh_script(p2shscript)
def output_key_to_p2tr_script(key):
assert len(key) == 32
return program_to_witness_script(1, key)
def check_key(key):
if isinstance(key, str):
key = bytes.fromhex(key) # Assuming this is hex string
if isinstance(key, bytes) and (len(key) == 33 or len(key) == 65):
return key
assert False
def check_script(script):
if isinstance(script, str):
script = bytes.fromhex(script) # Assuming this is hex string
if isinstance(script, bytes) or isinstance(script, CScript):
return script
assert False
class TestFrameworkScriptUtil(unittest.TestCase):
def test_multisig(self):
fake_pubkey = bytes([0]*33)
# check correct encoding of P2MS script with n,k <= 16
normal_ms_script = keys_to_multisig_script([fake_pubkey]*16, k=15)
self.assertEqual(len(normal_ms_script), 1 + 16*34 + 1 + 1)
self.assertTrue(normal_ms_script.startswith(bytes([OP_15])))
self.assertTrue(normal_ms_script.endswith(bytes([OP_16, OP_CHECKMULTISIG])))
# check correct encoding of P2MS script with n,k > 16
max_ms_script = keys_to_multisig_script([fake_pubkey]*20, k=19)
self.assertEqual(len(max_ms_script), 2 + 20*34 + 2 + 1)
self.assertTrue(max_ms_script.startswith(bytes([1, 19]))) # using OP_PUSH1
self.assertTrue(max_ms_script.endswith(bytes([1, 20, OP_CHECKMULTISIG])))
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