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kevacoin/test/functional/test_framework/script.py

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#!/usr/bin/env python3
# Copyright (c) 2015-2016 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Functionality to build scripts, as well as SignatureHash().
This file is modified from python-bitcoinlib.
"""
from .mininode import CTransaction, CTxOut, sha256, hash256, uint256_from_str, ser_uint256, ser_string
from binascii import hexlify
import hashlib
import sys
bchr = chr
bord = ord
if sys.version > '3':
long = int
bchr = lambda x: bytes([x])
bord = lambda x: x
import struct
from .bignum import bn2vch
MAX_SCRIPT_ELEMENT_SIZE = 520
OPCODE_NAMES = {}
def hash160(s):
return hashlib.new('ripemd160', sha256(s)).digest()
_opcode_instances = []
class CScriptOp(int):
"""A single script opcode"""
__slots__ = []
@staticmethod
def encode_op_pushdata(d):
"""Encode a PUSHDATA op, returning bytes"""
if len(d) < 0x4c:
return b'' + bchr(len(d)) + d # OP_PUSHDATA
elif len(d) <= 0xff:
return b'\x4c' + bchr(len(d)) + d # OP_PUSHDATA1
elif len(d) <= 0xffff:
return b'\x4d' + struct.pack(b'<H', len(d)) + d # OP_PUSHDATA2
elif len(d) <= 0xffffffff:
return b'\x4e' + struct.pack(b'<I', len(d)) + d # OP_PUSHDATA4
else:
raise ValueError("Data too long to encode in a PUSHDATA op")
@staticmethod
def encode_op_n(n):
"""Encode a small integer op, returning an opcode"""
if not (0 <= n <= 16):
raise ValueError('Integer must be in range 0 <= n <= 16, got %d' % n)
if n == 0:
return OP_0
else:
return CScriptOp(OP_1 + n-1)
def decode_op_n(self):
"""Decode a small integer opcode, returning an integer"""
if self == OP_0:
return 0
if not (self == OP_0 or OP_1 <= self <= OP_16):
raise ValueError('op %r is not an OP_N' % self)
return int(self - OP_1+1)
def is_small_int(self):
"""Return true if the op pushes a small integer to the stack"""
if 0x51 <= self <= 0x60 or self == 0:
return True
else:
return False
def __str__(self):
return repr(self)
def __repr__(self):
if self in OPCODE_NAMES:
return OPCODE_NAMES[self]
else:
return 'CScriptOp(0x%x)' % self
def __new__(cls, n):
try:
return _opcode_instances[n]
except IndexError:
assert len(_opcode_instances) == n
_opcode_instances.append(super(CScriptOp, cls).__new__(cls, n))
return _opcode_instances[n]
# Populate opcode instance table
for n in range(0xff+1):
CScriptOp(n)
# push value
OP_0 = CScriptOp(0x00)
OP_FALSE = OP_0
OP_PUSHDATA1 = CScriptOp(0x4c)
OP_PUSHDATA2 = CScriptOp(0x4d)
OP_PUSHDATA4 = CScriptOp(0x4e)
OP_1NEGATE = CScriptOp(0x4f)
OP_RESERVED = CScriptOp(0x50)
OP_1 = CScriptOp(0x51)
OP_TRUE=OP_1
OP_2 = CScriptOp(0x52)
OP_3 = CScriptOp(0x53)
OP_4 = CScriptOp(0x54)
OP_5 = CScriptOp(0x55)
OP_6 = CScriptOp(0x56)
OP_7 = CScriptOp(0x57)
OP_8 = CScriptOp(0x58)
OP_9 = CScriptOp(0x59)
OP_10 = CScriptOp(0x5a)
OP_11 = CScriptOp(0x5b)
OP_12 = CScriptOp(0x5c)
OP_13 = CScriptOp(0x5d)
OP_14 = CScriptOp(0x5e)
OP_15 = CScriptOp(0x5f)
OP_16 = CScriptOp(0x60)
# control
OP_NOP = CScriptOp(0x61)
OP_VER = CScriptOp(0x62)
OP_IF = CScriptOp(0x63)
OP_NOTIF = CScriptOp(0x64)
OP_VERIF = CScriptOp(0x65)
OP_VERNOTIF = CScriptOp(0x66)
OP_ELSE = CScriptOp(0x67)
OP_ENDIF = CScriptOp(0x68)
OP_VERIFY = CScriptOp(0x69)
OP_RETURN = CScriptOp(0x6a)
# stack ops
OP_TOALTSTACK = CScriptOp(0x6b)
OP_FROMALTSTACK = CScriptOp(0x6c)
OP_2DROP = CScriptOp(0x6d)
OP_2DUP = CScriptOp(0x6e)
OP_3DUP = CScriptOp(0x6f)
OP_2OVER = CScriptOp(0x70)
OP_2ROT = CScriptOp(0x71)
OP_2SWAP = CScriptOp(0x72)
OP_IFDUP = CScriptOp(0x73)
OP_DEPTH = CScriptOp(0x74)
OP_DROP = CScriptOp(0x75)
OP_DUP = CScriptOp(0x76)
OP_NIP = CScriptOp(0x77)
OP_OVER = CScriptOp(0x78)
OP_PICK = CScriptOp(0x79)
OP_ROLL = CScriptOp(0x7a)
OP_ROT = CScriptOp(0x7b)
OP_SWAP = CScriptOp(0x7c)
OP_TUCK = CScriptOp(0x7d)
# splice ops
OP_CAT = CScriptOp(0x7e)
OP_SUBSTR = CScriptOp(0x7f)
OP_LEFT = CScriptOp(0x80)
OP_RIGHT = CScriptOp(0x81)
OP_SIZE = CScriptOp(0x82)
# bit logic
OP_INVERT = CScriptOp(0x83)
OP_AND = CScriptOp(0x84)
OP_OR = CScriptOp(0x85)
OP_XOR = CScriptOp(0x86)
OP_EQUAL = CScriptOp(0x87)
OP_EQUALVERIFY = CScriptOp(0x88)
OP_RESERVED1 = CScriptOp(0x89)
OP_RESERVED2 = CScriptOp(0x8a)
# numeric
OP_1ADD = CScriptOp(0x8b)
OP_1SUB = CScriptOp(0x8c)
OP_2MUL = CScriptOp(0x8d)
OP_2DIV = CScriptOp(0x8e)
OP_NEGATE = CScriptOp(0x8f)
OP_ABS = CScriptOp(0x90)
OP_NOT = CScriptOp(0x91)
OP_0NOTEQUAL = CScriptOp(0x92)
OP_ADD = CScriptOp(0x93)
OP_SUB = CScriptOp(0x94)
OP_MUL = CScriptOp(0x95)
OP_DIV = CScriptOp(0x96)
OP_MOD = CScriptOp(0x97)
OP_LSHIFT = CScriptOp(0x98)
OP_RSHIFT = CScriptOp(0x99)
OP_BOOLAND = CScriptOp(0x9a)
OP_BOOLOR = CScriptOp(0x9b)
OP_NUMEQUAL = CScriptOp(0x9c)
OP_NUMEQUALVERIFY = CScriptOp(0x9d)
OP_NUMNOTEQUAL = CScriptOp(0x9e)
OP_LESSTHAN = CScriptOp(0x9f)
OP_GREATERTHAN = CScriptOp(0xa0)
OP_LESSTHANOREQUAL = CScriptOp(0xa1)
OP_GREATERTHANOREQUAL = CScriptOp(0xa2)
OP_MIN = CScriptOp(0xa3)
OP_MAX = CScriptOp(0xa4)
OP_WITHIN = CScriptOp(0xa5)
# crypto
OP_RIPEMD160 = CScriptOp(0xa6)
OP_SHA1 = CScriptOp(0xa7)
OP_SHA256 = CScriptOp(0xa8)
OP_HASH160 = CScriptOp(0xa9)
OP_HASH256 = CScriptOp(0xaa)
OP_CODESEPARATOR = CScriptOp(0xab)
OP_CHECKSIG = CScriptOp(0xac)
OP_CHECKSIGVERIFY = CScriptOp(0xad)
OP_CHECKMULTISIG = CScriptOp(0xae)
OP_CHECKMULTISIGVERIFY = CScriptOp(0xaf)
# expansion
OP_NOP1 = CScriptOp(0xb0)
OP_CHECKLOCKTIMEVERIFY = CScriptOp(0xb1)
OP_CHECKSEQUENCEVERIFY = CScriptOp(0xb2)
OP_NOP4 = CScriptOp(0xb3)
OP_NOP5 = CScriptOp(0xb4)
OP_NOP6 = CScriptOp(0xb5)
OP_NOP7 = CScriptOp(0xb6)
OP_NOP8 = CScriptOp(0xb7)
OP_NOP9 = CScriptOp(0xb8)
OP_NOP10 = CScriptOp(0xb9)
# template matching params
OP_SMALLINTEGER = CScriptOp(0xfa)
OP_PUBKEYS = CScriptOp(0xfb)
OP_PUBKEYHASH = CScriptOp(0xfd)
OP_PUBKEY = CScriptOp(0xfe)
OP_INVALIDOPCODE = CScriptOp(0xff)
OPCODE_NAMES.update({
OP_0 : 'OP_0',
OP_PUSHDATA1 : 'OP_PUSHDATA1',
OP_PUSHDATA2 : 'OP_PUSHDATA2',
OP_PUSHDATA4 : 'OP_PUSHDATA4',
OP_1NEGATE : 'OP_1NEGATE',
OP_RESERVED : 'OP_RESERVED',
OP_1 : 'OP_1',
OP_2 : 'OP_2',
OP_3 : 'OP_3',
OP_4 : 'OP_4',
OP_5 : 'OP_5',
OP_6 : 'OP_6',
OP_7 : 'OP_7',
OP_8 : 'OP_8',
OP_9 : 'OP_9',
OP_10 : 'OP_10',
OP_11 : 'OP_11',
OP_12 : 'OP_12',
OP_13 : 'OP_13',
OP_14 : 'OP_14',
OP_15 : 'OP_15',
OP_16 : 'OP_16',
OP_NOP : 'OP_NOP',
OP_VER : 'OP_VER',
OP_IF : 'OP_IF',
OP_NOTIF : 'OP_NOTIF',
OP_VERIF : 'OP_VERIF',
OP_VERNOTIF : 'OP_VERNOTIF',
OP_ELSE : 'OP_ELSE',
OP_ENDIF : 'OP_ENDIF',
OP_VERIFY : 'OP_VERIFY',
OP_RETURN : 'OP_RETURN',
OP_TOALTSTACK : 'OP_TOALTSTACK',
OP_FROMALTSTACK : 'OP_FROMALTSTACK',
OP_2DROP : 'OP_2DROP',
OP_2DUP : 'OP_2DUP',
OP_3DUP : 'OP_3DUP',
OP_2OVER : 'OP_2OVER',
OP_2ROT : 'OP_2ROT',
OP_2SWAP : 'OP_2SWAP',
OP_IFDUP : 'OP_IFDUP',
OP_DEPTH : 'OP_DEPTH',
OP_DROP : 'OP_DROP',
OP_DUP : 'OP_DUP',
OP_NIP : 'OP_NIP',
OP_OVER : 'OP_OVER',
OP_PICK : 'OP_PICK',
OP_ROLL : 'OP_ROLL',
OP_ROT : 'OP_ROT',
OP_SWAP : 'OP_SWAP',
OP_TUCK : 'OP_TUCK',
OP_CAT : 'OP_CAT',
OP_SUBSTR : 'OP_SUBSTR',
OP_LEFT : 'OP_LEFT',
OP_RIGHT : 'OP_RIGHT',
OP_SIZE : 'OP_SIZE',
OP_INVERT : 'OP_INVERT',
OP_AND : 'OP_AND',
OP_OR : 'OP_OR',
OP_XOR : 'OP_XOR',
OP_EQUAL : 'OP_EQUAL',
OP_EQUALVERIFY : 'OP_EQUALVERIFY',
OP_RESERVED1 : 'OP_RESERVED1',
OP_RESERVED2 : 'OP_RESERVED2',
OP_1ADD : 'OP_1ADD',
OP_1SUB : 'OP_1SUB',
OP_2MUL : 'OP_2MUL',
OP_2DIV : 'OP_2DIV',
OP_NEGATE : 'OP_NEGATE',
OP_ABS : 'OP_ABS',
OP_NOT : 'OP_NOT',
OP_0NOTEQUAL : 'OP_0NOTEQUAL',
OP_ADD : 'OP_ADD',
OP_SUB : 'OP_SUB',
OP_MUL : 'OP_MUL',
OP_DIV : 'OP_DIV',
OP_MOD : 'OP_MOD',
OP_LSHIFT : 'OP_LSHIFT',
OP_RSHIFT : 'OP_RSHIFT',
OP_BOOLAND : 'OP_BOOLAND',
OP_BOOLOR : 'OP_BOOLOR',
OP_NUMEQUAL : 'OP_NUMEQUAL',
OP_NUMEQUALVERIFY : 'OP_NUMEQUALVERIFY',
OP_NUMNOTEQUAL : 'OP_NUMNOTEQUAL',
OP_LESSTHAN : 'OP_LESSTHAN',
OP_GREATERTHAN : 'OP_GREATERTHAN',
OP_LESSTHANOREQUAL : 'OP_LESSTHANOREQUAL',
OP_GREATERTHANOREQUAL : 'OP_GREATERTHANOREQUAL',
OP_MIN : 'OP_MIN',
OP_MAX : 'OP_MAX',
OP_WITHIN : 'OP_WITHIN',
OP_RIPEMD160 : 'OP_RIPEMD160',
OP_SHA1 : 'OP_SHA1',
OP_SHA256 : 'OP_SHA256',
OP_HASH160 : 'OP_HASH160',
OP_HASH256 : 'OP_HASH256',
OP_CODESEPARATOR : 'OP_CODESEPARATOR',
OP_CHECKSIG : 'OP_CHECKSIG',
OP_CHECKSIGVERIFY : 'OP_CHECKSIGVERIFY',
OP_CHECKMULTISIG : 'OP_CHECKMULTISIG',
OP_CHECKMULTISIGVERIFY : 'OP_CHECKMULTISIGVERIFY',
OP_NOP1 : 'OP_NOP1',
OP_CHECKLOCKTIMEVERIFY : 'OP_CHECKLOCKTIMEVERIFY',
OP_CHECKSEQUENCEVERIFY : 'OP_CHECKSEQUENCEVERIFY',
OP_NOP4 : 'OP_NOP4',
OP_NOP5 : 'OP_NOP5',
OP_NOP6 : 'OP_NOP6',
OP_NOP7 : 'OP_NOP7',
OP_NOP8 : 'OP_NOP8',
OP_NOP9 : 'OP_NOP9',
OP_NOP10 : 'OP_NOP10',
OP_SMALLINTEGER : 'OP_SMALLINTEGER',
OP_PUBKEYS : 'OP_PUBKEYS',
OP_PUBKEYHASH : 'OP_PUBKEYHASH',
OP_PUBKEY : 'OP_PUBKEY',
OP_INVALIDOPCODE : 'OP_INVALIDOPCODE',
})
class CScriptInvalidError(Exception):
"""Base class for CScript exceptions"""
pass
class CScriptTruncatedPushDataError(CScriptInvalidError):
"""Invalid pushdata due to truncation"""
def __init__(self, msg, data):
self.data = data
super(CScriptTruncatedPushDataError, self).__init__(msg)
# This is used, eg, for blockchain heights in coinbase scripts (bip34)
class CScriptNum():
def __init__(self, d=0):
self.value = d
@staticmethod
def encode(obj):
r = bytearray(0)
if obj.value == 0:
return bytes(r)
neg = obj.value < 0
absvalue = -obj.value if neg else obj.value
while (absvalue):
r.append(absvalue & 0xff)
absvalue >>= 8
if r[-1] & 0x80:
r.append(0x80 if neg else 0)
elif neg:
r[-1] |= 0x80
return bytes(bchr(len(r)) + r)
class CScript(bytes):
"""Serialized script
A bytes subclass, so you can use this directly whenever bytes are accepted.
Note that this means that indexing does *not* work - you'll get an index by
byte rather than opcode. This format was chosen for efficiency so that the
general case would not require creating a lot of little CScriptOP objects.
iter(script) however does iterate by opcode.
"""
@classmethod
def __coerce_instance(cls, other):
# Coerce other into bytes
if isinstance(other, CScriptOp):
other = bchr(other)
elif isinstance(other, CScriptNum):
if (other.value == 0):
other = bchr(CScriptOp(OP_0))
else:
other = CScriptNum.encode(other)
elif isinstance(other, int):
if 0 <= other <= 16:
other = bytes(bchr(CScriptOp.encode_op_n(other)))
elif other == -1:
other = bytes(bchr(OP_1NEGATE))
else:
other = CScriptOp.encode_op_pushdata(bn2vch(other))
elif isinstance(other, (bytes, bytearray)):
other = CScriptOp.encode_op_pushdata(other)
return other
def __add__(self, other):
# Do the coercion outside of the try block so that errors in it are
# noticed.
other = self.__coerce_instance(other)
try:
# bytes.__add__ always returns bytes instances unfortunately
return CScript(super(CScript, self).__add__(other))
except TypeError:
raise TypeError('Can not add a %r instance to a CScript' % other.__class__)
def join(self, iterable):
# join makes no sense for a CScript()
raise NotImplementedError
def __new__(cls, value=b''):
if isinstance(value, bytes) or isinstance(value, bytearray):
return super(CScript, cls).__new__(cls, value)
else:
def coerce_iterable(iterable):
for instance in iterable:
yield cls.__coerce_instance(instance)
# Annoyingly on both python2 and python3 bytes.join() always
# returns a bytes instance even when subclassed.
return super(CScript, cls).__new__(cls, b''.join(coerce_iterable(value)))
def raw_iter(self):
"""Raw iteration
Yields tuples of (opcode, data, sop_idx) so that the different possible
PUSHDATA encodings can be accurately distinguished, as well as
determining the exact opcode byte indexes. (sop_idx)
"""
i = 0
while i < len(self):
sop_idx = i
opcode = bord(self[i])
i += 1
if opcode > OP_PUSHDATA4:
yield (opcode, None, sop_idx)
else:
datasize = None
pushdata_type = None
if opcode < OP_PUSHDATA1:
pushdata_type = 'PUSHDATA(%d)' % opcode
datasize = opcode
elif opcode == OP_PUSHDATA1:
pushdata_type = 'PUSHDATA1'
if i >= len(self):
raise CScriptInvalidError('PUSHDATA1: missing data length')
datasize = bord(self[i])
i += 1
elif opcode == OP_PUSHDATA2:
pushdata_type = 'PUSHDATA2'
if i + 1 >= len(self):
raise CScriptInvalidError('PUSHDATA2: missing data length')
datasize = bord(self[i]) + (bord(self[i+1]) << 8)
i += 2
elif opcode == OP_PUSHDATA4:
pushdata_type = 'PUSHDATA4'
if i + 3 >= len(self):
raise CScriptInvalidError('PUSHDATA4: missing data length')
datasize = bord(self[i]) + (bord(self[i+1]) << 8) + (bord(self[i+2]) << 16) + (bord(self[i+3]) << 24)
i += 4
else:
assert False # shouldn't happen
data = bytes(self[i:i+datasize])
# Check for truncation
if len(data) < datasize:
raise CScriptTruncatedPushDataError('%s: truncated data' % pushdata_type, data)
i += datasize
yield (opcode, data, sop_idx)
def __iter__(self):
"""'Cooked' iteration
Returns either a CScriptOP instance, an integer, or bytes, as
appropriate.
See raw_iter() if you need to distinguish the different possible
PUSHDATA encodings.
"""
for (opcode, data, sop_idx) in self.raw_iter():
if data is not None:
yield data
else:
opcode = CScriptOp(opcode)
if opcode.is_small_int():
yield opcode.decode_op_n()
else:
yield CScriptOp(opcode)
def __repr__(self):
# For Python3 compatibility add b before strings so testcases don't
# need to change
def _repr(o):
if isinstance(o, bytes):
return b"x('%s')" % hexlify(o).decode('ascii')
else:
return repr(o)
ops = []
i = iter(self)
while True:
op = None
try:
op = _repr(next(i))
except CScriptTruncatedPushDataError as err:
op = '%s...<ERROR: %s>' % (_repr(err.data), err)
break
except CScriptInvalidError as err:
op = '<ERROR: %s>' % err
break
except StopIteration:
break
finally:
if op is not None:
ops.append(op)
return "CScript([%s])" % ', '.join(ops)
def GetSigOpCount(self, fAccurate):
"""Get the SigOp count.
fAccurate - Accurately count CHECKMULTISIG, see BIP16 for details.
Note that this is consensus-critical.
"""
n = 0
lastOpcode = OP_INVALIDOPCODE
for (opcode, data, sop_idx) in self.raw_iter():
if opcode in (OP_CHECKSIG, OP_CHECKSIGVERIFY):
n += 1
elif opcode in (OP_CHECKMULTISIG, OP_CHECKMULTISIGVERIFY):
if fAccurate and (OP_1 <= lastOpcode <= OP_16):
n += opcode.decode_op_n()
else:
n += 20
lastOpcode = opcode
return n
SIGHASH_ALL = 1
SIGHASH_NONE = 2
SIGHASH_SINGLE = 3
SIGHASH_ANYONECANPAY = 0x80
def FindAndDelete(script, sig):
"""Consensus critical, see FindAndDelete() in Satoshi codebase"""
r = b''
last_sop_idx = sop_idx = 0
skip = True
for (opcode, data, sop_idx) in script.raw_iter():
if not skip:
r += script[last_sop_idx:sop_idx]
last_sop_idx = sop_idx
if script[sop_idx:sop_idx + len(sig)] == sig:
skip = True
else:
skip = False
if not skip:
r += script[last_sop_idx:]
return CScript(r)
def SignatureHash(script, txTo, inIdx, hashtype):
"""Consensus-correct SignatureHash
Returns (hash, err) to precisely match the consensus-critical behavior of
the SIGHASH_SINGLE bug. (inIdx is *not* checked for validity)
"""
HASH_ONE = b'\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
if inIdx >= len(txTo.vin):
return (HASH_ONE, "inIdx %d out of range (%d)" % (inIdx, len(txTo.vin)))
txtmp = CTransaction(txTo)
for txin in txtmp.vin:
txin.scriptSig = b''
txtmp.vin[inIdx].scriptSig = FindAndDelete(script, CScript([OP_CODESEPARATOR]))
if (hashtype & 0x1f) == SIGHASH_NONE:
txtmp.vout = []
for i in range(len(txtmp.vin)):
if i != inIdx:
txtmp.vin[i].nSequence = 0
elif (hashtype & 0x1f) == SIGHASH_SINGLE:
outIdx = inIdx
if outIdx >= len(txtmp.vout):
return (HASH_ONE, "outIdx %d out of range (%d)" % (outIdx, len(txtmp.vout)))
tmp = txtmp.vout[outIdx]
txtmp.vout = []
for i in range(outIdx):
txtmp.vout.append(CTxOut(-1))
txtmp.vout.append(tmp)
for i in range(len(txtmp.vin)):
if i != inIdx:
txtmp.vin[i].nSequence = 0
if hashtype & SIGHASH_ANYONECANPAY:
tmp = txtmp.vin[inIdx]
txtmp.vin = []
txtmp.vin.append(tmp)
s = txtmp.serialize()
s += struct.pack(b"<I", hashtype)
hash = hash256(s)
return (hash, None)
# TODO: Allow cached hashPrevouts/hashSequence/hashOutputs to be provided.
# Performance optimization probably not necessary for python tests, however.
# Note that this corresponds to sigversion == 1 in EvalScript, which is used
# for version 0 witnesses.
def SegwitVersion1SignatureHash(script, txTo, inIdx, hashtype, amount):
hashPrevouts = 0
hashSequence = 0
hashOutputs = 0
if not (hashtype & SIGHASH_ANYONECANPAY):
serialize_prevouts = bytes()
for i in txTo.vin:
serialize_prevouts += i.prevout.serialize()
hashPrevouts = uint256_from_str(hash256(serialize_prevouts))
if (not (hashtype & SIGHASH_ANYONECANPAY) and (hashtype & 0x1f) != SIGHASH_SINGLE and (hashtype & 0x1f) != SIGHASH_NONE):
serialize_sequence = bytes()
for i in txTo.vin:
serialize_sequence += struct.pack("<I", i.nSequence)
hashSequence = uint256_from_str(hash256(serialize_sequence))
if ((hashtype & 0x1f) != SIGHASH_SINGLE and (hashtype & 0x1f) != SIGHASH_NONE):
serialize_outputs = bytes()
for o in txTo.vout:
serialize_outputs += o.serialize()
hashOutputs = uint256_from_str(hash256(serialize_outputs))
elif ((hashtype & 0x1f) == SIGHASH_SINGLE and inIdx < len(txTo.vout)):
serialize_outputs = txTo.vout[inIdx].serialize()
hashOutputs = uint256_from_str(hash256(serialize_outputs))
ss = bytes()
ss += struct.pack("<i", txTo.nVersion)
ss += ser_uint256(hashPrevouts)
ss += ser_uint256(hashSequence)
ss += txTo.vin[inIdx].prevout.serialize()
ss += ser_string(script)
ss += struct.pack("<q", amount)
ss += struct.pack("<I", txTo.vin[inIdx].nSequence)
ss += ser_uint256(hashOutputs)
ss += struct.pack("<i", txTo.nLockTime)
ss += struct.pack("<I", hashtype)
return hash256(ss)