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Martino Salvettidgpv
Martino Salvetti
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dgpv
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Add Bech32 encoding/decoding; add CBech32Data
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‎bitcoin/bech32.py‎

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# Copyright (C) 2017 The python-bitcoinlib developers
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#
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# This file is part of python-bitcoinlib.
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#
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# It is subject to the license terms in the LICENSE file found in the top-level
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# directory of this distribution.
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#
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# No part of python-bitcoinlib, including this file, may be copied, modified,
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# propagated, or distributed except according to the terms contained in the
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# LICENSE file.
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"""Bech32 encoding and decoding"""
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import sys
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_bchr = chr
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_bord = ord
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if sys.version > '3':
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long = int
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_bchr = lambda x: bytes([x])
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_bord = lambda x: x
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from bitcoin.segwit_addr import encode, decode
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class Bech32Error(Exception):
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pass
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class Bech32ChecksumError(Bech32Error):
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pass
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class CBech32Data(bytes):
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"""Bech32-encoded data
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Includes a witver and checksum.
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"""
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def __new__(cls, s):
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"""from bech32 addr to """
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witver, data = decode('bc', s) # TODO: bc from bitcoin.params
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if witver is None and data is None:
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raise Bech32Error('Bech32 decoding error')
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return cls.from_bytes(witver, data)
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def __init__(self, s):
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"""Initialize from bech32-encoded string
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Note: subclasses put your initialization routines here, but ignore the
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argument - that's handled by __new__(), and .from_bytes() will call
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__init__() with None in place of the string.
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"""
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@classmethod
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def from_bytes(cls, witver, witprog):
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"""Instantiate from witver and data"""
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if not (0 <= witver <= 16):
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raise ValueError('witver must be in range 0 to 16 inclusive; got %d' % witver)
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self = bytes.__new__(cls, witprog)
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self.witver = witver
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return self
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def to_bytes(self):
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"""Convert to bytes instance
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Note that it's the data represented that is converted; the checkum and
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witver is not included.
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"""
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return b'' + self
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def __str__(self):
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"""Convert to string"""
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return encode('bc', self.witver, self) # TODO: bc from bitcoin.params
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def __repr__(self):
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return '%s(%r)' % (self.__class__.__name__, str(self))

‎bitcoin/segwit_addr.py‎

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# Copyright (c) 2017 Pieter Wuille
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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"""Reference implementation for Bech32 and segwit addresses."""
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CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l"
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def bech32_polymod(values):
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"""Internal function that computes the Bech32 checksum."""
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generator = [0x3b6a57b2, 0x26508e6d, 0x1ea119fa, 0x3d4233dd, 0x2a1462b3]
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chk = 1
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for value in values:
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top = chk >> 25
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chk = (chk & 0x1ffffff) << 5 ^ value
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for i in range(5):
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chk ^= generator[i] if ((top >> i) & 1) else 0
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return chk
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def bech32_hrp_expand(hrp):
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"""Expand the HRP into values for checksum computation."""
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return [ord(x) >> 5 for x in hrp] + [0] + [ord(x) & 31 for x in hrp]
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def bech32_verify_checksum(hrp, data):
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"""Verify a checksum given HRP and converted data characters."""
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return bech32_polymod(bech32_hrp_expand(hrp) + data) == 1
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def bech32_create_checksum(hrp, data):
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"""Compute the checksum values given HRP and data."""
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values = bech32_hrp_expand(hrp) + data
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polymod = bech32_polymod(values + [0, 0, 0, 0, 0, 0]) ^ 1
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return [(polymod >> 5 * (5 - i)) & 31 for i in range(6)]
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def bech32_encode(hrp, data):
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"""Compute a Bech32 string given HRP and data values."""
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combined = data + bech32_create_checksum(hrp, data)
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return hrp + '1' + ''.join([CHARSET[d] for d in combined])
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def bech32_decode(bech):
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"""Validate a Bech32 string, and determine HRP and data."""
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if ((any(ord(x) < 33 or ord(x) > 126 for x in bech)) or
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(bech.lower() != bech and bech.upper() != bech)):
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return (None, None)
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bech = bech.lower()
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pos = bech.rfind('1')
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if pos < 1 or pos + 7 > len(bech) or len(bech) > 90:
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return (None, None)
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if not all(x in CHARSET for x in bech[pos+1:]):
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return (None, None)
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hrp = bech[:pos]
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data = [CHARSET.find(x) for x in bech[pos+1:]]
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if not bech32_verify_checksum(hrp, data):
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return (None, None)
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return (hrp, data[:-6])
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def convertbits(data, frombits, tobits, pad=True):
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"""General power-of-2 base conversion."""
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acc = 0
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bits = 0
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ret = []
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maxv = (1 << tobits) - 1
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max_acc = (1 << (frombits + tobits - 1)) - 1
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for value in data:
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if value < 0 or (value >> frombits):
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return None
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acc = ((acc << frombits) | value) & max_acc
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bits += frombits
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while bits >= tobits:
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bits -= tobits
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ret.append((acc >> bits) & maxv)
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if pad:
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if bits:
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ret.append((acc << (tobits - bits)) & maxv)
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elif bits >= frombits or ((acc << (tobits - bits)) & maxv):
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return None
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return ret
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def decode(hrp, addr):
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"""Decode a segwit address."""
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hrpgot, data = bech32_decode(addr)
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if hrpgot != hrp:
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return (None, None)
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decoded = convertbits(data[1:], 5, 8, False)
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if decoded is None or len(decoded) < 2 or len(decoded) > 40:
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return (None, None)
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if data[0] > 16:
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return (None, None)
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if data[0] == 0 and len(decoded) != 20 and len(decoded) != 32:
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return (None, None)
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return (data[0], decoded)
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def encode(hrp, witver, witprog):
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"""Encode a segwit address."""
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ret = bech32_encode(hrp, [witver] + convertbits(witprog, 8, 5))
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if decode(hrp, ret) == (None, None):
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return None
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return ret

‎bitcoin/tests/data/bech32_encode_decode.json‎

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[
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["0014751e76e8199196d454941c45d1b3a323f1433bd6", "BC1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KV8F3T4"],
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["00201863143c14c5166804bd19203356da136c985678cd4d27a1b8c6329604903262", "tb1qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3q0sl5k7"],
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["5128751e76e8199196d454941c45d1b3a323f1433bd6751e76e8199196d454941c45d1b3a323f1433bd6", "bc1pw508d6qejxtdg4y5r3zarvary0c5xw7kw508d6qejxtdg4y5r3zarvary0c5xw7k7grplx"],
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["6002751e", "BC1SW50QA3JX3S"],
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["5210751e76e8199196d454941c45d1b3a323", "bc1zw508d6qejxtdg4y5r3zarvaryvg6kdaj"],
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["0020000000c4a5cad46221b2a187905e5266362b99d5e91c6ce24d165dab93e86433", "tb1qqqqqp399et2xygdj5xreqhjjvcmzhxw4aywxecjdzew6hylgvsesrxh6hy"]
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]

‎bitcoin/tests/data/bech32_invalid.json‎

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[
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["tc1qw508d6qejxtdg4y5r3zarvary0c5xw7kg3g4ty", "Invalid human-readable part"],
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["bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t5", "Invalid checksum"],
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["BC13W508D6QEJXTDG4Y5R3ZARVARY0C5XW7KN40WF2", "Invalid witness version"],
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["bc1rw5uspcuh", "Invalid program length"],
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["bc10w508d6qejxtdg4y5r3zarvary0c5xw7kw508d6qejxtdg4y5r3zarvary0c5xw7kw5rljs90", "Invalid program length"],
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["BC1QR508D6QEJXTDG4Y5R3ZARVARYV98GJ9P", "Invalid program length for witness version 0 (per BIP141)"],
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["tb1qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3q0sL5k7", "Mixed case"],
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["bc1zw508d6qejxtdg4y5r3zarvaryvqyzf3du", "zero padding of more than 4 bits"],
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["tb1qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3pjxtptv", "Non-zero padding in 8-to-5 conversion"],
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["bc1gmk9yu", "Empty data section"]
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]

‎bitcoin/tests/test_bech32.py‎

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# Copyright (C) 2013-2014 The python-bitcoinlib developers
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#
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# This file is part of python-bitcoinlib.
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#
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# It is subject to the license terms in the LICENSE file found in the top-level
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# directory of this distribution.
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#
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# No part of python-bitcoinlib, including this file, may be copied, modified,
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# propagated, or distributed except according to the terms contained in the
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# LICENSE file.
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from __future__ import absolute_import, division, print_function, unicode_literals
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import json
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import os
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import unittest
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from binascii import unhexlify
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from bitcoin.core.script import CScript, OP_0, OP_1, OP_16
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from bitcoin.bech32 import *
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def load_test_vectors(name):
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with open(os.path.dirname(__file__) + '/data/' + name, 'r') as fd:
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for testcase in json.load(fd):
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yield testcase
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def to_scriptPubKey(witver, witprog):
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"""Decoded bech32 address to script"""
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return CScript([witver]) + CScript(bytes(witprog))
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class Test_bech32(unittest.TestCase):
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def op_decode(self, witver):
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"""OP encoding to int"""
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if witver == OP_0:
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return 0
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if OP_1 <= witver <= OP_16:
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return witver - OP_1 + 1
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self.fail('Wrong witver: %d' % witver)
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def test_encode_decode(self):
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for exp_bin, exp_bech32 in load_test_vectors('bech32_encode_decode.json'):
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exp_bin = unhexlify(exp_bin.encode('utf8'))
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witver = self.op_decode(exp_bin[0])
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hrp = exp_bech32[:exp_bech32.rindex('1')].lower()
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self.assertEqual(exp_bin[1], len(exp_bin[2:]))
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act_bech32 = encode(hrp, witver, exp_bin[2:])
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act_bin = decode(hrp, exp_bech32)
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self.assertEqual(act_bech32.lower(), exp_bech32.lower())
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self.assertEqual(to_scriptPubKey(*act_bin), exp_bin)
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class Test_CBech32Data(unittest.TestCase):
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def test_from_data(self):
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b = CBech32Data.from_bytes(0, unhexlify('751e76e8199196d454941c45d1b3a323f1433bd6'))
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self.assertEqual(b.witver, 0)
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self.assertEqual(str(b).upper(), 'BC1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KV8F3T4')
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def test_invalid_bech32_exception(self):
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for invalid, _ in load_test_vectors("bech32_invalid.json"):
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msg = '%r should have raised Bech32Error but did not' % invalid
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with self.assertRaises(Bech32Error, msg=msg):
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CBech32Data(invalid)

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