dragonchain/dragonchain

# Copyright (c) 2017 Pieter Wuille
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

"""Reference implementation for Bech32 and segwit addresses.
From https://github.com/sammchardy/python-binance-chain/tree/master/binance_chain/utils
originally
From https://github.com/sipa/bech32
"""

import array
import hashlib

CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l"


def bech32_polymod(values):
    """Internal function that computes the Bech32 checksum."""
    generator = [0x3B6A57B2, 0x26508E6D, 0x1EA119FA, 0x3D4233DD, 0x2A1462B3]
    chk = 1
    for value in values:
        top = chk >> 25
        chk = (chk & 0x1FFFFFF) << 5 ^ value
        for i in range(5):
            chk ^= generator[i] if ((top >> i) & 1) else 0
    return chk


def bech32_hrp_expand(hrp):
    """Expand the HRP into values for checksum computation."""
    return [ord(x) >> 5 for x in hrp] + [0] + [ord(x) & 31 for x in hrp]


def bech32_verify_checksum(hrp, data):
    """Verify a checksum given HRP and converted data characters."""
    return bech32_polymod(bech32_hrp_expand(hrp) + data) == 1


def bech32_create_checksum(hrp, data):
    """Compute the checksum values given HRP and data."""
    values = bech32_hrp_expand(hrp) + data
    polymod = bech32_polymod(values + [0, 0, 0, 0, 0, 0]) ^ 1
    return [(polymod >> 5 * (5 - i)) & 31 for i in range(6)]


def bech32_encode(hrp, data):
    """Compute a Bech32 string given HRP and data values."""
    combined = data + bech32_create_checksum(hrp, data)
    return hrp + "1" + "".join([CHARSET[d] for d in combined])


def bech32_decode(bech):
    """Validate a Bech32 string, and determine HRP and data."""
    if (any(ord(x) < 33 or ord(x) > 126 for x in bech)) or (bech.lower() != bech and bech.upper() != bech):
        return None, None
    bech = bech.lower()
    pos = bech.rfind("1")
    if pos < 1 or pos + 7 > len(bech) or len(bech) > 90:
        return None, None
    if not all(x in CHARSET for x in bech[pos + 1 :]):
        return None, None
    hrp = bech[:pos]
    data = [CHARSET.find(x) for x in bech[pos + 1 :]]
    if not bech32_verify_checksum(hrp, data):
        return None, None
    return hrp, data[:-6]


def convertbits(data, frombits, tobits, pad=True):
    """General power-of-2 base conversion."""
    acc = 0
    bits = 0
    ret = []
    maxv = (1 << tobits) - 1
    max_acc = (1 << (frombits + tobits - 1)) - 1
    for value in data:
        if value < 0 or (value >> frombits):
            return None
        acc = ((acc << frombits) | value) & max_acc
        bits += frombits
        while bits >= tobits:
            bits -= tobits
            ret.append((acc >> bits) & maxv)
    if pad:
        if bits:
            ret.append((acc << (tobits - bits)) & maxv)
    elif bits >= frombits or ((acc << (tobits - bits)) & maxv):
        return None
    return ret


def encode(hrp, witprog):
    """Encode a segwit address."""
    return bech32_encode(hrp, convertbits(witprog, 8, 5))


def decode_address(address):
    hrp, data = bech32_decode(address)
    if hrp is None:
        return None

    bits = convertbits(data, 5, 8, False)
    return array.array("B", bits).tobytes()


def address_from_public_key(public_key, hrp="tbnb"):
    s = hashlib.new("sha256", public_key).digest()
    r = hashlib.new("ripemd160", s).digest()

    return encode(hrp, r)