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import hashlib | |
from binascii import hexlify | |
def sha256(payload: bytes) -> bytes: | |
return hashlib.sha256(payload).digest() | |
def double_sha256(payload: bytes) -> bytes: | |
return sha256(sha256(payload)) | |
def double_sha256_checksum(payload: bytes) -> bytes: | |
return double_sha256(payload)[:4] | |
def ripemd160_sha256(payload: bytes) -> bytes: | |
return hashlib.new('ripemd160', sha256(payload)).digest() | |
BASE58_ALPHABET = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz' | |
def b58_encode(payload: bytes) -> str: | |
pad = 0 | |
for byte in payload: | |
if byte == 0: | |
pad += 1 | |
else: | |
break | |
prefix = '1' * pad | |
num = int.from_bytes(payload, 'big') | |
result = '' | |
while num > 0: | |
num, remaining = divmod(num, 58) | |
result = BASE58_ALPHABET[remaining] + result | |
return prefix + result | |
def b58check_encode(payload: bytes) -> str: | |
return b58_encode(payload + double_sha256_checksum(payload)) | |
def int_to_bytes(num: int, byteorder: str = 'big') -> bytes: | |
"""Converts an int to the least number of bytes as possible.""" | |
return num.to_bytes((num.bit_length() + 7) // 8, byteorder) | |
def b58_decode(encoded: str) -> bytes: | |
pad = 0 | |
for char in encoded: | |
if char == '1': | |
pad += 1 | |
else: | |
break | |
prefix = b'\x00' * pad | |
num = 0 | |
try: | |
for char in encoded: | |
num *= 58 | |
num += BASE58_ALPHABET.index(char) | |
except KeyError: | |
raise ValueError(f'Invalid base58 encoded "{encoded}"') | |
return prefix + int_to_bytes(num) | |
def b58check_decode(encoded: str) -> bytes: | |
decoded = b58_decode(encoded) | |
payload = decoded[:-4] | |
decoded_checksum = decoded[-4:] | |
hash_checksum = double_sha256_checksum(payload) | |
if decoded_checksum != hash_checksum: | |
raise ValueError(f'Decoded checksum {hexlify(decoded_checksum)} from "{hexlify(decoded)}" is not equal to hash checksum {hexlify(hash_checksum)}') | |
return payload |
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