184 lines
4.7 KiB
Python
184 lines
4.7 KiB
Python
# Copyright (c) 2016-2017, Neil Booth
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# Copyright (c) 2018, LBRY Inc.
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#
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# All rights reserved.
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#
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# See the file "LICENCE" for information about the copyright
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# and warranty status of this software.
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""" Cryptography hash functions and related classes. """
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import six
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import aes
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import base64
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import hashlib
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import hmac
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import struct
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from binascii import hexlify, unhexlify
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from .util import bytes_to_int, int_to_bytes
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from .constants import CHAINS, MAIN_CHAIN
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_sha256 = hashlib.sha256
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_sha512 = hashlib.sha512
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_new_hash = hashlib.new
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_new_hmac = hmac.new
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def sha256(x):
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""" Simple wrapper of hashlib sha256. """
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return _sha256(x).digest()
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def sha512(x):
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""" Simple wrapper of hashlib sha512. """
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return _sha512(x).digest()
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def ripemd160(x):
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""" Simple wrapper of hashlib ripemd160. """
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h = _new_hash('ripemd160')
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h.update(x)
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return h.digest()
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def pow_hash(x):
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r = sha512(double_sha256(x))
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r1 = ripemd160(r[:len(r) / 2])
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r2 = ripemd160(r[len(r) / 2:])
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r3 = double_sha256(r1 + r2)
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return r3
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def double_sha256(x):
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""" SHA-256 of SHA-256, as used extensively in bitcoin. """
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return sha256(sha256(x))
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def hmac_sha512(key, msg):
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""" Use SHA-512 to provide an HMAC. """
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return _new_hmac(key, msg, _sha512).digest()
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def hash160(x):
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""" RIPEMD-160 of SHA-256.
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Used to make bitcoin addresses from pubkeys. """
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return ripemd160(sha256(x))
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def hash_to_hex_str(x):
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""" Convert a big-endian binary hash to displayed hex string.
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Display form of a binary hash is reversed and converted to hex. """
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return hexlify(reversed(x))
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def hex_str_to_hash(x):
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""" Convert a displayed hex string to a binary hash. """
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return reversed(unhexlify(x))
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def public_key_to_address(public_key, chain=MAIN_CHAIN):
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return hash160_to_address(hash160(public_key), chain)
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def hash160_to_address(h160, chain=MAIN_CHAIN):
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prefix = CHAINS[chain]['pubkey_address_prefix']
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raw_address = six.int2byte(prefix) + h160
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return Base58.encode(raw_address + double_sha256(raw_address)[0:4])
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def address_to_hash_160(address):
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bytes = Base58.decode(address)
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prefix, pubkey_bytes, addr_checksum = bytes[0], bytes[1:21], bytes[21:]
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return pubkey_bytes
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def claim_id_hash(txid, n):
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return hash160(txid + struct.pack('>I', n))
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def aes_encrypt(secret, value):
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return base64.b64encode(aes.encryptData(secret, value.encode('utf8')))
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def aes_decrypt(secret, value):
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return aes.decryptData(secret, base64.b64decode(value)).decode('utf8')
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class Base58Error(Exception):
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""" Exception used for Base58 errors. """
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class Base58(object):
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""" Class providing base 58 functionality. """
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chars = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
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assert len(chars) == 58
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cmap = {c: n for n, c in enumerate(chars)}
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@staticmethod
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def char_value(c):
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val = Base58.cmap.get(c)
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if val is None:
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raise Base58Error('invalid base 58 character "{}"'.format(c))
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return val
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@staticmethod
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def decode(txt):
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""" Decodes txt into a big-endian bytearray. """
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if not isinstance(txt, str):
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raise TypeError('a string is required')
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if not txt:
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raise Base58Error('string cannot be empty')
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value = 0
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for c in txt:
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value = value * 58 + Base58.char_value(c)
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result = int_to_bytes(value)
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# Prepend leading zero bytes if necessary
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count = 0
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for c in txt:
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if c != '1':
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break
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count += 1
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if count:
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result = six.int2byte(0)*count + result
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return result
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@staticmethod
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def encode(be_bytes):
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"""Converts a big-endian bytearray into a base58 string."""
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value = bytes_to_int(be_bytes)
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txt = ''
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while value:
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value, mod = divmod(value, 58)
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txt += Base58.chars[mod]
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for byte in be_bytes:
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if byte != 0:
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break
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txt += '1'
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return txt[::-1]
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@staticmethod
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def decode_check(txt, hash_fn=double_sha256):
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""" Decodes a Base58Check-encoded string to a payload. The version prefixes it. """
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be_bytes = Base58.decode(txt)
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result, check = be_bytes[:-4], be_bytes[-4:]
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if check != hash_fn(result)[:4]:
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raise Base58Error('invalid base 58 checksum for {}'.format(txt))
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return result
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@staticmethod
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def encode_check(payload, hash_fn=double_sha256):
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""" Encodes a payload bytearray (which includes the version byte(s))
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into a Base58Check string."""
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be_bytes = payload + hash_fn(payload)[:4]
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return Base58.encode(be_bytes)
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