lbry-sdk/lbry/wallet/server/hash.py

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# Copyright (c) 2016-2017, Neil Booth
#
# All rights reserved.
#
# The MIT License (MIT)
#
# 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.
"""Cryptograph hash functions and related classes."""
import hashlib
import hmac
from lbry.wallet.server.util import bytes_to_int, int_to_bytes, hex_to_bytes
_sha256 = hashlib.sha256
_sha512 = hashlib.sha512
_new_hash = hashlib.new
_new_hmac = hmac.new
HASHX_LEN = 11
def sha256(x):
"""Simple wrapper of hashlib sha256."""
return _sha256(x).digest()
def ripemd160(x):
"""Simple wrapper of hashlib ripemd160."""
h = _new_hash('ripemd160')
h.update(x)
return h.digest()
def double_sha256(x):
"""SHA-256 of SHA-256, as used extensively in bitcoin."""
return sha256(sha256(x))
def hmac_sha512(key, msg):
"""Use SHA-512 to provide an HMAC."""
return _new_hmac(key, msg, _sha512).digest()
def hash160(x):
"""RIPEMD-160 of SHA-256.
Used to make bitcoin addresses from pubkeys."""
return ripemd160(sha256(x))
def hash_to_hex_str(x):
"""Convert a big-endian binary hash to displayed hex string.
Display form of a binary hash is reversed and converted to hex.
"""
return bytes(reversed(x)).hex()
def hex_str_to_hash(x):
"""Convert a displayed hex string to a binary hash."""
return bytes(reversed(hex_to_bytes(x)))
class Base58Error(Exception):
"""Exception used for Base58 errors."""
2018-11-26 02:51:41 +01:00
class Base58:
"""Class providing base 58 functionality."""
chars = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
assert len(chars) == 58
cmap = {c: n for n, c in enumerate(chars)}
@staticmethod
def char_value(c):
val = Base58.cmap.get(c)
if val is None:
raise Base58Error(f'invalid base 58 character "{c}"')
return val
@staticmethod
def decode(txt):
"""Decodes txt into a big-endian bytearray."""
if not isinstance(txt, str):
raise TypeError('a string is required')
if not txt:
raise Base58Error('string cannot be empty')
value = 0
for c in txt:
value = value * 58 + Base58.char_value(c)
result = int_to_bytes(value)
# Prepend leading zero bytes if necessary
count = 0
for c in txt:
if c != '1':
break
count += 1
if count:
result = bytes(count) + result
return result
@staticmethod
def encode(be_bytes):
"""Converts a big-endian bytearray into a base58 string."""
value = bytes_to_int(be_bytes)
txt = ''
while value:
value, mod = divmod(value, 58)
txt += Base58.chars[mod]
for byte in be_bytes:
if byte != 0:
break
txt += '1'
return txt[::-1]
@staticmethod
def decode_check(txt, *, hash_fn=double_sha256):
"""Decodes a Base58Check-encoded string to a payload. The version
prefixes it."""
be_bytes = Base58.decode(txt)
result, check = be_bytes[:-4], be_bytes[-4:]
if check != hash_fn(result)[:4]:
raise Base58Error(f'invalid base 58 checksum for {txt}')
return result
@staticmethod
def encode_check(payload, *, hash_fn=double_sha256):
"""Encodes a payload bytearray (which includes the version byte(s))
into a Base58Check string."""
be_bytes = payload + hash_fn(payload)[:4]
return Base58.encode(be_bytes)