110 lines
4.2 KiB
Python
110 lines
4.2 KiB
Python
# Copyright (c) 2020 Pieter Wuille
|
|
# Distributed under the MIT software license, see the accompanying
|
|
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
|
|
"""Native Python MuHash3072 implementation."""
|
|
|
|
import hashlib
|
|
import unittest
|
|
|
|
from .util import modinv
|
|
|
|
def rot32(v, bits):
|
|
"""Rotate the 32-bit value v left by bits bits."""
|
|
bits %= 32 # Make sure the term below does not throw an exception
|
|
return ((v << bits) & 0xffffffff) | (v >> (32 - bits))
|
|
|
|
def chacha20_doubleround(s):
|
|
"""Apply a ChaCha20 double round to 16-element state array s.
|
|
|
|
See https://cr.yp.to/chacha/chacha-20080128.pdf and https://tools.ietf.org/html/rfc8439
|
|
"""
|
|
QUARTER_ROUNDS = [(0, 4, 8, 12),
|
|
(1, 5, 9, 13),
|
|
(2, 6, 10, 14),
|
|
(3, 7, 11, 15),
|
|
(0, 5, 10, 15),
|
|
(1, 6, 11, 12),
|
|
(2, 7, 8, 13),
|
|
(3, 4, 9, 14)]
|
|
|
|
for a, b, c, d in QUARTER_ROUNDS:
|
|
s[a] = (s[a] + s[b]) & 0xffffffff
|
|
s[d] = rot32(s[d] ^ s[a], 16)
|
|
s[c] = (s[c] + s[d]) & 0xffffffff
|
|
s[b] = rot32(s[b] ^ s[c], 12)
|
|
s[a] = (s[a] + s[b]) & 0xffffffff
|
|
s[d] = rot32(s[d] ^ s[a], 8)
|
|
s[c] = (s[c] + s[d]) & 0xffffffff
|
|
s[b] = rot32(s[b] ^ s[c], 7)
|
|
|
|
def chacha20_32_to_384(key32):
|
|
"""Specialized ChaCha20 implementation with 32-byte key, 0 IV, 384-byte output."""
|
|
# See RFC 8439 section 2.3 for chacha20 parameters
|
|
CONSTANTS = [0x61707865, 0x3320646e, 0x79622d32, 0x6b206574]
|
|
|
|
key_bytes = [0]*8
|
|
for i in range(8):
|
|
key_bytes[i] = int.from_bytes(key32[(4 * i):(4 * (i+1))], 'little')
|
|
|
|
INITIALIZATION_VECTOR = [0] * 4
|
|
init = CONSTANTS + key_bytes + INITIALIZATION_VECTOR
|
|
out = bytearray()
|
|
for counter in range(6):
|
|
init[12] = counter
|
|
s = init.copy()
|
|
for _ in range(10):
|
|
chacha20_doubleround(s)
|
|
for i in range(16):
|
|
out.extend(((s[i] + init[i]) & 0xffffffff).to_bytes(4, 'little'))
|
|
return bytes(out)
|
|
|
|
def data_to_num3072(data):
|
|
"""Hash a 32-byte array data to a 3072-bit number using 6 Chacha20 operations."""
|
|
bytes384 = chacha20_32_to_384(data)
|
|
return int.from_bytes(bytes384, 'little')
|
|
|
|
class MuHash3072:
|
|
"""Class representing the MuHash3072 computation of a set.
|
|
|
|
See https://cseweb.ucsd.edu/~mihir/papers/inchash.pdf and https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-May/014337.html
|
|
"""
|
|
|
|
MODULUS = 2**3072 - 1103717
|
|
|
|
def __init__(self):
|
|
"""Initialize for an empty set."""
|
|
self.numerator = 1
|
|
self.denominator = 1
|
|
|
|
def insert(self, data):
|
|
"""Insert a byte array data in the set."""
|
|
self.numerator = (self.numerator * data_to_num3072(data)) % self.MODULUS
|
|
|
|
def remove(self, data):
|
|
"""Remove a byte array from the set."""
|
|
self.denominator = (self.denominator * data_to_num3072(data)) % self.MODULUS
|
|
|
|
def digest(self):
|
|
"""Extract the final hash. Does not modify this object."""
|
|
val = (self.numerator * modinv(self.denominator, self.MODULUS)) % self.MODULUS
|
|
bytes384 = val.to_bytes(384, 'little')
|
|
return hashlib.sha256(bytes384).digest()
|
|
|
|
class TestFrameworkMuhash(unittest.TestCase):
|
|
def test_muhash(self):
|
|
muhash = MuHash3072()
|
|
muhash.insert([0]*32)
|
|
muhash.insert([1] + [0]*31)
|
|
muhash.remove([2] + [0]*31)
|
|
finalized = muhash.digest()
|
|
# This mirrors the result in the C++ MuHash3072 unit test
|
|
self.assertEqual(finalized[::-1].hex(), "a44e16d5e34d259b349af21c06e65d653915d2e208e4e03f389af750dc0bfdc3")
|
|
|
|
def test_chacha20(self):
|
|
def chacha_check(key, result):
|
|
self.assertEqual(chacha20_32_to_384(key)[:64].hex(), result)
|
|
|
|
# Test vectors from https://tools.ietf.org/html/draft-agl-tls-chacha20poly1305-04#section-7
|
|
# Since the nonce is hardcoded to 0 in our function we only use those vectors.
|
|
chacha_check([0]*32, "76b8e0ada0f13d90405d6ae55386bd28bdd219b8a08ded1aa836efcc8b770dc7da41597c5157488d7724e03fb8d84a376a43b8f41518a11cc387b669b2ee6586")
|
|
chacha_check([0]*31 + [1], "4540f05a9f1fb296d7736e7b208e3c96eb4fe1834688d2604f450952ed432d41bbe2a0b6ea7566d2a5d1e7e20d42af2c53d792b1c43fea817e9ad275ae546963")
|