def valid(self) -> bool:
"""Check if this object is valid or not"""
stamp = self.serialize().decode('utf-8') + self.suffix
valid = (self.hash == h(str.encode(stamp)).hexdigest())
valid = valid and hashcash.check(stamp, self.suffix, self.difficulty)
valid = valid and (len(self.serialize(True, True, True, True)) <=
Block.size_limit)
if self.id > 1:
prev_block = Block.query.get(self.id - 1)
valid = valid and self.prev_hash == prev_block.hash
difficulty = prev_block.difficulty
difficulty_check_block = Block.query.get(max(1, self.id - 10))
avg_timedelta = (
(self.created_at - difficulty_check_block.created_at) /
(self.id - difficulty_check_block.id))
if avg_timedelta <= datetime.timedelta(0, 5):
valid = valid and self.difficulty == max(0, difficulty + 1)
elif avg_timedelta > datetime.timedelta(0, 15):
valid = valid and self.difficulty == max(0, difficulty - 1)
else:
valid = valid and self.difficulty == difficulty
else:
valid = valid and self.prev_hash is None
valid = valid and self.difficulty == 0
valid = valid and self.root_hash == h(''.join(
sorted((m.id for m in self.moves))).encode('utf-8')).hexdigest()
for move in self.moves:
valid = valid and move.valid
return valid
def test_mint(challenge, bits):
answer = _mint(challenge, bits)
stamp = challenge + answer
digest = hashlib.sha256(stamp)
assert has_leading_zero_bits(digest.digest(), bits)
assert check(stamp)