def mock_make_attestations(parent_state, block, attester_share=0.8):
crystallized_state, active_state = parent_state
cycle_length = config['cycle_length']
in_cycle_slot_height = block.slot_number % cycle_length
indices = crystallized_state.indices_for_slots[cycle_length +
in_cycle_slot_height]
print("Generating attestations for shards: %s" % len(indices))
attestations = []
for shard_and_committee in indices:
shard_id = shard_and_committee.shard_id
committee_indices = shard_and_committee.committee
print("Generating attestation for shard %s" % shard_id)
print("Committee size %s" % len(committee_indices))
# Create attestation
attestation = AttestationRecord(
slot=block.slot_number,
shard_id=shard_and_committee.shard_id,
oblique_parent_hashes=[],
shard_block_hash=blake(bytes(str(shard_id), 'utf-8')),
attester_bitfield=get_empty_bitfield(len(committee_indices)))
# Randomly pick indices to include
is_attesting = [
random.random() < attester_share
for _ in range(len(committee_indices))
]
# Proposer always attests
is_attesting[0] = True
# Generating signatures and aggregating result
parent_hashes = get_hashes_to_sign(active_state, block, config)
message = blake(
attestation.slot.to_bytes(8, byteorder='big') +
b''.join(parent_hashes) +
shard_id.to_bytes(2, byteorder='big') +
attestation.shard_block_hash)
sigs = [
bls.sign(message,
keymap[crystallized_state.validators[indice].pubkey])
for i, indice in enumerate(committee_indices)
if is_attesting[i]
]
attestation.aggregate_sig = bls.aggregate_sigs(sigs)
print('Aggregated sig')
attestation_bitfield = get_empty_bitfield(len(committee_indices))
for i, attesting in enumerate(is_attesting):
if attesting:
attestation_bitfield = set_voted(attestation_bitfield, i)
attestation.attester_bitfield = attestation_bitfield
print('Aggregate bitfield:',
bin(int.from_bytes(attestation_bitfield, 'big')))
attestations.append(attestation)
return attestations
def genesis_crystallized_state(init_validator_keys,
init_shuffling_seed,
config):
return CrystallizedState(
active_validators=[ValidatorRecord(
pubkey=pub,
withdrawal_shard=0,
withdrawal_address=blake(pub.to_bytes(32, 'big'))[-20:],
randao_commitment=b'\x55'*32,
balance=DEFAULT_BALANCE,
switch_dynasty=DEFAULT_SWITCH_DYNASTY
) for pub in init_validator_keys],
queued_validators=[],
exited_validators=[],
current_shuffling=get_shuffling(init_shuffling_seed, len(init_validator_keys), config=config),
current_epoch=1,
last_justified_epoch=0,
last_finalized_epoch=0,
dynasty=1,
next_shard=0,
current_checkpoint=blake(b'insert EOS constitution here'),
crosslink_records=[
CrosslinkRecord(hash=b'\x00'*32, epoch=0) for i in range(SHARD_COUNT)
],
total_deposits=DEFAULT_BALANCE*len(init_validator_keys)
)
def mock_make_child(parent_state, parent, slot_number, attestations=None):
if attestations is None:
attestations = []
crystallized_state, active_state = parent_state
block = Block(parent_hash=parent.hash,
slot_number=slot_number,
randao_reveal=blake(
str(random.random()).encode('utf-8')),
attestations=attestations,
pow_chain_ref=b'\x00' * 32,
active_state_root=b'\x00' * 32,
crystallized_state_root=b'\x00' * 32)
print('Generated preliminary block header')
new_crystallized_state, new_active_state = compute_state_transition(
(crystallized_state, active_state), parent, block, config=config)
print('Calculated state transition')
if crystallized_state == new_crystallized_state:
block.crystallized_state_root = parent.crystallized_state_root
else:
block.crystallized_state_root = blake(
serialize(crystallized_state))
block.active_state_root = blake(serialize(active_state))
return block, new_crystallized_state, new_active_state
def mock_make_child(parent_state,
parent,
skips,
attester_share=0.8,
crosslink_shards=[]):
crystallized_state, active_state = parent_state
block, proposer = make_unfinished_block(parent_state, parent, skips,
attester_share,
crosslink_shards)
print('Generated preliminary block header')
new_crystallized_state, new_active_state = compute_state_transition(
(crystallized_state, active_state),
parent,
block,
verify_sig=False,
config=config)
print('Calculated state transition')
if crystallized_state == new_crystallized_state:
block.state_hash = blake(parent.state_hash[:32] +
blake(serialize(new_active_state)))
else:
block.state_hash = blake(
blake(serialize(new_crystallized_state)) +
blake(serialize(new_active_state)))
# Main signature
block.sign(
keymap[crystallized_state.active_validators[proposer].pubkey])
print('Signed')
return block, new_crystallized_state, new_active_state
def genesis_block(genesis_active_state, genesis_crystallized_state):
active_state_root = blake(serialize(genesis_active_state))
crystallized_state_root = blake(serialize(genesis_crystallized_state))
return get_genesis_block(
active_state_root=active_state_root,
crystallized_state_root=crystallized_state_root,
)
def mock_make_child(parent_state, parent, skips, attester_share=0.8, crosslink_shards=[]):
crystallized_state, active_state = parent_state
parent_attestation = serialize(parent)
indices, main_signer = get_attesters_and_signer(crystallized_state, active_state, skips)
print('Selected indices: %r' % indices)
print('Selected main signer: %d' % main_signer)
# Randomly pick indices to include
bitfield = [1 if random.random() < attester_share else 0 for i in indices]
# Attestations
sigs = [bls.sign(parent_attestation, keymap[crystallized_state.active_validators[indices[i]].pubkey])
for i in range(len(indices)) if bitfield[i]]
attestation_aggregate_sig = bls.aggregate_sigs(sigs)
print('Aggregated sig')
attestation_bitmask = bytearray((len(bitfield)-1) // 8 + 1)
for i, b in enumerate(bitfield):
attestation_bitmask[i//8] ^= (128 >> (i % 8)) * b
print('Aggregate bitmask:', bin(int.from_bytes(attestation_bitmask, 'big')))
# Randomly pick indices to include for crosslinks
shard_aggregate_votes = []
for shard, crosslinker_share in crosslink_shards:
print('Making crosslink in shard %d' % shard)
indices = get_shard_attesters(crystallized_state, shard)
print('Indices: %r' % indices)
bitfield = [1 if random.random() < crosslinker_share else 0 for i in indices]
bitmask = bytearray((len(bitfield)+7) // 8)
for i, b in enumerate(bitfield):
bitmask[i//8] ^= (128 >> (i % 8)) * b
print('Bitmask:', bin(int.from_bytes(bitmask, 'big')))
shard_block_hash = blake(bytes([shard]))
crosslink_attestation_hash = get_crosslink_aggvote_msg(shard, shard_block_hash, crystallized_state)
sigs = [bls.sign(crosslink_attestation_hash, keymap[crystallized_state.active_validators[indices[i]].pubkey])
for i in range(len(indices)) if bitfield[i]]
v = AggregateVote(shard_id=shard,
shard_block_hash=shard_block_hash,
signer_bitmask=bitmask,
aggregate_sig=list(bls.aggregate_sigs(sigs)))
shard_aggregate_votes.append(v)
print('Added %d shard aggregate votes' % len(crosslink_shards))
# State calculations
o = Block(parent_hash=blake(parent_attestation),
skip_count=skips,
randao_reveal=blake(str(random.random()).encode('utf-8')),
attestation_bitmask=attestation_bitmask,
attestation_aggregate_sig=list(attestation_aggregate_sig),
shard_aggregate_votes=shard_aggregate_votes,
main_chain_ref=b'\x00'*32,
state_hash=b'\x00'*64)
print('Generated preliminary block header')
new_crystallized_state, new_active_state = \
compute_state_transition((crystallized_state, active_state), parent, o, verify_sig=False)
print('Calculated state transition')
if crystallized_state == new_crystallized_state:
o.state_hash = blake(parent.state_hash[:32] + blake(serialize(new_active_state)))
else:
o.state_hash = blake(blake(serialize(new_crystallized_state)) + blake(serialize(new_active_state)))
# Main signature
o.sign(keymap[crystallized_state.active_validators[main_signer].pubkey])
print('Signed')
return o, new_crystallized_state, new_active_state
def validate_attestation(crystallized_state: CrystallizedState,
active_state: ActiveState,
attestation: 'AttestationRecord',
block: 'Block',
config: Dict[str, Any]=DEFAULT_CONFIG) -> None:
if not attestation.slot < block.slot_number:
raise Exception("Attestation slot number too high")
if not (attestation.slot > block.slot_number - config['cycle_length']):
raise Exception(
"Attestation slot number too low:\n"
"\tFound: %s, Needed greater than: %s" %
(attestation.slot, block.slot_number - config['cycle_length'])
)
parent_hashes = get_signed_parent_hashes(
active_state,
block,
attestation,
config
)
attestation_indices = get_attestation_indices(
crystallized_state,
attestation,
config
)
#
# validate bitfield
#
if not (len(attestation.attester_bitfield) == get_bitfield_length(len(attestation_indices))):
raise Exception(
"Attestation has incorrect bitfield length. Found: %s, Expected: %s" %
(len(attestation.attester_bitfield), get_bitfield_length(len(attestation_indices)))
)
# check if end bits are zero
last_bit = len(attestation_indices)
if last_bit % 8 != 0:
for i in range(8 - last_bit % 8):
if has_voted(attestation.attester_bitfield, last_bit + i):
raise Exception("Attestation has non-zero trailing bits")
#
# validate aggregate_sig
#
in_cycle_slot_height = attestation.slot % config['cycle_length']
pub_keys = [
crystallized_state.validators[index].pubkey
for i, index in enumerate(attestation_indices)
if has_voted(attestation.attester_bitfield, i)
]
message = blake(
in_cycle_slot_height.to_bytes(8, byteorder='big') +
b''.join(parent_hashes) +
attestation.shard_id.to_bytes(2, byteorder='big') +
attestation.shard_block_hash
)
if not bls.verify(message, bls.aggregate_pubs(pub_keys), attestation.aggregate_sig):
raise Exception("Attestation aggregate signature fails")
def test_get_genesis_block(genesis_active_state, genesis_crystallized_state):
active_state_root = blake(serialize(genesis_active_state))
crystallized_state_root = blake(serialize(genesis_crystallized_state))
block = get_genesis_block(
active_state_root=active_state_root,
crystallized_state_root=crystallized_state_root,
)
assert block.parent_hash == ZERO_HASH32
assert block.slot_number == 0
assert block.randao_reveal == ZERO_HASH32
assert block.num_attestations == 0
assert block.pow_chain_ref == ZERO_HASH32
assert block.active_state_root == active_state_root
assert block.crystallized_state_root == crystallized_state_root
def genesis_validators(init_validator_keys, config):
current_dynasty = 1
return [
ValidatorRecord(pubkey=pub,
withdrawal_shard=0,
withdrawal_address=blake(pub.to_bytes(32,
'big'))[-20:],
randao_commitment=b'\x55' * 32,
balance=config['deposit_size'],
start_dynasty=current_dynasty,
end_dynasty=config['default_end_dynasty'])
for pub in init_validator_keys
]
def get_hashes_to_sign(
active_state: 'ActiveState',
block: 'Block',
config: Dict[str, Any] = DEFAULT_CONFIG) -> List[Hash32]:
cycle_length = config['cycle_length']
hashes = get_hashes_from_active_state(
active_state,
block,
from_slot=block.slot_number - cycle_length + 1,
to_slot=block.slot_number - 1,
config=config,
) + [blake(serialize(block))]
return hashes
def get_shuffling(seed, validator_count, sample=None):
assert validator_count <= MAX_VALIDATORS
rand_max = MAX_VALIDATORS - MAX_VALIDATORS % validator_count
o = list(range(validator_count))
source = seed
i = 0
maxvalue = sample if sample is not None else validator_count
while i < maxvalue:
source = blake(source)
for pos in range(0, 30, 3):
m = int.from_bytes(source[pos:pos + 3], 'big')
remaining = validator_count - i
if remaining == 0:
break
if validator_count < rand_max:
replacement_pos = (m % remaining) + i
o[i], o[replacement_pos] = o[replacement_pos], o[i]
i += 1
return o[:maxvalue]
def shuffle(lst, seed, config=DEFAULT_CONFIG):
lst_count = len(lst)
assert lst_count <= 16777216
o = [x for x in lst]
source = seed
i = 0
while i < lst_count:
source = blake(source)
for pos in range(0, 30, 3):
m = int.from_bytes(source[pos:pos + 3], 'big')
remaining = lst_count - i
if remaining == 0:
break
rand_max = 16777216 - 16777216 % remaining
if m < rand_max:
replacement_pos = (m % remaining) + i
o[i], o[replacement_pos] = o[replacement_pos], o[i]
i += 1
return o
def get_shuffling(seed, validator_count, sample=None, config=DEFAULT_CONFIG):
max_validators = config['max_validators']
assert validator_count <= max_validators
rand_max = max_validators - max_validators % validator_count
o = list(range(validator_count))
source = seed
i = 0
maxvalue = sample if sample is not None else validator_count
while i < maxvalue:
source = blake(source)
for pos in range(0, 30, 3):
m = int.from_bytes(source[pos:pos + 3], 'big')
remaining = validator_count - i
if remaining == 0:
break
if validator_count < rand_max:
replacement_pos = (m % remaining) + i
o[i], o[replacement_pos] = o[replacement_pos], o[i]
i += 1
return o[:maxvalue]
def test_initialize_new_cycle(
genesis_crystallized_state, genesis_active_state, genesis_block,
last_state_recalc, last_justified_slot, justified_streak,
last_finalized_slot, fraction_voted, result_last_state_recalc,
result_justified_streak, result_last_finalized_slot, config):
# Fill the parent_crystallized_state with parematers
parent_crystallized_state = genesis_crystallized_state
parent_crystallized_state.last_state_recalc = last_state_recalc
parent_crystallized_state.last_justified_slot = last_justified_slot
parent_crystallized_state.justified_streak = justified_streak
parent_crystallized_state.last_finalized_slot = last_finalized_slot
parent_active_state = genesis_active_state
parent_block = genesis_block
block = copy.deepcopy(genesis_block)
block.slot_number = 258
block.parent_hash = blake(serialize(parent_block))
active_state = fill_recent_block_hashes(parent_active_state, parent_block,
block)
fraction_voted *= 1.01 # add margin for rounding error
# Fill the total_voter_deposits to simulate the different committee results
active_state.block_vote_cache[block.parent_hash] = {
'voter_indices':
set(),
'total_voter_deposits':
int(parent_crystallized_state.total_deposits * fraction_voted)
}
crystallized_state, active_state = initialize_new_cycle(
parent_crystallized_state,
active_state,
block,
config=config,
)
assert crystallized_state.last_state_recalc == result_last_state_recalc
assert crystallized_state.justified_streak == result_justified_streak
assert crystallized_state.last_finalized_slot == result_last_finalized_slot
def hash(self):
return blake(serialize(self))
def validate_attestation(crystallized_state: CrystallizedState,
active_state: ActiveState,
attestation: 'AttestationRecord',
block: 'Block',
parent_block: 'Block',
config: Dict[str, Any] = DEFAULT_CONFIG) -> bool:
#
# validate slot number
#
if not attestation.slot <= parent_block.slot_number:
raise ValidationError("Attestation slot number too high:\n"
"\tFound: %s Needed less than or equal to %s" %
(attestation.slot, parent_block.slot_number))
if not (attestation.slot >= max(
parent_block.slot_number - config['cycle_length'] + 1, 0)):
raise ValidationError(
"Attestation slot number too low:\n"
"\tFound: %s, Needed greater than or equalt to: %s" %
(attestation.slot,
max(parent_block.slot_number - config['cycle_length'] + 1, 0)))
#
# validate justified_slot and justified_block_hash
#
if attestation.justified_slot > crystallized_state.last_justified_slot:
raise ValidationError(
"attestation.justified_slot %s should be equal to or earlier than"
" crystallized_state.last_justified_slot %s" % (
attestation.justified_slot,
crystallized_state.last_justified_slot,
))
justified_block = active_state.chain.get_block_by_hash(
attestation.justified_block_hash)
if justified_block is None:
raise ValidationError(
"justified_block_hash %s is not in the canonical chain" %
attestation.justified_block_hash)
if justified_block.slot_number != attestation.justified_slot:
raise ValidationError(
"justified_slot %s doesn't match justified_block_hash" %
attestation.justified_slot)
parent_hashes = get_signed_parent_hashes(active_state, block, attestation,
config)
attestation_indices = get_attestation_indices(crystallized_state,
attestation, config)
#
# validate bitfield
#
if not (len(attestation.attester_bitfield) == get_bitfield_length(
len(attestation_indices))):
raise ValidationError(
"Attestation has incorrect bitfield length. Found: %s, Expected: %s"
% (len(attestation.attester_bitfield),
get_bitfield_length(len(attestation_indices))))
# check if end bits are zero
last_bit = len(attestation_indices)
if last_bit % 8 != 0:
for i in range(8 - last_bit % 8):
if has_voted(attestation.attester_bitfield, last_bit + i):
raise ValidationError("Attestation has non-zero trailing bits")
#
# validate aggregate_sig
#
pub_keys = [
crystallized_state.validators[validator_index].pubkey
for committee_index, validator_index in enumerate(attestation_indices)
if has_voted(attestation.attester_bitfield, committee_index)
]
message = blake(
attestation.slot.to_bytes(8, byteorder='big') +
b''.join(parent_hashes) +
attestation.shard_id.to_bytes(2, byteorder='big') +
attestation.shard_block_hash +
attestation.justified_slot.to_bytes(8, 'big'))
if not bls.verify(message, bls.aggregate_pubs(pub_keys),
attestation.aggregate_sig):
raise ValidationError("Attestation aggregate signature fails")
return True
def mock_make_attestations(parent_state, block, attester_share=0.8):
crystallized_state, active_state = parent_state
cycle_length = config['cycle_length']
in_cycle_slot_height = block.slot_number % cycle_length
indices = crystallized_state.shard_and_committee_for_slots[
cycle_length + in_cycle_slot_height]
print("Generating attestations for shards: %s" % len(indices))
proposer_index_in_committee, proposer_shard_id = get_proposer_position(
block,
crystallized_state,
config=config,
)
attestations = []
for shard_and_committee in indices:
shard_id = shard_and_committee.shard_id
committee_indices = shard_and_committee.committee
print("Generating attestation for shard %s" % shard_id)
print("Committee size %s" % len(committee_indices))
justified_slot = crystallized_state.last_justified_slot
justified_block_hash = active_state.chain.get_block_by_slot_number(
justified_slot).hash
# Create attestation
attestation = AttestationRecord(
slot=block.slot_number,
shard_id=shard_and_committee.shard_id,
oblique_parent_hashes=[],
shard_block_hash=blake(bytes(str(shard_id), 'utf-8')),
attester_bitfield=get_empty_bitfield(len(committee_indices)),
justified_slot=justified_slot,
justified_block_hash=justified_block_hash,
)
# fill with roughly attester share fraction of voters
is_attesting = [
i < attester_share * len(committee_indices)
for i in range(len(committee_indices))
]
# Proposer always attests
if shard_id == proposer_shard_id:
is_attesting[proposer_index_in_committee] = True
# Generating signatures and aggregating result
parent_hashes = get_hashes_to_sign(active_state, block, config)
message = blake(
attestation.slot.to_bytes(8, byteorder='big') +
b''.join(parent_hashes) +
shard_id.to_bytes(2, byteorder='big') +
attestation.shard_block_hash +
attestation.justified_slot.to_bytes(8, byteorder='big'))
sigs = [
bls.sign(message,
keymap[crystallized_state.validators[indice].pubkey])
for i, indice in enumerate(committee_indices)
if is_attesting[i]
]
attestation.aggregate_sig = bls.aggregate_sigs(sigs)
print('Aggregated sig')
attestation_bitfield = get_empty_bitfield(len(committee_indices))
for i, attesting in enumerate(is_attesting):
if attesting:
attestation_bitfield = set_voted(attestation_bitfield, i)
attestation.attester_bitfield = attestation_bitfield
print('Aggregate bitfield:',
bin(int.from_bytes(attestation_bitfield, 'big')))
attestations.append(attestation)
return attestations
def make_unfinished_block(parent_state,
parent,
skips,
attester_share=0.8,
crosslink_shards_and_shares=None):
if crosslink_shards_and_shares is None:
crosslink_shards_and_shares = []
crystallized_state, active_state = parent_state
parent_attestation = serialize(parent)
indices, proposer = get_attesters_and_proposer(crystallized_state,
active_state, skips,
config)
print('Selected indices: %r' % indices)
print('Selected block proposer: %d' % proposer)
# Randomly pick indices to include
bitfield = [
1 if random.random() < attester_share else 0 for i in indices
]
# Attestations
sigs = [
bls.sign(
parent_attestation, keymap[
crystallized_state.active_validators[indices[i]].pubkey])
for i in range(len(indices)) if bitfield[i]
]
attestation_aggregate_sig = bls.aggregate_sigs(sigs)
print('Aggregated sig')
attestation_bitfield = bytearray((len(bitfield) - 1) // 8 + 1)
for i, b in enumerate(bitfield):
attestation_bitfield[i // 8] ^= (128 >> (i % 8)) * b
print('Aggregate bitfield:',
bin(int.from_bytes(attestation_bitfield, 'big')))
# Randomly pick indices to include for crosslinks
shard_aggregate_votes = []
# The shards that are selected to be crosslinking
crosslink_shards = get_crosslink_shards(crystallized_state,
config=config)
for shard, crosslinker_share in crosslink_shards_and_shares:
# Check if this shard is in the crosslink shards list
assert shard in crosslink_shards
print('Making crosslink in shard %d' % shard)
indices = get_crosslink_notaries(crystallized_state,
shard,
crosslink_shards=crosslink_shards,
config=config)
print('Indices: %r' % indices)
bitfield = [
1 if random.random() < crosslinker_share else 0
for i in indices
]
bitmask = bytearray((len(bitfield) + 7) // 8)
for i, b in enumerate(bitfield):
bitmask[i // 8] ^= (128 >> (i % 8)) * b
print('Bitmask:', bin(int.from_bytes(bitmask, 'big')))
shard_block_hash = blake(bytes([shard]))
crosslink_attestation_hash = get_crosslink_aggvote_msg(
shard, shard_block_hash, crystallized_state)
sigs = [
bls.sign(
crosslink_attestation_hash,
keymap[crystallized_state.active_validators[
indices[i]].pubkey]) for i in range(len(indices))
if bitfield[i]
]
v = AggregateVote(shard_id=shard,
shard_block_hash=shard_block_hash,
signer_bitmask=bitmask,
aggregate_sig=list(bls.aggregate_sigs(sigs)))
shard_aggregate_votes.append(v)
print('Added %d shard aggregate votes' %
len(crosslink_shards_and_shares))
block = Block(
parent_hash=blake(parent_attestation),
skip_count=skips,
randao_reveal=blake(str(random.random()).encode('utf-8')),
attestation_bitfield=attestation_bitfield,
attestation_aggregate_sig=list(attestation_aggregate_sig),
shard_aggregate_votes=shard_aggregate_votes,
main_chain_ref=b'\x00' * 32,
state_hash=b'\x00' * 64)
return block, proposer
def make_unfinished_block(parent_state,
parent,
skips,
attester_share=0.8,
crosslink_shards_and_shares=None):
if crosslink_shards_and_shares is None:
crosslink_shards_and_shares = []
crystallized_state, active_state = parent_state
parent_attestation = serialize(parent)
indices, proposer = get_attesters_and_proposer(
crystallized_state,
active_state,
skips,
config
)
print('Selected indices: %r' % indices)
print('Selected block proposer: %d' % proposer)
# Randomly pick indices to include
is_attesting = [random.random() < attester_share for _ in indices]
# Attestations
sigs = [
bls.sign(
parent_attestation,
keymap[crystallized_state.active_validators[indices[i]].pubkey]
)
for i, attesting in enumerate(is_attesting) if attesting
]
attestation_aggregate_sig = bls.aggregate_sigs(sigs)
print('Aggregated sig')
attestation_bitfield = get_empty_bitfield(len(indices))
for i, attesting in enumerate(is_attesting):
if attesting:
attestation_bitfield = set_voted(attestation_bitfield, i)
print('Aggregate bitfield:', bin(int.from_bytes(attestation_bitfield, 'big')))
# Randomly pick indices to include for crosslinks
shard_aggregate_votes = []
# The shards that are selected to be crosslinking
crosslink_shards = get_crosslink_shards(crystallized_state, config=config)
for shard, crosslinker_share in crosslink_shards_and_shares:
# Check if this shard is in the crosslink shards list
assert shard in crosslink_shards
print('Making crosslink in shard %d' % shard)
indices = get_crosslink_notaries(crystallized_state, shard, crosslink_shards=crosslink_shards, config=config)
print('Indices: %r' % indices)
is_notarizing = [random.random() < attester_share for _ in indices]
notary_bitfield = get_empty_bitfield(len(indices))
for i, notarizing in enumerate(is_notarizing):
if notarizing:
notary_bitfield = set_voted(notary_bitfield, i)
print('Bitfield:', bin(int.from_bytes(notary_bitfield, 'big')))
shard_block_hash = blake(bytes([shard]))
crosslink_attestation_hash = get_crosslink_aggvote_msg(
shard,
shard_block_hash,
crystallized_state
)
sigs = [
bls.sign(
crosslink_attestation_hash,
keymap[crystallized_state.active_validators[indices[i]].pubkey]
)
for i, notarizing in enumerate(is_notarizing) if notarizing
]
v = AggregateVote(
shard_id=shard,
shard_block_hash=shard_block_hash,
notary_bitfield=notary_bitfield,
aggregate_sig=list(bls.aggregate_sigs(sigs))
)
shard_aggregate_votes.append(v)
print('Added %d shard aggregate votes' % len(crosslink_shards_and_shares))
block = Block(
parent_hash=blake(parent_attestation),
skip_count=skips,
randao_reveal=blake(str(random.random()).encode('utf-8')),
attestation_bitfield=attestation_bitfield,
attestation_aggregate_sig=list(attestation_aggregate_sig),
shard_aggregate_votes=shard_aggregate_votes,
main_chain_ref=b'\x00'*32,
state_hash=b'\x00'*64
)
return block, proposer
def validate_attestation(crystallized_state: CrystallizedState,
active_state: ActiveState,
attestation: 'AttestationRecord',
block: 'Block',
parent_block: 'Block',
config: Dict[str, Any] = DEFAULT_CONFIG) -> None:
# Verify attestation.slot_number
if not attestation.slot <= parent_block.slot_number:
raise Exception("Attestation slot number too high:\n"
"\tFound: %s Needed less than or equal to %s" %
(attestation.slot, parent_block.slot_number))
if not (attestation.slot >= max(
parent_block.slot_number - config['cycle_length'] + 1, 0)):
raise Exception(
"Attestation slot number too low:\n"
"\tFound: %s, Needed greater than or equalt to: %s" %
(attestation.slot,
max(parent_block.slot_number - config['cycle_length'] + 1, 0)))
# TODO: Verify that the justified_slot and justified_block_hash given are in
# the chain and are equal to or earlier than the last_justified_slot
# in the crystallized state.
parent_hashes = get_signed_parent_hashes(active_state, block, attestation,
config)
attestation_indices = get_attestation_indices(crystallized_state,
attestation, config)
#
# validate bitfield
#
if not (len(attestation.attester_bitfield) == get_bitfield_length(
len(attestation_indices))):
raise Exception(
"Attestation has incorrect bitfield length. Found: %s, Expected: %s"
% (len(attestation.attester_bitfield),
get_bitfield_length(len(attestation_indices))))
# check if end bits are zero
last_bit = len(attestation_indices)
if last_bit % 8 != 0:
for i in range(8 - last_bit % 8):
if has_voted(attestation.attester_bitfield, last_bit + i):
raise Exception("Attestation has non-zero trailing bits")
#
# validate aggregate_sig
#
pub_keys = [
crystallized_state.validators[index].pubkey
for i, index in enumerate(attestation_indices)
if has_voted(attestation.attester_bitfield, i)
]
message = blake(
attestation.slot.to_bytes(8, byteorder='big') +
b''.join(parent_hashes) +
attestation.shard_id.to_bytes(2, byteorder='big') +
attestation.shard_block_hash +
attestation.justified_slot.to_bytes(8, 'big'))
if not bls.verify(message, bls.aggregate_pubs(pub_keys),
attestation.aggregate_sig):
raise Exception("Attestation aggregate signature fails")
def state_hash(crystallized_state, active_state):
return blake(serialize(crystallized_state)) + blake(
serialize(active_state))
def privkeys():
return [int.from_bytes(blake(str(i).encode('utf-8'))[:4], 'big') for i in range(1000)]