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 update_ffg_and_crosslink_progress(crystallized_state,
crosslinks,
ffg_voter_bitfield,
votes,
config=DEFAULT_CONFIG):
# Verify the attestations of crosslink hashes
crosslink_votes = {
vote.shard_block_hash + vote.shard_id.to_bytes(2, 'big'):
vote.voter_bitfield
for vote in crosslinks
}
new_ffg_bitfield = ffg_voter_bitfield
total_voters = 0
# The shards that are selected to be crosslinking
crosslink_shards = get_crosslink_shards(crystallized_state, config=config)
for vote in votes:
attestation = get_crosslink_aggvote_msg(vote.shard_id,
vote.shard_block_hash,
crystallized_state)
# Check if this shard is in the crosslink shards list
assert vote.shard_id in crosslink_shards
indices = get_crosslink_notaries(
crystallized_state,
vote.shard_id,
crosslink_shards=crosslink_shards,
config=config,
)
votekey = vote.shard_block_hash + vote.shard_id.to_bytes(2, 'big')
if votekey not in crosslink_votes:
crosslink_votes[votekey] = b"" * get_bitfield_length(len(indices))
bitfield = crosslink_votes[votekey]
pubs = []
for i, index in enumerate(indices):
if has_voted(vote.notary_bitfield, i):
pubs.append(crystallized_state.active_validators[index].pubkey)
if has_voted(new_ffg_bitfield, index):
new_ffg_bitfield = set_voted(new_ffg_bitfield, index)
bitfield = set_voted(bitfield, i)
total_voters += 1
assert bls.verify(attestation, bls.aggregate_pubs(pubs),
vote.aggregate_sig)
crosslink_votes[votekey] = bitfield
print('Verified aggregate vote')
new_crosslinks = [
PartialCrosslinkRecord(shard_id=int.from_bytes(h[32:], 'big'),
shard_block_hash=h[:32],
voter_bitfield=crosslink_votes[h])
for h in sorted(crosslink_votes.keys())
]
return new_crosslinks, new_ffg_bitfield, total_voters
def process_attestations(validator_set, attestation_indices,
attestation_bitfield, msg, aggregate_sig):
# Verify the attestations of the parent
pubs = []
balance_deltas = []
assert len(attestation_bitfield) == (len(attestation_indices) + 7) // 8
for i, index in enumerate(attestation_indices):
if attestation_bitfield[i // 8] & (128 >> (i % 8)):
pubs.append(validator_set[index].pubkey)
balance_deltas.append((index << 24) + 1)
assert len(balance_deltas) <= 128
assert bls.verify(msg, bls.aggregate_pubs(pubs), aggregate_sig)
print('Verified aggregate sig')
return balance_deltas
def process_attestations(validator_set, attestation_indices,
attestation_bitfield, msg, aggregate_sig):
# Verify the attestations of the parent
pubs = []
attesters = []
assert len(attestation_bitfield) == get_bitfield_length(
len(attestation_indices))
for i, index in enumerate(attestation_indices):
if has_voted(attestation_bitfield, i):
pubs.append(validator_set[index].pubkey)
attesters.append(index)
assert len(attesters) <= 128
assert bls.verify(msg, bls.aggregate_pubs(pubs), aggregate_sig)
print('Verified aggregate sig')
return attesters
def update_ffg_and_crosslink_progress(crystallized_state,
crosslinks,
ffg_voter_bitfield,
votes,
config=DEFAULT_CONFIG):
# Verify the attestations of crosslink hashes
crosslink_votes = {
vote.shard_block_hash + vote.shard_id.to_bytes(2, 'big'):
vote.voter_bitfield
for vote in crosslinks
}
new_ffg_bitfield = bytearray(ffg_voter_bitfield)
total_voters = 0
for vote in votes:
attestation = get_crosslink_aggvote_msg(vote.shard_id,
vote.shard_block_hash,
crystallized_state)
indices = get_shard_attesters(crystallized_state, vote.shard_id,
config)
votekey = vote.shard_block_hash + vote.shard_id.to_bytes(2, 'big')
if votekey not in crosslink_votes:
crosslink_votes[votekey] = bytearray((len(indices) + 7) // 8)
bitfield = crosslink_votes[votekey]
pubs = []
for i, index in enumerate(indices):
if vote.signer_bitmask[i // 8] & (128 >> (i % 8)):
pubs.append(crystallized_state.active_validators[index].pubkey)
if new_ffg_bitfield[index // 8] & (128 >> (index % 8)) == 0:
new_ffg_bitfield[index // 8] ^= 128 >> (index % 8)
bitfield[i // 8] ^= 128 >> (i % 8)
total_voters += 1
assert bls.verify(attestation, bls.aggregate_pubs(pubs),
vote.aggregate_sig)
crosslink_votes[votekey] = bitfield
print('Verified aggregate vote')
new_crosslinks = [
PartialCrosslinkRecord(shard_id=int.from_bytes(h[32:], 'big'),
shard_block_hash=h[:32],
voter_bitfield=crosslink_votes[h])
for h in sorted(crosslink_votes.keys())
]
return new_crosslinks, new_ffg_bitfield, total_voters
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 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 test_signature_aggregation(msg, privkeys):
sigs = [sign(msg, k) for k in privkeys]
pubs = [privtopub(k) for k in privkeys]
aggsig = aggregate_sigs(sigs)
aggpub = aggregate_pubs(pubs)
assert verify(msg, aggpub, aggsig)
