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Merge pull request #1009 from ethereum/vbuterin-patch-2 

Attestation committee refactor
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Danny Ryan 2019-05-01 16:25:13 -06:00 committed by GitHub
parent 9d1ec584d3 ef72b7ec20
commit 2ed8d99ac5
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8 changed files with 164 additions and 247 deletions
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16
scripts/phase0/build_spec.py
View File

@ -39,24 +39,20 @@ Store = None
code_lines += function_puller.get_spec(sourcefile)
code_lines.append("""
# Monkey patch validator get committee code
# Monkey patch validator compute committee code
_compute_committee = compute_committee
committee_cache = {}
def compute_committee(validator_indices: List[ValidatorIndex],
seed: Bytes32,
index: int,
total_committees: int) -> List[ValidatorIndex]:
param_hash = (hash_tree_root(validator_indices), seed, index, total_committees)
def compute_committee(indices: List[ValidatorIndex], seed: Bytes32, index: int, count: int) -> List[ValidatorIndex]:
param_hash = (hash_tree_root(indices), seed, index, count)
if param_hash in committee_cache:
# print("Cache hit, epoch={0}".format(epoch))
print("Cache hit, param_hash: ", param_hash)
return committee_cache[param_hash]
else:
# print("Cache miss, epoch={0}".format(epoch))
ret = _compute_committee(validator_indices, seed, index, total_committees)
print("Cache miss, param_hash: ", param_hash)
ret = _compute_committee(indices, seed, index, count)
committee_cache[param_hash] = ret
return ret

344
specs/core/0_beacon-chain.md
View File

@ -60,12 +60,10 @@
- [`get_active_validator_indices`](#get_active_validator_indices)
- [`increase_balance`](#increase_balance)
- [`decrease_balance`](#decrease_balance)
- [`get_permuted_index`](#get_permuted_index)
- [`get_split_offset`](#get_split_offset)
- [`get_epoch_committee_count`](#get_epoch_committee_count)
- [`get_shard_delta`](#get_shard_delta)
- [`compute_committee`](#compute_committee)
- [`get_crosslink_committees_at_slot`](#get_crosslink_committees_at_slot)
- [`get_epoch_start_shard`](#get_epoch_start_shard)
- [`get_attestation_slot`](#get_attestation_slot)
- [`get_block_root_at_slot`](#get_block_root_at_slot)
- [`get_block_root`](#get_block_root)
- [`get_state_root`](#get_state_root)
@ -74,6 +72,9 @@
- [`generate_seed`](#generate_seed)
- [`get_beacon_proposer_index`](#get_beacon_proposer_index)
- [`verify_merkle_branch`](#verify_merkle_branch)
- [`get_shuffled_index`](#get_shuffled_index)
- [`compute_committee`](#compute_committee)
- [`get_crosslink_committee`](#get_crosslink_committee)
- [`get_attesting_indices`](#get_attesting_indices)
- [`int_to_bytes1`, `int_to_bytes2`, ...](#int_to_bytes1-int_to_bytes2-)
- [`bytes_to_int`](#bytes_to_int)
@ -83,8 +84,7 @@
- [`verify_bitfield`](#verify_bitfield)
- [`convert_to_indexed`](#convert_to_indexed)
- [`verify_indexed_attestation`](#verify_indexed_attestation)
- [`is_double_vote`](#is_double_vote)
- [`is_surround_vote`](#is_surround_vote)
- [`is_slashable_attestation_data`](#is_slashable_attestation_data)
- [`integer_squareroot`](#integer_squareroot)
- [`get_delayed_activation_exit_epoch`](#get_delayed_activation_exit_epoch)
- [`get_churn_limit`](#get_churn_limit)
@ -307,12 +307,12 @@ The types are defined topologically to aid in facilitating an executable version
```python
{
# LMD GHOST vote
'slot': 'uint64',
'beacon_block_root': 'bytes32',
# FFG vote
'source_epoch': 'uint64',
'source_root': 'bytes32',
'target_epoch': 'uint64',
'target_root': 'bytes32',
# Crosslink vote
@ -404,8 +404,8 @@ The types are defined topologically to aid in facilitating an executable version
'aggregation_bitfield': 'bytes',
# Attestation data
'data': AttestationData,
# Inclusion slot
'inclusion_slot': 'uint64',
# Inclusion delay
'inclusion_delay': 'uint64',
# Proposer index
'proposer_index': 'uint64',
}
@ -719,43 +719,6 @@ def decrease_balance(state: BeaconState, index: ValidatorIndex, delta: Gwei) ->
state.balances[index] = 0 if delta > state.balances[index] else state.balances[index] - delta
```
### `get_permuted_index`
```python
def get_permuted_index(index: int, list_size: int, seed: Bytes32) -> int:
"""
Return `p(index)` in a pseudorandom permutation `p` of `0...list_size - 1` with ``seed`` as entropy.
Utilizes 'swap or not' shuffling found in
https://link.springer.com/content/pdf/10.1007%2F978-3-642-32009-5_1.pdf
See the 'generalized domain' algorithm on page 3.
"""
assert index < list_size
assert list_size <= 2**40
for round in range(SHUFFLE_ROUND_COUNT):
pivot = bytes_to_int(hash(seed + int_to_bytes1(round))[0:8]) % list_size
flip = (pivot - index) % list_size
position = max(index, flip)
source = hash(seed + int_to_bytes1(round) + int_to_bytes4(position // 256))
byte = source[(position % 256) // 8]
bit = (byte >> (position % 8)) % 2
index = flip if bit else index
return index
```
### `get_split_offset`
```python
def get_split_offset(list_size: int, chunks: int, index: int) -> int:
"""
Returns a value such that for a list L, chunk count k and index i,
split(L, k)[i] == L[get_split_offset(len(L), k, i): get_split_offset(len(L), k, i+1)]
"""
return (list_size * index) // chunks
```
### `get_epoch_committee_count`
```python
@ -783,65 +746,27 @@ def get_shard_delta(state: BeaconState, epoch: Epoch) -> int:
return min(get_epoch_committee_count(state, epoch), SHARD_COUNT - SHARD_COUNT // SLOTS_PER_EPOCH)
```
### `compute_committee`
### `get_epoch_start_shard`
```python
def compute_committee(validator_indices: List[ValidatorIndex],
seed: Bytes32,
index: int,
total_committees: int) -> List[ValidatorIndex]:
"""
Return the ``index``'th shuffled committee out of a total ``total_committees``
using ``validator_indices`` and ``seed``.
"""
start_offset = get_split_offset(len(validator_indices), total_committees, index)
end_offset = get_split_offset(len(validator_indices), total_committees, index + 1)
return [
validator_indices[get_permuted_index(i, len(validator_indices), seed)]
for i in range(start_offset, end_offset)
]
def get_epoch_start_shard(state: BeaconState, epoch: Epoch) -> Shard:
assert epoch <= get_current_epoch(state) + 1
check_epoch = get_current_epoch(state) + 1
shard = (state.latest_start_shard + get_shard_delta(state, get_current_epoch(state))) % SHARD_COUNT
while check_epoch > epoch:
check_epoch -= 1
shard = (shard + SHARD_COUNT - get_shard_delta(state, check_epoch)) % SHARD_COUNT
return shard
```
Note: this definition and the next few definitions are highly inefficient as algorithms, as they re-calculate many sub-expressions. Production implementations are expected to appropriately use caching/memoization to avoid redoing work.
### `get_crosslink_committees_at_slot`
### `get_attestation_slot`
```python
def get_crosslink_committees_at_slot(state: BeaconState,
slot: Slot) -> List[Tuple[List[ValidatorIndex], Shard]]:
"""
Return the list of ``(committee, shard)`` tuples for the ``slot``.
"""
epoch = slot_to_epoch(slot)
current_epoch = get_current_epoch(state)
previous_epoch = get_previous_epoch(state)
next_epoch = current_epoch + 1
assert previous_epoch <= epoch <= next_epoch
indices = get_active_validator_indices(state, epoch)
if epoch == current_epoch:
start_shard = state.latest_start_shard
elif epoch == previous_epoch:
previous_shard_delta = get_shard_delta(state, previous_epoch)
start_shard = (state.latest_start_shard - previous_shard_delta) % SHARD_COUNT
elif epoch == next_epoch:
current_shard_delta = get_shard_delta(state, current_epoch)
start_shard = (state.latest_start_shard + current_shard_delta) % SHARD_COUNT
committees_per_epoch = get_epoch_committee_count(state, epoch)
committees_per_slot = committees_per_epoch // SLOTS_PER_EPOCH
offset = slot % SLOTS_PER_EPOCH
slot_start_shard = (start_shard + committees_per_slot * offset) % SHARD_COUNT
seed = generate_seed(state, epoch)
return [
(
compute_committee(indices, seed, committees_per_slot * offset + i, committees_per_epoch),
(slot_start_shard + i) % SHARD_COUNT,
)
for i in range(committees_per_slot)
]
def get_attestation_slot(state: BeaconState, attestation: Attestation) -> Slot:
epoch = attestation.data.target_epoch
committee_count = get_epoch_committee_count(state, epoch)
offset = (attestation.data.shard + SHARD_COUNT - get_epoch_start_shard(state, epoch)) % SHARD_COUNT
return get_epoch_start_slot(epoch) + offset // (committee_count // SLOTS_PER_EPOCH)
```
### `get_block_root_at_slot`
@ -923,15 +848,18 @@ def generate_seed(state: BeaconState,
```python
def get_beacon_proposer_index(state: BeaconState) -> ValidatorIndex:
"""
Return the beacon proposer index at ``state.slot``.
Return the current beacon proposer index.
"""
current_epoch = get_current_epoch(state)
first_committee, _ = get_crosslink_committees_at_slot(state, state.slot)[0]
epoch = get_current_epoch(state)
committees_per_slot = get_epoch_committee_count(state, epoch) // SLOTS_PER_EPOCH
offset = committees_per_slot * (state.slot % SLOTS_PER_EPOCH)
shard = (get_epoch_start_shard(state, epoch) + offset) % SHARD_COUNT
first_committee = get_crosslink_committee(state, epoch, shard)
MAX_RANDOM_BYTE = 2**8 - 1
seed = generate_seed(state, current_epoch)
seed = generate_seed(state, epoch)
i = 0
while True:
candidate_index = first_committee[(current_epoch + i) % len(first_committee)]
candidate_index = first_committee[(epoch + i) % len(first_committee)]
random_byte = hash(seed + int_to_bytes8(i // 32))[i % 32]
effective_balance = state.validator_registry[candidate_index].effective_balance
if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE * random_byte:
@ -956,6 +884,51 @@ def verify_merkle_branch(leaf: Bytes32, proof: List[Bytes32], depth: int, index:
return value == root
```
### `get_shuffled_index`
```python
def get_shuffled_index(index: ValidatorIndex, index_count: int, seed: Bytes32) -> ValidatorIndex:
"""
Return the shuffled validator index corresponding to ``seed`` (and ``index_count``).
"""
assert index < index_count
assert index_count <= 2**40
# Swap or not (https://link.springer.com/content/pdf/10.1007%2F978-3-642-32009-5_1.pdf)
# See the 'generalized domain' algorithm on page 3
for round in range(SHUFFLE_ROUND_COUNT):
pivot = bytes_to_int(hash(seed + int_to_bytes1(round))[0:8]) % index_count
flip = (pivot - index) % index_count
position = max(index, flip)
source = hash(seed + int_to_bytes1(round) + int_to_bytes4(position // 256))
byte = source[(position % 256) // 8]
bit = (byte >> (position % 8)) % 2
index = flip if bit else index
return index
```
### `compute_committee`
```python
def compute_committee(indices: List[ValidatorIndex], seed: Bytes32, index: int, count: int) -> List[ValidatorIndex]:
start = (len(indices) * index) // count
end = (len(indices) * (index + 1)) // count
return [indices[get_shuffled_index(i, len(indices), seed)] for i in range(start, end)]
```
### `get_crosslink_committee`
```python
def get_crosslink_committee(state: BeaconState, epoch: Epoch, shard: Shard) -> List[ValidatorIndex]:
return compute_committee(
indices=get_active_validator_indices(state, epoch),
seed=generate_seed(state, epoch),
index=(shard + SHARD_COUNT - get_epoch_start_shard(state, epoch)) % SHARD_COUNT,
count=get_epoch_committee_count(state, epoch),
)
```
### `get_attesting_indices`
```python
@ -965,10 +938,9 @@ def get_attesting_indices(state: BeaconState,
"""
Return the sorted attesting indices corresponding to ``attestation_data`` and ``bitfield``.
"""
crosslink_committees = get_crosslink_committees_at_slot(state, attestation_data.slot)
crosslink_committee = [committee for committee, shard in crosslink_committees if shard == attestation_data.shard][0]
assert verify_bitfield(bitfield, len(crosslink_committee))
return sorted([index for i, index in enumerate(crosslink_committee) if get_bitfield_bit(bitfield, i) == 0b1])
committee = get_crosslink_committee(state, attestation_data.target_epoch, attestation_data.shard)
assert verify_bitfield(bitfield, len(committee))
return sorted([index for i, index in enumerate(committee) if get_bitfield_bit(bitfield, i) == 0b1])
```
### `int_to_bytes1`, `int_to_bytes2`, ...
@ -1088,37 +1060,23 @@ def verify_indexed_attestation(state: BeaconState, indexed_attestation: IndexedA
hash_tree_root(AttestationDataAndCustodyBit(data=indexed_attestation.data, custody_bit=0b1)),
],
signature=indexed_attestation.signature,
domain=get_domain(state, DOMAIN_ATTESTATION, slot_to_epoch(indexed_attestation.data.slot)),
domain=get_domain(state, DOMAIN_ATTESTATION, indexed_attestation.data.target_epoch),
)
```
### `is_double_vote`
### `is_slashable_attestation_data`
```python
def is_double_vote(attestation_data_1: AttestationData,
attestation_data_2: AttestationData) -> bool:
def is_slashable_attestation_data(data_1: AttestationData, data_2: AttestationData) -> bool:
"""
Check if ``attestation_data_1`` and ``attestation_data_2`` have the same target.
Check if ``data_1`` and ``data_2`` are slashable according to Casper FFG rules.
"""
target_epoch_1 = slot_to_epoch(attestation_data_1.slot)
target_epoch_2 = slot_to_epoch(attestation_data_2.slot)
return target_epoch_1 == target_epoch_2
```
### `is_surround_vote`
```python
def is_surround_vote(attestation_data_1: AttestationData,
attestation_data_2: AttestationData) -> bool:
"""
Check if ``attestation_data_1`` surrounds ``attestation_data_2``.
"""
source_epoch_1 = attestation_data_1.source_epoch
source_epoch_2 = attestation_data_2.source_epoch
target_epoch_1 = slot_to_epoch(attestation_data_1.slot)
target_epoch_2 = slot_to_epoch(attestation_data_2.slot)
return source_epoch_1 < source_epoch_2 and target_epoch_2 < target_epoch_1
return (
# Double vote
(data_1 != data_2 and data_1.target_epoch == data_2.target_epoch) or
# Surround vote
(data_1.source_epoch < data_2.source_epoch and data_2.target_epoch < data_1.target_epoch)
)
```
### `integer_squareroot`
@ -1179,7 +1137,6 @@ Note: All functions in this section mutate `state`.
def initiate_validator_exit(state: BeaconState, index: ValidatorIndex) -> None:
"""
Initiate the validator of the given ``index``.
Note that this function mutates ``state``.
"""
# Return if validator already initiated exit
validator = state.validator_registry[index]
@ -1204,7 +1161,6 @@ def initiate_validator_exit(state: BeaconState, index: ValidatorIndex) -> None:
def slash_validator(state: BeaconState, slashed_index: ValidatorIndex, whistleblower_index: ValidatorIndex=None) -> None:
"""
Slash the validator with index ``slashed_index``.
Note that this function mutates ``state``.
"""
current_epoch = get_current_epoch(state)
initiate_validator_exit(state, slashed_index)
@ -1331,7 +1287,7 @@ def get_matching_target_attestations(state: BeaconState, epoch: Epoch) -> List[P
def get_matching_head_attestations(state: BeaconState, epoch: Epoch) -> List[PendingAttestation]:
return [
a for a in get_matching_source_attestations(state, epoch)
if a.data.beacon_block_root == get_block_root_at_slot(state, a.data.slot)
if a.data.beacon_block_root == get_block_root_at_slot(state, get_attestation_slot(state, a))
]
```
@ -1351,14 +1307,14 @@ def get_attesting_balance(state: BeaconState, attestations: List[PendingAttestat
```python
def get_crosslink_from_attestation_data(state: BeaconState, data: AttestationData) -> Crosslink:
return Crosslink(
epoch=min(slot_to_epoch(data.slot), state.current_crosslinks[data.shard].epoch + MAX_CROSSLINK_EPOCHS),
epoch=min(data.target_epoch, state.current_crosslinks[data.shard].epoch + MAX_CROSSLINK_EPOCHS),
previous_crosslink_root=data.previous_crosslink_root,
crosslink_data_root=data.crosslink_data_root,
)
```
```python
def get_winning_crosslink_and_attesting_indices(state: BeaconState, shard: Shard, epoch: Epoch) -> Tuple[Crosslink, List[ValidatorIndex]]:
def get_winning_crosslink_and_attesting_indices(state: BeaconState, epoch: Epoch, shard: Shard) -> Tuple[Crosslink, List[ValidatorIndex]]:
shard_attestations = [a for a in get_matching_source_attestations(state, epoch) if a.data.shard == shard]
shard_crosslinks = [get_crosslink_from_attestation_data(state, a.data) for a in shard_attestations]
candidate_crosslinks = [
@ -1366,7 +1322,7 @@ def get_winning_crosslink_and_attesting_indices(state: BeaconState, shard: Shard
if hash_tree_root(state.current_crosslinks[shard]) in (c.previous_crosslink_root, hash_tree_root(c))
]
if len(candidate_crosslinks) == 0:
return Crosslink(epoch=GENESIS_EPOCH), []
return Crosslink(), []
def get_attestations_for(crosslink: Crosslink) -> List[PendingAttestation]:
return [a for a in shard_attestations if get_crosslink_from_attestation_data(state, a.data) == crosslink]
@ -1378,13 +1334,6 @@ def get_winning_crosslink_and_attesting_indices(state: BeaconState, shard: Shard
return winning_crosslink, get_unslashed_attesting_indices(state, get_attestations_for(winning_crosslink))
```
```python
def get_earliest_attestation(state: BeaconState, attestations: List[PendingAttestation], index: ValidatorIndex) -> PendingAttestation:
return min([
a for a in attestations if index in get_attesting_indices(state, a.data, a.aggregation_bitfield)
], key=lambda a: a.inclusion_slot)
```
#### Justification and finalization
Run the following function:
@ -1441,12 +1390,11 @@ Run the following function:
```python
def process_crosslinks(state: BeaconState) -> None:
state.previous_crosslinks = [c for c in state.current_crosslinks]
previous_epoch = get_previous_epoch(state)
next_epoch = get_current_epoch(state) + 1
for slot in range(get_epoch_start_slot(previous_epoch), get_epoch_start_slot(next_epoch)):
epoch = slot_to_epoch(slot)
for crosslink_committee, shard in get_crosslink_committees_at_slot(state, slot):
winning_crosslink, attesting_indices = get_winning_crosslink_and_attesting_indices(state, shard, epoch)
for epoch in (get_previous_epoch(state), get_current_epoch(state)):
for offset in range(get_epoch_committee_count(state, epoch)):
shard = (get_epoch_start_shard(state, epoch) + offset) % SHARD_COUNT
crosslink_committee = get_crosslink_committee(state, epoch, shard)
winning_crosslink, attesting_indices = get_winning_crosslink_and_attesting_indices(state, epoch, shard)
if 3 * get_total_balance(state, attesting_indices) >= 2 * get_total_balance(state, crosslink_committee):
state.current_crosslinks[shard] = winning_crosslink
```
@ -1489,10 +1437,11 @@ def get_attestation_deltas(state: BeaconState) -> Tuple[List[Gwei], List[Gwei]]:
# Proposer and inclusion delay micro-rewards
for index in get_unslashed_attesting_indices(state, matching_source_attestations):
earliest_attestation = get_earliest_attestation(state, matching_source_attestations, index)
rewards[earliest_attestation.proposer_index] += get_base_reward(state, index) // PROPOSER_REWARD_QUOTIENT
inclusion_delay = earliest_attestation.inclusion_slot - earliest_attestation.data.slot
rewards[index] += get_base_reward(state, index) * MIN_ATTESTATION_INCLUSION_DELAY // inclusion_delay
attestation = min([
a for a in attestations if index in get_attesting_indices(state, a.data, a.aggregation_bitfield)
], key=lambda a: a.inclusion_delay)
rewards[attestation.proposer_index] += get_base_reward(state, index) // PROPOSER_REWARD_QUOTIENT
rewards[index] += get_base_reward(state, index) * MIN_ATTESTATION_INCLUSION_DELAY // attestation.inclusion_delay
# Inactivity penalty
finality_delay = previous_epoch - state.finalized_epoch
@ -1508,20 +1457,21 @@ def get_attestation_deltas(state: BeaconState) -> Tuple[List[Gwei], List[Gwei]]:
```python
def get_crosslink_deltas(state: BeaconState) -> Tuple[List[Gwei], List[Gwei]]:
rewards = [0 for _ in range(len(state.validator_registry))]
penalties = [0 for _ in range(len(state.validator_registry))]
for slot in range(get_epoch_start_slot(get_previous_epoch(state)), get_epoch_start_slot(get_current_epoch(state))):
epoch = slot_to_epoch(slot)
for crosslink_committee, shard in get_crosslink_committees_at_slot(state, slot):
winning_crosslink, attesting_indices = get_winning_crosslink_and_attesting_indices(state, shard, epoch)
attesting_balance = get_total_balance(state, attesting_indices)
committee_balance = get_total_balance(state, crosslink_committee)
for index in crosslink_committee:
base_reward = get_base_reward(state, index)
if index in attesting_indices:
rewards[index] += base_reward * attesting_balance // committee_balance
else:
penalties[index] += base_reward
rewards = [0 for index in range(len(state.validator_registry))]
penalties = [0 for index in range(len(state.validator_registry))]
epoch = get_previous_epoch(state)
for offset in range(get_epoch_committee_count(state, epoch)):
shard = (get_epoch_start_shard(state, epoch) + offset) % SHARD_COUNT
crosslink_committee = get_crosslink_committee(state, epoch, shard)
winning_crosslink, attesting_indices = get_winning_crosslink_and_attesting_indices(state, epoch, shard)
attesting_balance = get_total_balance(state, attesting_indices)
committee_balance = get_total_balance(state, crosslink_committee)
for index in crosslink_committee:
base_reward = get_base_reward(state, index)
if index in attesting_indices:
rewards[index] += base_reward * attesting_balance // committee_balance
else:
penalties[index] += base_reward
return rewards, penalties
```
@ -1691,6 +1641,8 @@ def process_eth1_data(state: BeaconState, block: BeaconBlock) -> None:
#### Operations
Note: All functions in this section mutate `state`.
##### Proposer slashings
Verify that `len(block.body.proposer_slashings) <= MAX_PROPOSER_SLASHINGS`.
@ -1702,7 +1654,6 @@ def process_proposer_slashing(state: BeaconState,
proposer_slashing: ProposerSlashing) -> None:
"""
Process ``ProposerSlashing`` operation.
Note that this function mutates ``state``.
"""
proposer = state.validator_registry[proposer_slashing.proposer_index]
# Verify that the epoch is the same
@ -1730,31 +1681,21 @@ def process_attester_slashing(state: BeaconState,
attester_slashing: AttesterSlashing) -> None:
"""
Process ``AttesterSlashing`` operation.
Note that this function mutates ``state``.
"""
attestation1 = attester_slashing.attestation_1
attestation2 = attester_slashing.attestation_2
# Check that the attestations are conflicting
assert attestation1.data != attestation2.data
assert (
is_double_vote(attestation1.data, attestation2.data) or
is_surround_vote(attestation1.data, attestation2.data)
)
attestation_1 = attester_slashing.attestation_1
attestation_2 = attester_slashing.attestation_2
assert is_slashable_attestation_data(attestation_1.data, attestation_2.data)
assert verify_indexed_attestation(state, attestation_1)
assert verify_indexed_attestation(state, attestation_2)
assert verify_indexed_attestation(state, attestation1)
assert verify_indexed_attestation(state, attestation2)
attesting_indices_1 = attestation1.custody_bit_0_indices + attestation1.custody_bit_1_indices
attesting_indices_2 = attestation2.custody_bit_0_indices + attestation2.custody_bit_1_indices
slashable_indices = [
index for index in attesting_indices_1
if (
index in attesting_indices_2 and
is_slashable_validator(state.validator_registry[index], get_current_epoch(state))
)
]
assert len(slashable_indices) >= 1
for index in slashable_indices:
slash_validator(state, index)
slashed_any = False
attesting_indices_1 = attestation_1.custody_bit_0_indices + attestation_1.custody_bit_1_indices
attesting_indices_2 = attestation_2.custody_bit_0_indices + attestation_2.custody_bit_1_indices
for index in set(attesting_indices_1).intersection(attesting_indices_2):
if is_slashable_validator(state.validator_registry[index], get_current_epoch(state)):
slash_validator(state, index)
slashed_any = True
assert slashed_any
```
##### Attestations
@ -1767,15 +1708,13 @@ For each `attestation` in `block.body.attestations`, run the following function:
def process_attestation(state: BeaconState, attestation: Attestation) -> None:
"""
Process ``Attestation`` operation.
Note that this function mutates ``state``.
"""
data = attestation.data
min_slot = state.slot - SLOTS_PER_EPOCH if get_current_epoch(state) > GENESIS_EPOCH else GENESIS_SLOT
assert min_slot <= data.slot <= state.slot - MIN_ATTESTATION_INCLUSION_DELAY
attestation_slot = get_attestation_slot(state, attestation)
assert attestation_slot + MIN_ATTESTATION_INCLUSION_DELAY <= state.slot <= attestation_slot + SLOTS_PER_EPOCH
# Check target epoch, source epoch, source root, and source crosslink
target_epoch = slot_to_epoch(data.slot)
assert (target_epoch, data.source_epoch, data.source_root, data.previous_crosslink_root) in {
data = attestation.data
assert (data.target_epoch, data.source_epoch, data.source_root, data.previous_crosslink_root) in {
(get_current_epoch(state), state.current_justified_epoch, state.current_justified_root, hash_tree_root(state.current_crosslinks[data.shard])),
(get_previous_epoch(state), state.previous_justified_epoch, state.previous_justified_root, hash_tree_root(state.previous_crosslinks[data.shard])),
}
@ -1790,10 +1729,10 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
pending_attestation = PendingAttestation(
data=data,
aggregation_bitfield=attestation.aggregation_bitfield,
inclusion_slot=state.slot,
inclusion_delay=state.slot - attestation_slot,
proposer_index=get_beacon_proposer_index(state),
)
if target_epoch == get_current_epoch(state):
if data.target_epoch == get_current_epoch(state):
state.current_epoch_attestations.append(pending_attestation)
else:
state.previous_epoch_attestations.append(pending_attestation)
@ -1809,7 +1748,6 @@ For each `deposit` in `block.body.deposits`, run the following function:
def process_deposit(state: BeaconState, deposit: Deposit) -> None:
"""
Process an Eth1 deposit, registering a validator or increasing its balance.
Note that this function mutates ``state``.
"""
# Verify the Merkle branch
assert verify_merkle_branch(
@ -1859,7 +1797,6 @@ For each `exit` in `block.body.voluntary_exits`, run the following function:
def process_voluntary_exit(state: BeaconState, exit: VoluntaryExit) -> None:
"""
Process ``VoluntaryExit`` operation.
Note that this function mutates ``state``.
"""
validator = state.validator_registry[exit.validator_index]
# Verify the validator is active
@ -1887,7 +1824,6 @@ For each `transfer` in `block.body.transfers`, run the following function:
def process_transfer(state: BeaconState, transfer: Transfer) -> None:
"""
Process ``Transfer`` operation.
Note that this function mutates ``state``.
"""
# Verify the amount and fee are not individually too big (for anti-overflow purposes)
assert state.balances[transfer.sender] >= max(transfer.amount, transfer.fee)

18
specs/core/1_shard-data-chains.md
View File

@ -120,21 +120,15 @@ This document describes the shard data layer and the shard fork choice rule in P
### `get_period_committee`
```python
def get_period_committee(state: BeaconState,
shard: Shard,
committee_start_epoch: Epoch,
index: int,
committee_count: int) -> List[ValidatorIndex]:
def get_period_committee(state: BeaconState, epoch: Epoch, shard: Shard, index: int, count: int) -> List[ValidatorIndex]:
"""
Return committee for a period. Used to construct persistent committees.
"""
active_validator_indices = get_active_validator_indices(state.validator_registry, committee_start_epoch)
seed = generate_seed(state, committee_start_epoch)
return compute_committee(
validator_indices=active_validator_indices,
seed=seed,
index=shard * committee_count + index,
total_committees=SHARD_COUNT * committee_count,
indices=get_active_validator_indices(state, epoch),
seed=generate_seed(state, epoch),
index=shard * count + index,
count=SHARD_COUNT * count,
)
```
@ -165,7 +159,7 @@ def get_persistent_committee(state: BeaconState,
len(get_active_validator_indices(state.validator_registry, later_start_epoch)) //
(SHARD_COUNT * TARGET_COMMITTEE_SIZE),
) + 1
index = slot % committee_count
earlier_committee = get_period_committee(state, shard, earlier_start_epoch, index, committee_count)
later_committee = get_period_committee(state, shard, later_start_epoch, index, committee_count)

2
specs/validator/0_beacon-chain-validator.md
View File

@ -410,7 +410,7 @@ If the software crashes at some point within this routine, then when the validat
### Attester slashing
To avoid "attester slashings", a validator must not sign two conflicting [`AttestationData`](../core/0_beacon-chain.md#attestationdata) objects where conflicting is defined as a set of two attestations that satisfy either [`is_double_vote`](../core/0_beacon-chain.md#is_double_vote) or [`is_surround_vote`](../core/0_beacon-chain.md#is_surround_vote).
To avoid "attester slashings", a validator must not sign two conflicting [`AttestationData`](../core/0_beacon-chain.md#attestationdata) objects, i.e. two attestations that satisfy [`is_slashable_attestation_data`](../core/0_beacon-chain.md#is_slashable_attestation_data).
Specifically, when signing an `Attestation`, a validator should perform the following steps in the following order:
1. Save a record to hard disk that an attestation has been signed for source -- `attestation_data.source_epoch` -- and target -- `slot_to_epoch(attestation_data.slot)`.

3
test_libs/pyspec/tests/block_processing/test_process_attestation.py
View File

@ -38,8 +38,7 @@ def run_attestation_processing(state, attestation, valid=True):
process_attestation(post_state, attestation)
current_epoch = get_current_epoch(state)
target_epoch = slot_to_epoch(attestation.data.slot)
if target_epoch == current_epoch:
if attestation.data.target_epoch == current_epoch:
assert len(post_state.current_epoch_attestations) == len(state.current_epoch_attestations) + 1
else:
assert len(post_state.previous_epoch_attestations) == len(state.previous_epoch_attestations) + 1

4
test_libs/pyspec/tests/block_processing/test_process_attester_slashing.py
View File

@ -65,7 +65,7 @@ def test_success_surround(state):
# set attestion1 to surround attestation 2
attester_slashing.attestation_1.data.source_epoch = attester_slashing.attestation_2.data.source_epoch - 1
attester_slashing.attestation_1.data.slot = attester_slashing.attestation_2.data.slot + spec.SLOTS_PER_EPOCH
attester_slashing.attestation_1.data.target_epoch = attester_slashing.attestation_2.data.target_epoch + 1
pre_state, post_state = run_attester_slashing_processing(state, attester_slashing)
@ -85,7 +85,7 @@ def test_same_data(state):
def test_no_double_or_surround(state):
attester_slashing = get_valid_attester_slashing(state)
attester_slashing.attestation_1.data.slot += spec.SLOTS_PER_EPOCH
attester_slashing.attestation_1.data.target_epoch += 1
pre_state, post_state = run_attester_slashing_processing(state, attester_slashing, False)

6
test_libs/pyspec/tests/epoch_processing/test_process_crosslinks.py
View File

@ -15,7 +15,7 @@ from tests.helpers import (
add_attestation_to_state,
build_empty_block_for_next_slot,
fill_aggregate_attestation,
get_crosslink_committee_for_attestation,
get_crosslink_committee,
get_valid_attestation,
next_epoch,
next_slot,
@ -88,7 +88,7 @@ def test_single_crosslink_update_from_previous_epoch(state):
assert post_state.previous_crosslinks[shard] != post_state.current_crosslinks[shard]
assert pre_state.current_crosslinks[shard] != post_state.current_crosslinks[shard]
# ensure rewarded
for index in get_crosslink_committee_for_attestation(state, attestation.data):
for index in get_crosslink_committee(state, attestation.data.target_epoch, attestation.data.shard):
assert crosslink_deltas[0][index] > 0
assert crosslink_deltas[1][index] == 0
@ -129,7 +129,7 @@ def test_double_late_crosslink(state):
# ensure that the current crosslinks were not updated by the second attestation
assert post_state.previous_crosslinks[shard] == post_state.current_crosslinks[shard]
# ensure no reward, only penalties for the failed crosslink
for index in get_crosslink_committee_for_attestation(state, attestation_2.data):
for index in get_crosslink_committee(state, attestation_2.data.target_epoch, attestation_2.data.shard):
assert crosslink_deltas[0][index] == 0
assert crosslink_deltas[1][index] > 0

18
test_libs/pyspec/tests/helpers.py
View File

@ -29,7 +29,7 @@ from eth2spec.phase0.spec import (
get_attesting_indices,
get_block_root,
get_block_root_at_slot,
get_crosslink_committees_at_slot,
get_crosslink_committee,
get_current_epoch,
get_domain,
get_epoch_start_slot,
@ -174,11 +174,11 @@ def build_attestation_data(state, slot, shard):
crosslinks = state.current_crosslinks if slot_to_epoch(slot) == get_current_epoch(state) else state.previous_crosslinks
return AttestationData(
slot=slot,
shard=shard,
beacon_block_root=block_root,
source_epoch=justified_epoch,
source_root=justified_block_root,
target_epoch=slot_to_epoch(slot),
target_root=epoch_boundary_root,
crosslink_data_root=spec.ZERO_HASH,
previous_crosslink_root=hash_tree_root(crosslinks[shard]),
@ -276,14 +276,6 @@ def get_valid_attester_slashing(state):
)
def get_crosslink_committee_for_attestation(state, attestation_data):
"""
Return the crosslink committee corresponding to ``attestation_data``.
"""
crosslink_committees = get_crosslink_committees_at_slot(state, attestation_data.slot)
return [committee for committee, shard in crosslink_committees if shard == attestation_data.shard][0]
def get_valid_attestation(state, slot=None):
if slot is None:
slot = state.slot
@ -296,7 +288,7 @@ def get_valid_attestation(state, slot=None):
attestation_data = build_attestation_data(state, slot, shard)
crosslink_committee = get_crosslink_committee_for_attestation(state, attestation_data)
crosslink_committee = get_crosslink_committee(state, attestation_data.target_epoch, attestation_data.shard)
committee_size = len(crosslink_committee)
bitfield_length = (committee_size + 7) // 8
@ -383,13 +375,13 @@ def get_attestation_signature(state, attestation_data, privkey, custody_bit=0b0)
domain=get_domain(
state=state,
domain_type=spec.DOMAIN_ATTESTATION,
message_epoch=slot_to_epoch(attestation_data.slot),
message_epoch=attestation_data.target_epoch,
)
)
def fill_aggregate_attestation(state, attestation):
crosslink_committee = get_crosslink_committee_for_attestation(state, attestation.data)
crosslink_committee = get_crosslink_committee(state, attestation.data.target_epoch, attestation.data.shard)
for i in range(len(crosslink_committee)):
attestation.aggregation_bitfield = set_bitfield_bit(attestation.aggregation_bitfield, i)