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Apply strict uint64 casting
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hwwhww committed Apr 23, 2020
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112 changes: 58 additions & 54 deletions specs/phase0/beacon-chain.md
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Original file line number Diff line number Diff line change
Expand Up @@ -166,9 +166,9 @@ The following values are (non-configurable) constants used throughout the specif
| `GENESIS_SLOT` | `Slot(0)` |
| `GENESIS_EPOCH` | `Epoch(0)` |
| `FAR_FUTURE_EPOCH` | `Epoch(2**64 - 1)` |
| `BASE_REWARDS_PER_EPOCH` | `4` |
| `DEPOSIT_CONTRACT_TREE_DEPTH` | `2**5` (= 32) |
| `JUSTIFICATION_BITS_LENGTH` | `4` |
| `BASE_REWARDS_PER_EPOCH` | `uint64(4)` |
| `DEPOSIT_CONTRACT_TREE_DEPTH` | `uint64(2**5)` (= 32) |
| `JUSTIFICATION_BITS_LENGTH` | `uint64(4)` |
| `ENDIANNESS` | `'little'` |

## Configuration
Expand All @@ -179,17 +179,17 @@ The following values are (non-configurable) constants used throughout the specif

| Name | Value |
| - | - |
| `MAX_COMMITTEES_PER_SLOT` | `2**6` (= 64) |
| `TARGET_COMMITTEE_SIZE` | `2**7` (= 128) |
| `MAX_VALIDATORS_PER_COMMITTEE` | `2**11` (= 2,048) |
| `MIN_PER_EPOCH_CHURN_LIMIT` | `2**2` (= 4) |
| `CHURN_LIMIT_QUOTIENT` | `2**16` (= 65,536) |
| `SHUFFLE_ROUND_COUNT` | `90` |
| `MIN_GENESIS_ACTIVE_VALIDATOR_COUNT` | `2**14` (= 16,384) |
| `MIN_GENESIS_TIME` | `1578009600` (Jan 3, 2020) |
| `HYSTERESIS_QUOTIENT` | `4` |
| `HYSTERESIS_DOWNWARD_MULTIPLIER` | `1` |
| `HYSTERESIS_UPWARD_MULTIPLIER` | `5` |
| `MAX_COMMITTEES_PER_SLOT` | `uint64(2**6)` (= 64) |
| `TARGET_COMMITTEE_SIZE` | `uint64(2**7)` (= 128) |
| `MAX_VALIDATORS_PER_COMMITTEE` | `uint64(2**11)` (= 2,048) |
| `MIN_PER_EPOCH_CHURN_LIMIT` | `uint64(2**2)` (= 4) |
| `CHURN_LIMIT_QUOTIENT` | `uint64(2**16)` (= 65,536) |
| `SHUFFLE_ROUND_COUNT` | `uint64(90)` |
| `MIN_GENESIS_ACTIVE_VALIDATOR_COUNT` | `uint64(2**14)` (= 16,384) |
| `MIN_GENESIS_TIME` | `uint64(1578009600)` (Jan 3, 2020) |
| `HYSTERESIS_QUOTIENT` | `uint64(4)` |
| `HYSTERESIS_DOWNWARD_MULTIPLIER` | `uint64(1)` |
| `HYSTERESIS_UPWARD_MULTIPLIER` | `uint64(5)` |

- For the safety of committees, `TARGET_COMMITTEE_SIZE` exceeds [the recommended minimum committee size of 111](http://web.archive.org/web/20190504131341/https://vitalik.ca/files/Ithaca201807_Sharding.pdf); with sufficient active validators (at least `SLOTS_PER_EPOCH * TARGET_COMMITTEE_SIZE`), the shuffling algorithm ensures committee sizes of at least `TARGET_COMMITTEE_SIZE`. (Unbiasable randomness with a Verifiable Delay Function (VDF) will improve committee robustness and lower the safe minimum committee size.)

Expand All @@ -213,36 +213,36 @@ The following values are (non-configurable) constants used throughout the specif

| Name | Value | Unit | Duration |
| - | - | :-: | :-: |
| `MIN_GENESIS_DELAY` | `86400` | seconds | 1 day |
| `SECONDS_PER_SLOT` | `12` | seconds | 12 seconds |
| `MIN_ATTESTATION_INCLUSION_DELAY` | `2**0` (= 1) | slots | 12 seconds |
| `SLOTS_PER_EPOCH` | `2**5` (= 32) | slots | 6.4 minutes |
| `MIN_SEED_LOOKAHEAD` | `2**0` (= 1) | epochs | 6.4 minutes |
| `MAX_SEED_LOOKAHEAD` | `2**2` (= 4) | epochs | 25.6 minutes |
| `MIN_EPOCHS_TO_INACTIVITY_PENALTY` | `2**2` (= 4) | epochs | 25.6 minutes |
| `EPOCHS_PER_ETH1_VOTING_PERIOD` | `2**5` (= 32) | epochs | ~3.4 hours |
| `SLOTS_PER_HISTORICAL_ROOT` | `2**13` (= 8,192) | slots | ~27 hours |
| `MIN_VALIDATOR_WITHDRAWABILITY_DELAY` | `2**8` (= 256) | epochs | ~27 hours |
| `PERSISTENT_COMMITTEE_PERIOD` | `2**11` (= 2,048) | epochs | 9 days |
| `MIN_GENESIS_DELAY` | `uint64(86400)` | seconds | 1 day |
| `SECONDS_PER_SLOT` | `uint64(12)` | seconds | 12 seconds |
| `MIN_ATTESTATION_INCLUSION_DELAY` | `uint64(2**0)` (= 1) | slots | 12 seconds |
| `SLOTS_PER_EPOCH` | `uint64(2**5)` (= 32) | slots | 6.4 minutes |
| `MIN_SEED_LOOKAHEAD` | `uint64(2**0)` (= 1) | epochs | 6.4 minutes |
| `MAX_SEED_LOOKAHEAD` | `uint64(2**2)` (= 4) | epochs | 25.6 minutes |
| `MIN_EPOCHS_TO_INACTIVITY_PENALTY` | `uint64(2**2)` (= 4) | epochs | 25.6 minutes |
| `EPOCHS_PER_ETH1_VOTING_PERIOD` | `uint64(2**5)` (= 32) | epochs | ~3.4 hours |
| `SLOTS_PER_HISTORICAL_ROOT` | `uint64(2**13)` (= 8,192) | slots | ~27 hours |
| `MIN_VALIDATOR_WITHDRAWABILITY_DELAY` | `uint64(2**8)` (= 256) | epochs | ~27 hours |
| `PERSISTENT_COMMITTEE_PERIOD` | `uint64(2**11)` (= 2,048) | epochs | 9 days |

### State list lengths

| Name | Value | Unit | Duration |
| - | - | :-: | :-: |
| `EPOCHS_PER_HISTORICAL_VECTOR` | `2**16` (= 65,536) | epochs | ~0.8 years |
| `EPOCHS_PER_SLASHINGS_VECTOR` | `2**13` (= 8,192) | epochs | ~36 days |
| `HISTORICAL_ROOTS_LIMIT` | `2**24` (= 16,777,216) | historical roots | ~52,262 years |
| `VALIDATOR_REGISTRY_LIMIT` | `2**40` (= 1,099,511,627,776) | validators |
| `EPOCHS_PER_HISTORICAL_VECTOR` | `uint64(2**16)` (= 65,536) | epochs | ~0.8 years |
| `EPOCHS_PER_SLASHINGS_VECTOR` | `uint64(2**13)` (= 8,192) | epochs | ~36 days |
| `HISTORICAL_ROOTS_LIMIT` | `uint64(2**24)` (= 16,777,216) | historical roots | ~52,262 years |
| `VALIDATOR_REGISTRY_LIMIT` | `uint64(2**40)` (= 1,099,511,627,776) | validators |

### Rewards and penalties

| Name | Value |
| - | - |
| `BASE_REWARD_FACTOR` | `2**6` (= 64) |
| `WHISTLEBLOWER_REWARD_QUOTIENT` | `2**9` (= 512) |
| `PROPOSER_REWARD_QUOTIENT` | `2**3` (= 8) |
| `INACTIVITY_PENALTY_QUOTIENT` | `2**24` (= 16,777,216) |
| `MIN_SLASHING_PENALTY_QUOTIENT` | `2**5` (= 32) |
| `BASE_REWARD_FACTOR` | `uint64(2**6)` (= 64) |
| `WHISTLEBLOWER_REWARD_QUOTIENT` | `uint64(2**9)` (= 512) |
| `PROPOSER_REWARD_QUOTIENT` | `uint64(2**3)` (= 8) |
| `INACTIVITY_PENALTY_QUOTIENT` | `uint64(2**24)` (= 16,777,216) |
| `MIN_SLASHING_PENALTY_QUOTIENT` | `uint64(2**5)` (= 32) |

- The `INACTIVITY_PENALTY_QUOTIENT` equals `INVERSE_SQRT_E_DROP_TIME**2` where `INVERSE_SQRT_E_DROP_TIME := 2**12` epochs (about 18 days) is the time it takes the inactivity penalty to reduce the balance of non-participating validators to about `1/sqrt(e) ~= 60.6%`. Indeed, the balance retained by offline validators after `n` epochs is about `(1 - 1/INACTIVITY_PENALTY_QUOTIENT)**(n**2/2)`; so after `INVERSE_SQRT_E_DROP_TIME` epochs, it is roughly `(1 - 1/INACTIVITY_PENALTY_QUOTIENT)**(INACTIVITY_PENALTY_QUOTIENT/2) ~= 1/sqrt(e)`.

Expand Down Expand Up @@ -555,9 +555,9 @@ def integer_squareroot(n: uint64) -> uint64:
x = n
y = (x + 1) // 2
while y < x:
x = y
x = uint64(y)
y = (x + n // x) // 2
return x
return uint64(x)
```

#### `xor`
Expand Down Expand Up @@ -587,7 +587,7 @@ def bytes_to_int(data: bytes) -> uint64:
"""
Return the integer deserialization of ``data`` interpreted as ``ENDIANNESS``-endian.
"""
return int.from_bytes(data, ENDIANNESS)
return uint64(int.from_bytes(data, ENDIANNESS))
```

### Crypto
Expand Down Expand Up @@ -728,14 +728,18 @@ def compute_shuffled_index(index: uint64, index_count: uint64, seed: Bytes32) ->

# 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 current_round in range(SHUFFLE_ROUND_COUNT):
pivot = bytes_to_int(hash(seed + int_to_bytes(current_round, length=1))[0:8]) % index_count
for current_round in map(uint64, range(SHUFFLE_ROUND_COUNT)):
pivot = bytes_to_int(hash(seed + int_to_bytes(current_round, length=uint64(1)))[0:8]) % index_count
flip = (pivot + index_count - index) % index_count
position = max(index, flip)
source = hash(seed + int_to_bytes(current_round, length=1) + int_to_bytes(position // 256, length=4))
source = hash(
seed
+ int_to_bytes(current_round, length=uint64(1))
+ int_to_bytes(uint64(position // 256), length=uint64(4))
)
byte = source[(position % 256) // 8]
bit = (byte >> (position % 8)) % 2
index = flip if bit else index
index = uint64(flip) if bit else index

return index
```
Expand All @@ -751,8 +755,8 @@ def compute_proposer_index(state: BeaconState, indices: Sequence[ValidatorIndex]
MAX_RANDOM_BYTE = 2**8 - 1
i = 0
while True:
candidate_index = indices[compute_shuffled_index(i % len(indices), len(indices), seed)]
random_byte = hash(seed + int_to_bytes(i // 32, length=8))[i % 32]
candidate_index = indices[compute_shuffled_index(uint64(i % len(indices)), uint64(len(indices)), seed)]
random_byte = hash(seed + int_to_bytes(uint64(i // 32), length=uint64(8)))[i % 32]
effective_balance = state.validators[candidate_index].effective_balance
if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE * random_byte:
return candidate_index
Expand All @@ -771,7 +775,7 @@ def compute_committee(indices: Sequence[ValidatorIndex],
"""
start = (len(indices) * index) // count
end = (len(indices) * (index + 1)) // count
return [indices[compute_shuffled_index(i, len(indices), seed)] for i in range(start, end)]
return [indices[compute_shuffled_index(uint64(i), uint64(len(indices)), seed)] for i in range(start, end)]
```

#### `compute_epoch_at_slot`
Expand Down Expand Up @@ -930,7 +934,7 @@ def get_validator_churn_limit(state: BeaconState) -> uint64:
Return the validator churn limit for the current epoch.
"""
active_validator_indices = get_active_validator_indices(state, get_current_epoch(state))
return max(MIN_PER_EPOCH_CHURN_LIMIT, len(active_validator_indices) // CHURN_LIMIT_QUOTIENT)
return max(MIN_PER_EPOCH_CHURN_LIMIT, uint64(len(active_validator_indices) // CHURN_LIMIT_QUOTIENT))
```

#### `get_seed`
Expand All @@ -941,7 +945,7 @@ def get_seed(state: BeaconState, epoch: Epoch, domain_type: DomainType) -> Bytes
Return the seed at ``epoch``.
"""
mix = get_randao_mix(state, Epoch(epoch + EPOCHS_PER_HISTORICAL_VECTOR - MIN_SEED_LOOKAHEAD - 1)) # Avoid underflow
return hash(domain_type + int_to_bytes(epoch, length=8) + mix)
return hash(domain_type + int_to_bytes(epoch, length=uint64(8)) + mix)
```

#### `get_committee_count_at_slot`
Expand All @@ -952,9 +956,9 @@ def get_committee_count_at_slot(state: BeaconState, slot: Slot) -> uint64:
Return the number of committees at ``slot``.
"""
epoch = compute_epoch_at_slot(slot)
return max(1, min(
return max(uint64(1), min(
MAX_COMMITTEES_PER_SLOT,
len(get_active_validator_indices(state, epoch)) // SLOTS_PER_EPOCH // TARGET_COMMITTEE_SIZE,
uint64(len(get_active_validator_indices(state, epoch)) // SLOTS_PER_EPOCH // TARGET_COMMITTEE_SIZE),
))
```

Expand All @@ -970,8 +974,8 @@ def get_beacon_committee(state: BeaconState, slot: Slot, index: CommitteeIndex)
return compute_committee(
indices=get_active_validator_indices(state, epoch),
seed=get_seed(state, epoch, DOMAIN_BEACON_ATTESTER),
index=(slot % SLOTS_PER_EPOCH) * committees_per_slot + index,
count=committees_per_slot * SLOTS_PER_EPOCH,
index=uint64((slot % SLOTS_PER_EPOCH) * committees_per_slot + index),
count=uint64(committees_per_slot * SLOTS_PER_EPOCH),
)
```

Expand All @@ -983,7 +987,7 @@ def get_beacon_proposer_index(state: BeaconState) -> ValidatorIndex:
Return the beacon proposer index at the current slot.
"""
epoch = get_current_epoch(state)
seed = hash(get_seed(state, epoch, DOMAIN_BEACON_PROPOSER) + int_to_bytes(state.slot, length=8))
seed = hash(get_seed(state, epoch, DOMAIN_BEACON_PROPOSER) + int_to_bytes(state.slot, length=uint64(8)))
indices = get_active_validator_indices(state, epoch)
return compute_proposer_index(state, indices, seed)
```
Expand Down Expand Up @@ -1091,7 +1095,7 @@ def initiate_validator_exit(state: BeaconState, index: ValidatorIndex) -> None:
exit_queue_epoch = max(exit_epochs + [compute_activation_exit_epoch(get_current_epoch(state))])
exit_queue_churn = len([v for v in state.validators if v.exit_epoch == exit_queue_epoch])
if exit_queue_churn >= get_validator_churn_limit(state):
exit_queue_epoch += Epoch(1)
exit_queue_epoch = Epoch(exit_queue_epoch + 1)

# Set validator exit epoch and withdrawable epoch
validator.exit_epoch = exit_queue_epoch
Expand Down Expand Up @@ -1637,13 +1641,13 @@ def process_deposit(state: BeaconState, deposit: Deposit) -> None:
assert is_valid_merkle_branch(
leaf=hash_tree_root(deposit.data),
branch=deposit.proof,
depth=DEPOSIT_CONTRACT_TREE_DEPTH + 1, # Add 1 for the List length mix-in
depth=uint64(DEPOSIT_CONTRACT_TREE_DEPTH + 1), # Add 1 for the List length mix-in
index=state.eth1_deposit_index,
root=state.eth1_data.deposit_root,
)

# Deposits must be processed in order
state.eth1_deposit_index += 1
state.eth1_deposit_index = uint64(state.eth1_deposit_index + 1)

pubkey = deposit.data.pubkey
amount = deposit.data.amount
Expand Down
8 changes: 4 additions & 4 deletions specs/phase0/fork-choice.md
View file
Original file line number Diff line number Diff line change
Expand Up @@ -100,15 +100,15 @@ _The block for `anchor_root` is incorrectly initialized to the block header, rat

```python
def get_forkchoice_store(anchor_state: BeaconState) -> Store:
anchor_block_header = anchor_state.latest_block_header.copy()
anchor_block_header: BeaconBlockHeader = anchor_state.latest_block_header.copy()
if anchor_block_header.state_root == Bytes32():
anchor_block_header.state_root = hash_tree_root(anchor_state)
anchor_root = hash_tree_root(anchor_block_header)
anchor_epoch = get_current_epoch(anchor_state)
justified_checkpoint = Checkpoint(epoch=anchor_epoch, root=anchor_root)
finalized_checkpoint = Checkpoint(epoch=anchor_epoch, root=anchor_root)
return Store(
time=anchor_state.genesis_time + SECONDS_PER_SLOT * anchor_state.slot,
time=uint64(anchor_state.genesis_time + SECONDS_PER_SLOT * anchor_state.slot),
genesis_time=anchor_state.genesis_time,
justified_checkpoint=justified_checkpoint,
finalized_checkpoint=finalized_checkpoint,
Expand Down Expand Up @@ -297,7 +297,7 @@ def validate_on_attestation(store: Store, attestation: Attestation) -> None:
def store_target_checkpoint_state(store: Store, target: Checkpoint) -> None:
# Store target checkpoint state if not yet seen
if target not in store.checkpoint_states:
base_state = store.block_states[target.root].copy()
base_state: BeaconState = store.block_states[target.root].copy()
process_slots(base_state, compute_start_slot_at_epoch(target.epoch))
store.checkpoint_states[target] = base_state
```
Expand Down Expand Up @@ -341,7 +341,7 @@ def on_block(store: Store, signed_block: SignedBeaconBlock) -> None:
block = signed_block.message
# Make a copy of the state to avoid mutability issues
assert block.parent_root in store.block_states
pre_state = store.block_states[block.parent_root].copy()
pre_state: BeaconState = store.block_states[block.parent_root].copy()
# Blocks cannot be in the future. If they are, their consideration must be delayed until the are in the past.
assert get_current_slot(store) >= block.slot
# Add new block to the store
Expand Down
2 changes: 1 addition & 1 deletion specs/phase0/validator.md
View file
Original file line number Diff line number Diff line change
Expand Up @@ -269,7 +269,7 @@ An honest block proposer sets `block.body.eth1_data = get_eth1_vote(state)` wher

```python
def compute_time_at_slot(state: BeaconState, slot: Slot) -> uint64:
return state.genesis_time + slot * SECONDS_PER_SLOT
return uint64(state.genesis_time + slot * SECONDS_PER_SLOT)
```

```python
Expand Down

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