def initialize_beacon_state_from_eth1(eth1_block_hash: Bytes32,
eth1_timestamp: uint64,
deposits: Sequence[Deposit]) -> BeaconState:
state = BeaconState(
genesis_time=eth1_timestamp - eth1_timestamp % SECONDS_PER_DAY + 2 * SECONDS_PER_DAY,
eth1_data=Eth1Data(block_hash=eth1_block_hash, deposit_count=len(deposits)),
latest_block_header=BeaconBlockHeader(body_root=hash_tree_root(BeaconBlockBody())),
randao_mixes=[eth1_block_hash] * EPOCHS_PER_HISTORICAL_VECTOR, # Seed RANDAO with Eth1 entropy
)
# Process deposits
leaves = list(map(lambda deposit: deposit.data, deposits))
for index, deposit in enumerate(deposits):
deposit_data_list = List[DepositData, 2**DEPOSIT_CONTRACT_TREE_DEPTH](*leaves[:index + 1])
state.eth1_data.deposit_root = hash_tree_root(deposit_data_list)
process_deposit(state, deposit)
# Process activations
for index, validator in enumerate(state.validators):
balance = state.balances[index]
validator.effective_balance = min(balance - balance % EFFECTIVE_BALANCE_INCREMENT, MAX_EFFECTIVE_BALANCE)
if validator.effective_balance == MAX_EFFECTIVE_BALANCE:
validator.activation_eligibility_epoch = GENESIS_EPOCH
validator.activation_epoch = GENESIS_EPOCH
return state
def aggregate_attestations(state, attestations):
# Take in a set of attestations
# Output aggregated attestations
hashes = [hash_tree_root(att) for att in attestations]
return [
build_aggregate(state, [
att for att in attestations if att_hash == hash_tree_root(att)
]) for att_hash in hashes
]
def process_slot(state: BeaconState) -> None:
# Cache state root
previous_state_root = hash_tree_root(state)
state.state_roots[state.slot % SLOTS_PER_HISTORICAL_ROOT] = previous_state_root
# Cache latest block header state root
if state.latest_block_header.state_root == Bytes32():
state.latest_block_header.state_root = previous_state_root
# Cache block root
previous_block_root = hash_tree_root(state.latest_block_header)
state.block_roots[state.slot % SLOTS_PER_HISTORICAL_ROOT] = previous_block_root
def process_block_header(state: BeaconState, block: BeaconBlock) -> None:
# Verify that the slots match
assert block.slot == state.slot
# Verify that the parent matches
assert block.parent_root == hash_tree_root(state.latest_block_header)
# Save current block as the new latest block
state.latest_block_header = BeaconBlockHeader(
slot=block.slot,
parent_root=block.parent_root,
# `state_root` is zeroed and overwritten in the next `process_slot` call
body_root=hash_tree_root(block.body),
)
# Verify proposer is not slashed
proposer = state.validators[get_beacon_proposer_index(state)]
assert not proposer.slashed
def propose_block(params, step, sL, s):
# Given state w-[s], propose a block for slot s
# `state` is w-[s]
state = s['beacon_state']
# `current_slot` is s
current_slot = state.slot
print("propose a block, current_slot", current_slot)
# If this is the first slot, use the `genesis_block`
if current_slot == 0:
return ({'block': get_genesis_block(state)})
# Later on, we populate the `BeaconBlockBody`. For now, our validators merely produce empty blocks.
beacon_block_body = BeaconBlockBody(attestations=s[
'current_slot_attestations'] # <--- THIS IS THE NEW LINE
)
beacon_block = BeaconBlock(
slot=current_slot,
parent_root=hash_tree_root(
state.latest_block_header
), # the parent root is accessed from the state
body=beacon_block_body)
signed_beacon_block = SignedBeaconBlock(message=beacon_block)
return ({'block': signed_beacon_block})
def process_randao(state: BeaconState, body: BeaconBlockBody) -> None:
epoch = get_current_epoch(state)
# Verify RANDAO reveal
proposer = state.validators[get_beacon_proposer_index(state)]
assert bls_verify(proposer.pubkey, hash_tree_root(epoch), body.randao_reveal, get_domain(state, DOMAIN_RANDAO))
# Mix in RANDAO reveal
mix = xor(get_randao_mix(state, epoch), hash(body.randao_reveal))
state.randao_mixes[epoch % EPOCHS_PER_HISTORICAL_VECTOR] = mix
def process_deposit(state: BeaconState, deposit: Deposit) -> None:
# Verify the Merkle branch
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
index=state.eth1_deposit_index,
root=state.eth1_data.deposit_root,
)
# Deposits must be processed in order
state.eth1_deposit_index += 1
pubkey = deposit.data.pubkey
amount = deposit.data.amount
validator_pubkeys = [v.pubkey for v in state.validators]
if pubkey not in validator_pubkeys:
# Verify the deposit signature (proof of possession) for new validators.
# Note: The deposit contract does not check signatures.
# Note: Deposits are valid across forks, thus the deposit domain is retrieved directly from `compute_domain`.
domain = compute_domain(DOMAIN_DEPOSIT)
deposit_message = DepositMessage(
pubkey=deposit.data.pubkey,
withdrawal_credentials=deposit.data.withdrawal_credentials,
amount=deposit.data.amount)
if not bls_verify(pubkey, hash_tree_root(deposit_message), deposit.data.signature, domain):
return
# Add validator and balance entries
state.validators.append(Validator(
pubkey=pubkey,
withdrawal_credentials=deposit.data.withdrawal_credentials,
activation_eligibility_epoch=FAR_FUTURE_EPOCH,
activation_epoch=FAR_FUTURE_EPOCH,
exit_epoch=FAR_FUTURE_EPOCH,
withdrawable_epoch=FAR_FUTURE_EPOCH,
effective_balance=min(amount - amount % EFFECTIVE_BALANCE_INCREMENT, MAX_EFFECTIVE_BALANCE),
))
state.balances.append(amount)
else:
# Increase balance by deposit amount
index = ValidatorIndex(validator_pubkeys.index(pubkey))
increase_balance(state, index, amount)
def state_transition(state: BeaconState, signed_block: SignedBeaconBlock, validate_result: bool=True) -> BeaconState:
# Process slots (including those with no blocks) since block
process_slots(state, signed_block.message.slot)
# Verify signature
if validate_result:
assert verify_block_signature(state, signed_block)
# Process block
process_block(state, signed_block.message)
if validate_result:
assert signed_block.message.state_root == hash_tree_root(state) # Validate state root
# Return post-state
return state
def process_voluntary_exit(state: BeaconState, signed_voluntary_exit: SignedVoluntaryExit) -> None:
voluntary_exit = signed_voluntary_exit.message
validator = state.validators[voluntary_exit.validator_index]
# Verify the validator is active
assert is_active_validator(validator, get_current_epoch(state))
# Verify the validator has not yet exited
assert validator.exit_epoch == FAR_FUTURE_EPOCH
# Exits must specify an epoch when they become valid; they are not valid before then
assert get_current_epoch(state) >= voluntary_exit.epoch
# Verify the validator has been active long enough
assert get_current_epoch(state) >= validator.activation_epoch + PERSISTENT_COMMITTEE_PERIOD
# Verify signature
domain = get_domain(state, DOMAIN_VOLUNTARY_EXIT, voluntary_exit.epoch)
assert bls_verify(validator.pubkey, hash_tree_root(voluntary_exit), signed_voluntary_exit.signature, domain)
# Initiate exit
initiate_validator_exit(state, voluntary_exit.validator_index)
def is_valid_indexed_attestation(state: BeaconState, indexed_attestation: IndexedAttestation) -> bool:
"""
Check if ``indexed_attestation`` has valid indices and signature.
"""
indices = indexed_attestation.attesting_indices
# Verify max number of indices
if not len(indices) <= MAX_VALIDATORS_PER_COMMITTEE:
return False
# Verify indices are sorted
if not indices == sorted(indices):
return False
# Verify aggregate signature
if not bls_verify(
pubkey=aggregate_pubkeys([state.validators[i].pubkey for i in indices]),
message_hash=hash_tree_root(indexed_attestation.data),
signature=indexed_attestation.signature,
domain=get_domain(state, DOMAIN_BEACON_ATTESTER, indexed_attestation.data.target.epoch),
):
return False
return True
def process_final_updates(state: BeaconState) -> None:
current_epoch = get_current_epoch(state)
next_epoch = Epoch(current_epoch + 1)
# Reset eth1 data votes
if (state.slot + 1) % SLOTS_PER_ETH1_VOTING_PERIOD == 0:
state.eth1_data_votes = []
# Update effective balances with hysteresis
for index, validator in enumerate(state.validators):
balance = state.balances[index]
HALF_INCREMENT = EFFECTIVE_BALANCE_INCREMENT // 2
if balance < validator.effective_balance or validator.effective_balance + 3 * HALF_INCREMENT < balance:
validator.effective_balance = min(balance - balance % EFFECTIVE_BALANCE_INCREMENT, MAX_EFFECTIVE_BALANCE)
# Reset slashings
state.slashings[next_epoch % EPOCHS_PER_SLASHINGS_VECTOR] = Gwei(0)
# Set randao mix
state.randao_mixes[next_epoch % EPOCHS_PER_HISTORICAL_VECTOR] = get_randao_mix(state, current_epoch)
# Set historical root accumulator
if next_epoch % (SLOTS_PER_HISTORICAL_ROOT // SLOTS_PER_EPOCH) == 0:
historical_batch = HistoricalBatch(block_roots=state.block_roots, state_roots=state.state_roots)
state.historical_roots.append(hash_tree_root(historical_batch))
# Rotate current/previous epoch attestations
state.previous_epoch_attestations = state.current_epoch_attestations
state.current_epoch_attestations = []
def verify_block_signature(state: BeaconState, signed_block: SignedBeaconBlock) -> bool:
proposer = state.validators[get_beacon_proposer_index(state)]
domain = get_domain(state, DOMAIN_BEACON_PROPOSER)
return bls_verify(proposer.pubkey, hash_tree_root(signed_block.message), signed_block.signature, domain)
def hash_tree_root(self):
from ssz_impl import hash_tree_root
return hash_tree_root(self)
def get_genesis_block(genesis_state):
return SignedBeaconBlock(message=BeaconBlock(
state_root=hash_tree_root(genesis_state),
parent_root=hash_tree_root(genesis_state.latest_block_header)))
def process_genesis_block(genesis_state):
genesis_block = specs.SignedBeaconBlock(message=specs.BeaconBlock(
state_root=hash_tree_root(genesis_state),
parent_root=hash_tree_root(genesis_state.latest_block_header)))
specs.process_block(genesis_state, genesis_block.message)
