417 lines
15 KiB
Markdown
417 lines
15 KiB
Markdown
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# DepositEIP -- The Beacon Chain
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## Table of contents
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<!-- TOC -->
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<!-- START doctoc generated TOC please keep comment here to allow auto update -->
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<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
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- [Introduction](#introduction)
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- [Preset](#preset)
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- [State list lengths](#state-list-lengths)
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- [Execution](#execution)
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- [Containers](#containers)
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- [New containers](#new-containers)
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- [`DepositReceipt`](#depositreceipt)
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- [`IndexedDepositData`](#indexeddepositdata)
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- [Extended Containers](#extended-containers)
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- [`ExecutionPayload`](#executionpayload)
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- [`ExecutionPayloadHeader`](#executionpayloadheader)
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- [`BeaconState`](#beaconstate)
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- [Beacon chain state transition function](#beacon-chain-state-transition-function)
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- [Epoch processing](#epoch-processing)
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- [Helper functions](#helper-functions)
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- [New `get_validator_from_indexed_deposit_data`](#new-get_validator_from_indexed_deposit_data)
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- [New `apply_pending_deposit`](#new-apply_pending_deposit)
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- [New `process_pending_deposits`](#new-process_pending_deposits)
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- [Block processing](#block-processing)
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- [New `process_deposit_receipts`](#new-process_deposit_receipts)
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- [Modified `process_execution_payload`](#modified-process_execution_payload)
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- [Modified `process_operations`](#modified-process_operations)
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- [Testing](#testing)
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<!-- END doctoc generated TOC please keep comment here to allow auto update -->
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<!-- /TOC -->
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## Introduction
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This is the beacon chain specification of in-protocol deposits processing mechanism.
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This mechanism relies on the changes proposed by the corresponding EIP.
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*Note:* This specification is under development and should be used with care.
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## Preset
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### State list lengths
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| Name | Value |
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| - | - |
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| `PENDING_DEPOSITS_LIMIT` | `2**32` (= 4,294,967,296) |
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### Execution
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| Name | Value | Description |
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| - | - | - |
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| `MAX_DEPOSIT_RECEIPTS_PER_PAYLOAD` | `uint64(2**10)` (= 1,024) | Maximum number of deposit receipts allowed in each payload |
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## Containers
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### New containers
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#### `DepositReceipt`
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```python
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class DepositReceipt(Container):
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pubkey: BLSPubkey
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withdrawal_credentials: Bytes32
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amount: Gwei
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signature: BLSSignature
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index: uint64
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```
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#### `IndexedDepositData`
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```python
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class IndexedDepositData(Container):
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pubkey: BLSPubkey
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withdrawal_credentials: Bytes32
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amount: Gwei
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index: uint64
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epoch: Epoch
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```
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### Extended Containers
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#### `ExecutionPayload`
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```python
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class ExecutionPayload(Container):
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# Execution block header fields
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parent_hash: Hash32
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fee_recipient: ExecutionAddress
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state_root: Bytes32
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receipts_root: Bytes32
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logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
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prev_randao: Bytes32
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block_number: uint64
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gas_limit: uint64
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gas_used: uint64
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timestamp: uint64
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extra_data: ByteList[MAX_EXTRA_DATA_BYTES]
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base_fee_per_gas: uint256
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# Extra payload fields
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block_hash: Hash32
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transactions: List[Transaction, MAX_TRANSACTIONS_PER_PAYLOAD]
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withdrawals: List[Withdrawal, MAX_WITHDRAWALS_PER_PAYLOAD]
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deposit_receipts: List[DepositReceipt, MAX_DEPOSIT_RECEIPTS_PER_PAYLOAD] # [New in DepositEIP]
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```
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#### `ExecutionPayloadHeader`
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```python
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class ExecutionPayloadHeader(Container):
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# Execution block header fields
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parent_hash: Hash32
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fee_recipient: ExecutionAddress
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state_root: Bytes32
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receipts_root: Bytes32
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logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
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prev_randao: Bytes32
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block_number: uint64
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gas_limit: uint64
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gas_used: uint64
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timestamp: uint64
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extra_data: ByteList[MAX_EXTRA_DATA_BYTES]
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base_fee_per_gas: uint256
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# Extra payload fields
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block_hash: Hash32
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transactions_root: Root
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withdrawals_root: Root
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deposit_receipts_root: Root # [New in DepositEIP]
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```
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#### `BeaconState`
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```python
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class BeaconState(Container):
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# Versioning
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genesis_time: uint64
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genesis_validators_root: Root
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slot: Slot
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fork: Fork
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# History
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latest_block_header: BeaconBlockHeader
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block_roots: Vector[Root, SLOTS_PER_HISTORICAL_ROOT]
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state_roots: Vector[Root, SLOTS_PER_HISTORICAL_ROOT]
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historical_roots: List[Root, HISTORICAL_ROOTS_LIMIT]
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# Eth1
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eth1_data: Eth1Data
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eth1_data_votes: List[Eth1Data, EPOCHS_PER_ETH1_VOTING_PERIOD * SLOTS_PER_EPOCH]
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eth1_deposit_index: uint64
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# Registry
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validators: List[Validator, VALIDATOR_REGISTRY_LIMIT]
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balances: List[Gwei, VALIDATOR_REGISTRY_LIMIT]
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# Randomness
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randao_mixes: Vector[Bytes32, EPOCHS_PER_HISTORICAL_VECTOR]
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# Slashings
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slashings: Vector[Gwei, EPOCHS_PER_SLASHINGS_VECTOR] # Per-epoch sums of slashed effective balances
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# Participation
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previous_epoch_participation: List[ParticipationFlags, VALIDATOR_REGISTRY_LIMIT]
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current_epoch_participation: List[ParticipationFlags, VALIDATOR_REGISTRY_LIMIT]
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# Finality
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justification_bits: Bitvector[JUSTIFICATION_BITS_LENGTH] # Bit set for every recent justified epoch
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previous_justified_checkpoint: Checkpoint
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current_justified_checkpoint: Checkpoint
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finalized_checkpoint: Checkpoint
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# Inactivity
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inactivity_scores: List[uint64, VALIDATOR_REGISTRY_LIMIT]
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# Sync
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current_sync_committee: SyncCommittee
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next_sync_committee: SyncCommittee
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# Execution
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latest_execution_payload_header: ExecutionPayloadHeader
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# Withdrawals
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next_withdrawal_index: WithdrawalIndex
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next_withdrawal_validator_index: ValidatorIndex
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# DepositsEIP
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pending_deposits: List[IndexedDepositData, PENDING_DEPOSITS_LIMIT]
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```
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## Beacon chain state transition function
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### Epoch processing
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```python
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def process_epoch(state: BeaconState) -> None:
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process_justification_and_finalization(state)
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process_inactivity_updates(state)
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process_rewards_and_penalties(state)
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# Run before registry and after finality updates
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process_pending_deposits(state) # [New in DepositsEIP]
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process_registry_updates(state)
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process_slashings(state)
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process_eth1_data_reset(state)
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process_effective_balance_updates(state)
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process_slashings_reset(state)
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process_randao_mixes_reset(state)
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process_historical_roots_update(state)
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process_participation_flag_updates(state)
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process_sync_committee_updates(state)
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```
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#### Helper functions
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##### New `get_validator_from_indexed_deposit_data`
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```python
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def get_validator_from_indexed_deposit_data(indexed_deposit_data: IndexedDepositData) -> Validator:
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amount = indexed_deposit_data.amount
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effective_balance = min(amount - amount % EFFECTIVE_BALANCE_INCREMENT, MAX_EFFECTIVE_BALANCE)
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return Validator(
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pubkey=indexed_deposit_data.pubkey,
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withdrawal_credentials=indexed_deposit_data.withdrawal_credentials,
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activation_eligibility_epoch=FAR_FUTURE_EPOCH,
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activation_epoch=FAR_FUTURE_EPOCH,
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exit_epoch=FAR_FUTURE_EPOCH,
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withdrawable_epoch=FAR_FUTURE_EPOCH,
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effective_balance=effective_balance,
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)
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```
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##### New `apply_pending_deposit`
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```python
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def apply_pending_deposit(state: BeaconState, indexed_deposit_data: IndexedDepositData) -> None:
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pubkey = indexed_deposit_data.pubkey
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amount = indexed_deposit_data.amount
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validator_pubkeys = [v.pubkey for v in state.validators]
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if pubkey not in validator_pubkeys:
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# Add validator and balance entries
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state.validators.append(get_validator_from_indexed_deposit_data(indexed_deposit_data))
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state.balances.append(amount)
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else:
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# Increase balance by deposit amount
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index = ValidatorIndex(validator_pubkeys.index(pubkey))
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increase_balance(state, index, amount)
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```
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#### New `process_pending_deposits`
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```python
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def process_pending_deposits(state: BeaconState) -> None:
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finalized_epoch = state.finalized_checkpoint.epoch
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next_pending_deposit_index = 0
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for pending_deposit in state.pending_deposits:
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# Apply only finalized deposits
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if pending_deposit.epoch > finalized_epoch
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break
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# Skip already applied deposits
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if pending_deposit.index >= state.eth1_deposit_index:
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apply_pending_deposit(state, pending_deposit)
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state.eth1_deposit_index += 1
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next_pending_deposit_index += 1
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state.pending_deposit = state.pending_deposit[next_pending_deposit_index:]
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```
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### Block processing
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```python
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def process_block(state: BeaconState, block: BeaconBlock) -> None:
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process_block_header(state, block)
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if is_execution_enabled(state, block.body):
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process_withdrawals(state, block.body.execution_payload)
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process_execution_payload(state, block.body.execution_payload, EXECUTION_ENGINE) # [Modified in DepositsEIP]
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process_deposit_receipts(state, block.body.execution_payload) # [New in DepositsEIP]
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process_randao(state, block.body)
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process_eth1_data(state, block.body)
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process_operations(state, block.body) # [Modified in DepositsEIP]
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process_sync_aggregate(state, block.body.sync_aggregate)
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```
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#### New `process_deposit_receipts`
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```python
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def process_deposit_receipts(state: BeaconState, payload: ExecutionPayload) -> None:
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current_epoch = get_current_epoch(state)
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for deposit_receipt in payload.deposit_receipts:
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if pubkey not in validator_pubkeys:
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# Verify the deposit signature (proof of possession) which is not checked by the deposit contract
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deposit_message = DepositMessage(
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pubkey=deposit_receipt.pubkey,
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withdrawal_credentials=deposit_receipt.withdrawal_credentials,
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amount=deposit_receipt.amount,
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)
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domain = compute_domain(DOMAIN_DEPOSIT) # Fork-agnostic domain since deposits are valid across forks
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signing_root = compute_signing_root(deposit_message, domain)
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if not bls.Verify(pubkey, signing_root, deposit.data.signature):
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continue
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pending_deposit = IndexedDepositData(
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pubkey=deposit_receipt.pubkey,
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withdrawal_credentials=deposit_receipt.withdrawal_credentials,
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amount=deposit_receipt.amount,
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index=deposit_receipt.index,
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epoch=current_epoch,
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)
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state.pending_deposits.append(pending_deposit)
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```
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#### Modified `process_execution_payload`
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*Note*: The function `process_execution_payload` is modified to use the new `ExecutionPayloadHeader` type.
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```python
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def process_execution_payload(state: BeaconState, payload: ExecutionPayload, execution_engine: ExecutionEngine) -> None:
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# Verify consistency of the parent hash with respect to the previous execution payload header
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if is_merge_transition_complete(state):
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assert payload.parent_hash == state.latest_execution_payload_header.block_hash
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# Verify prev_randao
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assert payload.prev_randao == get_randao_mix(state, get_current_epoch(state))
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# Verify timestamp
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assert payload.timestamp == compute_timestamp_at_slot(state, state.slot)
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# Verify the execution payload is valid
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assert execution_engine.notify_new_payload(payload)
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# Cache execution payload header
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state.latest_execution_payload_header = ExecutionPayloadHeader(
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parent_hash=payload.parent_hash,
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fee_recipient=payload.fee_recipient,
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state_root=payload.state_root,
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receipts_root=payload.receipts_root,
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logs_bloom=payload.logs_bloom,
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prev_randao=payload.prev_randao,
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block_number=payload.block_number,
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gas_limit=payload.gas_limit,
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gas_used=payload.gas_used,
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timestamp=payload.timestamp,
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extra_data=payload.extra_data,
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base_fee_per_gas=payload.base_fee_per_gas,
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block_hash=payload.block_hash,
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transactions_root=hash_tree_root(payload.transactions),
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withdrawals_root=hash_tree_root(payload.withdrawals),
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deposit_receipts_root=hash_tree_root(payload.deposit_receipts), # [New in DepositsEIP]
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)
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```
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#### Modified `process_operations`
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*Note*: The function `process_operations` is modified to process `BLSToExecutionChange` operations included in the block.
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```python
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def process_operations(state: BeaconState, body: BeaconBlockBody) -> None:
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# Verify that outstanding deposits are processed up to the maximum number of deposits
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unprocessed_deposits_count = max(0, state.eth1_data.deposit_count - state.eth1_deposit_index) # [New in DepositsEIP]
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assert len(body.deposits) == min(MAX_DEPOSITS, unprocessed_deposits_count) # [Modified in DepositsEIP]
|
||
|
|
|
||
|
|
def for_ops(operations: Sequence[Any], fn: Callable[[BeaconState, Any], None]) -> None:
|
||
|
|
for operation in operations:
|
||
|
|
fn(state, operation)
|
||
|
|
|
||
|
|
for_ops(body.proposer_slashings, process_proposer_slashing)
|
||
|
|
for_ops(body.attester_slashings, process_attester_slashing)
|
||
|
|
for_ops(body.attestations, process_attestation)
|
||
|
|
for_ops(body.deposits, process_deposit)
|
||
|
|
for_ops(body.voluntary_exits, process_voluntary_exit)
|
||
|
|
for_ops(body.bls_to_execution_changes, process_bls_to_execution_change) # [New in Capella]
|
||
|
|
```
|
||
|
|
|
||
|
|
## Testing
|
||
|
|
|
||
|
|
*Note*: The function `initialize_beacon_state_from_eth1` is modified for pure DepositsEIP testing only.
|
||
|
|
Modifications include:
|
||
|
|
1. Use `DEPOSITS_EIP_FORK_VERSION` as the previous and current fork version.
|
||
|
|
2. Utilize the DepositsEIP `BeaconBlockBody` when constructing the initial `latest_block_header`.
|
||
|
|
|
||
|
|
```python
|
||
|
|
def initialize_beacon_state_from_eth1(eth1_block_hash: Hash32,
|
||
|
|
eth1_timestamp: uint64,
|
||
|
|
deposits: Sequence[Deposit],
|
||
|
|
execution_payload_header: ExecutionPayloadHeader=ExecutionPayloadHeader()
|
||
|
|
) -> BeaconState:
|
||
|
|
fork = Fork(
|
||
|
|
previous_version=CAPELLA_FORK_VERSION, # [Modified in Capella] for testing only
|
||
|
|
current_version=CAPELLA_FORK_VERSION, # [Modified in Capella]
|
||
|
|
epoch=GENESIS_EPOCH,
|
||
|
|
)
|
||
|
|
state = BeaconState(
|
||
|
|
genesis_time=eth1_timestamp + GENESIS_DELAY,
|
||
|
|
fork=fork,
|
||
|
|
eth1_data=Eth1Data(block_hash=eth1_block_hash, deposit_count=uint64(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
|
||
|
|
|
||
|
|
# Set genesis validators root for domain separation and chain versioning
|
||
|
|
state.genesis_validators_root = hash_tree_root(state.validators)
|
||
|
|
|
||
|
|
# Fill in sync committees
|
||
|
|
# Note: A duplicate committee is assigned for the current and next committee at genesis
|
||
|
|
state.current_sync_committee = get_next_sync_committee(state)
|
||
|
|
state.next_sync_committee = get_next_sync_committee(state)
|
||
|
|
|
||
|
|
# Initialize the execution payload header
|
||
|
|
state.latest_execution_payload_header = execution_payload_header
|
||
|
|
|
||
|
|
return state
|
||
|
|
```
|