Vote for block hash along with deposit root (#448)

specs/core/0_beacon-chain.md

@@ -45,10 +45,11 @@
             - [`BeaconState`](#beaconstate)
             - [`Validator`](#validator)
             - [`Crosslink`](#crosslink)
-            - [`DepositRootVote`](#depositrootvote)
             - [`PendingAttestation`](#pendingattestation)
             - [`Fork`](#fork)
             - [`ValidatorRegistryDeltaBlock`](#validatorregistrydeltablock)
+            - [`Eth1Data`](#eth1data)
+            - [`Eth1DataVote`](#eth1datavote)
     - [Ethereum 1.0 deposit contract](#ethereum-10-deposit-contract)
         - [Deposit arguments](#deposit-arguments)
         - [Withdrawal credentials](#withdrawal-credentials)
@@ -96,7 +97,7 @@
         - [Slot](#slot)
         - [Proposer signature](#proposer-signature)
         - [RANDAO](#randao)
-        - [Deposit root](#deposit-root)
+        - [Eth1 data](#eth1-data)
         - [Operations](#operations)
             - [Proposer slashings](#proposer-slashings-1)
             - [Casper slashings](#casper-slashings-1)
@@ -106,7 +107,7 @@
             - [Custody](#custody)
     - [Per-epoch processing](#per-epoch-processing)
         - [Helpers](#helpers)
-        - [Deposit roots](#deposit-roots)
+        - [Eth1 data](#eth1-data-1)
         - [Justification](#justification)
         - [Crosslinks](#crosslinks)
         - [Rewards and penalties](#rewards-and-penalties)
@@ -202,7 +203,7 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted
 | `EPOCH_LENGTH` | `2**6` (= 64) | slots | 6.4 minutes |
 | `SEED_LOOKAHEAD` | `2**6` (= 64) | slots | 6.4 minutes |
 | `ENTRY_EXIT_DELAY` | `2**8` (= 256) | slots | 25.6 minutes |
-| `DEPOSIT_ROOT_VOTING_PERIOD` | `2**10` (= 1,024) | slots | ~1.7 hours |
+| `ETH1_DATA_VOTING_PERIOD` | `2**10` (= 1,024) | slots | ~1.7 hours |
 | `MIN_VALIDATOR_WITHDRAWAL_TIME` | `2**14` (= 16,384) | slots | ~27 hours |
 
 ### Reward and penalty quotients
@@ -423,7 +424,7 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted
     'parent_root': 'hash32',
     'state_root': 'hash32',
     'randao_reveal': 'hash32',
-    'deposit_root': 'hash32',
+    'eth1_data': Eth1Data,
     'signature': ['uint384'],
 
     ## Body ##
@@ -505,9 +506,9 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted
     'latest_attestations': [PendingAttestation],
     'batched_block_roots': ['hash32'],
 
-    # Ethereum 1.0 deposit root
+    # Ethereum 1.0 chain data
-    'latest_deposit_root': 'hash32',
+    'latest_eth1_data': Eth1Data,
-    'deposit_root_votes': [DepositRootVote],
+    'eth1_data_votes': [Eth1DataVote],
 }
 ```
 
@@ -555,17 +556,6 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted
 }
 ```
 
-#### `DepositRootVote`
-
-```python
-{
-    # Deposit root
-    'deposit_root': 'hash32',
-    # Vote count
-    'vote_count': 'uint64',
-}
-```
-
 #### `PendingAttestation`
 
 ```python
@@ -598,11 +588,33 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted
 
 ```python
 {
-    latest_registry_delta_root: 'hash32',
+    'latest_registry_delta_root': 'hash32',
-    validator_index: 'uint24',
+    'validator_index': 'uint24',
-    pubkey: 'uint384',
+    'pubkey': 'uint384',
-    slot: 'uint64',
+    'slot': 'uint64',
-    flag: 'uint64',
+    'flag': 'uint64',
+}
+```
+
+#### `Eth1Data`
+
+```python
+{
+    # Root of the deposit tree
+    'deposit_root': 'hash32',
+    # Block hash
+    'block_hash': 'hash32',
+}
+```
+
+#### `Eth1DataVote`
+
+```python
+{
+    # Data being voted for
+    'eth1_data': Eth1Data,
+    # Vote count
+    'vote_count': 'uint64',
 }
 ```
 
@@ -632,7 +644,7 @@ Every Ethereum 1.0 deposit, of size between `MIN_DEPOSIT_AMOUNT` and `MAX_DEPOSI
 When sufficiently many full deposits have been made the deposit contract emits the `ChainStart` log. The beacon chain state may then be initialized by calling the `get_initial_beacon_state` function (defined below) where:
 
 * `genesis_time` equals `time` in the `ChainStart` log
-* `latest_deposit_root` equals `deposit_root` in the `ChainStart` log
+* `latest_eth1_data.deposit_root` equals `deposit_root` in the `ChainStart` log, and `latest_eth1_data.block_hash` equals the hash of the block that included the log
 * `initial_validator_deposits` is a list of `Deposit` objects built according to the `Deposit` logs up to the deposit that triggered the `ChainStart` log, processed in the order in which they were emitted (oldest to newest)
 
 ### Vyper code
@@ -713,7 +725,7 @@ For a beacon chain block, `block`, to be processed by a node, the following cond
 
 * The parent block with root `block.parent_root` has been processed and accepted.
 * The node has processed its `state` up to slot, `block.slot - 1`.
-* An Ethereum 1.0 block pointed to by the `state.latest_deposit_root` has been processed and accepted.
+* An Ethereum 1.0 block pointed to by the `state.latest_eth1_data.block_hash` has been processed and accepted.
 * The node's local clock time is greater than or equal to `state.genesis_time + block.slot * SLOT_DURATION`.
 
 If these conditions are not met, the client should delay processing the beacon block until the conditions are all satisfied.
@@ -1183,7 +1195,10 @@ A valid block with slot `GENESIS_SLOT` (a "genesis block") has the following val
     parent_root=ZERO_HASH,
     state_root=STARTUP_STATE_ROOT,
     randao_reveal=ZERO_HASH,
-    deposit_root=ZERO_HASH,
+    eth1_data=Eth1Data(
+        deposit_root=ZERO_HASH,
+        block_hash=ZERO_HASH
+    ),
     signature=EMPTY_SIGNATURE,
     body=BeaconBlockBody(
         proposer_slashings=[],
@@ -1203,7 +1218,7 @@ A valid block with slot `GENESIS_SLOT` (a "genesis block") has the following val
 ```python
 def get_initial_beacon_state(initial_validator_deposits: List[Deposit],
                              genesis_time: int,
-                             latest_deposit_root: Hash32) -> BeaconState:
+                             latest_eth1_data: Eth1Data) -> BeaconState:
     state = BeaconState(
         # Misc
         slot=GENESIS_SLOT,
@@ -1247,9 +1262,9 @@ def get_initial_beacon_state(initial_validator_deposits: List[Deposit],
         latest_attestations=[],
         batched_block_roots=[],
 
-        # Deposit root
+        # Ethereum 1.0 chain data
-        latest_deposit_root=latest_deposit_root,
+        latest_eth1_data=latest_eth1_data,
-        deposit_root_votes=[],
+        eth1_data_votes=[],
     )
 
     # Process initial deposits
@@ -1466,10 +1481,10 @@ Below are the processing steps that happen at every `block`.
 * Set `proposer.randao_commitment = block.randao_reveal`.
 * Set `proposer.randao_layers = 0`.
 
-### Deposit root
+### Eth1 data
 
-* If `block.deposit_root` is `deposit_root_vote.deposit_root` for some `deposit_root_vote` in `state.deposit_root_votes`, set `deposit_root_vote.vote_count += 1`.
+* If `block.eth1_data` equals `eth1_data_vote.eth1_data` for some `eth1_data_vote` in `state.eth1_data_votes`, set `eth1_data_vote.vote_count += 1`.
-* Otherwise, append to `state.deposit_root_votes` a new `DepositRootVote(deposit_root=block.deposit_root, vote_count=1)`.
+* Otherwise, append to `state.eth1_data_votes` a new `Eth1DataVote(eth1_data=block.eth1_data, vote_count=1)`.
 
 ### Operations
 
@@ -1533,7 +1548,7 @@ Verify that `len(block.body.deposits) <= MAX_DEPOSITS`.
 For each `deposit` in `block.body.deposits`:
 
 * Let `serialized_deposit_data` be the serialized form of `deposit.deposit_data`. It should be 8 bytes for `deposit_data.amount` followed by 8 bytes for `deposit_data.timestamp` and then the `DepositInput` bytes. That is, it should match `deposit_data` in the [Ethereum 1.0 deposit contract](#ethereum-10-deposit-contract) of which the hash was placed into the Merkle tree.
-* Verify that `verify_merkle_branch(hash(serialized_deposit_data), deposit.branch, DEPOSIT_CONTRACT_TREE_DEPTH, deposit.index, state.latest_deposit_root)` is `True`.
+* Verify that `verify_merkle_branch(hash(serialized_deposit_data), deposit.branch, DEPOSIT_CONTRACT_TREE_DEPTH, deposit.index, state.latest_eth1_data.deposit_root)` is `True`.
 
 ```python
 def verify_merkle_branch(leaf: Hash32, branch: [Hash32], depth: int, index: int, root: Hash32) -> bool:
@@ -1629,12 +1644,12 @@ Define the following helpers to process attestation inclusion rewards and inclus
 * Let `inclusion_slot(state, index) = a.slot_included` for the attestation `a` where `index` is in `get_attestation_participants(state, a.data, a.aggregation_bitfield)`.
 * Let `inclusion_distance(state, index) = a.slot_included - a.data.slot` where `a` is the above attestation.
 
-### Deposit roots
+### Eth1 data
 
-If `state.slot % DEPOSIT_ROOT_VOTING_PERIOD == 0`:
+If `state.slot % ETH1_DATA_VOTING_PERIOD == 0`:
 
-* Set `state.latest_deposit_root = deposit_root_vote.deposit_root` if `deposit_root_vote.vote_count * 2 > DEPOSIT_ROOT_VOTING_PERIOD` for some `deposit_root_vote` in `state.deposit_root_votes`.
+* Set `state.latest_eth1_data = eth1_data_vote.data` if `eth1_data_vote.vote_count * 2 > ETH1_DATA_VOTING_PERIOD` for some `eth1_data_vote` in `state.eth1_data_votes`.
-* Set `state.deposit_root_votes = []`.
+* Set `state.eth1_data_votes = []`.
 
 ### Justification