Merge pull request #2479 from mkalinin/randao_in_execution_payload

Add randao to execution payload

setup.py

@@ -532,7 +532,7 @@ class NoopExecutionEngine(ExecutionEngine):
     def finalize_block(self, block_hash: Hash32) -> bool:
         return True
 
-    def assemble_block(self, block_hash: Hash32, timestamp: uint64) -> ExecutionPayload:
+    def assemble_block(self, block_hash: Hash32, timestamp: uint64, random: Bytes32) -> ExecutionPayload:
         raise NotImplementedError("no default block production")
 
 

specs/merge/beacon-chain.md

@@ -92,8 +92,9 @@ class ExecutionPayload(Container):
     parent_hash: Hash32
     coinbase: Bytes20  # 'beneficiary' in the yellow paper
     state_root: Bytes32
-    logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
     receipt_root: Bytes32  # 'receipts root' in the yellow paper
+    logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
+    random: Bytes32  # 'difficulty' in the yellow paper
     block_number: uint64  # 'number' in the yellow paper
     gas_limit: uint64
     gas_used: uint64
@@ -111,8 +112,9 @@ class ExecutionPayloadHeader(Container):
     parent_hash: Hash32
     coinbase: Bytes20
     state_root: Bytes32
-    logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
     receipt_root: Bytes32
+    logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
+    random: Bytes32
     block_number: uint64
     gas_limit: uint64
     gas_used: uint64
@@ -196,12 +198,15 @@ def process_block(state: BeaconState, block: BeaconBlock) -> None:
 
 #### `process_execution_payload`
 
+*Note:* This function depends on `process_randao` function call as it retrieves the most recent randao mix from the `state`. Implementations that are considering parallel processing of execution payload with respect to beacon chain state transition function should work around this dependency.
+
 ```python
 def process_execution_payload(state: BeaconState, payload: ExecutionPayload, execution_engine: ExecutionEngine) -> None:
-    # Verify consistency of the parent hash and block number
+    # Verify consistency of the parent hash, block number and random
     if is_merge_complete(state):
         assert payload.parent_hash == state.latest_execution_payload_header.block_hash
         assert payload.block_number == state.latest_execution_payload_header.block_number + uint64(1)
+        assert payload.random == get_randao_mix(state, get_current_epoch(state))
     # Verify timestamp
     assert payload.timestamp == compute_timestamp_at_slot(state, state.slot)
     # Verify the execution payload is valid
@@ -211,8 +216,9 @@ def process_execution_payload(state: BeaconState, payload: ExecutionPayload, exe
         parent_hash=payload.parent_hash,
         coinbase=payload.coinbase,
         state_root=payload.state_root,
-        logs_bloom=payload.logs_bloom,
         receipt_root=payload.receipt_root,
+        logs_bloom=payload.logs_bloom,
+        random=payload.random,
         block_number=payload.block_number,
         gas_limit=payload.gas_limit,
         gas_used=payload.gas_used,
@@ -266,6 +272,7 @@ def initialize_beacon_state_from_eth1(eth1_block_hash: Bytes32,
     # [New in Merge] Initialize the execution payload header (with block number set to 0)
     state.latest_execution_payload_header.block_hash = eth1_block_hash
     state.latest_execution_payload_header.timestamp = eth1_timestamp
+    state.latest_execution_payload_header.random = eth1_block_hash
 
     return state
 ```

specs/merge/validator.md

@@ -49,7 +49,7 @@ The body of this function is implementation dependent.
 The Consensus API may be used to implement this with an external execution engine.
 
 ```python
-def assemble_block(self: ExecutionEngine, block_hash: Hash32, timestamp: uint64) -> ExecutionPayload:
+def assemble_block(self: ExecutionEngine, block_hash: Hash32, timestamp: uint64, random: Bytes32) -> ExecutionPayload:
     ...
 ```
 
@@ -70,8 +70,23 @@ Let `get_pow_chain_head() -> PowBlock` be the function that returns the head of
 * Set `block.body.execution_payload = get_execution_payload(state, transition_store, execution_engine)` where:
 
 ```python
+def compute_randao_mix(state: BeaconState, randao_reveal: BLSSignature) -> Bytes32:
+    epoch = get_current_epoch(state)
+    return xor(get_randao_mix(state, epoch), hash(randao_reveal))
+
+
+def produce_execution_payload(state: BeaconState,
+                              parent_hash: Hash32,
+                              randao_reveal: BLSSignature,
+                              execution_engine: ExecutionEngine) -> ExecutionPayload:
+    timestamp = compute_timestamp_at_slot(state, state.slot)
+    randao_mix = compute_randao_mix(state, randao_reveal)
+    return execution_engine.assemble_block(parent_hash, timestamp, randao_mix)
+
+
 def get_execution_payload(state: BeaconState,
                           transition_store: TransitionStore,
+                          randao_reveal: BLSSignature,
                           execution_engine: ExecutionEngine) -> ExecutionPayload:
     if not is_merge_complete(state):
         pow_block = get_pow_chain_head()
@@ -80,11 +95,9 @@ def get_execution_payload(state: BeaconState,
             return ExecutionPayload()
         else:
             # Signify merge via producing on top of the last PoW block
-            timestamp = compute_time_at_slot(state, state.slot)
+            return produce_execution_payload(state, pow_block.block_hash, randao_reveal, execution_engine)
-            return execution_engine.assemble_block(pow_block.block_hash, timestamp)
 
     # Post-merge, normal payload
-    execution_parent_hash = state.latest_execution_payload_header.block_hash
+    parent_hash = state.latest_execution_payload_header.block_hash
-    timestamp = compute_time_at_slot(state, state.slot)
+    return produce_execution_payload(state, parent_hash, randao_reveal, execution_engine)
-    return execution_engine.assemble_block(execution_parent_hash, timestamp)
 ```

tests/core/pyspec/eth2spec/test/helpers/block.py

@@ -93,13 +93,15 @@ def build_empty_block(spec, state, slot=None):
     empty_block.body.eth1_data.deposit_count = state.eth1_deposit_index
     empty_block.parent_root = parent_block_root
 
+    apply_randao_reveal(spec, state, empty_block)
+
     if is_post_altair(spec):
         empty_block.body.sync_aggregate.sync_committee_signature = spec.G2_POINT_AT_INFINITY
 
     if is_post_merge(spec):
-        empty_block.body.execution_payload = build_empty_execution_payload(spec, state)
+        randao_mix = spec.compute_randao_mix(state, empty_block.body.randao_reveal)
+        empty_block.body.execution_payload = build_empty_execution_payload(spec, state, randao_mix)
 
-    apply_randao_reveal(spec, state, empty_block)
     return empty_block
 
 

tests/core/pyspec/eth2spec/test/helpers/execution_payload.py

@@ -1,4 +1,4 @@
-def build_empty_execution_payload(spec, state):
+def build_empty_execution_payload(spec, state, randao_mix=None):
     """
     Assuming a pre-state of the same slot, build a valid ExecutionPayload without any transactions.
     """
@@ -6,13 +6,17 @@ def build_empty_execution_payload(spec, state):
     timestamp = spec.compute_time_at_slot(state, state.slot)
     empty_txs = spec.List[spec.Transaction, spec.MAX_TRANSACTIONS_PER_PAYLOAD]()
 
+    if randao_mix is None:
+        randao_mix = spec.get_randao_mix(state, spec.get_current_epoch(state))
+
     payload = spec.ExecutionPayload(
         parent_hash=latest.block_hash,
         coinbase=spec.Bytes20(),
         state_root=latest.state_root,  # no changes to the state
-        logs_bloom=spec.ByteVector[spec.BYTES_PER_LOGS_BLOOM](),  # TODO: zeroed logs bloom for empty logs ok?
         receipt_root=b"no receipts here" + b"\x00" * 16,  # TODO: root of empty MPT may be better.
+        logs_bloom=spec.ByteVector[spec.BYTES_PER_LOGS_BLOOM](),  # TODO: zeroed logs bloom for empty logs ok?
         block_number=latest.block_number + 1,
+        random=randao_mix,
         gas_limit=latest.gas_limit,  # retain same limit
         gas_used=0,  # empty block, 0 gas
         timestamp=timestamp,
@@ -30,8 +34,9 @@ def get_execution_payload_header(spec, execution_payload):
         parent_hash=execution_payload.parent_hash,
         coinbase=execution_payload.coinbase,
         state_root=execution_payload.state_root,
-        logs_bloom=execution_payload.logs_bloom,
         receipt_root=execution_payload.receipt_root,
+        logs_bloom=execution_payload.logs_bloom,
+        random=execution_payload.random,
         block_number=execution_payload.block_number,
         gas_limit=execution_payload.gas_limit,
         gas_used=execution_payload.gas_used,