Merge pull request #2581 from mkalinin/set-random-to-prev-randao-mix

Set the value of the random field to the previous randao_mix

specs/merge/beacon-chain.md

@@ -249,15 +249,17 @@ The above function is accessed through the `EXECUTION_ENGINE` module which insta
 
 ### Block processing
 
+*Note*: The call to the `process_execution_payload` must happen before the call to the `process_randao` as the former depends on the `randao_mix` computed with the reveal of the previous block.
+
 ```python
 def process_block(state: BeaconState, block: BeaconBlock) -> None:
     process_block_header(state, block)
+    if is_execution_enabled(state, block.body):
+        process_execution_payload(state, block.body.execution_payload, EXECUTION_ENGINE)  # [New in Merge]
     process_randao(state, block.body)
     process_eth1_data(state, block.body)
     process_operations(state, block.body)
     process_sync_aggregate(state, block.body.sync_aggregate)
-    if is_execution_enabled(state, block.body):
-        process_execution_payload(state, block.body.execution_payload, EXECUTION_ENGINE)  # [New in Merge]
 ```
 
 ### Execution payload processing
@@ -287,8 +289,6 @@ def is_valid_gas_limit(payload: ExecutionPayload, parent: ExecutionPayloadHeader
 
 #### `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, block number, base fee per gas and gas limit

specs/merge/validator.md

@@ -75,23 +75,16 @@ def get_pow_block_at_total_difficulty(total_difficulty: uint256, pow_chain: Sequ
     return None
 
 
-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)
+    randao_mix = get_randao_mix(state, get_current_epoch(state))
     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,
                           pow_chain: Sequence[PowBlock]) -> ExecutionPayload:
     if not is_merge_complete(state):
@@ -101,9 +94,9 @@ def get_execution_payload(state: BeaconState,
             return ExecutionPayload()
         else:
             # Signify merge via producing on top of the last PoW block
-            return produce_execution_payload(state, terminal_pow_block.block_hash, randao_reveal, execution_engine)
+            return produce_execution_payload(state, terminal_pow_block.block_hash, execution_engine)
 
     # Post-merge, normal payload
     parent_hash = state.latest_execution_payload_header.block_hash
-    return produce_execution_payload(state, parent_hash, randao_reveal, execution_engine)
+    return produce_execution_payload(state, parent_hash, execution_engine)
 ```

specs/sharding/beacon-chain.md

@@ -552,12 +552,12 @@ def compute_committee_index_from_shard(state: BeaconState, slot: Slot, shard: Sh
 ```python
 def process_block(state: BeaconState, block: BeaconBlock) -> None:
     process_block_header(state, block)
+    # is_execution_enabled is omitted, execution is enabled by default.
+    process_execution_payload(state, block.body.execution_payload, EXECUTION_ENGINE)
     process_randao(state, block.body)
     process_eth1_data(state, block.body)
     process_operations(state, block.body)  # [Modified in Sharding]
     process_sync_aggregate(state, block.body.sync_aggregate)
-    # is_execution_enabled is omitted, execution is enabled by default. 
-    process_execution_payload(state, block.body.execution_payload, EXECUTION_ENGINE)
 ```
 
 #### Operations

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

@@ -99,8 +99,7 @@ def build_empty_block(spec, state, slot=None):
         empty_block.body.sync_aggregate.sync_committee_signature = spec.G2_POINT_AT_INFINITY
 
     if is_post_merge(spec):
-        randao_mix = spec.compute_randao_mix(state, empty_block.body.randao_reveal)
+        empty_block.body.execution_payload = build_empty_execution_payload(spec, state)
-        empty_block.body.execution_payload = build_empty_execution_payload(spec, state, randao_mix)
 
     return empty_block
 

tests/core/pyspec/eth2spec/test/phase0/sanity/test_blocks.py

@@ -143,6 +143,9 @@ def process_and_sign_block_without_header_validations(spec, state, block):
         state_root=spec.Bytes32(),
         body_root=block.body.hash_tree_root(),
     )
+    if is_post_merge(spec):
+        if spec.is_execution_enabled(state, block.body):
+            spec.process_execution_payload(state, block.body.execution_payload, spec.EXECUTION_ENGINE)
 
     # Perform rest of process_block transitions
     spec.process_randao(state, block.body)
@@ -150,9 +153,6 @@ def process_and_sign_block_without_header_validations(spec, state, block):
     spec.process_operations(state, block.body)
     if is_post_altair(spec):
         spec.process_sync_aggregate(state, block.body.sync_aggregate)
-    if is_post_merge(spec):
-        if spec.is_execution_enabled(state, block.body):
-            spec.process_execution_payload(state, block.body.execution_payload, spec.EXECUTION_ENGINE)
 
     # Insert post-state rot
     block.state_root = state.hash_tree_root()
@@ -196,8 +196,7 @@ def test_parent_from_same_slot(spec, state):
     child_block.parent_root = state.latest_block_header.hash_tree_root()
 
     if is_post_merge(spec):
-        randao_mix = spec.compute_randao_mix(state, child_block.body.randao_reveal)
+        child_block.body.execution_payload = build_empty_execution_payload(spec, state)
-        child_block.body.execution_payload = build_empty_execution_payload(spec, state, randao_mix)
 
     # Show that normal path through transition fails
     failed_state = state.copy()