Implements validate_proposer_signature function

Author: Bhargavasomu

eth/beacon/state_machines/validation.py

@@ -0,0 +1,48 @@
+from eth_utils import (
+    ValidationError,
+)
+
+from eth.beacon.enums import (
+    SignatureDomain,
+)
+from eth.beacon.helpers import (
+    get_beacon_proposer_index,
+    get_domain,
+)
+from eth.beacon.types.blocks import (
+    BaseBeaconBlock,
+)
+from eth.beacon.types.proposal_signed_data import (
+    ProposalSignedData,
+)
+from eth.beacon.types.states import (
+    BeaconState,
+)
+
+from eth._utils.bls import (
+    verify,
+)
+
+
+def validate_proposer_signature(state: BeaconState,
+                                block: BaseBeaconBlock,
+                                beacon_chain_shard_number: int,
+                                epoch_length: int) -> None:
+    block_without_signature_root = BaseBeaconBlock.create_block_without_signature_root(block).root
+
+    proposal_root = ProposalSignedData(
+        state.slot,
+        beacon_chain_shard_number,
+        block_without_signature_root
+    ).root
+
+    # Get the public key of proposer
+    beacon_proposer_index = get_beacon_proposer_index(state, state.slot, epoch_length)
+    proposer_pubkey = state.validator_registry[beacon_proposer_index].pubkey
+
+    if not verify(
+            pubkey=proposer_pubkey,
+            message=proposal_root,
+            signature=block.signature,
+            domain=get_domain(state.fork_data, state.slot, SignatureDomain.DOMAIN_PROPOSAL)):
+        raise ValidationError("Invalid Proposer Signature on block")

eth/beacon/types/blocks.py

@@ -19,6 +19,8 @@
     uint64,
     uint384,
 )
+
+from eth.beacon.constants import EMPTY_SIGNATURE
 from eth.beacon._utils.hash import hash_eth2
 
 from .attestations import Attestation
@@ -111,3 +113,17 @@ def root(self) -> Hash32:
     @property
     def num_attestations(self) -> int:
         return len(self.body.attestations)
+
+    @classmethod
+    def create_block_without_signature_root(
+            cls,
+            block: 'BaseBeaconBlock') -> 'BaseBeaconBlock':
+        return cls(
+            slot=block.slot,
+            parent_root=block.parent_root,
+            state_root=block.state_root,
+            randao_reveal=block.randao_reveal,
+            candidate_pow_receipt_root=block.candidate_pow_receipt_root,
+            signature=EMPTY_SIGNATURE,
+            body=block.body,
+        )

eth/beacon/types/proposal_signed_data.py

@@ -3,6 +3,8 @@
 )
 import rlp
 
+from eth.beacon._utils.hash import hash_eth2
+
 from eth.rlp.sedes import (
     uint64,
     hash32,
@@ -31,3 +33,17 @@ def __init__(self,
             shard,
             block_root,
         )
+
+    _hash = None
+
+    @property
+    def hash(self) -> Hash32:
+        if self._hash is None:
+            self._hash = hash_eth2(rlp.encode(self))
+        return self._hash
+
+    @property
+    def root(self) -> Hash32:
+        # Alias of `hash`.
+        # Using flat hash, might change to SSZ tree hash.
+        return self.hash