Ursula confirms ritual participation before responding to a decryption request

nucypher/blockchain/eth/agents.py

@@ -644,7 +644,13 @@ class CoordinatorAgent(EthereumContractAgent):
         return receipt
 
     @contract_api(TRANSACTION)
-    def post_transcript(self, ritual_id: int, transcript: bytes, node_index: int, transacting_power: TransactingPower) -> TxReceipt:
+    def post_transcript(
+            self,
+            ritual_id: int,
+            transcript: bytes,
+            node_index: int,
+            transacting_power: TransactingPower
+    ) -> TxReceipt:
         contract_function: ContractFunction = self.contract.functions.postTranscript(
             ritualId=ritual_id,
             nodeIndex=node_index,
@@ -659,16 +665,17 @@ class CoordinatorAgent(EthereumContractAgent):
         self,
         ritual_id: int,
         node_index: int,
-        aggregated_transcript: AggregatedTranscript,
+        aggregated_transcript: bytes,
         transacting_power: TransactingPower,
     ) -> TxReceipt:
         contract_function: ContractFunction = self.contract.functions.postAggregation(
             ritualId=ritual_id,
             nodeIndex=node_index,
-            aggregatedTranscript=bytes(aggregated_transcript),
+            aggregatedTranscript=aggregated_transcript,
         )
         receipt = self.blockchain.send_transaction(
-            contract_function=contract_function, transacting_power=transacting_power
+            contract_function=contract_function,
+            transacting_power=transacting_power
         )
         return receipt
 

nucypher/blockchain/eth/trackers/dkg.py

@@ -1,17 +1,7 @@
 import os
 import time
-from typing import Callable, List, Optional, Tuple, Type, Union
-
-from eth_typing import ChecksumAddress
-from ferveo_py import (
-    AggregatedTranscript,
-    DecryptionShare,
-    Dkg,
-    Keypair,
-    PublicKey,
-    Transcript,
-)
 from twisted.internet import threads
+from typing import Callable, List, Optional, Tuple, Type, Union
 from web3 import Web3
 from web3.contract import Contract, ContractEvent
 from web3.datastructures import AttributeDict
@@ -60,7 +50,7 @@ class EventScannerTask(SimpleTask):
         raise args[0]
 
 
-class RitualTracker:
+class ActiveRitualTracker:
 
     MAX_CHUNK_SIZE = 10000
 
@@ -68,8 +58,9 @@ class RitualTracker:
                  ritualist,
                  eth_provider: BaseProvider,
                  contract: Contract,
-                 start_block: int = 0,
-                 persistent: bool = False):
+                 start_block: int = 0,  # TODO: use a start block that correlates to the ritual timeout
+                 persistent: bool = False  # TODO: use persistent storage?
+                 ):
 
         self.log = Logger("RitualTracker")
 

nucypher/characters/lawful.py

@@ -15,7 +15,8 @@ from cryptography.hazmat.primitives.serialization import Encoding
 from cryptography.x509 import Certificate, NameOID
 from eth_typing.evm import ChecksumAddress
 from eth_utils import to_checksum_address
-from ferveo_py import Ciphertext, DecryptionShare, combine_decryption_shares, decrypt_with_shared_secret
+from ferveo_py import Ciphertext, DecryptionShare, combine_decryption_shares, decrypt_with_shared_secret, \
+    ExternalValidator, Transcript
 from pathlib import Path
 from queue import Queue
 from twisted.internet import reactor
@@ -38,7 +39,7 @@ import nucypher
 from nucypher.acumen.nicknames import Nickname
 from nucypher.acumen.perception import ArchivedFleetState, RemoteUrsulaStatus
 from nucypher.blockchain.eth.actors import Operator, PolicyAuthor, Ritualist
-from nucypher.blockchain.eth.agents import ContractAgency, PREApplicationAgent
+from nucypher.blockchain.eth.agents import ContractAgency, PREApplicationAgent, CoordinatorAgent
 from nucypher.blockchain.eth.interfaces import BlockchainInterfaceFactory
 from nucypher.blockchain.eth.registry import BaseContractRegistry
 from nucypher.blockchain.eth.signers.software import Web3Signer
@@ -50,6 +51,7 @@ from nucypher.characters.banners import (
 )
 from nucypher.characters.base import Character, Learner
 from nucypher.config.storages import NodeStorage
+from nucypher.crypto.ferveo.dkg import aggregate_transcripts
 from nucypher.crypto.keypairs import HostingKeypair
 from nucypher.crypto.powers import (
     DecryptingPower,
@@ -1121,6 +1123,14 @@ class Ursula(Teacher, Character, Operator, Ritualist):
                                  balance_eth=balance_eth,
                                  )
 
+    def as_external_validator(self) -> ExternalValidator:
+        """Returns an ExternalValidator instance for this Ursula for use in DKG operations."""
+        validator = ExternalValidator(
+            address=self.checksum_address,
+            public_key=self.public_keys(RitualisticPower)
+        )
+        return validator
+
 
 class LocalUrsulaStatus(NamedTuple):
     nickname: Nickname

nucypher/network/exceptions.py

@@ -1,5 +1,3 @@
-
-
 import requests
 import socket
 

nucypher/network/server.py

@@ -143,18 +143,23 @@ def _make_rest_app(this_node, log: Logger) -> Flask:
         decryption_request = ThresholdDecryptionRequest.from_bytes(request.data)
 
         # Deserialize and instantiate ConditionLingo from the request data
-        lingo = ConditionLingo.from_list(json.loads(str(decryption_request.conditions)))
-
         # requester-supplied condition eval context
+        # evaluate the conditions for this ciphertext
+        lingo = ConditionLingo.from_list(json.loads(str(decryption_request.conditions)))
         context = None
         if decryption_request.context:
             context = json.loads(str(decryption_request.context)) or dict()
-
-        # evaluate the conditions for this ciphertext
         error = evaluate_condition_lingo(lingo, context)
         if error:
             return Response(error.message, status=error.status_code)
 
+        # TODO: confirm this node is tracking the ritual and is an authorized recipient
+        # dkg_public_key = this_node.dkg_storage.get_public_key(decryption_request.ritual_id)
+        ritual = this_node.coordinator_agent.get_ritual(decryption_request.ritual_id, with_participants=True)
+        participants = [p.node for p in ritual.participants]
+        if this_node.checksum_address not in participants:
+            return Response(f'Node not part of ritual {decryption_request.ritual_id}', status=HTTPStatus.FORBIDDEN)
+
         # derive the decryption share
         decryption_share = this_node.derive_decryption_share(
             ritual_id=decryption_request.ritual_id,
@@ -163,6 +168,7 @@ def _make_rest_app(this_node, log: Logger) -> Flask:
         )
 
         # return the decryption share
+        # TODO: encrypt the response with the requester's public key # 3079
         response = ThresholdDecryptionResponse(decryption_share=decryption_share)
         return Response(bytes(response), headers={'Content-Type': 'application/octet-stream'})