Add type hints to the crypto module. (#8999)

synapse/crypto/event_signing.py

@@ -18,7 +18,7 @@
 import collections.abc
 import hashlib
 import logging
-from typing import Dict
+from typing import Any, Callable, Dict, Tuple
 
 from canonicaljson import encode_canonical_json
 from signedjson.sign import sign_json
@@ -27,13 +27,18 @@ from unpaddedbase64 import decode_base64, encode_base64
 
 from synapse.api.errors import Codes, SynapseError
 from synapse.api.room_versions import RoomVersion
+from synapse.events import EventBase
 from synapse.events.utils import prune_event, prune_event_dict
 from synapse.types import JsonDict
 
 logger = logging.getLogger(__name__)
 
+Hasher = Callable[[bytes], "hashlib._Hash"]
 
-def check_event_content_hash(event, hash_algorithm=hashlib.sha256):
+
+def check_event_content_hash(
+    event: EventBase, hash_algorithm: Hasher = hashlib.sha256
+) -> bool:
     """Check whether the hash for this PDU matches the contents"""
     name, expected_hash = compute_content_hash(event.get_pdu_json(), hash_algorithm)
     logger.debug(
@@ -67,18 +72,19 @@ def check_event_content_hash(event, hash_algorithm=hashlib.sha256):
     return message_hash_bytes == expected_hash
 
 
-def compute_content_hash(event_dict, hash_algorithm):
+def compute_content_hash(
+    event_dict: Dict[str, Any], hash_algorithm: Hasher
+) -> Tuple[str, bytes]:
     """Compute the content hash of an event, which is the hash of the
     unredacted event.
 
     Args:
-        event_dict (dict): The unredacted event as a dict
+        event_dict: The unredacted event as a dict
         hash_algorithm: A hasher from `hashlib`, e.g. hashlib.sha256, to use
             to hash the event
 
     Returns:
-        tuple[str, bytes]: A tuple of the name of hash and the hash as raw
-        bytes.
+        A tuple of the name of hash and the hash as raw bytes.
     """
     event_dict = dict(event_dict)
     event_dict.pop("age_ts", None)
@@ -94,18 +100,19 @@ def compute_content_hash(event_dict, hash_algorithm):
     return hashed.name, hashed.digest()
 
 
-def compute_event_reference_hash(event, hash_algorithm=hashlib.sha256):
+def compute_event_reference_hash(
+    event, hash_algorithm: Hasher = hashlib.sha256
+) -> Tuple[str, bytes]:
     """Computes the event reference hash. This is the hash of the redacted
     event.
 
     Args:
-        event (FrozenEvent)
+        event
         hash_algorithm: A hasher from `hashlib`, e.g. hashlib.sha256, to use
             to hash the event
 
     Returns:
-        tuple[str, bytes]: A tuple of the name of hash and the hash as raw
-        bytes.
+        A tuple of the name of hash and the hash as raw bytes.
     """
     tmp_event = prune_event(event)
     event_dict = tmp_event.get_pdu_json()
@@ -156,7 +163,7 @@ def add_hashes_and_signatures(
     event_dict: JsonDict,
     signature_name: str,
     signing_key: SigningKey,
-):
+) -> None:
     """Add content hash and sign the event
 
     Args: