diff --git a/synapse/crypto/event_signing.py b/synapse/crypto/event_signing.py
index 8774b28967..d01ac5075c 100644
--- a/synapse/crypto/event_signing.py
+++ b/synapse/crypto/event_signing.py
@@ -23,14 +23,14 @@ from signedjson.sign import sign_json
from unpaddedbase64 import decode_base64, encode_base64
from synapse.api.errors import Codes, SynapseError
-from synapse.events.utils import prune_event
+from synapse.events.utils import prune_event, prune_event_dict
logger = logging.getLogger(__name__)
def check_event_content_hash(event, hash_algorithm=hashlib.sha256):
"""Check whether the hash for this PDU matches the contents"""
- name, expected_hash = compute_content_hash(event, hash_algorithm)
+ name, expected_hash = compute_content_hash(event.get_pdu_json(), hash_algorithm)
logger.debug("Expecting hash: %s", encode_base64(expected_hash))
# some malformed events lack a 'hashes'. Protect against it being missing
@@ -59,35 +59,70 @@ def check_event_content_hash(event, hash_algorithm=hashlib.sha256):
return message_hash_bytes == expected_hash
-def compute_content_hash(event, hash_algorithm):
- event_json = event.get_pdu_json()
- event_json.pop("age_ts", None)
- event_json.pop("unsigned", None)
- event_json.pop("signatures", None)
- event_json.pop("hashes", None)
- event_json.pop("outlier", None)
- event_json.pop("destinations", None)
+def compute_content_hash(event_dict, hash_algorithm):
+ """Compute the content hash of an event, which is the hash of the
+ unredacted event.
- event_json_bytes = encode_canonical_json(event_json)
+ Args:
+ event_dict (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.
+ """
+ event_dict = dict(event_dict)
+ event_dict.pop("age_ts", None)
+ event_dict.pop("unsigned", None)
+ event_dict.pop("signatures", None)
+ event_dict.pop("hashes", None)
+ event_dict.pop("outlier", None)
+ event_dict.pop("destinations", None)
+
+ event_json_bytes = encode_canonical_json(event_dict)
hashed = hash_algorithm(event_json_bytes)
return (hashed.name, hashed.digest())
def compute_event_reference_hash(event, hash_algorithm=hashlib.sha256):
+ """Computes the event reference hash. This is the hash of the redacted
+ event.
+
+ Args:
+ event (FrozenEvent)
+ 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.
+ """
tmp_event = prune_event(event)
- event_json = tmp_event.get_pdu_json()
- event_json.pop("signatures", None)
- event_json.pop("age_ts", None)
- event_json.pop("unsigned", None)
- event_json_bytes = encode_canonical_json(event_json)
+ event_dict = tmp_event.get_pdu_json()
+ event_dict.pop("signatures", None)
+ event_dict.pop("age_ts", None)
+ event_dict.pop("unsigned", None)
+ event_json_bytes = encode_canonical_json(event_dict)
hashed = hash_algorithm(event_json_bytes)
return (hashed.name, hashed.digest())
-def compute_event_signature(event, signature_name, signing_key):
- tmp_event = prune_event(event)
- redact_json = tmp_event.get_pdu_json()
+def compute_event_signature(event_dict, signature_name, signing_key):
+ """Compute the signature of the event for the given name and key.
+
+ Args:
+ event_dict (dict): The event as a dict
+ signature_name (str): The name of the entity signing the event
+ (typically the server's hostname).
+ signing_key (syutil.crypto.SigningKey): The key to sign with
+
+ Returns:
+ dict[str, dict[str, str]]: Returns a dictionary in the same format of
+ an event's signatures field.
+ """
+ redact_json = prune_event_dict(event_dict)
redact_json.pop("age_ts", None)
redact_json.pop("unsigned", None)
logger.debug("Signing event: %s", encode_canonical_json(redact_json))
@@ -98,23 +133,27 @@ def compute_event_signature(event, signature_name, signing_key):
def add_hashes_and_signatures(event, signature_name, signing_key,
hash_algorithm=hashlib.sha256):
- # if hasattr(event, "old_state_events"):
- # state_json_bytes = encode_canonical_json(
- # [e.event_id for e in event.old_state_events.values()]
- # )
- # hashed = hash_algorithm(state_json_bytes)
- # event.state_hash = {
- # hashed.name: encode_base64(hashed.digest())
- # }
-
- name, digest = compute_content_hash(event, hash_algorithm=hash_algorithm)
+ """Add content hash and sign the event
+
+ Args:
+ event_dict (EventBuilder): The event to add hashes to and sign
+ signature_name (str): The name of the entity signing the event
+ (typically the server's hostname).
+ signing_key (syutil.crypto.SigningKey): The key to sign with
+ hash_algorithm: A hasher from `hashlib`, e.g. hashlib.sha256, to use
+ to hash the event
+ """
+
+ name, digest = compute_content_hash(
+ event.get_pdu_json(), hash_algorithm=hash_algorithm,
+ )
if not hasattr(event, "hashes"):
event.hashes = {}
event.hashes[name] = encode_base64(digest)
event.signatures = compute_event_signature(
- event,
+ event.get_pdu_json(),
signature_name=signature_name,
signing_key=signing_key,
)
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index 652941ca0d..63f693f259 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -38,8 +38,31 @@ def prune_event(event):
This is used when we "redact" an event. We want to remove all fields that
the user has specified, but we do want to keep necessary information like
type, state_key etc.
+
+ Args:
+ event (FrozenEvent)
+
+ Returns:
+ FrozenEvent
+ """
+ pruned_event_dict = prune_event_dict(event.get_dict())
+
+ from . import event_type_from_format_version
+ return event_type_from_format_version(event.format_version)(
+ pruned_event_dict, event.internal_metadata.get_dict()
+ )
+
+
+def prune_event_dict(event_dict):
+ """Redacts the event_dict in the same way as `prune_event`, except it
+ operates on dicts rather than event objects
+
+ Args:
+ event_dict (dict)
+
+ Returns:
+ dict: A copy of the pruned event dict
"""
- event_type = event.type
allowed_keys = [
"event_id",
@@ -59,13 +82,13 @@ def prune_event(event):
"membership",
]
- event_dict = event.get_dict()
+ event_type = event_dict["type"]
new_content = {}
def add_fields(*fields):
for field in fields:
- if field in event.content:
+ if field in event_dict["content"]:
new_content[field] = event_dict["content"][field]
if event_type == EventTypes.Member:
@@ -98,17 +121,17 @@ def prune_event(event):
allowed_fields["content"] = new_content
- allowed_fields["unsigned"] = {}
+ unsigned = {}
+ allowed_fields["unsigned"] = unsigned
- if "age_ts" in event.unsigned:
- allowed_fields["unsigned"]["age_ts"] = event.unsigned["age_ts"]
- if "replaces_state" in event.unsigned:
- allowed_fields["unsigned"]["replaces_state"] = event.unsigned["replaces_state"]
+ event_unsigned = event_dict.get("unsigned", {})
- return type(event)(
- allowed_fields,
- internal_metadata_dict=event.internal_metadata.get_dict()
- )
+ if "age_ts" in event_unsigned:
+ unsigned["age_ts"] = event_unsigned["age_ts"]
+ if "replaces_state" in event_unsigned:
+ unsigned["replaces_state"] = event_unsigned["replaces_state"]
+
+ return allowed_fields
def _copy_field(src, dst, field):
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