diff options
Diffstat (limited to 'synapse/crypto/event_signing.py')
| -rw-r--r-- | synapse/crypto/event_signing.py | 109 |
1 files changed, 72 insertions, 37 deletions
diff --git a/synapse/crypto/event_signing.py b/synapse/crypto/event_signing.py index 8774b28967..1dfa727fcf 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)) @@ -96,25 +131,25 @@ def compute_event_signature(event, signature_name, signing_key): return redact_json["signatures"] -def add_hashes_and_signatures(event, signature_name, signing_key, +def add_hashes_and_signatures(event_dict, 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) - - if not hasattr(event, "hashes"): - event.hashes = {} - event.hashes[name] = encode_base64(digest) - - event.signatures = compute_event_signature( - event, + """Add content hash and sign the event + + Args: + event_dict (dict): 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_dict, hash_algorithm=hash_algorithm) + + event_dict.setdefault("hashes", {})[name] = encode_base64(digest) + + event_dict["signatures"] = compute_event_signature( + event_dict, signature_name=signature_name, signing_key=signing_key, ) |