Fix bugs in generating event signatures and hashing

4 files changed, 42 insertions, 83 deletions

diff --git a/synapse/api/events/__init__.py b/synapse/api/events/__init__.py
index b855811b98..168b812311 100644
--- a/synapse/api/events/__init__.py
+++ b/synapse/api/events/__init__.py
@@ -61,6 +61,7 @@ class SynapseEvent(JsonEncodedObject):
         "prev_content",
         "prev_state",
         "redacted_because",
+        "origin_server_ts",
     ]
 
     internal_keys = [
diff --git a/synapse/crypto/event_signing.py b/synapse/crypto/event_signing.py
index 0e8bc7eb6c..de5d2e7465 100644
--- a/synapse/crypto/event_signing.py
+++ b/synapse/crypto/event_signing.py
@@ -15,11 +15,11 @@
 # limitations under the License.
 
 
-from synapse.federation.units import Pdu
-from synapse.api.events.utils import prune_pdu, prune_event
+from synapse.api.events.utils import prune_event
 from syutil.jsonutil import encode_canonical_json
 from syutil.base64util import encode_base64, decode_base64
-from syutil.crypto.jsonsign import sign_json, verify_signed_json
+from syutil.crypto.jsonsign import sign_json
+from synapse.api.events.room import GenericEvent
 
 import copy
 import hashlib
@@ -28,20 +28,14 @@ import logging
 logger = logging.getLogger(__name__)
 
 
-def add_event_pdu_content_hash(pdu, hash_algorithm=hashlib.sha256):
-    hashed = _compute_content_hash(pdu, hash_algorithm)
-    pdu.hashes[hashed.name] = encode_base64(hashed.digest())
-    return pdu
-
-
-def check_event_pdu_content_hash(pdu, hash_algorithm=hashlib.sha256):
+def check_event_content_hash(event, hash_algorithm=hashlib.sha256):
     """Check whether the hash for this PDU matches the contents"""
-    computed_hash = _compute_content_hash(pdu, hash_algorithm)
-    if computed_hash.name not in pdu.hashes:
+    computed_hash = _compute_content_hash(event, hash_algorithm)
+    if computed_hash.name not in event.hashes:
         raise Exception("Algorithm %s not in hashes %s" % (
-            computed_hash.name, list(pdu.hashes)
+            computed_hash.name, list(event.hashes)
         ))
-    message_hash_base64 = pdu.hashes[computed_hash.name]
+    message_hash_base64 = event.hashes[computed_hash.name]
     try:
         message_hash_bytes = decode_base64(message_hash_base64)
     except:
@@ -49,70 +43,52 @@ def check_event_pdu_content_hash(pdu, hash_algorithm=hashlib.sha256):
     return message_hash_bytes == computed_hash.digest()
 
 
-def _compute_content_hash(pdu, hash_algorithm):
-    pdu_json = pdu.get_dict()
-    #TODO: Make "age_ts" key internal
-    pdu_json.pop("age_ts", None)
-    pdu_json.pop("unsigned", None)
-    pdu_json.pop("signatures", None)
-    pdu_json.pop("hashes", None)
-    pdu_json_bytes = encode_canonical_json(pdu_json)
-    return hash_algorithm(pdu_json_bytes)
-
-
-def compute_pdu_event_reference_hash(pdu, hash_algorithm=hashlib.sha256):
-    tmp_pdu = Pdu(**pdu.get_dict())
-    tmp_pdu = prune_pdu(tmp_pdu)
-    pdu_json = tmp_pdu.get_dict()
-    pdu_json.pop("signatures", None)
-    pdu_json_bytes = encode_canonical_json(pdu_json)
-    hashed = hash_algorithm(pdu_json_bytes)
-    return (hashed.name, hashed.digest())
+def _compute_content_hash(event, hash_algorithm):
+    event_json = event.get_full_dict()
+    #TODO: We need to sign the JSON that is going out via fedaration.
+    event_json.pop("age_ts", None)
+    event_json.pop("unsigned", None)
+    event_json.pop("signatures", None)
+    event_json.pop("hashes", None)
+    event_json_bytes = encode_canonical_json(event_json)
+    return hash_algorithm(event_json_bytes)
 
 
 def compute_event_reference_hash(event, hash_algorithm=hashlib.sha256):
-    tmp_event = copy.deepcopy(event)
+    # FIXME(erikj): GenericEvent!
+    tmp_event = GenericEvent(**event.get_full_dict())
     tmp_event = prune_event(tmp_event)
     event_json = tmp_event.get_dict()
     event_json.pop("signatures", None)
+    event_json.pop("age_ts", None)
+    event_json.pop("unsigned", None)
     event_json_bytes = encode_canonical_json(event_json)
     hashed = hash_algorithm(event_json_bytes)
     return (hashed.name, hashed.digest())
 
 
-def sign_event_pdu(pdu, signature_name, signing_key):
-    tmp_pdu = Pdu(**pdu.get_dict())
-    tmp_pdu = prune_pdu(tmp_pdu)
-    pdu_json = tmp_pdu.get_dict()
-    pdu_json = sign_json(pdu_json, signature_name, signing_key)
-    pdu.signatures = pdu_json["signatures"]
-    return pdu
-
-
-def verify_signed_event_pdu(pdu, signature_name, verify_key):
-    tmp_pdu = Pdu(**pdu.get_dict())
-    tmp_pdu = prune_pdu(tmp_pdu)
-    pdu_json = tmp_pdu.get_dict()
-    verify_signed_json(pdu_json, signature_name, verify_key)
-
-
-def add_hashes_and_signatures(event, signature_name, signing_key,
-                              hash_algorithm=hashlib.sha256):
+def compute_event_signature(event, signature_name, signing_key):
     tmp_event = copy.deepcopy(event)
     tmp_event = prune_event(tmp_event)
-    redact_json = tmp_event.get_dict()
+    redact_json = tmp_event.get_full_dict()
     redact_json.pop("signatures", None)
+    redact_json.pop("age_ts", None)
+    redact_json.pop("unsigned", None)
+    logger.debug("Signing event: %s", redact_json)
     redact_json = sign_json(redact_json, signature_name, signing_key)
-    event.signatures = redact_json["signatures"]
+    return redact_json["signatures"]
+
+
+def add_hashes_and_signatures(event, signature_name, signing_key,
+                              hash_algorithm=hashlib.sha256):
+    hashed = _compute_content_hash(event, hash_algorithm=hash_algorithm)
 
-    event_json = event.get_full_dict()
-    #TODO: We need to sign the JSON that is going out via fedaration.
-    event_json.pop("age_ts", None)
-    event_json.pop("unsigned", None)
-    event_json.pop("signatures", None)
-    event_json.pop("hashes", None)
-    event_json_bytes = encode_canonical_json(event_json)
-    hashed = hash_algorithm(event_json_bytes)
     if not hasattr(event, "hashes"):
         event.hashes = {}
     event.hashes[hashed.name] = encode_base64(hashed.digest())
+
+    event.signatures = compute_event_signature(
+        event,
+        signature_name=signature_name,
+        signing_key=signing_key,
+    )
diff --git a/synapse/federation/pdu_codec.py b/synapse/federation/pdu_codec.py
index 5ec97a698e..52c84efb5b 100644
--- a/synapse/federation/pdu_codec.py
+++ b/synapse/federation/pdu_codec.py
@@ -14,10 +14,6 @@
 # limitations under the License.
 
 from .units import Pdu
-from synapse.crypto.event_signing import (
-    add_event_pdu_content_hash, sign_event_pdu
-)
-from synapse.types import EventID
 
 import copy
 
@@ -49,17 +45,10 @@ class PduCodec(object):
     def pdu_from_event(self, event):
         d = event.get_full_dict()
 
-        if hasattr(event, "state_key"):
-            d["is_state"] = True
-
         kwargs = copy.deepcopy(event.unrecognized_keys)
         kwargs.update({
             k: v for k, v in d.items()
         })
 
-        if "origin_server_ts" not in kwargs:
-            kwargs["origin_server_ts"] = int(self.clock.time_msec())
-
         pdu = Pdu(**kwargs)
-        pdu = add_event_pdu_content_hash(pdu)
-        return sign_event_pdu(pdu, self.server_name, self.signing_key)
+        return pdu
diff --git a/synapse/federation/units.py b/synapse/federation/units.py
index c94dcf64cf..c2d8dca8f3 100644
--- a/synapse/federation/units.py
+++ b/synapse/federation/units.py
@@ -65,8 +65,7 @@ class Pdu(JsonEncodedObject):
         "content",
         "outlier",
         "hashes",
-        "signatures",
-        "is_state",  # Below this are keys valid only for State Pdus.
+        "signatures",  # Below this are keys valid only for State Pdus.
         "state_key",
         "prev_state",
         "required_power_level",
@@ -91,16 +90,10 @@ class Pdu(JsonEncodedObject):
     # TODO: We need to make this properly load content rather than
     # just leaving it as a dict. (OR DO WE?!)
 
-    def __init__(self, destinations=[], is_state=False, prev_events=[],
+    def __init__(self, destinations=[], prev_events=[],
                  outlier=False, hashes={}, signatures={}, **kwargs):
-        if is_state:
-            for required_key in ["state_key"]:
-                if required_key not in kwargs:
-                    raise RuntimeError("Key %s is required" % required_key)
-
         super(Pdu, self).__init__(
             destinations=destinations,
-            is_state=bool(is_state),
             prev_events=prev_events,
             outlier=outlier,
             hashes=hashes,