persist hashes and origin signatures for PDUs

6 files changed, 132 insertions, 14 deletions

diff --git a/synapse/api/events/utils.py b/synapse/api/events/utils.py
index c3a32be8c1..7fdf45a264 100644
--- a/synapse/api/events/utils.py
+++ b/synapse/api/events/utils.py
@@ -27,7 +27,14 @@ def prune_event(event):
     the user has specified, but we do want to keep necessary information like
     type, state_key etc.
     """
+    return _prune_event_or_pdu(event.type, event)
 
+def prune_pdu(pdu):
+    """Removes keys that contain unrestricted and non-essential data from a PDU
+    """
+    return _prune_event_or_pdu(pdu.pdu_type, pdu)
+
+def _prune_event_or_pdu(event_type, event):
     # Remove all extraneous fields.
     event.unrecognized_keys = {}
 
@@ -38,25 +45,25 @@ def prune_event(event):
             if field in event.content:
                 new_content[field] = event.content[field]
 
-    if event.type == RoomMemberEvent.TYPE:
+    if event_type == RoomMemberEvent.TYPE:
         add_fields("membership")
-    elif event.type == RoomCreateEvent.TYPE:
+    elif event_type == RoomCreateEvent.TYPE:
         add_fields("creator")
-    elif event.type == RoomJoinRulesEvent.TYPE:
+    elif event_type == RoomJoinRulesEvent.TYPE:
         add_fields("join_rule")
-    elif event.type == RoomPowerLevelsEvent.TYPE:
+    elif event_type == RoomPowerLevelsEvent.TYPE:
         # TODO: Actually check these are valid user_ids etc.
         add_fields("default")
         for k, v in event.content.items():
             if k.startswith("@") and isinstance(v, (int, long)):
                 new_content[k] = v
-    elif event.type == RoomAddStateLevelEvent.TYPE:
+    elif event_type == RoomAddStateLevelEvent.TYPE:
         add_fields("level")
-    elif event.type == RoomSendEventLevelEvent.TYPE:
+    elif event_type == RoomSendEventLevelEvent.TYPE:
         add_fields("level")
-    elif event.type == RoomOpsPowerLevelsEvent.TYPE:
+    elif event_type == RoomOpsPowerLevelsEvent.TYPE:
         add_fields("kick_level", "ban_level", "redact_level")
-    elif event.type == RoomAliasesEvent.TYPE:
+    elif event_type == RoomAliasesEvent.TYPE:
         add_fields("aliases")
 
     event.content = new_content
diff --git a/synapse/crypto/event_signing.py b/synapse/crypto/event_signing.py
new file mode 100644
index 0000000000..6557727e06
--- /dev/null
+++ b/synapse/crypto/event_signing.py
@@ -0,0 +1,70 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2014 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+from synapse.api.events.utils import prune_pdu
+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
+
+import hashlib
+
+
+def hash_event_pdu(pdu, hash_algortithm=hashlib.sha256):
+    hashed = _compute_hash(pdu, hash_algortithm)
+    hashes[hashed.name] = encode_base64(hashed.digest())
+    pdu.hashes = hashes
+    return pdu
+
+
+def check_event_pdu_hash(pdu, hash_algorithm=hashlib.sha256):
+    """Check whether the hash for this PDU matches the contents"""
+    computed_hash = _compute_hash(pdu, hash_algortithm)
+    if computed_hash.name not in pdu.hashes:
+        raise Exception("Algorithm %s not in hashes %s" % (
+            computed_hash.name, list(pdu.hashes)
+        ))
+    message_hash_base64 = hashes[computed_hash.name]
+    try:
+        message_hash_bytes = decode_base64(message_hash_base64)
+    except:
+        raise Exception("Invalid base64: %s" % (message_hash_base64,))
+    return message_hash_bytes == computed_hash.digest()
+
+
+def _compute_hash(pdu, hash_algorithm):
+    pdu_json = pdu.get_dict()
+    pdu_json.pop("meta", None)
+    pdu_json.pop("signatures", None)
+    hashes = pdu_json.pop("hashes", {})
+    pdu_json_bytes = encode_canonical_json(pdu_json)
+    return hash_algorithm(pdu_json_bytes)
+
+
+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_jdon = 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)
diff --git a/synapse/federation/units.py b/synapse/federation/units.py
index d97aeb698e..3518efb215 100644
--- a/synapse/federation/units.py
+++ b/synapse/federation/units.py
@@ -18,6 +18,7 @@ server protocol.
 """
 
 from synapse.util.jsonobject import JsonEncodedObject
+from syutil.base64util import encode_base64
 
 import logging
 import json
@@ -63,6 +64,8 @@ class Pdu(JsonEncodedObject):
         "depth",
         "content",
         "outlier",
+        "hashes",
+        "signatures",
         "is_state",  # Below this are keys valid only for State Pdus.
         "state_key",
         "power_level",
@@ -91,7 +94,7 @@ class Pdu(JsonEncodedObject):
     # just leaving it as a dict. (OR DO WE?!)
 
     def __init__(self, destinations=[], is_state=False, prev_pdus=[],
-                 outlier=False, **kwargs):
+                 outlier=False, hashes={}, signatures={}, **kwargs):
         if is_state:
             for required_key in ["state_key"]:
                 if required_key not in kwargs:
@@ -102,6 +105,8 @@ class Pdu(JsonEncodedObject):
             is_state=is_state,
             prev_pdus=prev_pdus,
             outlier=outlier,
+            hashes=hashes,
+            signatures=signatures,
             **kwargs
         )
 
@@ -126,6 +131,16 @@ class Pdu(JsonEncodedObject):
             if "unrecognized_keys" in d and d["unrecognized_keys"]:
                 args.update(json.loads(d["unrecognized_keys"]))
 
+            hashes = {
+                alg: encode_base64(hsh)
+                for alg, hsh in pdu_tuple.hashes.items()
+            }
+
+            signatures = {
+                kid: encode_base64(sig)
+                for kid, sig in pdu_tuple.signatures.items()
+            }
+
             return Pdu(
                 prev_pdus=pdu_tuple.prev_pdu_list,
                 **args
diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index 6dadeb8cce..bfeab7d1e8 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -40,6 +40,8 @@ from .stream import StreamStore
 from .pdu import StatePduStore, PduStore, PdusTable
 from .transactions import TransactionStore
 from .keys import KeyStore
+from .signatures import SignatureStore
+
 
 import json
 import logging
@@ -59,6 +61,7 @@ SCHEMAS = [
     "room_aliases",
     "keys",
     "redactions",
+    "signatures",
 ]
 
 
@@ -76,7 +79,7 @@ class _RollbackButIsFineException(Exception):
 class DataStore(RoomMemberStore, RoomStore,
                 RegistrationStore, StreamStore, ProfileStore, FeedbackStore,
                 PresenceStore, PduStore, StatePduStore, TransactionStore,
-                DirectoryStore, KeyStore):
+                DirectoryStore, KeyStore, SignatureStore):
 
     def __init__(self, hs):
         super(DataStore, self).__init__(hs)
@@ -144,6 +147,8 @@ class DataStore(RoomMemberStore, RoomStore,
     def _persist_event_pdu_txn(self, txn, pdu):
         cols = dict(pdu.__dict__)
         unrec_keys = dict(pdu.unrecognized_keys)
+        del cols["hashes"]
+        del cols["signatures"]
         del cols["content"]
         del cols["prev_pdus"]
         cols["content_json"] = json.dumps(pdu.content)
@@ -157,6 +162,20 @@ class DataStore(RoomMemberStore, RoomStore,
 
         logger.debug("Persisting: %s", repr(cols))
 
+        for hash_alg, hash_base64 in pdu.hashes.items():
+            hash_bytes = decode_base64(hash_base64)
+            self._store_pdu_hash_txn(
+                txn, pdu.pdu_id, pdu.origin, hash_alg, hash_bytes,
+            )
+
+        signatures = pdu.sigatures.get(pdu.orgin, {})
+
+        for key_id, signature_base64 in signatures:
+            signature_bytes = decode_base64(signature_base64)
+            self.store_pdu_origin_signatures_txn(
+                txn, pdu.pdu_id, pdu.origin, key_id, signature_bytes,
+            )
+
         if pdu.is_state:
             self._persist_state_txn(txn, pdu.prev_pdus, cols)
         else:
diff --git a/synapse/storage/pdu.py b/synapse/storage/pdu.py
index d70467dcd6..9d624429b7 100644
--- a/synapse/storage/pdu.py
+++ b/synapse/storage/pdu.py
@@ -64,6 +64,11 @@ class PduStore(SQLBaseStore):
                 for r in PduEdgesTable.decode_results(txn.fetchall())
             ]
 
+            hashes = self._get_pdu_hashes_txn(txn, pdu_id, origin)
+            signatures = self._get_pdu_origin_signatures_txn(
+                txn, pdu_id, origin
+            )
+
             query = (
                 "SELECT %(fields)s FROM %(pdus)s as p "
                 "LEFT JOIN %(state)s as s "
@@ -80,7 +85,9 @@ class PduStore(SQLBaseStore):
 
             row = txn.fetchone()
             if row:
-                results.append(PduTuple(PduEntry(*row), edges))
+                results.append(PduTuple(
+                    PduEntry(*row), edges, hashes, signatures
+                ))
 
         return results
 
@@ -908,7 +915,7 @@ This does not include a prev_pdus key.
 
 PduTuple = namedtuple(
     "PduTuple",
-    ("pdu_entry", "prev_pdu_list")
+    ("pdu_entry", "prev_pdu_list", "hashes", "signatures")
 )
 """ This is a tuple of a `PduEntry` and a list of `PduIdTuple` that represent
 the `prev_pdus` key of a PDU.
diff --git a/synapse/storage/schema/signatures.sql b/synapse/storage/schema/signatures.sql
index ba3bbb5471..86ee0f2377 100644
--- a/synapse/storage/schema/signatures.sql
+++ b/synapse/storage/schema/signatures.sql
@@ -28,9 +28,9 @@ CREATE TABLE IF NOT EXISTS pdu_origin_signatures (
   origin TEXT,
   key_id TEXT,
   signature BLOB,
-  CONSTRAINT uniqueness UNIQUE (pdu_id, origin, algorithm)
+  CONSTRAINT uniqueness UNIQUE (pdu_id, origin, key_id)
 );
 
 CREATE INDEX IF NOT EXISTS pdu_origin_signatures_id ON pdu_origin_signatures (
-    pdu_id, origin,
+    pdu_id, origin
 );