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-rw-r--r--synapse/api/auth.py201
-rw-r--r--synapse/api/events/__init__.py4
-rw-r--r--synapse/api/events/factory.py18
-rw-r--r--synapse/api/events/utils.py23
-rw-r--r--synapse/crypto/event_signing.py116
-rw-r--r--synapse/federation/pdu_codec.py49
-rw-r--r--synapse/federation/persistence.py70
-rw-r--r--synapse/federation/replication.py189
-rw-r--r--synapse/federation/transport.py139
-rw-r--r--synapse/federation/units.py36
-rw-r--r--synapse/handlers/_base.py14
-rw-r--r--synapse/handlers/directory.py5
-rw-r--r--synapse/handlers/federation.py405
-rw-r--r--synapse/handlers/message.py19
-rw-r--r--synapse/handlers/profile.py5
-rw-r--r--synapse/handlers/room.py19
-rw-r--r--synapse/rest/base.py5
-rw-r--r--synapse/rest/events.py34
-rw-r--r--synapse/server.py7
-rw-r--r--synapse/state.py213
-rw-r--r--synapse/storage/__init__.py148
-rw-r--r--synapse/storage/_base.py167
-rw-r--r--synapse/storage/directory.py1
-rw-r--r--synapse/storage/event_federation.py253
-rw-r--r--synapse/storage/pdu.py915
-rw-r--r--synapse/storage/registration.py7
-rw-r--r--synapse/storage/room.py2
-rw-r--r--synapse/storage/schema/edge_pdus.sql31
-rw-r--r--synapse/storage/schema/event_edges.sql49
-rw-r--r--synapse/storage/schema/event_signatures.sql65
-rw-r--r--synapse/storage/schema/im.sql1
-rw-r--r--synapse/storage/schema/pdu.sql106
-rw-r--r--synapse/storage/schema/state.sql33
-rw-r--r--synapse/storage/signatures.py165
-rw-r--r--synapse/storage/state.py101
-rw-r--r--synapse/storage/stream.py5
-rw-r--r--synapse/storage/transactions.py67
-rw-r--r--synapse/types.py10
-rw-r--r--synapse/util/async.py7
39 files changed, 1996 insertions, 1708 deletions
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index e1b1823cd7..c684265101 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -21,6 +21,8 @@ from synapse.api.constants import Membership, JoinRules
 from synapse.api.errors import AuthError, StoreError, Codes, SynapseError
 from synapse.api.events.room import (
     RoomMemberEvent, RoomPowerLevelsEvent, RoomRedactionEvent,
+    RoomJoinRulesEvent, RoomOpsPowerLevelsEvent, InviteJoinEvent,
+    RoomCreateEvent,
 )
 from synapse.util.logutils import log_function
 
@@ -47,42 +49,60 @@ class Auth(object):
         """
         try:
             if hasattr(event, "room_id"):
+                if event.old_state_events is None:
+                    # Oh, we don't know what the state of the room was, so we
+                    # are trusting that this is allowed (at least for now)
+                    defer.returnValue(True)
+
+                if hasattr(event, "outlier") and event.outlier is True:
+                    # TODO (erikj): Auth for outliers is done differently.
+                    defer.returnValue(True)
+
                 is_state = hasattr(event, "state_key")
 
+                if event.type == RoomCreateEvent.TYPE:
+                    # FIXME
+                    defer.returnValue(True)
+
                 if event.type == RoomMemberEvent.TYPE:
-                    yield self._can_replace_state(event)
-                    allowed = yield self.is_membership_change_allowed(event)
+                    self._can_replace_state(event)
+                    allowed = self.is_membership_change_allowed(event)
+                    if allowed:
+                        logger.debug("Allowing! %s", event)
+                    else:
+                        logger.debug("Denying! %s", event)
                     defer.returnValue(allowed)
                     return
 
-                self._check_joined_room(
-                    member=snapshot.membership_state,
-                    user_id=snapshot.user_id,
-                    room_id=snapshot.room_id,
-                )
+                if not event.type == InviteJoinEvent.TYPE:
+                    self.check_event_sender_in_room(event)
 
                 if is_state:
                     # TODO (erikj): This really only should be called for *new*
                     # state
                     yield self._can_add_state(event)
-                    yield self._can_replace_state(event)
+                    self._can_replace_state(event)
                 else:
                     yield self._can_send_event(event)
 
                 if event.type == RoomPowerLevelsEvent.TYPE:
-                    yield self._check_power_levels(event)
+                    self._check_power_levels(event)
 
                 if event.type == RoomRedactionEvent.TYPE:
-                    yield self._check_redaction(event)
+                    self._check_redaction(event)
 
+
+                logger.debug("Allowing! %s", event)
                 defer.returnValue(True)
             else:
                 raise AuthError(500, "Unknown event: %s" % event)
         except AuthError as e:
             logger.info("Event auth check failed on event %s with msg: %s",
                         event, e.msg)
+            logger.info("Denying! %s", event)
             if raises:
                 raise e
+
         defer.returnValue(False)
 
     @defer.inlineCallbacks
@@ -98,45 +118,72 @@ class Auth(object):
             pass
         defer.returnValue(None)
 
+    def check_event_sender_in_room(self, event):
+        key = (RoomMemberEvent.TYPE, event.user_id, )
+        member_event = event.state_events.get(key)
+
+        return self._check_joined_room(
+            member_event,
+            event.user_id,
+            event.room_id
+        )
+
     def _check_joined_room(self, member, user_id, room_id):
         if not member or member.membership != Membership.JOIN:
             raise AuthError(403, "User %s not in room %s (%s)" % (
                 user_id, room_id, repr(member)
             ))
 
-    @defer.inlineCallbacks
+    @log_function
     def is_membership_change_allowed(self, event):
         target_user_id = event.state_key
 
-        # does this room even exist
-        room = yield self.store.get_room(event.room_id)
-        if not room:
-            raise AuthError(403, "Room does not exist")
-
         # get info about the caller
-        try:
-            caller = yield self.store.get_room_member(
-                user_id=event.user_id,
-                room_id=event.room_id)
-        except:
-            caller = None
+        key = (RoomMemberEvent.TYPE, event.user_id, )
+        caller = event.old_state_events.get(key)
+
         caller_in_room = caller and caller.membership == "join"
 
         # get info about the target
-        try:
-            target = yield self.store.get_room_member(
-                user_id=target_user_id,
-                room_id=event.room_id)
-        except:
-            target = None
+        key = (RoomMemberEvent.TYPE, target_user_id, )
+        target = event.old_state_events.get(key)
+
         target_in_room = target and target.membership == "join"
 
         membership = event.content["membership"]
 
-        join_rule = yield self.store.get_room_join_rule(event.room_id)
-        if not join_rule:
+        key = (RoomJoinRulesEvent.TYPE, "", )
+        join_rule_event = event.old_state_events.get(key)
+        if join_rule_event:
+            join_rule = join_rule_event.content.get(
+                "join_rule", JoinRules.INVITE
+            )
+        else:
             join_rule = JoinRules.INVITE
 
+        user_level = self._get_power_level_from_event_state(
+            event,
+            event.user_id,
+        )
+
+        ban_level, kick_level, redact_level = (
+            self._get_ops_level_from_event_state(
+                event
+            )
+        )
+
+        logger.debug(
+            "is_membership_change_allowed: %s",
+            {
+                "caller_in_room": caller_in_room,
+                "target_in_room": target_in_room,
+                "membership": membership,
+                "join_rule": join_rule,
+                "target_user_id": target_user_id,
+                "event.user_id": event.user_id,
+            }
+        )
+
         if Membership.INVITE == membership:
             # TODO (erikj): We should probably handle this more intelligently
             # PRIVATE join rules.
@@ -153,13 +200,10 @@ class Auth(object):
             # joined: It's a NOOP
             if event.user_id != target_user_id:
                 raise AuthError(403, "Cannot force another user to join.")
-            elif join_rule == JoinRules.PUBLIC or room.is_public:
+            elif join_rule == JoinRules.PUBLIC:
                 pass
             elif join_rule == JoinRules.INVITE:
-                if (
-                    not caller or caller.membership not in
-                    [Membership.INVITE, Membership.JOIN]
-                ):
+                if not caller_in_room:
                     raise AuthError(403, "You are not invited to this room.")
             else:
                 # TODO (erikj): may_join list
@@ -171,29 +215,16 @@ class Auth(object):
             if not caller_in_room:  # trying to leave a room you aren't joined
                 raise AuthError(403, "You are not in room %s." % event.room_id)
             elif target_user_id != event.user_id:
-                user_level = yield self.store.get_power_level(
-                    event.room_id,
-                    event.user_id,
-                )
-                _, kick_level, _ = yield self.store.get_ops_levels(event.room_id)
-
                 if kick_level:
                     kick_level = int(kick_level)
                 else:
-                    kick_level = 50
+                    kick_level = 50  # FIXME (erikj): What should we do here?
 
                 if user_level < kick_level:
                     raise AuthError(
                         403, "You cannot kick user %s." % target_user_id
                     )
         elif Membership.BAN == membership:
-            user_level = yield self.store.get_power_level(
-                event.room_id,
-                event.user_id,
-            )
-
-            ban_level, _, _  = yield self.store.get_ops_levels(event.room_id)
-
             if ban_level:
                 ban_level = int(ban_level)
             else:
@@ -204,7 +235,30 @@ class Auth(object):
         else:
             raise AuthError(500, "Unknown membership %s" % membership)
 
-        defer.returnValue(True)
+        return True
+
+    def _get_power_level_from_event_state(self, event, user_id):
+        key = (RoomPowerLevelsEvent.TYPE, "", )
+        power_level_event = event.old_state_events.get(key)
+        level = None
+        if power_level_event:
+            level = power_level_event.content.get(user_id)
+            if not level:
+                level = power_level_event.content.get("default", 0)
+
+        return level
+
+    def _get_ops_level_from_event_state(self, event):
+        key = (RoomOpsPowerLevelsEvent.TYPE, "", )
+        ops_event = event.old_state_events.get(key)
+
+        if ops_event:
+            return (
+                ops_event.content.get("ban_level"),
+                ops_event.content.get("kick_level"),
+                ops_event.content.get("redact_level"),
+            )
+        return None, None, None,
 
     @defer.inlineCallbacks
     def get_user_by_req(self, request):
@@ -282,8 +336,8 @@ class Auth(object):
         else:
             send_level = 0
 
-        user_level = yield self.store.get_power_level(
-            event.room_id,
+        user_level = self._get_power_level_from_event_state(
+            event,
             event.user_id,
         )
 
@@ -308,8 +362,8 @@ class Auth(object):
 
         add_level = int(add_level)
 
-        user_level = yield self.store.get_power_level(
-            event.room_id,
+        user_level = self._get_power_level_from_event_state(
+            event,
             event.user_id,
         )
 
@@ -322,19 +376,9 @@ class Auth(object):
 
         defer.returnValue(True)
 
-    @defer.inlineCallbacks
     def _can_replace_state(self, event):
-        current_state = yield self.store.get_current_state(
-            event.room_id,
-            event.type,
-            event.state_key,
-        )
-
-        if current_state:
-            current_state = current_state[0]
-
-        user_level = yield self.store.get_power_level(
-            event.room_id,
+        user_level = self._get_power_level_from_event_state(
+            event,
             event.user_id,
         )
 
@@ -346,6 +390,10 @@ class Auth(object):
         logger.debug(
             "Checking power level for %s, %s", event.user_id, user_level
         )
+
+        key = (event.type, event.state_key, )
+        current_state = event.old_state_events.get(key)
+
         if current_state and hasattr(current_state, "required_power_level"):
             req = current_state.required_power_level
 
@@ -356,10 +404,9 @@ class Auth(object):
                     "You don't have permission to change that state"
                 )
 
-    @defer.inlineCallbacks
     def _check_redaction(self, event):
-        user_level = yield self.store.get_power_level(
-            event.room_id,
+        user_level = self._get_power_level_from_event_state(
+            event,
             event.user_id,
         )
 
@@ -368,7 +415,9 @@ class Auth(object):
         else:
             user_level = 0
 
-        _, _, redact_level  = yield self.store.get_ops_levels(event.room_id)
+        _, _, redact_level = self._get_ops_level_from_event_state(
+            event
+        )
 
         if not redact_level:
             redact_level = 50
@@ -379,7 +428,6 @@ class Auth(object):
                 "You don't have permission to redact events"
             )
 
-    @defer.inlineCallbacks
     def _check_power_levels(self, event):
         for k, v in event.content.items():
             if k == "default":
@@ -399,19 +447,16 @@ class Auth(object):
             except:
                 raise SynapseError(400, "Not a valid power level: %s" % (v,))
 
-        current_state = yield self.store.get_current_state(
-            event.room_id,
-            event.type,
-            event.state_key,
-        )
+        key = (event.type, event.state_key, )
+        current_state = event.old_state_events.get(key)
 
         if not current_state:
             return
         else:
             current_state = current_state[0]
 
-        user_level = yield self.store.get_power_level(
-            event.room_id,
+        user_level = self._get_power_level_from_event_state(
+            event,
             event.user_id,
         )
 
diff --git a/synapse/api/events/__init__.py b/synapse/api/events/__init__.py
index f66fea2904..b855811b98 100644
--- a/synapse/api/events/__init__.py
+++ b/synapse/api/events/__init__.py
@@ -65,13 +65,15 @@ class SynapseEvent(JsonEncodedObject):
 
     internal_keys = [
         "is_state",
-        "prev_events",
         "depth",
         "destinations",
         "origin",
         "outlier",
         "power_level",
         "redacted",
+        "prev_events",
+        "hashes",
+        "signatures",
     ]
 
     required_keys = [
diff --git a/synapse/api/events/factory.py b/synapse/api/events/factory.py
index 74d0ef77f4..750096c618 100644
--- a/synapse/api/events/factory.py
+++ b/synapse/api/events/factory.py
@@ -21,6 +21,8 @@ from synapse.api.events.room import (
     RoomRedactionEvent,
 )
 
+from synapse.types import EventID
+
 from synapse.util.stringutils import random_string
 
 
@@ -51,12 +53,22 @@ class EventFactory(object):
         self.clock = hs.get_clock()
         self.hs = hs
 
+        self.event_id_count = 0
+
+    def create_event_id(self):
+        i = str(self.event_id_count)
+        self.event_id_count += 1
+
+        local_part = str(int(self.clock.time())) + i + random_string(5)
+
+        e_id = EventID.create_local(local_part, self.hs)
+
+        return e_id.to_string()
+
     def create_event(self, etype=None, **kwargs):
         kwargs["type"] = etype
         if "event_id" not in kwargs:
-            kwargs["event_id"] = "%s@%s" % (
-                random_string(10), self.hs.hostname
-            )
+            kwargs["event_id"] = self.create_event_id()
 
         if "origin_server_ts" not in kwargs:
             kwargs["origin_server_ts"] = int(self.clock.time_msec())
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..cb2db01c04
--- /dev/null
+++ b/synapse/crypto/event_signing.py
@@ -0,0 +1,116 @@
+# -*- 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.federation.units import Pdu
+from synapse.api.events.utils import prune_pdu, 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
+
+import copy
+import hashlib
+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):
+    """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:
+        raise Exception("Algorithm %s not in hashes %s" % (
+            computed_hash.name, list(pdu.hashes)
+        ))
+    message_hash_base64 = pdu.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_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_event_reference_hash(event, hash_algorithm=hashlib.sha256):
+    tmp_event = copy.deepcopy(event)
+    tmp_event = prune_event(tmp_event)
+    event_json = tmp_event.get_dict()
+    event_json.pop("signatures", 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):
+    tmp_event = copy.deepcopy(event)
+    tmp_event = prune_event(tmp_event)
+    redact_json = tmp_event.get_dict()
+    redact_json.pop("signatures", None)
+    redact_json = sign_json(redact_json, signature_name, signing_key)
+    event.signatures = redact_json["signatures"]
+
+    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)
+    event.hashes[hashed.name] = encode_base64(hashed.digest())
diff --git a/synapse/federation/pdu_codec.py b/synapse/federation/pdu_codec.py
index e8180d94fd..d4c896e163 100644
--- a/synapse/federation/pdu_codec.py
+++ b/synapse/federation/pdu_codec.py
@@ -14,41 +14,43 @@
 # 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
 
 
-def decode_event_id(event_id, server_name):
-    parts = event_id.split("@")
-    if len(parts) < 2:
-        return (event_id, server_name)
-    else:
-        return (parts[0], "".join(parts[1:]))
-
-
-def encode_event_id(pdu_id, origin):
-    return "%s@%s" % (pdu_id, origin)
-
-
 class PduCodec(object):
 
     def __init__(self, hs):
+        self.signing_key = hs.config.signing_key[0]
         self.server_name = hs.hostname
         self.event_factory = hs.get_event_factory()
         self.clock = hs.get_clock()
+        self.hs = hs
+
+    def encode_event_id(self, local, domain):
+        return local
+
+    def decode_event_id(self, event_id):
+        e_id = self.hs.parse_eventid(event_id)
+        return event_id, e_id.domain
 
     def event_from_pdu(self, pdu):
         kwargs = {}
 
-        kwargs["event_id"] = encode_event_id(pdu.pdu_id, pdu.origin)
+        kwargs["event_id"] = self.encode_event_id(pdu.pdu_id, pdu.origin)
         kwargs["room_id"] = pdu.context
         kwargs["etype"] = pdu.pdu_type
         kwargs["prev_events"] = [
-            encode_event_id(p[0], p[1]) for p in pdu.prev_pdus
+            (self.encode_event_id(i, o), s)
+            for i, o, s in pdu.prev_pdus
         ]
 
         if hasattr(pdu, "prev_state_id") and hasattr(pdu, "prev_state_origin"):
-            kwargs["prev_state"] = encode_event_id(
+            kwargs["prev_state"] = self.encode_event_id(
                 pdu.prev_state_id, pdu.prev_state_origin
             )
 
@@ -70,21 +72,24 @@ class PduCodec(object):
     def pdu_from_event(self, event):
         d = event.get_full_dict()
 
-        d["pdu_id"], d["origin"] = decode_event_id(
-            event.event_id, self.server_name
+        d["pdu_id"], d["origin"] = self.decode_event_id(
+            event.event_id
         )
         d["context"] = event.room_id
         d["pdu_type"] = event.type
 
         if hasattr(event, "prev_events"):
+            def f(e, s):
+                i, o = self.decode_event_id(e)
+                return i, o, s
             d["prev_pdus"] = [
-                decode_event_id(e, self.server_name)
-                for e in event.prev_events
+                f(e, s)
+                for e, s in event.prev_events
             ]
 
         if hasattr(event, "prev_state"):
             d["prev_state_id"], d["prev_state_origin"] = (
-                decode_event_id(event.prev_state, self.server_name)
+                self.decode_event_id(event.prev_state)
             )
 
         if hasattr(event, "state_key"):
@@ -99,4 +104,6 @@ class PduCodec(object):
         if "origin_server_ts" not in kwargs:
             kwargs["origin_server_ts"] = int(self.clock.time_msec())
 
-        return Pdu(**kwargs)
+        pdu = Pdu(**kwargs)
+        pdu = add_event_pdu_content_hash(pdu)
+        return sign_event_pdu(pdu, self.server_name, self.signing_key)
diff --git a/synapse/federation/persistence.py b/synapse/federation/persistence.py
index 7043fcc504..a565375e68 100644
--- a/synapse/federation/persistence.py
+++ b/synapse/federation/persistence.py
@@ -32,76 +32,6 @@ import logging
 logger = logging.getLogger(__name__)
 
 
-class PduActions(object):
-    """ Defines persistence actions that relate to handling PDUs.
-    """
-
-    def __init__(self, datastore):
-        self.store = datastore
-
-    @log_function
-    def mark_as_processed(self, pdu):
-        """ Persist the fact that we have fully processed the given `Pdu`
-
-        Returns:
-            Deferred
-        """
-        return self.store.mark_pdu_as_processed(pdu.pdu_id, pdu.origin)
-
-    @defer.inlineCallbacks
-    @log_function
-    def after_transaction(self, transaction_id, destination, origin):
-        """ Returns all `Pdu`s that we sent to the given remote home server
-        after a given transaction id.
-
-        Returns:
-            Deferred: Results in a list of `Pdu`s
-        """
-        results = yield self.store.get_pdus_after_transaction(
-            transaction_id,
-            destination
-        )
-
-        defer.returnValue([Pdu.from_pdu_tuple(p) for p in results])
-
-    @defer.inlineCallbacks
-    @log_function
-    def get_all_pdus_from_context(self, context):
-        results = yield self.store.get_all_pdus_from_context(context)
-        defer.returnValue([Pdu.from_pdu_tuple(p) for p in results])
-
-    @defer.inlineCallbacks
-    @log_function
-    def backfill(self, context, pdu_list, limit):
-        """ For a given list of PDU id and origins return the proceeding
-        `limit` `Pdu`s in the given `context`.
-
-        Returns:
-            Deferred: Results in a list of `Pdu`s.
-        """
-        results = yield self.store.get_backfill(
-            context, pdu_list, limit
-        )
-
-        defer.returnValue([Pdu.from_pdu_tuple(p) for p in results])
-
-    @log_function
-    def is_new(self, pdu):
-        """ When we receive a `Pdu` from a remote home server, we want to
-        figure out whether it is `new`, i.e. it is not some historic PDU that
-        we haven't seen simply because we haven't backfilled back that far.
-
-        Returns:
-            Deferred: Results in a `bool`
-        """
-        return self.store.is_pdu_new(
-            pdu_id=pdu.pdu_id,
-            origin=pdu.origin,
-            context=pdu.context,
-            depth=pdu.depth
-        )
-
-
 class TransactionActions(object):
     """ Defines persistence actions that relate to handling Transactions.
     """
diff --git a/synapse/federation/replication.py b/synapse/federation/replication.py
index 092411eaf9..159af4eed7 100644
--- a/synapse/federation/replication.py
+++ b/synapse/federation/replication.py
@@ -21,7 +21,7 @@ from twisted.internet import defer
 
 from .units import Transaction, Pdu, Edu
 
-from .persistence import PduActions, TransactionActions
+from .persistence import TransactionActions
 
 from synapse.util.logutils import log_function
 
@@ -57,7 +57,7 @@ class ReplicationLayer(object):
         self.transport_layer.register_request_handler(self)
 
         self.store = hs.get_datastore()
-        self.pdu_actions = PduActions(self.store)
+        # self.pdu_actions = PduActions(self.store)
         self.transaction_actions = TransactionActions(self.store)
 
         self._transaction_queue = _TransactionQueue(
@@ -106,7 +106,6 @@ class ReplicationLayer(object):
 
         self.query_handlers[query_type] = handler
 
-    @defer.inlineCallbacks
     @log_function
     def send_pdu(self, pdu):
         """Informs the replication layer about a new PDU generated within the
@@ -135,7 +134,7 @@ class ReplicationLayer(object):
         logger.debug("[%s] Persisting PDU", pdu.pdu_id)
 
         # Save *before* trying to send
-        yield self.store.persist_event(pdu=pdu)
+        # yield self.store.persist_event(pdu=pdu)
 
         logger.debug("[%s] Persisted PDU", pdu.pdu_id)
         logger.debug("[%s] transaction_layer.enqueue_pdu... ", pdu.pdu_id)
@@ -181,7 +180,7 @@ class ReplicationLayer(object):
 
     @defer.inlineCallbacks
     @log_function
-    def backfill(self, dest, context, limit):
+    def backfill(self, dest, context, limit, extremities):
         """Requests some more historic PDUs for the given context from the
         given destination server.
 
@@ -189,12 +188,12 @@ class ReplicationLayer(object):
             dest (str): The remote home server to ask.
             context (str): The context to backfill.
             limit (int): The maximum number of PDUs to return.
+            extremities (list): List of PDU id and origins of the first pdus
+                we have seen from the context
 
         Returns:
             Deferred: Results in the received PDUs.
         """
-        extremities = yield self.store.get_oldest_pdus_in_context(context)
-
         logger.debug("backfill extrem=%s", extremities)
 
         # If there are no extremeties then we've (probably) reached the start.
@@ -244,13 +243,14 @@ class ReplicationLayer(object):
         pdu = None
         if pdu_list:
             pdu = pdu_list[0]
-            yield self._handle_new_pdu(pdu)
+            yield self._handle_new_pdu(destination, pdu)
 
         defer.returnValue(pdu)
 
     @defer.inlineCallbacks
     @log_function
-    def get_state_for_context(self, destination, context):
+    def get_state_for_context(self, destination, context, pdu_id=None,
+                              pdu_origin=None):
         """Requests all of the `current` state PDUs for a given context from
         a remote home server.
 
@@ -263,29 +263,30 @@ class ReplicationLayer(object):
         """
 
         transaction_data = yield self.transport_layer.get_context_state(
-            destination, context)
+            destination, context, pdu_id=pdu_id, pdu_origin=pdu_origin,
+        )
 
         transaction = Transaction(**transaction_data)
 
         pdus = [Pdu(outlier=True, **p) for p in transaction.pdus]
         for pdu in pdus:
-            yield self._handle_new_pdu(pdu)
+            yield self._handle_new_pdu(destination, pdu)
 
         defer.returnValue(pdus)
 
     @defer.inlineCallbacks
     @log_function
     def on_context_pdus_request(self, context):
-        pdus = yield self.pdu_actions.get_all_pdus_from_context(
-            context
+        raise NotImplementedError(
+            "on_context_pdus_request is a security violation"
         )
-        defer.returnValue((200, self._transaction_from_pdus(pdus).get_dict()))
 
     @defer.inlineCallbacks
     @log_function
     def on_backfill_request(self, context, versions, limit):
-
-        pdus = yield self.pdu_actions.backfill(context, versions, limit)
+        pdus = yield self.handler.on_backfill_request(
+            context, versions, limit
+        )
 
         defer.returnValue((200, self._transaction_from_pdus(pdus).get_dict()))
 
@@ -295,6 +296,10 @@ class ReplicationLayer(object):
         transaction = Transaction(**transaction_data)
 
         for p in transaction.pdus:
+            if "unsigned" in p:
+                unsigned = p["unsigned"]
+                if "age" in unsigned:
+                    p["age"] = unsigned["age"]
             if "age" in p:
                 p["age_ts"] = int(self._clock.time_msec()) - int(p["age"])
                 del p["age"]
@@ -315,7 +320,7 @@ class ReplicationLayer(object):
 
         dl = []
         for pdu in pdu_list:
-            dl.append(self._handle_new_pdu(pdu))
+            dl.append(self._handle_new_pdu(transaction.origin, pdu))
 
         if hasattr(transaction, "edus"):
             for edu in [Edu(**x) for x in transaction.edus]:
@@ -347,14 +352,20 @@ class ReplicationLayer(object):
 
     @defer.inlineCallbacks
     @log_function
-    def on_context_state_request(self, context):
-        results = yield self.store.get_current_state_for_context(
-            context
-        )
-
-        logger.debug("Context returning %d results", len(results))
+    def on_context_state_request(self, context, pdu_id, pdu_origin):
+        if pdu_id and pdu_origin:
+            pdus = yield self.handler.get_state_for_pdu(
+                pdu_id, pdu_origin
+            )
+        else:
+            raise NotImplementedError("Specify an event")
+        #     results = yield self.store.get_current_state_for_context(
+        #         context
+        #     )
+        #     pdus = [Pdu.from_pdu_tuple(p) for p in results]
+        #
+        # logger.debug("Context returning %d results", len(pdus))
 
-        pdus = [Pdu.from_pdu_tuple(p) for p in results]
         defer.returnValue((200, self._transaction_from_pdus(pdus).get_dict()))
 
     @defer.inlineCallbacks
@@ -372,20 +383,22 @@ class ReplicationLayer(object):
     @defer.inlineCallbacks
     @log_function
     def on_pull_request(self, origin, versions):
-        transaction_id = max([int(v) for v in versions])
-
-        response = yield self.pdu_actions.after_transaction(
-            transaction_id,
-            origin,
-            self.server_name
-        )
-
-        if not response:
-            response = []
-
-        defer.returnValue(
-            (200, self._transaction_from_pdus(response).get_dict())
-        )
+        raise NotImplementedError("Pull transacions not implemented")
+
+        # transaction_id = max([int(v) for v in versions])
+        #
+        # response = yield self.pdu_actions.after_transaction(
+        #     transaction_id,
+        #     origin,
+        #     self.server_name
+        # )
+        #
+        # if not response:
+        #     response = []
+        #
+        # defer.returnValue(
+        #     (200, self._transaction_from_pdus(response).get_dict())
+        # )
 
     @defer.inlineCallbacks
     def on_query_request(self, query_type, args):
@@ -393,11 +406,56 @@ class ReplicationLayer(object):
             response = yield self.query_handlers[query_type](args)
             defer.returnValue((200, response))
         else:
-            defer.returnValue((404, "No handler for Query type '%s'"
-                % (query_type)
-            ))
+            defer.returnValue(
+                (404, "No handler for Query type '%s'" % (query_type, ))
+            )
+
+    @defer.inlineCallbacks
+    def on_make_join_request(self, context, user_id):
+        pdu = yield self.handler.on_make_join_request(context, user_id)
+        defer.returnValue(pdu.get_dict())
+
+    @defer.inlineCallbacks
+    def on_invite_request(self, origin, content):
+        pdu = Pdu(**content)
+        ret_pdu = yield self.handler.on_send_join_request(origin, pdu)
+        defer.returnValue((200, ret_pdu.get_dict()))
 
     @defer.inlineCallbacks
+    def on_send_join_request(self, origin, content):
+        pdu = Pdu(**content)
+        state = yield self.handler.on_send_join_request(origin, pdu)
+        defer.returnValue((200, self._transaction_from_pdus(state).get_dict()))
+
+    @defer.inlineCallbacks
+    def make_join(self, destination, context, user_id):
+        pdu_dict = yield self.transport_layer.make_join(
+            destination=destination,
+            context=context,
+            user_id=user_id,
+        )
+
+        logger.debug("Got response to make_join: %s", pdu_dict)
+
+        defer.returnValue(Pdu(**pdu_dict))
+
+    @defer.inlineCallbacks
+    def send_join(self, destination, pdu):
+        _, content = yield self.transport_layer.send_join(
+            destination,
+            pdu.context,
+            pdu.pdu_id,
+            pdu.origin,
+            pdu.get_dict(),
+        )
+
+        logger.debug("Got content: %s", content)
+        pdus = [Pdu(outlier=True, **p) for p in content.get("pdus", [])]
+        for pdu in pdus:
+            yield self._handle_new_pdu(destination, pdu)
+
+        defer.returnValue(pdus)
+
     @log_function
     def _get_persisted_pdu(self, pdu_id, pdu_origin):
         """ Get a PDU from the database with given origin and id.
@@ -405,29 +463,29 @@ class ReplicationLayer(object):
         Returns:
             Deferred: Results in a `Pdu`.
         """
-        pdu_tuple = yield self.store.get_pdu(pdu_id, pdu_origin)
-
-        defer.returnValue(Pdu.from_pdu_tuple(pdu_tuple))
+        return self.handler.get_persisted_pdu(pdu_id, pdu_origin)
 
     def _transaction_from_pdus(self, pdu_list):
         """Returns a new Transaction containing the given PDUs suitable for
         transmission.
         """
         pdus = [p.get_dict() for p in pdu_list]
+        time_now = self._clock.time_msec()
         for p in pdus:
-            if "age_ts" in pdus:
-                p["age"] = int(self.clock.time_msec()) - p["age_ts"]
-
+            if "age_ts" in p:
+                age = time_now - p["age_ts"]
+                p.setdefault("unsigned", {})["age"] = int(age)
+                del p["age_ts"]
         return Transaction(
             origin=self.server_name,
             pdus=pdus,
-            origin_server_ts=int(self._clock.time_msec()),
+            origin_server_ts=int(time_now),
             destination=None,
         )
 
     @defer.inlineCallbacks
     @log_function
-    def _handle_new_pdu(self, pdu, backfilled=False):
+    def _handle_new_pdu(self, origin, pdu, backfilled=False):
         # We reprocess pdus when we have seen them only as outliers
         existing = yield self._get_persisted_pdu(pdu.pdu_id, pdu.origin)
 
@@ -436,14 +494,17 @@ class ReplicationLayer(object):
             defer.returnValue({})
             return
 
+        state = None
+
         # Get missing pdus if necessary.
-        is_new = yield self.pdu_actions.is_new(pdu)
-        if is_new and not pdu.outlier:
+        if not pdu.outlier:
             # We only backfill backwards to the min depth.
-            min_depth = yield self.store.get_min_depth_for_context(pdu.context)
+            min_depth = yield self.handler.get_min_depth_for_context(
+                pdu.context
+            )
 
             if min_depth and pdu.depth > min_depth:
-                for pdu_id, origin in pdu.prev_pdus:
+                for pdu_id, origin, hashes in pdu.prev_pdus:
                     exists = yield self._get_persisted_pdu(pdu_id, origin)
 
                     if not exists:
@@ -459,16 +520,26 @@ class ReplicationLayer(object):
                         except:
                             # TODO(erikj): Do some more intelligent retries.
                             logger.exception("Failed to get PDU")
+            else:
+                # We need to get the state at this event, since we have reached
+                # a backward extremity edge.
+                state = yield self.get_state_for_context(
+                    origin, pdu.context, pdu.pdu_id, pdu.origin,
+                )
 
         # Persist the Pdu, but don't mark it as processed yet.
-        yield self.store.persist_event(pdu=pdu)
+        # yield self.store.persist_event(pdu=pdu)
 
         if not backfilled:
-            ret = yield self.handler.on_receive_pdu(pdu, backfilled=backfilled)
+            ret = yield self.handler.on_receive_pdu(
+                pdu,
+                backfilled=backfilled,
+                state=state,
+            )
         else:
             ret = None
 
-        yield self.pdu_actions.mark_as_processed(pdu)
+        # yield self.pdu_actions.mark_as_processed(pdu)
 
         defer.returnValue(ret)
 
@@ -589,7 +660,7 @@ class _TransactionQueue(object):
             logger.debug("TX [%s] Persisting transaction...", destination)
 
             transaction = Transaction.create_new(
-                origin_server_ts=self._clock.time_msec(),
+                origin_server_ts=int(self._clock.time_msec()),
                 transaction_id=str(self._next_txn_id),
                 origin=self.server_name,
                 destination=destination,
@@ -614,7 +685,9 @@ class _TransactionQueue(object):
                 if "pdus" in data:
                     for p in data["pdus"]:
                         if "age_ts" in p:
-                            p["age"] = now - int(p["age_ts"])
+                            unsigned = p.setdefault("unsigned", {})
+                            unsigned["age"] = now - int(p["age_ts"])
+                            del p["age_ts"]
                 return data
 
             code, response = yield self.transport_layer.send_transaction(
diff --git a/synapse/federation/transport.py b/synapse/federation/transport.py
index e7517cac4d..7f01b4faaf 100644
--- a/synapse/federation/transport.py
+++ b/synapse/federation/transport.py
@@ -72,7 +72,8 @@ class TransportLayer(object):
         self.received_handler = None
 
     @log_function
-    def get_context_state(self, destination, context):
+    def get_context_state(self, destination, context, pdu_id=None,
+                          pdu_origin=None):
         """ Requests all state for a given context (i.e. room) from the
         given server.
 
@@ -89,7 +90,14 @@ class TransportLayer(object):
 
         subpath = "/state/%s/" % context
 
-        return self._do_request_for_transaction(destination, subpath)
+        args = {}
+        if pdu_id and pdu_origin:
+            args["pdu_id"] = pdu_id
+            args["pdu_origin"] = pdu_origin
+
+        return self._do_request_for_transaction(
+            destination, subpath, args=args
+        )
 
     @log_function
     def get_pdu(self, destination, pdu_origin, pdu_id):
@@ -135,8 +143,10 @@ class TransportLayer(object):
 
         subpath = "/backfill/%s/" % context
 
-        args = {"v": ["%s,%s" % (i, o) for i, o in pdu_tuples]}
-        args["limit"] = limit
+        args = {
+            "v": ["%s,%s" % (i, o) for i, o in pdu_tuples],
+            "limit": limit,
+        }
 
         return self._do_request_for_transaction(
             dest,
@@ -198,6 +208,59 @@ class TransportLayer(object):
         defer.returnValue(response)
 
     @defer.inlineCallbacks
+    @log_function
+    def make_join(self, destination, context, user_id, retry_on_dns_fail=True):
+        path = PREFIX + "/make_join/%s/%s" % (context, user_id,)
+
+        response = yield self.client.get_json(
+            destination=destination,
+            path=path,
+            retry_on_dns_fail=retry_on_dns_fail,
+        )
+
+        defer.returnValue(response)
+
+    @defer.inlineCallbacks
+    @log_function
+    def send_join(self, destination, context, pdu_id, origin, content):
+        path = PREFIX + "/send_join/%s/%s/%s" % (
+            context,
+            origin,
+            pdu_id,
+        )
+
+        code, content = yield self.client.put_json(
+            destination=destination,
+            path=path,
+            data=content,
+        )
+
+        if not 200 <= code < 300:
+            raise RuntimeError("Got %d from send_join", code)
+
+        defer.returnValue(json.loads(content))
+
+    @defer.inlineCallbacks
+    @log_function
+    def send_invite(self, destination, context, pdu_id, origin, content):
+        path = PREFIX + "/invite/%s/%s/%s" % (
+            context,
+            origin,
+            pdu_id,
+        )
+
+        code, content = yield self.client.put_json(
+            destination=destination,
+            path=path,
+            data=content,
+        )
+
+        if not 200 <= code < 300:
+            raise RuntimeError("Got %d from send_invite", code)
+
+        defer.returnValue(json.loads(content))
+
+    @defer.inlineCallbacks
     def _authenticate_request(self, request):
         json_request = {
             "method": request.method,
@@ -326,7 +389,11 @@ class TransportLayer(object):
             re.compile("^" + PREFIX + "/state/([^/]*)/$"),
             self._with_authentication(
                 lambda origin, content, query, context:
-                handler.on_context_state_request(context)
+                handler.on_context_state_request(
+                    context,
+                    query.get("pdu_id", [None])[0],
+                    query.get("pdu_origin", [None])[0]
+                )
             )
         )
 
@@ -362,6 +429,39 @@ class TransportLayer(object):
             )
         )
 
+        self.server.register_path(
+            "GET",
+            re.compile("^" + PREFIX + "/make_join/([^/]*)/([^/]*)$"),
+            self._with_authentication(
+                lambda origin, content, query, context, user_id:
+                self._on_make_join_request(
+                    origin, content, query, context, user_id
+                )
+            )
+        )
+
+        self.server.register_path(
+            "PUT",
+            re.compile("^" + PREFIX + "/send_join/([^/]*)/([^/]*)/([^/]*)$"),
+            self._with_authentication(
+                lambda origin, content, query, context, pdu_origin, pdu_id:
+                self._on_send_join_request(
+                    origin, content, query,
+                )
+            )
+        )
+
+        self.server.register_path(
+            "PUT",
+            re.compile("^" + PREFIX + "/invite/([^/]*)/([^/]*)/([^/]*)$"),
+            self._with_authentication(
+                lambda origin, content, query, context, pdu_origin, pdu_id:
+                self._on_invite_request(
+                    origin, content, query,
+                )
+            )
+        )
+
     @defer.inlineCallbacks
     @log_function
     def _on_send_request(self, origin, content, query, transaction_id):
@@ -451,7 +551,34 @@ class TransportLayer(object):
         versions = [v.split(",", 1) for v in v_list]
 
         return self.request_handler.on_backfill_request(
-            context, versions, limit)
+            context, versions, limit
+        )
+
+    @defer.inlineCallbacks
+    @log_function
+    def _on_make_join_request(self, origin, content, query, context, user_id):
+        content = yield self.request_handler.on_make_join_request(
+            context, user_id,
+        )
+        defer.returnValue((200, content))
+
+    @defer.inlineCallbacks
+    @log_function
+    def _on_send_join_request(self, origin, content, query):
+        content = yield self.request_handler.on_send_join_request(
+            origin, content,
+        )
+
+        defer.returnValue((200, content))
+
+    @defer.inlineCallbacks
+    @log_function
+    def _on_invite_request(self, origin, content, query):
+        content = yield self.request_handler.on_invite_request(
+            origin, content,
+        )
+
+        defer.returnValue((200, content))
 
 
 class TransportReceivedHandler(object):
diff --git a/synapse/federation/units.py b/synapse/federation/units.py
index b2fb964180..adc3385644 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
@@ -63,9 +64,10 @@ class Pdu(JsonEncodedObject):
         "depth",
         "content",
         "outlier",
+        "hashes",
+        "signatures",
         "is_state",  # Below this are keys valid only for State Pdus.
         "state_key",
-        "power_level",
         "prev_state_id",
         "prev_state_origin",
         "required_power_level",
@@ -91,7 +93,7 @@ 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:
@@ -99,9 +101,11 @@ class Pdu(JsonEncodedObject):
 
         super(Pdu, self).__init__(
             destinations=destinations,
-            is_state=is_state,
+            is_state=bool(is_state),
             prev_pdus=prev_pdus,
             outlier=outlier,
+            hashes=hashes,
+            signatures=signatures,
             **kwargs
         )
 
@@ -120,6 +124,10 @@ class Pdu(JsonEncodedObject):
             d = copy.copy(pdu_tuple.pdu_entry._asdict())
             d["origin_server_ts"] = d.pop("ts")
 
+            for k in d.keys():
+                if d[k] is None:
+                    del d[k]
+
             d["content"] = json.loads(d["content_json"])
             del d["content_json"]
 
@@ -127,8 +135,28 @@ 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()
+            }
+
+            prev_pdus = []
+            for prev_pdu in pdu_tuple.prev_pdu_list:
+                prev_hashes = pdu_tuple.edge_hashes.get(prev_pdu, {})
+                prev_hashes = {
+                    alg: encode_base64(hsh) for alg, hsh in prev_hashes.items()
+                }
+                prev_pdus.append((prev_pdu[0], prev_pdu[1], prev_hashes))
+
             return Pdu(
-                prev_pdus=pdu_tuple.prev_pdu_list,
+                prev_pdus=prev_pdus,
+                hashes=hashes,
+                signatures=signatures,
                 **args
             )
         else:
diff --git a/synapse/handlers/_base.py b/synapse/handlers/_base.py
index de4d23bbb3..787a01efc5 100644
--- a/synapse/handlers/_base.py
+++ b/synapse/handlers/_base.py
@@ -16,6 +16,8 @@
 from twisted.internet import defer
 from synapse.api.errors import LimitExceededError
 
+from synapse.util.async import run_on_reactor
+
 class BaseHandler(object):
 
     def __init__(self, hs):
@@ -44,9 +46,19 @@ class BaseHandler(object):
 
     @defer.inlineCallbacks
     def _on_new_room_event(self, event, snapshot, extra_destinations=[],
-                           extra_users=[]):
+                           extra_users=[], suppress_auth=False):
+        yield run_on_reactor()
+
         snapshot.fill_out_prev_events(event)
 
+        yield self.state_handler.annotate_state_groups(event)
+
+        if not suppress_auth:
+            yield self.auth.check(event, snapshot, raises=True)
+
+        if hasattr(event, "state_key"):
+            yield self.state_handler.handle_new_event(event, snapshot)
+
         yield self.store.persist_event(event)
 
         destinations = set(extra_destinations)
diff --git a/synapse/handlers/directory.py b/synapse/handlers/directory.py
index a56830d520..6e897e915d 100644
--- a/synapse/handlers/directory.py
+++ b/synapse/handlers/directory.py
@@ -152,5 +152,6 @@ class DirectoryHandler(BaseHandler):
             user_id=user_id,
         )
 
-        yield self.state_handler.handle_new_event(event, snapshot)
-        yield self._on_new_room_event(event, snapshot, extra_users=[user_id])
+        yield self._on_new_room_event(
+            event, snapshot, extra_users=[user_id], suppress_auth=True
+        )
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index f52591d2a3..18cb1d4e97 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -22,6 +22,8 @@ from synapse.api.constants import Membership
 from synapse.util.logutils import log_function
 from synapse.federation.pdu_codec import PduCodec
 from synapse.api.errors import SynapseError
+from synapse.util.async import run_on_reactor
+from synapse.types import EventID
 
 from twisted.internet import defer, reactor
 
@@ -62,6 +64,9 @@ class FederationHandler(BaseHandler):
 
         self.pdu_codec = PduCodec(hs)
 
+        # When joining a room we need to queue any events for that room up
+        self.room_queues = {}
+
     @log_function
     @defer.inlineCallbacks
     def handle_new_event(self, event, snapshot):
@@ -78,6 +83,8 @@ class FederationHandler(BaseHandler):
             processing.
         """
 
+        yield run_on_reactor()
+
         pdu = self.pdu_codec.pdu_from_event(event)
 
         if not hasattr(pdu, "destinations") or not pdu.destinations:
@@ -87,98 +94,83 @@ class FederationHandler(BaseHandler):
 
     @log_function
     @defer.inlineCallbacks
-    def on_receive_pdu(self, pdu, backfilled):
+    def on_receive_pdu(self, pdu, backfilled, state=None):
         """ Called by the ReplicationLayer when we have a new pdu. We need to
-        do auth checks and put it throught the StateHandler.
+        do auth checks and put it through the StateHandler.
         """
         event = self.pdu_codec.event_from_pdu(pdu)
 
         logger.debug("Got event: %s", event.event_id)
 
-        with (yield self.lock_manager.lock(pdu.context)):
-            if event.is_state and not backfilled:
-                is_new_state = yield self.state_handler.handle_new_state(
-                    pdu
-                )
-            else:
-                is_new_state = False
+        if event.room_id in self.room_queues:
+            self.room_queues[event.room_id].append(pdu)
+            return
+
+        logger.debug("Processing event: %s", event.event_id)
+
+        if state:
+            state = [self.pdu_codec.event_from_pdu(p) for p in state]
+
+        is_new_state = yield self.state_handler.annotate_state_groups(
+            event,
+            old_state=state
+        )
+
+        logger.debug("Event: %s", event)
+
+        if not backfilled:
+            yield self.auth.check(event, None, raises=True)
+
+        is_new_state = is_new_state and not backfilled
+
         # TODO: Implement something in federation that allows us to
         # respond to PDU.
 
-        target_is_mine = False
-        if hasattr(event, "target_host"):
-            target_is_mine = event.target_host == self.hs.hostname
-
-        if event.type == InviteJoinEvent.TYPE:
-            if not target_is_mine:
-                logger.debug("Ignoring invite/join event %s", event)
-                return
-
-            # If we receive an invite/join event then we need to join the
-            # sender to the given room.
-            # TODO: We should probably auth this or some such
-            content = event.content
-            content.update({"membership": Membership.JOIN})
-            new_event = self.event_factory.create_event(
-                etype=RoomMemberEvent.TYPE,
-                state_key=event.user_id,
-                room_id=event.room_id,
-                user_id=event.user_id,
-                membership=Membership.JOIN,
-                content=content
+        with (yield self.room_lock.lock(event.room_id)):
+            yield self.store.persist_event(
+                event,
+                backfilled,
+                is_new_state=is_new_state
             )
 
-            yield self.hs.get_handlers().room_member_handler.change_membership(
-                new_event,
-                do_auth=False,
-            )
+        room = yield self.store.get_room(event.room_id)
 
-        else:
-            with (yield self.room_lock.lock(event.room_id)):
-                yield self.store.persist_event(
-                    event,
-                    backfilled,
-                    is_new_state=is_new_state
+        if not room:
+            # Huh, let's try and get the current state
+            try:
+                yield self.replication_layer.get_state_for_context(
+                    event.origin, event.room_id, pdu.pdu_id, pdu.origin,
                 )
 
-            room = yield self.store.get_room(event.room_id)
-
-            if not room:
-                # Huh, let's try and get the current state
-                try:
-                    yield self.replication_layer.get_state_for_context(
-                        event.origin, event.room_id
-                    )
-
-                    hosts = yield self.store.get_joined_hosts_for_room(
-                        event.room_id
-                    )
-                    if self.hs.hostname in hosts:
-                        try:
-                            yield self.store.store_room(
-                                room_id=event.room_id,
-                                room_creator_user_id="",
-                                is_public=False,
-                            )
-                        except:
-                            pass
-                except:
-                    logger.exception(
-                        "Failed to get current state for room %s",
-                        event.room_id
-                    )
-
-            if not backfilled:
-                extra_users = []
-                if event.type == RoomMemberEvent.TYPE:
-                    target_user_id = event.state_key
-                    target_user = self.hs.parse_userid(target_user_id)
-                    extra_users.append(target_user)
-
-                yield self.notifier.on_new_room_event(
-                    event, extra_users=extra_users
+                hosts = yield self.store.get_joined_hosts_for_room(
+                    event.room_id
+                )
+                if self.hs.hostname in hosts:
+                    try:
+                        yield self.store.store_room(
+                            room_id=event.room_id,
+                            room_creator_user_id="",
+                            is_public=False,
+                        )
+                    except:
+                        pass
+            except:
+                logger.exception(
+                    "Failed to get current state for room %s",
+                    event.room_id
                 )
 
+        if not backfilled:
+            extra_users = []
+            if event.type == RoomMemberEvent.TYPE:
+                target_user_id = event.state_key
+                target_user = self.hs.parse_userid(target_user_id)
+                extra_users.append(target_user)
+
+            yield self.notifier.on_new_room_event(
+                event, extra_users=extra_users
+            )
+
         if event.type == RoomMemberEvent.TYPE:
             if event.membership == Membership.JOIN:
                 user = self.hs.parse_userid(event.state_key)
@@ -189,13 +181,28 @@ class FederationHandler(BaseHandler):
     @log_function
     @defer.inlineCallbacks
     def backfill(self, dest, room_id, limit):
-        pdus = yield self.replication_layer.backfill(dest, room_id, limit)
+        extremities = yield self.store.get_oldest_events_in_room(room_id)
+
+        pdus = yield self.replication_layer.backfill(
+            dest,
+            room_id,
+            limit,
+            extremities=[
+                self.pdu_codec.decode_event_id(e)
+                for e in extremities
+            ]
+        )
 
         events = []
 
         for pdu in pdus:
             event = self.pdu_codec.event_from_pdu(pdu)
+
+            # FIXME (erikj): Not sure this actually works :/
+            yield self.state_handler.annotate_state_groups(event)
+
             events.append(event)
+
             yield self.store.persist_event(event, backfilled=True)
 
         defer.returnValue(events)
@@ -203,62 +210,232 @@ class FederationHandler(BaseHandler):
     @log_function
     @defer.inlineCallbacks
     def do_invite_join(self, target_host, room_id, joinee, content, snapshot):
-
         hosts = yield self.store.get_joined_hosts_for_room(room_id)
         if self.hs.hostname in hosts:
             # We are already in the room.
             logger.debug("We're already in the room apparently")
             defer.returnValue(False)
 
-        # First get current state to see if we are already joined.
+        pdu = yield self.replication_layer.make_join(
+            target_host,
+            room_id,
+            joinee
+        )
+
+        logger.debug("Got response to make_join: %s", pdu)
+
+        event = self.pdu_codec.event_from_pdu(pdu)
+
+        # We should assert some things.
+        assert(event.type == RoomMemberEvent.TYPE)
+        assert(event.user_id == joinee)
+        assert(event.state_key == joinee)
+        assert(event.room_id == room_id)
+
+        event.outlier = False
+
+        self.room_queues[room_id] = []
+
         try:
-            yield self.replication_layer.get_state_for_context(
-                target_host, room_id
+            event.event_id = self.event_factory.create_event_id()
+            event.content = content
+
+            state = yield self.replication_layer.send_join(
+                target_host,
+                self.pdu_codec.pdu_from_event(event)
             )
 
-            hosts = yield self.store.get_joined_hosts_for_room(room_id)
-            if self.hs.hostname in hosts:
-                # Oh, we were actually in the room already.
-                logger.debug("We're already in the room apparently")
-                defer.returnValue(False)
-        except Exception:
-            logger.exception("Failed to get current state")
-
-        new_event = self.event_factory.create_event(
-            etype=InviteJoinEvent.TYPE,
-            target_host=target_host,
-            room_id=room_id,
-            user_id=joinee,
-            content=content
-        )
+            state = [self.pdu_codec.event_from_pdu(p) for p in state]
 
-        new_event.destinations = [target_host]
+            logger.debug("do_invite_join state: %s", state)
 
-        snapshot.fill_out_prev_events(new_event)
-        yield self.handle_new_event(new_event, snapshot)
+            is_new_state = yield self.state_handler.annotate_state_groups(
+                event,
+                old_state=state
+            )
 
-        # TODO (erikj): Time out here.
-        d = defer.Deferred()
-        self.waiting_for_join_list.setdefault((joinee, room_id), []).append(d)
-        reactor.callLater(10, d.cancel)
+            logger.debug("do_invite_join event: %s", event)
 
-        try:
-            yield d
-        except defer.CancelledError:
-            raise SynapseError(500, "Unable to join remote room")
+            try:
+                yield self.store.store_room(
+                    room_id=room_id,
+                    room_creator_user_id="",
+                    is_public=False
+                )
+            except:
+                # FIXME
+                pass
 
-        try:
-            yield self.store.store_room(
-                room_id=room_id,
-                room_creator_user_id="",
-                is_public=False
+            for e in state:
+                # FIXME: Auth these.
+                e.outlier = True
+
+                yield self.state_handler.annotate_state_groups(
+                    e,
+                )
+
+                yield self.store.persist_event(
+                    e,
+                    backfilled=False,
+                    is_new_state=False
+                )
+
+            yield self.store.persist_event(
+                event,
+                backfilled=False,
+                is_new_state=is_new_state
             )
-        except:
-            pass
+        finally:
+            room_queue = self.room_queues[room_id]
+            del self.room_queues[room_id]
 
+            for p in room_queue:
+                try:
+                    yield self.on_receive_pdu(p, backfilled=False)
+                except:
+                    pass
 
         defer.returnValue(True)
 
+    @defer.inlineCallbacks
+    @log_function
+    def on_make_join_request(self, context, user_id):
+        event = self.event_factory.create_event(
+            etype=RoomMemberEvent.TYPE,
+            content={"membership": Membership.JOIN},
+            room_id=context,
+            user_id=user_id,
+            state_key=user_id,
+        )
+
+        snapshot = yield self.store.snapshot_room(
+            event.room_id, event.user_id,
+        )
+        snapshot.fill_out_prev_events(event)
+
+        yield self.state_handler.annotate_state_groups(event)
+        yield self.auth.check(event, None, raises=True)
+
+        pdu = self.pdu_codec.pdu_from_event(event)
+
+        defer.returnValue(pdu)
+
+    @defer.inlineCallbacks
+    @log_function
+    def on_send_join_request(self, origin, pdu):
+        event = self.pdu_codec.event_from_pdu(pdu)
+
+        event.outlier = False
+
+        is_new_state = yield self.state_handler.annotate_state_groups(event)
+        yield self.auth.check(event, None, raises=True)
+
+        # FIXME (erikj):  All this is duplicated above :(
+
+        yield self.store.persist_event(
+            event,
+            backfilled=False,
+            is_new_state=is_new_state
+        )
+
+        extra_users = []
+        if event.type == RoomMemberEvent.TYPE:
+            target_user_id = event.state_key
+            target_user = self.hs.parse_userid(target_user_id)
+            extra_users.append(target_user)
+
+        yield self.notifier.on_new_room_event(
+            event, extra_users=extra_users
+        )
+
+        if event.type == RoomMemberEvent.TYPE:
+            if event.membership == Membership.JOIN:
+                user = self.hs.parse_userid(event.state_key)
+                self.distributor.fire(
+                    "user_joined_room", user=user, room_id=event.room_id
+                )
+
+        new_pdu = self.pdu_codec.pdu_from_event(event);
+        new_pdu.destinations = yield self.store.get_joined_hosts_for_room(
+            event.room_id
+        )
+
+        yield self.replication_layer.send_pdu(new_pdu)
+
+        defer.returnValue([
+            self.pdu_codec.pdu_from_event(e)
+            for e in event.state_events.values()
+        ])
+
+    @defer.inlineCallbacks
+    def get_state_for_pdu(self, pdu_id, pdu_origin):
+        yield run_on_reactor()
+
+        event_id = EventID.create(pdu_id, pdu_origin, self.hs).to_string()
+
+        state_groups = yield self.store.get_state_groups(
+            [event_id]
+        )
+
+        if state_groups:
+            results = {
+                (e.type, e.state_key): e for e in state_groups[0].state
+            }
+
+            event = yield self.store.get_event(event_id)
+            if hasattr(event, "state_key"):
+                # Get previous state
+                if hasattr(event, "prev_state") and event.prev_state:
+                    prev_event = yield self.store.get_event(event.prev_state)
+                    results[(event.type, event.state_key)] = prev_event
+                else:
+                    del results[(event.type, event.state_key)]
+
+            defer.returnValue(
+                [
+                    self.pdu_codec.pdu_from_event(s)
+                    for s in results.values()
+                ]
+            )
+        else:
+            defer.returnValue([])
+
+    @defer.inlineCallbacks
+    @log_function
+    def on_backfill_request(self, context, pdu_list, limit):
+
+        events = yield self.store.get_backfill_events(
+            context,
+            [self.pdu_codec.encode_event_id(i, o) for i, o in pdu_list],
+            limit
+        )
+
+        defer.returnValue([
+            self.pdu_codec.pdu_from_event(e)
+            for e in events
+        ])
+
+    @defer.inlineCallbacks
+    @log_function
+    def get_persisted_pdu(self, pdu_id, origin):
+        """ Get a PDU from the database with given origin and id.
+
+        Returns:
+            Deferred: Results in a `Pdu`.
+        """
+        event = yield self.store.get_event(
+            self.pdu_codec.encode_event_id(pdu_id, origin),
+            allow_none=True,
+        )
+
+        if event:
+            defer.returnValue(self.pdu_codec.pdu_from_event(event))
+        else:
+            defer.returnValue(None)
+
+    @log_function
+    def get_min_depth_for_context(self, context):
+        return self.store.get_min_depth(context)
 
     @log_function
     def _on_user_joined(self, user, room_id):
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 72894869ea..c6f6ab14d1 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -83,10 +83,9 @@ class MessageHandler(BaseHandler):
 
         snapshot = yield self.store.snapshot_room(event.room_id, event.user_id)
 
-        if not suppress_auth:
-            yield self.auth.check(event, snapshot, raises=True)
-
-        yield self._on_new_room_event(event, snapshot)
+        yield self._on_new_room_event(
+            event, snapshot, suppress_auth=suppress_auth
+        )
 
         self.hs.get_handlers().presence_handler.bump_presence_active_time(
             user
@@ -149,10 +148,6 @@ class MessageHandler(BaseHandler):
             state_key=event.state_key,
         )
 
-        yield self.auth.check(event, snapshot, raises=True)
-
-        yield self.state_handler.handle_new_event(event, snapshot)
-
         yield self._on_new_room_event(event, snapshot)
 
     @defer.inlineCallbacks
@@ -201,7 +196,7 @@ class MessageHandler(BaseHandler):
                 raise RoomError(
                     403, "Member does not meet private room rules.")
 
-        data = yield self.store.get_current_state(
+        data = yield self.state_handler.get_current_state(
             room_id, event_type, state_key
         )
         defer.returnValue(data)
@@ -221,8 +216,6 @@ class MessageHandler(BaseHandler):
     def send_feedback(self, event):
         snapshot = yield self.store.snapshot_room(event.room_id, event.user_id)
 
-        yield self.auth.check(event, snapshot, raises=True)
-
         # store message in db
         yield self._on_new_room_event(event, snapshot)
 
@@ -239,7 +232,7 @@ class MessageHandler(BaseHandler):
         yield self.auth.check_joined_room(room_id, user_id)
 
         # TODO: This is duplicating logic from snapshot_all_rooms
-        current_state = yield self.store.get_current_state(room_id)
+        current_state = yield self.state_handler.get_current_state(room_id)
         defer.returnValue([self.hs.serialize_event(c) for c in current_state])
 
     @defer.inlineCallbacks
@@ -316,7 +309,7 @@ class MessageHandler(BaseHandler):
                     "end": end_token.to_string(),
                 }
 
-                current_state = yield self.store.get_current_state(
+                current_state = yield self.state_handler.get_current_state(
                     event.room_id
                 )
                 d["state"] = [self.hs.serialize_event(c) for c in current_state]
diff --git a/synapse/handlers/profile.py b/synapse/handlers/profile.py
index dab9b03f04..4cd0a06093 100644
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -218,5 +218,6 @@ class ProfileHandler(BaseHandler):
                 user_id=j.state_key,
             )
 
-            yield self.state_handler.handle_new_event(new_event, snapshot)
-            yield self._on_new_room_event(new_event, snapshot)
+            yield self._on_new_room_event(
+                new_event, snapshot, suppress_auth=True
+            )
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 81ce1a5907..ffc0892f1a 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -129,8 +129,9 @@ class RoomCreationHandler(BaseHandler):
 
             logger.debug("Event: %s", event)
 
-            yield self.state_handler.handle_new_event(event, snapshot)
-            yield self._on_new_room_event(event, snapshot, extra_users=[user])
+            yield self._on_new_room_event(
+                event, snapshot, extra_users=[user], suppress_auth=True
+            )
 
         for event in creation_events:
             yield handle_event(event)
@@ -391,8 +392,6 @@ class RoomMemberHandler(BaseHandler):
             yield self._do_join(event, snapshot, do_auth=do_auth)
         else:
             # This is not a JOIN, so we can handle it normally.
-            if do_auth:
-                yield self.auth.check(event, snapshot, raises=True)
 
             # If we're banning someone, set a req power level
             if event.membership == Membership.BAN:
@@ -414,6 +413,7 @@ class RoomMemberHandler(BaseHandler):
                 event,
                 membership=event.content["membership"],
                 snapshot=snapshot,
+                do_auth=do_auth,
             )
 
         defer.returnValue({"room_id": room_id})
@@ -502,14 +502,11 @@ class RoomMemberHandler(BaseHandler):
         if not have_joined:
             logger.debug("Doing normal join")
 
-            if do_auth:
-                yield self.auth.check(event, snapshot, raises=True)
-
-            yield self.state_handler.handle_new_event(event, snapshot)
             yield self._do_local_membership_update(
                 event,
                 membership=event.content["membership"],
                 snapshot=snapshot,
+                do_auth=do_auth,
             )
 
         user = self.hs.parse_userid(event.user_id)
@@ -553,7 +550,8 @@ class RoomMemberHandler(BaseHandler):
 
         defer.returnValue([r.room_id for r in rooms])
 
-    def _do_local_membership_update(self, event, membership, snapshot):
+    def _do_local_membership_update(self, event, membership, snapshot,
+                                    do_auth):
         destinations = []
 
         # If we're inviting someone, then we should also send it to that
@@ -570,9 +568,10 @@ class RoomMemberHandler(BaseHandler):
 
         return self._on_new_room_event(
             event, snapshot, extra_destinations=destinations,
-            extra_users=[target_user]
+            extra_users=[target_user], suppress_auth=(not do_auth),
         )
 
+
 class RoomListHandler(BaseHandler):
 
     @defer.inlineCallbacks
diff --git a/synapse/rest/base.py b/synapse/rest/base.py
index 2e8e3fa7d4..dc784c1527 100644
--- a/synapse/rest/base.py
+++ b/synapse/rest/base.py
@@ -18,6 +18,11 @@ from synapse.api.urls import CLIENT_PREFIX
 from synapse.rest.transactions import HttpTransactionStore
 import re
 
+import logging
+
+
+logger = logging.getLogger(__name__)
+
 
 def client_path_pattern(path_regex):
     """Creates a regex compiled client path with the correct client path
diff --git a/synapse/rest/events.py b/synapse/rest/events.py
index 097195d7cc..92ff5e5ca7 100644
--- a/synapse/rest/events.py
+++ b/synapse/rest/events.py
@@ -20,6 +20,12 @@ from synapse.api.errors import SynapseError
 from synapse.streams.config import PaginationConfig
 from synapse.rest.base import RestServlet, client_path_pattern
 
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
 
 class EventStreamRestServlet(RestServlet):
     PATTERN = client_path_pattern("/events$")
@@ -29,18 +35,22 @@ class EventStreamRestServlet(RestServlet):
     @defer.inlineCallbacks
     def on_GET(self, request):
         auth_user = yield self.auth.get_user_by_req(request)
-
-        handler = self.handlers.event_stream_handler
-        pagin_config = PaginationConfig.from_request(request)
-        timeout = EventStreamRestServlet.DEFAULT_LONGPOLL_TIME_MS
-        if "timeout" in request.args:
-            try:
-                timeout = int(request.args["timeout"][0])
-            except ValueError:
-                raise SynapseError(400, "timeout must be in milliseconds.")
-
-        chunk = yield handler.get_stream(auth_user.to_string(), pagin_config,
-                                         timeout=timeout)
+        try:
+            handler = self.handlers.event_stream_handler
+            pagin_config = PaginationConfig.from_request(request)
+            timeout = EventStreamRestServlet.DEFAULT_LONGPOLL_TIME_MS
+            if "timeout" in request.args:
+                try:
+                    timeout = int(request.args["timeout"][0])
+                except ValueError:
+                    raise SynapseError(400, "timeout must be in milliseconds.")
+
+            chunk = yield handler.get_stream(
+                auth_user.to_string(), pagin_config, timeout=timeout
+            )
+        except:
+            logger.exception("Event stream failed")
+            raise
 
         defer.returnValue((200, chunk))
 
diff --git a/synapse/server.py b/synapse/server.py
index a4d2d4aba5..d770b20b19 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -28,7 +28,7 @@ from synapse.handlers import Handlers
 from synapse.rest import RestServletFactory
 from synapse.state import StateHandler
 from synapse.storage import DataStore
-from synapse.types import UserID, RoomAlias, RoomID
+from synapse.types import UserID, RoomAlias, RoomID, EventID
 from synapse.util import Clock
 from synapse.util.distributor import Distributor
 from synapse.util.lockutils import LockManager
@@ -143,6 +143,11 @@ class BaseHomeServer(object):
         object."""
         return RoomID.from_string(s, hs=self)
 
+    def parse_eventid(self, s):
+        """Parse the string given by 's' as a Event ID and return a EventID
+        object."""
+        return EventID.from_string(s, hs=self)
+
     def serialize_event(self, e):
         return serialize_event(self, e)
 
diff --git a/synapse/state.py b/synapse/state.py
index 9db84c9b5c..2548deed28 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -16,11 +16,14 @@
 
 from twisted.internet import defer
 
-from synapse.federation.pdu_codec import encode_event_id, decode_event_id
 from synapse.util.logutils import log_function
+from synapse.util.async import run_on_reactor
+
+from synapse.types import EventID
 
 from collections import namedtuple
 
+import copy
 import logging
 import hashlib
 
@@ -35,13 +38,14 @@ KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))
 
 
 class StateHandler(object):
-    """ Repsonsible for doing state conflict resolution.
+    """ Responsible for doing state conflict resolution.
     """
 
     def __init__(self, hs):
         self.store = hs.get_datastore()
         self._replication = hs.get_replication_layer()
         self.server_name = hs.hostname
+        self.hs = hs
 
     @defer.inlineCallbacks
     @log_function
@@ -50,7 +54,7 @@ class StateHandler(object):
         to update the state and b) works out what the prev_state should be.
 
         Returns:
-            Deferred: Resolved with a boolean indicating if we succesfully
+            Deferred: Resolved with a boolean indicating if we successfully
             updated the state.
 
         Raised:
@@ -71,128 +75,157 @@ class StateHandler(object):
         # (w.r.t. to power levels)
 
         snapshot.fill_out_prev_events(event)
+        yield self.annotate_state_groups(event)
 
-        event.prev_events = [
-            e for e in event.prev_events if e != event.event_id
-        ]
-
-        current_state = snapshot.prev_state_pdu
-
-        if current_state:
-            event.prev_state = encode_event_id(
-                current_state.pdu_id, current_state.origin
+        if event.old_state_events:
+            current_state = event.old_state_events.get(
+                (event.type, event.state_key)
             )
 
+            if current_state:
+                event.prev_state = current_state.event_id
+
         # TODO check current_state to see if the min power level is less
         # than the power level of the user
         # power_level = self._get_power_level_for_event(event)
 
-        pdu_id, origin = decode_event_id(event.event_id, self.server_name)
-
-        yield self.store.update_current_state(
-            pdu_id=pdu_id,
-            origin=origin,
-            context=key.context,
-            pdu_type=key.type,
-            state_key=key.state_key
-        )
-
         defer.returnValue(True)
 
     @defer.inlineCallbacks
     @log_function
-    def handle_new_state(self, new_pdu):
-        """ Apply conflict resolution to `new_pdu`.
+    def annotate_state_groups(self, event, old_state=None):
+        yield run_on_reactor()
 
-        This should be called on every new state pdu, regardless of whether or
-        not there is a conflict.
+        if old_state:
+            event.state_group = None
+            event.old_state_events = {
+                (s.type, s.state_key): s for s in old_state
+            }
+            event.state_events = event.old_state_events
 
-        This function is safe against the race of it getting called with two
-        `PDU`s trying to update the same state.
-        """
+            if hasattr(event, "state_key"):
+                event.state_events[(event.type, event.state_key)] = event
 
-        # This needs to be done in a transaction.
+            defer.returnValue(False)
+            return
 
-        is_new = yield self._handle_new_state(new_pdu)
+        if hasattr(event, "outlier") and event.outlier:
+            event.state_group = None
+            event.old_state_events = None
+            event.state_events = {}
+            defer.returnValue(False)
+            return
 
-        logger.debug("is_new: %s %s %s", is_new, new_pdu.pdu_id, new_pdu.origin)
+        new_state = yield self.resolve_state_groups(
+            [e for e, _ in event.prev_events]
+        )
 
-        if is_new:
-            yield self.store.update_current_state(
-                pdu_id=new_pdu.pdu_id,
-                origin=new_pdu.origin,
-                context=new_pdu.context,
-                pdu_type=new_pdu.pdu_type,
-                state_key=new_pdu.state_key
-            )
+        event.old_state_events = copy.deepcopy(new_state)
 
-        defer.returnValue(is_new)
+        if hasattr(event, "state_key"):
+            new_state[(event.type, event.state_key)] = event
 
-    def _get_power_level_for_event(self, event):
-        # return self._persistence.get_power_level_for_user(event.room_id,
-            # event.sender)
-        return event.power_level
+        event.state_group = None
+        event.state_events = new_state
+
+        defer.returnValue(hasattr(event, "state_key"))
 
     @defer.inlineCallbacks
-    @log_function
-    def _handle_new_state(self, new_pdu):
-        tree, missing_branch = yield self.store.get_unresolved_state_tree(
-            new_pdu
-        )
-        new_branch, current_branch = tree
+    def get_current_state(self, room_id, event_type=None, state_key=""):
+        events = yield self.store.get_latest_events_in_room(room_id)
 
-        logger.debug(
-            "_handle_new_state new=%s, current=%s",
-            new_branch, current_branch
-        )
+        event_ids = [
+            e_id
+            for e_id, _, _ in events
+        ]
 
-        if missing_branch is not None:
-            # We're missing some PDUs. Fetch them.
-            # TODO (erikj): Limit this.
-            missing_prev = tree[missing_branch][-1]
+        res = yield self.resolve_state_groups(event_ids)
 
-            pdu_id = missing_prev.prev_state_id
-            origin = missing_prev.prev_state_origin
+        if event_type:
+            defer.returnValue(res.get((event_type, state_key)))
+            return
 
-            is_missing = yield self.store.get_pdu(pdu_id, origin) is None
-            if not is_missing:
-                raise Exception("Conflict resolution failed")
+        defer.returnValue(res.values())
 
-            yield self._replication.get_pdu(
-                destination=missing_prev.origin,
-                pdu_origin=origin,
-                pdu_id=pdu_id,
-                outlier=True
-            )
+    @defer.inlineCallbacks
+    @log_function
+    def resolve_state_groups(self, event_ids):
+        state_groups = yield self.store.get_state_groups(
+            event_ids
+        )
 
-            updated_current = yield self._handle_new_state(new_pdu)
-            defer.returnValue(updated_current)
+        state = {}
+        for group in state_groups:
+            for s in group.state:
+                state.setdefault(
+                    (s.type, s.state_key),
+                    {}
+                )[s.event_id] = s
+
+        unconflicted_state = {
+            k: v.values()[0] for k, v in state.items()
+            if len(v.values()) == 1
+        }
+
+        conflicted_state = {
+            k: v.values()
+            for k, v in state.items()
+            if len(v.values()) > 1
+        }
+
+        try:
+            new_state = {}
+            new_state.update(unconflicted_state)
+            for key, events in conflicted_state.items():
+                new_state[key] = yield self._resolve_state_events(events)
+        except:
+            logger.exception("Failed to resolve state")
+            raise
+
+        defer.returnValue(new_state)
 
-        if not current_branch:
-            # There is no current state
-            defer.returnValue(True)
-            return
+    @defer.inlineCallbacks
+    @log_function
+    def _resolve_state_events(self, events):
+        curr_events = events
 
-        n = new_branch[-1]
-        c = current_branch[-1]
+        new_powers_deferreds = []
+        for e in curr_events:
+            new_powers_deferreds.append(
+                self.store.get_power_level(e.room_id, e.user_id)
+            )
 
-        common_ancestor = n.pdu_id == c.pdu_id and n.origin == c.origin
+        new_powers = yield defer.gatherResults(
+            new_powers_deferreds,
+            consumeErrors=True
+        )
 
-        if common_ancestor:
-            # We found a common ancestor!
+        max_power = max([int(p) for p in new_powers])
 
-            if len(current_branch) == 1:
-                # This is a direct clobber so we can just...
-                defer.returnValue(True)
+        curr_events = [
+            z[0] for z in zip(curr_events, new_powers)
+            if int(z[1]) == max_power
+        ]
 
-        else:
-            # We didn't find a common ancestor. This is probably fine.
-            pass
+        if not curr_events:
+            raise RuntimeError("Max didn't get a max?")
+        elif len(curr_events) == 1:
+            defer.returnValue(curr_events[0])
 
-        result = yield self._do_conflict_res(
-            new_branch, current_branch, common_ancestor
+        # TODO: For now, just choose the one with the largest event_id.
+        defer.returnValue(
+            sorted(
+                curr_events,
+                key=lambda e: hashlib.sha1(
+                    e.event_id + e.user_id + e.room_id + e.type
+                ).hexdigest()
+            )[0]
         )
-        defer.returnValue(result)
+
+    def _get_power_level_for_event(self, event):
+        # return self._persistence.get_power_level_for_user(event.room_id,
+            # event.sender)
+        return event.power_level
 
     @defer.inlineCallbacks
     def _do_conflict_res(self, new_branch, current_branch, common_ancestor):
diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index 4e9291fdff..1f39a4094e 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -37,9 +37,17 @@ from .registration import RegistrationStore
 from .room import RoomStore
 from .roommember import RoomMemberStore
 from .stream import StreamStore
-from .pdu import StatePduStore, PduStore, PdusTable
 from .transactions import TransactionStore
 from .keys import KeyStore
+from .event_federation import EventFederationStore
+
+from .state import StateStore
+from .signatures import SignatureStore
+
+from syutil.base64util import decode_base64
+
+from synapse.crypto.event_signing import compute_event_reference_hash
+
 
 import json
 import logging
@@ -51,7 +59,6 @@ logger = logging.getLogger(__name__)
 
 SCHEMAS = [
     "transactions",
-    "pdu",
     "users",
     "profiles",
     "presence",
@@ -59,6 +66,9 @@ SCHEMAS = [
     "room_aliases",
     "keys",
     "redactions",
+    "state",
+    "event_edges",
+    "event_signatures",
 ]
 
 
@@ -73,10 +83,12 @@ class _RollbackButIsFineException(Exception):
     """
     pass
 
+
 class DataStore(RoomMemberStore, RoomStore,
                 RegistrationStore, StreamStore, ProfileStore, FeedbackStore,
-                PresenceStore, PduStore, StatePduStore, TransactionStore,
-                DirectoryStore, KeyStore):
+                PresenceStore, TransactionStore,
+                DirectoryStore, KeyStore, StateStore, SignatureStore,
+                EventFederationStore, ):
 
     def __init__(self, hs):
         super(DataStore, self).__init__(hs)
@@ -99,6 +111,7 @@ class DataStore(RoomMemberStore, RoomStore,
 
         try:
             yield self.runInteraction(
+                "persist_event",
                 self._persist_pdu_event_txn,
                 pdu=pdu,
                 event=event,
@@ -119,7 +132,8 @@ class DataStore(RoomMemberStore, RoomStore,
                 "type",
                 "room_id",
                 "content",
-                "unrecognized_keys"
+                "unrecognized_keys",
+                "depth",
             ],
             allow_none=allow_none,
         )
@@ -133,39 +147,12 @@ class DataStore(RoomMemberStore, RoomStore,
     def _persist_pdu_event_txn(self, txn, pdu=None, event=None,
                                backfilled=False, stream_ordering=None,
                                is_new_state=True):
-        if pdu is not None:
-            self._persist_event_pdu_txn(txn, pdu)
         if event is not None:
             return self._persist_event_txn(
                 txn, event, backfilled, stream_ordering,
                 is_new_state=is_new_state,
             )
 
-    def _persist_event_pdu_txn(self, txn, pdu):
-        cols = dict(pdu.__dict__)
-        unrec_keys = dict(pdu.unrecognized_keys)
-        del cols["content"]
-        del cols["prev_pdus"]
-        cols["content_json"] = json.dumps(pdu.content)
-
-        unrec_keys.update({
-            k: v for k, v in cols.items()
-            if k not in PdusTable.fields
-        })
-
-        cols["unrecognized_keys"] = json.dumps(unrec_keys)
-
-        cols["ts"] = cols.pop("origin_server_ts")
-
-        logger.debug("Persisting: %s", repr(cols))
-
-        if pdu.is_state:
-            self._persist_state_txn(txn, pdu.prev_pdus, cols)
-        else:
-            self._persist_pdu_txn(txn, pdu.prev_pdus, cols)
-
-        self._update_min_depth_for_context_txn(txn, pdu.context, pdu.depth)
-
     @log_function
     def _persist_event_txn(self, txn, event, backfilled, stream_ordering=None,
                            is_new_state=True):
@@ -190,6 +177,10 @@ class DataStore(RoomMemberStore, RoomStore,
         elif event.type == RoomRedactionEvent.TYPE:
             self._store_redaction(txn, event)
 
+        outlier = False
+        if hasattr(event, "outlier"):
+            outlier = event.outlier
+
         vals = {
             "topological_ordering": event.depth,
             "event_id": event.event_id,
@@ -197,25 +188,30 @@ class DataStore(RoomMemberStore, RoomStore,
             "room_id": event.room_id,
             "content": json.dumps(event.content),
             "processed": True,
+            "outlier": outlier,
+            "depth": event.depth,
         }
 
         if stream_ordering is not None:
             vals["stream_ordering"] = stream_ordering
 
-        if hasattr(event, "outlier"):
-            vals["outlier"] = event.outlier
-        else:
-            vals["outlier"] = False
-
         unrec = {
             k: v
             for k, v in event.get_full_dict().items()
-            if k not in vals.keys() and k not in ["redacted", "redacted_because"]
+            if k not in vals.keys() and k not in [
+                "redacted", "redacted_because", "signatures", "hashes",
+                "prev_events",
+            ]
         }
         vals["unrecognized_keys"] = json.dumps(unrec)
 
         try:
-            self._simple_insert_txn(txn, "events", vals)
+            self._simple_insert_txn(
+                txn,
+                "events",
+                vals,
+                or_replace=(not outlier),
+            )
         except:
             logger.warn(
                 "Failed to persist, probably duplicate: %s",
@@ -224,6 +220,16 @@ class DataStore(RoomMemberStore, RoomStore,
             )
             raise _RollbackButIsFineException("_persist_event")
 
+        self._handle_prev_events(
+            txn,
+            outlier=outlier,
+            event_id=event.event_id,
+            prev_events=event.prev_events,
+            room_id=event.room_id,
+        )
+
+        self._store_state_groups_txn(txn, event)
+
         is_state = hasattr(event, "state_key") and event.state_key is not None
         if is_new_state and is_state:
             vals = {
@@ -249,6 +255,35 @@ class DataStore(RoomMemberStore, RoomStore,
                 }
             )
 
+        for hash_alg, hash_base64 in event.hashes.items():
+            hash_bytes = decode_base64(hash_base64)
+            self._store_event_content_hash_txn(
+                txn, event.event_id, hash_alg, hash_bytes,
+            )
+
+        if hasattr(event, "signatures"):
+            signatures = event.signatures.get(event.origin, {})
+
+            for key_id, signature_base64 in signatures.items():
+                signature_bytes = decode_base64(signature_base64)
+                self._store_event_origin_signature_txn(
+                    txn, event.event_id, event.origin, key_id, signature_bytes,
+                )
+
+        for prev_event_id, prev_hashes in event.prev_events:
+            for alg, hash_base64 in prev_hashes.items():
+                hash_bytes = decode_base64(hash_base64)
+                self._store_prev_event_hash_txn(
+                    txn, event.event_id, prev_event_id, alg, hash_bytes
+                )
+
+        (ref_alg, ref_hash_bytes) = compute_event_reference_hash(event)
+        self._store_event_reference_hash_txn(
+            txn, event.event_id, ref_alg, ref_hash_bytes
+        )
+
+        self._update_min_depth_for_room_txn(txn, event.room_id, event.depth)
+
     def _store_redaction(self, txn, event):
         txn.execute(
             "INSERT OR IGNORE INTO redactions "
@@ -331,28 +366,19 @@ class DataStore(RoomMemberStore, RoomStore,
         """
         def _snapshot(txn):
             membership_state = self._get_room_member(txn, user_id, room_id)
-            prev_pdus = self._get_latest_pdus_in_context(
-                txn, room_id
-            )
-            if state_type is not None and state_key is not None:
-                prev_state_pdu = self._get_current_state_pdu(
-                    txn, room_id, state_type, state_key
-                )
-            else:
-                prev_state_pdu = None
+            prev_events = self._get_latest_events_in_room(txn, room_id)
 
             return Snapshot(
                 store=self,
                 room_id=room_id,
                 user_id=user_id,
-                prev_pdus=prev_pdus,
+                prev_events=prev_events,
                 membership_state=membership_state,
                 state_type=state_type,
                 state_key=state_key,
-                prev_state_pdu=prev_state_pdu,
             )
 
-        return self.runInteraction(_snapshot)
+        return self.runInteraction("snapshot_room", _snapshot)
 
 
 class Snapshot(object):
@@ -361,7 +387,7 @@ class Snapshot(object):
         store (DataStore): The datastore.
         room_id (RoomId): The room of the snapshot.
         user_id (UserId): The user this snapshot is for.
-        prev_pdus (list): The list of PDU ids this snapshot is after.
+        prev_events (list): The list of event ids this snapshot is after.
         membership_state (RoomMemberEvent): The current state of the user in
             the room.
         state_type (str, optional): State type captured by the snapshot
@@ -370,13 +396,13 @@ class Snapshot(object):
             the previous value of the state type and key in the room.
     """
 
-    def __init__(self, store, room_id, user_id, prev_pdus,
+    def __init__(self, store, room_id, user_id, prev_events,
                  membership_state, state_type=None, state_key=None,
                  prev_state_pdu=None):
         self.store = store
         self.room_id = room_id
         self.user_id = user_id
-        self.prev_pdus = prev_pdus
+        self.prev_events = prev_events
         self.membership_state = membership_state
         self.state_type = state_type
         self.state_key = state_key
@@ -386,14 +412,13 @@ class Snapshot(object):
         if hasattr(event, "prev_events"):
             return
 
-        es = [
-            "%s@%s" % (p_id, origin) for p_id, origin, _ in self.prev_pdus
+        event.prev_events = [
+            (event_id, hashes)
+            for event_id, hashes, _ in self.prev_events
         ]
 
-        event.prev_events = [e for e in es if e != event.event_id]
-
-        if self.prev_pdus:
-            event.depth = max([int(v) for _, _, v in self.prev_pdus]) + 1
+        if self.prev_events:
+            event.depth = max([int(v) for _, _, v in self.prev_events]) + 1
         else:
             event.depth = 0
 
@@ -452,9 +477,10 @@ def prepare_database(db_conn):
             db_conn.commit()
 
     else:
-        sql_script = "BEGIN TRANSACTION;"
+        sql_script = "BEGIN TRANSACTION;\n"
         for sql_loc in SCHEMAS:
             sql_script += read_schema(sql_loc)
+            sql_script += "\n"
         sql_script += "COMMIT TRANSACTION;"
         c.executescript(sql_script)
         db_conn.commit()
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 65a86e9056..464b12f032 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -19,54 +19,66 @@ from twisted.internet import defer
 from synapse.api.errors import StoreError
 from synapse.api.events.utils import prune_event
 from synapse.util.logutils import log_function
+from syutil.base64util import encode_base64
 
 import collections
 import copy
 import json
+import sys
+import time
 
 
 logger = logging.getLogger(__name__)
 
 sql_logger = logging.getLogger("synapse.storage.SQL")
+transaction_logger = logging.getLogger("synapse.storage.txn")
 
 
 class LoggingTransaction(object):
     """An object that almost-transparently proxies for the 'txn' object
     passed to the constructor. Adds logging to the .execute() method."""
-    __slots__ = ["txn"]
+    __slots__ = ["txn", "name"]
 
-    def __init__(self, txn):
+    def __init__(self, txn, name):
         object.__setattr__(self, "txn", txn)
+        object.__setattr__(self, "name", name)
 
-    def __getattribute__(self, name):
-        if name == "execute":
-            return object.__getattribute__(self, "execute")
-
-        return getattr(object.__getattribute__(self, "txn"), name)
+    def __getattr__(self, name):
+        return getattr(self.txn, name)
 
     def __setattr__(self, name, value):
-        setattr(object.__getattribute__(self, "txn"), name, value)
+        setattr(self.txn, name, value)
 
     def execute(self, sql, *args, **kwargs):
         # TODO(paul): Maybe use 'info' and 'debug' for values?
-        sql_logger.debug("[SQL] %s", sql)
+        sql_logger.debug("[SQL] {%s} %s", self.name, sql)
         try:
             if args and args[0]:
                 values = args[0]
-                sql_logger.debug("[SQL values] " +
-                    ", ".join(("<%s>",) * len(values)), *values)
+                sql_logger.debug(
+                    "[SQL values] {%s} " + ", ".join(("<%s>",) * len(values)),
+                    self.name,
+                    *values
+                )
         except:
             # Don't let logging failures stop SQL from working
             pass
 
-        # TODO(paul): Here would be an excellent place to put some timing
-        #   measurements, and log (warning?) slow queries.
-        return object.__getattribute__(self, "txn").execute(
-            sql, *args, **kwargs
-        )
+        start = time.clock() * 1000
+        try:
+            return self.txn.execute(
+                sql, *args, **kwargs
+            )
+        except:
+                logger.exception("[SQL FAIL] {%s}", self.name)
+                raise
+        finally:
+            end = time.clock() * 1000
+            sql_logger.debug("[SQL time] {%s} %f", self.name, end - start)
 
 
 class SQLBaseStore(object):
+    _TXN_ID = 0
 
     def __init__(self, hs):
         self.hs = hs
@@ -74,10 +86,30 @@ class SQLBaseStore(object):
         self.event_factory = hs.get_event_factory()
         self._clock = hs.get_clock()
 
-    def runInteraction(self, func, *args, **kwargs):
+    def runInteraction(self, desc, func, *args, **kwargs):
         """Wraps the .runInteraction() method on the underlying db_pool."""
         def inner_func(txn, *args, **kwargs):
-            return func(LoggingTransaction(txn), *args, **kwargs)
+            start = time.clock() * 1000
+            txn_id = SQLBaseStore._TXN_ID
+
+            # We don't really need these to be unique, so lets stop it from
+            # growing really large.
+            self._TXN_ID = (self._TXN_ID + 1) % (sys.maxint - 1)
+
+            name = "%s-%x" % (desc, txn_id, )
+
+            transaction_logger.debug("[TXN START] {%s}", name)
+            try:
+                return func(LoggingTransaction(txn, name), *args, **kwargs)
+            except:
+                logger.exception("[TXN FAIL] {%s}", name)
+                raise
+            finally:
+                end = time.clock() * 1000
+                transaction_logger.debug(
+                    "[TXN END] {%s} %f",
+                    name, end - start
+                )
 
         return self._db_pool.runInteraction(inner_func, *args, **kwargs)
 
@@ -113,7 +145,7 @@ class SQLBaseStore(object):
             else:
                 return cursor.fetchall()
 
-        return self.runInteraction(interaction)
+        return self.runInteraction("_execute", interaction)
 
     def _execute_and_decode(self, query, *args):
         return self._execute(self.cursor_to_dict, query, *args)
@@ -130,6 +162,7 @@ class SQLBaseStore(object):
             or_replace : bool; if True performs an INSERT OR REPLACE
         """
         return self.runInteraction(
+            "_simple_insert",
             self._simple_insert_txn, table, values, or_replace=or_replace,
             or_ignore=or_ignore,
         )
@@ -170,7 +203,6 @@ class SQLBaseStore(object):
             table, keyvalues, retcols=retcols, allow_none=allow_none
         )
 
-    @defer.inlineCallbacks
     def _simple_select_one_onecol(self, table, keyvalues, retcol,
                                   allow_none=False):
         """Executes a SELECT query on the named table, which is expected to
@@ -181,19 +213,41 @@ class SQLBaseStore(object):
             keyvalues : dict of column names and values to select the row with
             retcol : string giving the name of the column to return
         """
-        ret = yield self._simple_select_one(
+        return self.runInteraction(
+            "_simple_select_one_onecol_txn",
+            self._simple_select_one_onecol_txn,
+            table, keyvalues, retcol, allow_none=allow_none,
+        )
+
+    def _simple_select_one_onecol_txn(self, txn, table, keyvalues, retcol,
+                                      allow_none=False):
+        ret = self._simple_select_onecol_txn(
+            txn,
             table=table,
             keyvalues=keyvalues,
-            retcols=[retcol],
-            allow_none=allow_none
+            retcol=retcol,
         )
 
         if ret:
-            defer.returnValue(ret[retcol])
+            return ret[0]
         else:
-            defer.returnValue(None)
+            if allow_none:
+                return None
+            else:
+                raise StoreError(404, "No row found")
+
+    def _simple_select_onecol_txn(self, txn, table, keyvalues, retcol):
+        sql = "SELECT %(retcol)s FROM %(table)s WHERE %(where)s" % {
+            "retcol": retcol,
+            "table": table,
+            "where": " AND ".join("%s = ?" % k for k in keyvalues.keys()),
+        }
+
+        txn.execute(sql, keyvalues.values())
+
+        return [r[0] for r in txn.fetchall()]
+
 
-    @defer.inlineCallbacks
     def _simple_select_onecol(self, table, keyvalues, retcol):
         """Executes a SELECT query on the named table, which returns a list
         comprising of the values of the named column from the selected rows.
@@ -206,19 +260,11 @@ class SQLBaseStore(object):
         Returns:
             Deferred: Results in a list
         """
-        sql = "SELECT %(retcol)s FROM %(table)s WHERE %(where)s" % {
-            "retcol": retcol,
-            "table": table,
-            "where": " AND ".join("%s = ?" % k for k in keyvalues.keys()),
-        }
-
-        def func(txn):
-            txn.execute(sql, keyvalues.values())
-            return txn.fetchall()
-
-        res = yield self.runInteraction(func)
-
-        defer.returnValue([r[0] for r in res])
+        return self.runInteraction(
+            "_simple_select_onecol",
+            self._simple_select_onecol_txn,
+            table, keyvalues, retcol
+        )
 
     def _simple_select_list(self, table, keyvalues, retcols):
         """Executes a SELECT query on the named table, which may return zero or
@@ -239,7 +285,7 @@ class SQLBaseStore(object):
             txn.execute(sql, keyvalues.values())
             return self.cursor_to_dict(txn)
 
-        return self.runInteraction(func)
+        return self.runInteraction("_simple_select_list", func)
 
     def _simple_update_one(self, table, keyvalues, updatevalues,
                            retcols=None):
@@ -307,7 +353,7 @@ class SQLBaseStore(object):
                     raise StoreError(500, "More than one row matched")
 
             return ret
-        return self.runInteraction(func)
+        return self.runInteraction("_simple_selectupdate_one", func)
 
     def _simple_delete_one(self, table, keyvalues):
         """Executes a DELETE query on the named table, expecting to delete a
@@ -319,7 +365,7 @@ class SQLBaseStore(object):
         """
         sql = "DELETE FROM %s WHERE %s" % (
             table,
-            " AND ".join("%s = ?" % (k) for k in keyvalues)
+            " AND ".join("%s = ?" % (k, ) for k in keyvalues)
         )
 
         def func(txn):
@@ -328,7 +374,25 @@ class SQLBaseStore(object):
                 raise StoreError(404, "No row found")
             if txn.rowcount > 1:
                 raise StoreError(500, "more than one row matched")
-        return self.runInteraction(func)
+        return self.runInteraction("_simple_delete_one", func)
+
+    def _simple_delete(self, table, keyvalues):
+        """Executes a DELETE query on the named table.
+
+        Args:
+            table : string giving the table name
+            keyvalues : dict of column names and values to select the row with
+        """
+
+        return self.runInteraction("_simple_delete", self._simple_delete_txn)
+
+    def _simple_delete_txn(self, txn, table, keyvalues):
+        sql = "DELETE FROM %s WHERE %s" % (
+            table,
+            " AND ".join("%s = ?" % (k, ) for k in keyvalues)
+        )
+
+        return txn.execute(sql, keyvalues.values())
 
     def _simple_max_id(self, table):
         """Executes a SELECT query on the named table, expecting to return the
@@ -346,7 +410,7 @@ class SQLBaseStore(object):
                 return 0
             return max_id
 
-        return self.runInteraction(func)
+        return self.runInteraction("_simple_max_id", func)
 
     def _parse_event_from_row(self, row_dict):
         d = copy.deepcopy({k: v for k, v in row_dict.items()})
@@ -370,7 +434,9 @@ class SQLBaseStore(object):
         )
 
     def _parse_events(self, rows):
-        return self.runInteraction(self._parse_events_txn, rows)
+        return self.runInteraction(
+            "_parse_events", self._parse_events_txn, rows
+        )
 
     def _parse_events_txn(self, txn, rows):
         events = [self._parse_event_from_row(r) for r in rows]
@@ -378,6 +444,17 @@ class SQLBaseStore(object):
         sql = "SELECT * FROM events WHERE event_id = ?"
 
         for ev in events:
+            signatures = self._get_event_origin_signatures_txn(
+                txn, ev.event_id,
+            )
+
+            ev.signatures = {
+                k: encode_base64(v) for k, v in signatures.items()
+            }
+
+            prev_events = self._get_latest_events_in_room(txn, ev.room_id)
+            ev.prev_events = [(e_id, s,) for e_id, s, _ in prev_events]
+
             if hasattr(ev, "prev_state"):
                 # Load previous state_content.
                 # TODO: Should we be pulling this out above?
diff --git a/synapse/storage/directory.py b/synapse/storage/directory.py
index 52373a28a6..d6a7113b9c 100644
--- a/synapse/storage/directory.py
+++ b/synapse/storage/directory.py
@@ -95,6 +95,7 @@ class DirectoryStore(SQLBaseStore):
 
     def delete_room_alias(self, room_alias):
         return self.runInteraction(
+            "delete_room_alias",
             self._delete_room_alias_txn,
             room_alias,
         )
diff --git a/synapse/storage/event_federation.py b/synapse/storage/event_federation.py
new file mode 100644
index 0000000000..dcc116bad2
--- /dev/null
+++ b/synapse/storage/event_federation.py
@@ -0,0 +1,253 @@
+# -*- 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 ._base import SQLBaseStore
+from syutil.base64util import encode_base64
+
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
+class EventFederationStore(SQLBaseStore):
+
+    def get_oldest_events_in_room(self, room_id):
+        return self.runInteraction(
+            "get_oldest_events_in_room",
+            self._get_oldest_events_in_room_txn,
+            room_id,
+        )
+
+    def _get_oldest_events_in_room_txn(self, txn, room_id):
+        return self._simple_select_onecol_txn(
+            txn,
+            table="event_backward_extremities",
+            keyvalues={
+                "room_id": room_id,
+            },
+            retcol="event_id",
+        )
+
+    def get_latest_events_in_room(self, room_id):
+        return self.runInteraction(
+            "get_latest_events_in_room",
+            self._get_latest_events_in_room,
+            room_id,
+        )
+
+    def _get_latest_events_in_room(self, txn, room_id):
+        self._simple_select_onecol_txn(
+            txn,
+            table="event_forward_extremities",
+            keyvalues={
+                "room_id": room_id,
+            },
+            retcol="event_id",
+        )
+
+        sql = (
+            "SELECT e.event_id, e.depth FROM events as e "
+            "INNER JOIN event_forward_extremities as f "
+            "ON e.event_id = f.event_id "
+            "WHERE f.room_id = ?"
+        )
+
+        txn.execute(sql, (room_id, ))
+
+        results = []
+        for event_id, depth in txn.fetchall():
+            hashes = self._get_event_reference_hashes_txn(txn, event_id)
+            prev_hashes = {
+                k: encode_base64(v) for k, v in hashes.items()
+                if k == "sha256"
+            }
+            results.append((event_id, prev_hashes, depth))
+
+        return results
+
+    def get_min_depth(self, room_id):
+        return self.runInteraction(
+            "get_min_depth",
+            self._get_min_depth_interaction,
+            room_id,
+        )
+
+    def _get_min_depth_interaction(self, txn, room_id):
+        min_depth = self._simple_select_one_onecol_txn(
+            txn,
+            table="room_depth",
+            keyvalues={"room_id": room_id,},
+            retcol="min_depth",
+            allow_none=True,
+        )
+
+        return int(min_depth) if min_depth is not None else None
+
+    def _update_min_depth_for_room_txn(self, txn, room_id, depth):
+        min_depth = self._get_min_depth_interaction(txn, room_id)
+
+        do_insert = depth < min_depth if min_depth else True
+
+        if do_insert:
+            self._simple_insert_txn(
+                txn,
+                table="room_depth",
+                values={
+                    "room_id": room_id,
+                    "min_depth": depth,
+                },
+                or_replace=True,
+            )
+
+    def _handle_prev_events(self, txn, outlier, event_id, prev_events,
+                            room_id):
+        for e_id, _ in prev_events:
+            # TODO (erikj): This could be done as a bulk insert
+            self._simple_insert_txn(
+                txn,
+                table="event_edges",
+                values={
+                    "event_id": event_id,
+                    "prev_event_id": e_id,
+                    "room_id": room_id,
+                },
+                or_ignore=True,
+            )
+
+        # Update the extremities table if this is not an outlier.
+        if not outlier:
+            for e_id, _ in prev_events:
+                # TODO (erikj): This could be done as a bulk insert
+                self._simple_delete_txn(
+                    txn,
+                    table="event_forward_extremities",
+                    keyvalues={
+                        "event_id": e_id,
+                        "room_id": room_id,
+                    }
+                )
+
+
+
+            # We only insert as a forward extremity the new pdu if there are no
+            # other pdus that reference it as a prev pdu
+            query = (
+                "INSERT OR IGNORE INTO %(table)s (event_id, room_id) "
+                "SELECT ?, ? WHERE NOT EXISTS ("
+                "SELECT 1 FROM %(event_edges)s WHERE "
+                "prev_event_id = ? "
+                ")"
+            ) % {
+                "table": "event_forward_extremities",
+                "event_edges": "event_edges",
+            }
+
+            logger.debug("query: %s", query)
+
+            txn.execute(query, (event_id, room_id, event_id))
+
+            # Insert all the prev_pdus as a backwards thing, they'll get
+            # deleted in a second if they're incorrect anyway.
+            for e_id, _ in prev_events:
+                # TODO (erikj): This could be done as a bulk insert
+                self._simple_insert_txn(
+                    txn,
+                    table="event_backward_extremities",
+                    values={
+                        "event_id": e_id,
+                        "room_id": room_id,
+                    },
+                    or_ignore=True,
+                )
+
+            # Also delete from the backwards extremities table all ones that
+            # reference pdus that we have already seen
+            query = (
+                "DELETE FROM event_backward_extremities WHERE EXISTS ("
+                "SELECT 1 FROM events "
+                "WHERE "
+                "event_backward_extremities.event_id = events.event_id "
+                "AND not events.outlier "
+                ")"
+            )
+            txn.execute(query)
+
+
+    def get_backfill_events(self, room_id, event_list, limit):
+        """Get a list of Events for a given topic that occured before (and
+        including) the pdus in pdu_list. Return a list of max size `limit`.
+
+        Args:
+            txn
+            room_id (str)
+            event_list (list)
+            limit (int)
+
+        Return:
+            list: A list of PduTuples
+        """
+        return self.runInteraction(
+            "get_backfill_events",
+            self._get_backfill_events, room_id, event_list, limit
+        )
+
+    def _get_backfill_events(self, txn, room_id, event_list, limit):
+        logger.debug(
+            "_get_backfill_events: %s, %s, %s",
+            room_id, repr(event_list), limit
+        )
+
+        # We seed the pdu_results with the things from the pdu_list.
+        event_results = event_list
+
+        front = event_list
+
+        query = (
+            "SELECT prev_event_id FROM event_edges "
+            "WHERE room_id = ? AND event_id = ? "
+            "LIMIT ?"
+        )
+
+        # We iterate through all event_ids in `front` to select their previous
+        # events. These are dumped in `new_front`.
+        # We continue until we reach the limit *or* new_front is empty (i.e.,
+        # we've run out of things to select
+        while front and len(event_results) < limit:
+
+            new_front = []
+            for event_id in front:
+                logger.debug(
+                    "_backfill_interaction: id=%s",
+                    event_id
+                )
+
+                txn.execute(
+                    query,
+                    (room_id, event_id, limit - len(event_results))
+                )
+
+                for row in txn.fetchall():
+                    logger.debug(
+                        "_backfill_interaction: got id=%s",
+                        *row
+                    )
+                    new_front.append(row)
+
+            front = new_front
+            event_results += new_front
+
+        # We also want to update the `prev_pdus` attributes before returning.
+        return self._get_pdu_tuples(txn, event_results)
diff --git a/synapse/storage/pdu.py b/synapse/storage/pdu.py
deleted file mode 100644
index d70467dcd6..0000000000
--- a/synapse/storage/pdu.py
+++ /dev/null
@@ -1,915 +0,0 @@
-# -*- 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 twisted.internet import defer
-
-from ._base import SQLBaseStore, Table, JoinHelper
-
-from synapse.federation.units import Pdu
-from synapse.util.logutils import log_function
-
-from collections import namedtuple
-
-import logging
-
-logger = logging.getLogger(__name__)
-
-
-class PduStore(SQLBaseStore):
-    """A collection of queries for handling PDUs.
-    """
-
-    def get_pdu(self, pdu_id, origin):
-        """Given a pdu_id and origin, get a PDU.
-
-        Args:
-            txn
-            pdu_id (str)
-            origin (str)
-
-        Returns:
-            PduTuple: If the pdu does not exist in the database, returns None
-        """
-
-        return self.runInteraction(
-            self._get_pdu_tuple, pdu_id, origin
-        )
-
-    def _get_pdu_tuple(self, txn, pdu_id, origin):
-        res = self._get_pdu_tuples(txn, [(pdu_id, origin)])
-        return res[0] if res else None
-
-    def _get_pdu_tuples(self, txn, pdu_id_tuples):
-        results = []
-        for pdu_id, origin in pdu_id_tuples:
-            txn.execute(
-                PduEdgesTable.select_statement("pdu_id = ? AND origin = ?"),
-                (pdu_id, origin)
-            )
-
-            edges = [
-                (r.prev_pdu_id, r.prev_origin)
-                for r in PduEdgesTable.decode_results(txn.fetchall())
-            ]
-
-            query = (
-                "SELECT %(fields)s FROM %(pdus)s as p "
-                "LEFT JOIN %(state)s as s "
-                "ON p.pdu_id = s.pdu_id AND p.origin = s.origin "
-                "WHERE p.pdu_id = ? AND p.origin = ? "
-            ) % {
-                "fields": _pdu_state_joiner.get_fields(
-                    PdusTable="p", StatePdusTable="s"),
-                "pdus": PdusTable.table_name,
-                "state": StatePdusTable.table_name,
-            }
-
-            txn.execute(query, (pdu_id, origin))
-
-            row = txn.fetchone()
-            if row:
-                results.append(PduTuple(PduEntry(*row), edges))
-
-        return results
-
-    def get_current_state_for_context(self, context):
-        """Get a list of PDUs that represent the current state for a given
-        context
-
-        Args:
-            context (str)
-
-        Returns:
-            list: A list of PduTuples
-        """
-
-        return self.runInteraction(
-            self._get_current_state_for_context,
-            context
-        )
-
-    def _get_current_state_for_context(self, txn, context):
-        query = (
-            "SELECT pdu_id, origin FROM %s WHERE context = ?"
-            % CurrentStateTable.table_name
-        )
-
-        logger.debug("get_current_state %s, Args=%s", query, context)
-        txn.execute(query, (context,))
-
-        res = txn.fetchall()
-
-        logger.debug("get_current_state %d results", len(res))
-
-        return self._get_pdu_tuples(txn, res)
-
-    def _persist_pdu_txn(self, txn, prev_pdus, cols):
-        """Inserts a (non-state) PDU into the database.
-
-        Args:
-            txn,
-            prev_pdus (list)
-            **cols: The columns to insert into the PdusTable.
-        """
-        entry = PdusTable.EntryType(
-            **{k: cols.get(k, None) for k in PdusTable.fields}
-        )
-
-        txn.execute(PdusTable.insert_statement(), entry)
-
-        self._handle_prev_pdus(
-            txn, entry.outlier, entry.pdu_id, entry.origin,
-            prev_pdus, entry.context
-        )
-
-    def mark_pdu_as_processed(self, pdu_id, pdu_origin):
-        """Mark a received PDU as processed.
-
-        Args:
-            txn
-            pdu_id (str)
-            pdu_origin (str)
-        """
-
-        return self.runInteraction(
-            self._mark_as_processed, pdu_id, pdu_origin
-        )
-
-    def _mark_as_processed(self, txn, pdu_id, pdu_origin):
-        txn.execute("UPDATE %s SET have_processed = 1" % PdusTable.table_name)
-
-    def get_all_pdus_from_context(self, context):
-        """Get a list of all PDUs for a given context."""
-        return self.runInteraction(
-            self._get_all_pdus_from_context, context,
-        )
-
-    def _get_all_pdus_from_context(self, txn, context):
-        query = (
-            "SELECT pdu_id, origin FROM %s "
-            "WHERE context = ?"
-        ) % PdusTable.table_name
-
-        txn.execute(query, (context,))
-
-        return self._get_pdu_tuples(txn, txn.fetchall())
-
-    def get_backfill(self, context, pdu_list, limit):
-        """Get a list of Pdus for a given topic that occured before (and
-        including) the pdus in pdu_list. Return a list of max size `limit`.
-
-        Args:
-            txn
-            context (str)
-            pdu_list (list)
-            limit (int)
-
-        Return:
-            list: A list of PduTuples
-        """
-        return self.runInteraction(
-            self._get_backfill, context, pdu_list, limit
-        )
-
-    def _get_backfill(self, txn, context, pdu_list, limit):
-        logger.debug(
-            "backfill: %s, %s, %s",
-            context, repr(pdu_list), limit
-        )
-
-        # We seed the pdu_results with the things from the pdu_list.
-        pdu_results = pdu_list
-
-        front = pdu_list
-
-        query = (
-            "SELECT prev_pdu_id, prev_origin FROM %(edges_table)s "
-            "WHERE context = ? AND pdu_id = ? AND origin = ? "
-            "LIMIT ?"
-        ) % {
-            "edges_table": PduEdgesTable.table_name,
-        }
-
-        # We iterate through all pdu_ids in `front` to select their previous
-        # pdus. These are dumped in `new_front`. We continue until we reach the
-        # limit *or* new_front is empty (i.e., we've run out of things to
-        # select
-        while front and len(pdu_results) < limit:
-
-            new_front = []
-            for pdu_id, origin in front:
-                logger.debug(
-                    "_backfill_interaction: i=%s, o=%s",
-                    pdu_id, origin
-                )
-
-                txn.execute(
-                    query,
-                    (context, pdu_id, origin, limit - len(pdu_results))
-                )
-
-                for row in txn.fetchall():
-                    logger.debug(
-                        "_backfill_interaction: got i=%s, o=%s",
-                        *row
-                    )
-                    new_front.append(row)
-
-            front = new_front
-            pdu_results += new_front
-
-        # We also want to update the `prev_pdus` attributes before returning.
-        return self._get_pdu_tuples(txn, pdu_results)
-
-    def get_min_depth_for_context(self, context):
-        """Get the current minimum depth for a context
-
-        Args:
-            txn
-            context (str)
-        """
-        return self.runInteraction(
-            self._get_min_depth_for_context, context
-        )
-
-    def _get_min_depth_for_context(self, txn, context):
-        return self._get_min_depth_interaction(txn, context)
-
-    def _get_min_depth_interaction(self, txn, context):
-        txn.execute(
-            "SELECT min_depth FROM %s WHERE context = ?"
-            % ContextDepthTable.table_name,
-            (context,)
-        )
-
-        row = txn.fetchone()
-
-        return row[0] if row else None
-
-    def _update_min_depth_for_context_txn(self, txn, context, depth):
-        """Update the minimum `depth` of the given context, which is the line
-        on which we stop backfilling backwards.
-
-        Args:
-            context (str)
-            depth (int)
-        """
-        min_depth = self._get_min_depth_interaction(txn, context)
-
-        do_insert = depth < min_depth if min_depth else True
-
-        if do_insert:
-            txn.execute(
-                "INSERT OR REPLACE INTO %s (context, min_depth) "
-                "VALUES (?,?)" % ContextDepthTable.table_name,
-                (context, depth)
-            )
-
-    def _get_latest_pdus_in_context(self, txn, context):
-        """Get's a list of the most current pdus for a given context. This is
-        used when we are sending a Pdu and need to fill out the `prev_pdus`
-        key
-
-        Args:
-            txn
-            context
-        """
-        query = (
-            "SELECT p.pdu_id, p.origin, p.depth FROM %(pdus)s as p "
-            "INNER JOIN %(forward)s as f ON p.pdu_id = f.pdu_id "
-            "AND f.origin = p.origin "
-            "WHERE f.context = ?"
-        ) % {
-            "pdus": PdusTable.table_name,
-            "forward": PduForwardExtremitiesTable.table_name,
-        }
-
-        logger.debug("get_prev query: %s", query)
-
-        txn.execute(
-            query,
-            (context, )
-        )
-
-        results = txn.fetchall()
-
-        return [(row[0], row[1], row[2]) for row in results]
-
-    @defer.inlineCallbacks
-    def get_oldest_pdus_in_context(self, context):
-        """Get a list of Pdus that we haven't backfilled beyond yet (and havent
-        seen). This list is used when we want to backfill backwards and is the
-        list we send to the remote server.
-
-        Args:
-            txn
-            context (str)
-
-        Returns:
-            list: A list of PduIdTuple.
-        """
-        results = yield self._execute(
-            None,
-            "SELECT pdu_id, origin FROM %(back)s WHERE context = ?"
-            % {"back": PduBackwardExtremitiesTable.table_name, },
-            context
-        )
-
-        defer.returnValue([PduIdTuple(i, o) for i, o in results])
-
-    def is_pdu_new(self, pdu_id, origin, context, depth):
-        """For a given Pdu, try and figure out if it's 'new', i.e., if it's
-        not something we got randomly from the past, for example when we
-        request the current state of the room that will probably return a bunch
-        of pdus from before we joined.
-
-        Args:
-            txn
-            pdu_id (str)
-            origin (str)
-            context (str)
-            depth (int)
-
-        Returns:
-            bool
-        """
-
-        return self.runInteraction(
-            self._is_pdu_new,
-            pdu_id=pdu_id,
-            origin=origin,
-            context=context,
-            depth=depth
-        )
-
-    def _is_pdu_new(self, txn, pdu_id, origin, context, depth):
-        # If depth > min depth in back table, then we classify it as new.
-        # OR if there is nothing in the back table, then it kinda needs to
-        # be a new thing.
-        query = (
-            "SELECT min(p.depth) FROM %(edges)s as e "
-            "INNER JOIN %(back)s as b "
-            "ON e.prev_pdu_id = b.pdu_id AND e.prev_origin = b.origin "
-            "INNER JOIN %(pdus)s as p "
-            "ON e.pdu_id = p.pdu_id AND p.origin = e.origin "
-            "WHERE p.context = ?"
-        ) % {
-            "pdus": PdusTable.table_name,
-            "edges": PduEdgesTable.table_name,
-            "back": PduBackwardExtremitiesTable.table_name,
-        }
-
-        txn.execute(query, (context,))
-
-        min_depth, = txn.fetchone()
-
-        if not min_depth or depth > int(min_depth):
-            logger.debug(
-                "is_new true: id=%s, o=%s, d=%s min_depth=%s",
-                pdu_id, origin, depth, min_depth
-            )
-            return True
-
-        # If this pdu is in the forwards table, then it also is a new one
-        query = (
-            "SELECT * FROM %(forward)s WHERE pdu_id = ? AND origin = ?"
-        ) % {
-            "forward": PduForwardExtremitiesTable.table_name,
-        }
-
-        txn.execute(query, (pdu_id, origin))
-
-        # Did we get anything?
-        if txn.fetchall():
-            logger.debug(
-                "is_new true: id=%s, o=%s, d=%s was forward",
-                pdu_id, origin, depth
-            )
-            return True
-
-        logger.debug(
-            "is_new false: id=%s, o=%s, d=%s",
-            pdu_id, origin, depth
-        )
-
-        # FINE THEN. It's probably old.
-        return False
-
-    @staticmethod
-    @log_function
-    def _handle_prev_pdus(txn, outlier, pdu_id, origin, prev_pdus,
-                          context):
-        txn.executemany(
-            PduEdgesTable.insert_statement(),
-            [(pdu_id, origin, p[0], p[1], context) for p in prev_pdus]
-        )
-
-        # Update the extremities table if this is not an outlier.
-        if not outlier:
-
-            # First, we delete the new one from the forwards extremities table.
-            query = (
-                "DELETE FROM %s WHERE pdu_id = ? AND origin = ?"
-                % PduForwardExtremitiesTable.table_name
-            )
-            txn.executemany(query, prev_pdus)
-
-            # We only insert as a forward extremety the new pdu if there are no
-            # other pdus that reference it as a prev pdu
-            query = (
-                "INSERT INTO %(table)s (pdu_id, origin, context) "
-                "SELECT ?, ?, ? WHERE NOT EXISTS ("
-                "SELECT 1 FROM %(pdu_edges)s WHERE "
-                "prev_pdu_id = ? AND prev_origin = ?"
-                ")"
-            ) % {
-                "table": PduForwardExtremitiesTable.table_name,
-                "pdu_edges": PduEdgesTable.table_name
-            }
-
-            logger.debug("query: %s", query)
-
-            txn.execute(query, (pdu_id, origin, context, pdu_id, origin))
-
-            # Insert all the prev_pdus as a backwards thing, they'll get
-            # deleted in a second if they're incorrect anyway.
-            txn.executemany(
-                PduBackwardExtremitiesTable.insert_statement(),
-                [(i, o, context) for i, o in prev_pdus]
-            )
-
-            # Also delete from the backwards extremities table all ones that
-            # reference pdus that we have already seen
-            query = (
-                "DELETE FROM %(pdu_back)s WHERE EXISTS ("
-                "SELECT 1 FROM %(pdus)s AS pdus "
-                "WHERE "
-                "%(pdu_back)s.pdu_id = pdus.pdu_id "
-                "AND %(pdu_back)s.origin = pdus.origin "
-                "AND not pdus.outlier "
-                ")"
-            ) % {
-                "pdu_back": PduBackwardExtremitiesTable.table_name,
-                "pdus": PdusTable.table_name,
-            }
-            txn.execute(query)
-
-
-class StatePduStore(SQLBaseStore):
-    """A collection of queries for handling state PDUs.
-    """
-
-    def _persist_state_txn(self, txn, prev_pdus, cols):
-        """Inserts a state PDU into the database
-
-        Args:
-            txn,
-            prev_pdus (list)
-            **cols: The columns to insert into the PdusTable and StatePdusTable
-        """
-        pdu_entry = PdusTable.EntryType(
-            **{k: cols.get(k, None) for k in PdusTable.fields}
-        )
-        state_entry = StatePdusTable.EntryType(
-            **{k: cols.get(k, None) for k in StatePdusTable.fields}
-        )
-
-        logger.debug("Inserting pdu: %s", repr(pdu_entry))
-        logger.debug("Inserting state: %s", repr(state_entry))
-
-        txn.execute(PdusTable.insert_statement(), pdu_entry)
-        txn.execute(StatePdusTable.insert_statement(), state_entry)
-
-        self._handle_prev_pdus(
-            txn,
-            pdu_entry.outlier, pdu_entry.pdu_id, pdu_entry.origin, prev_pdus,
-            pdu_entry.context
-        )
-
-    def get_unresolved_state_tree(self, new_state_pdu):
-        return self.runInteraction(
-            self._get_unresolved_state_tree, new_state_pdu
-        )
-
-    @log_function
-    def _get_unresolved_state_tree(self, txn, new_pdu):
-        current = self._get_current_interaction(
-            txn,
-            new_pdu.context, new_pdu.pdu_type, new_pdu.state_key
-        )
-
-        ReturnType = namedtuple(
-            "StateReturnType", ["new_branch", "current_branch"]
-        )
-        return_value = ReturnType([new_pdu], [])
-
-        if not current:
-            logger.debug("get_unresolved_state_tree No current state.")
-            return (return_value, None)
-
-        return_value.current_branch.append(current)
-
-        enum_branches = self._enumerate_state_branches(
-            txn, new_pdu, current
-        )
-
-        missing_branch = None
-        for branch, prev_state, state in enum_branches:
-            if state:
-                return_value[branch].append(state)
-            else:
-                # We don't have prev_state :(
-                missing_branch = branch
-                break
-
-        return (return_value, missing_branch)
-
-    def update_current_state(self, pdu_id, origin, context, pdu_type,
-                             state_key):
-        return self.runInteraction(
-            self._update_current_state,
-            pdu_id, origin, context, pdu_type, state_key
-        )
-
-    def _update_current_state(self, txn, pdu_id, origin, context, pdu_type,
-                              state_key):
-        query = (
-            "INSERT OR REPLACE INTO %(curr)s (%(fields)s) VALUES (%(qs)s)"
-        ) % {
-            "curr": CurrentStateTable.table_name,
-            "fields": CurrentStateTable.get_fields_string(),
-            "qs": ", ".join(["?"] * len(CurrentStateTable.fields))
-        }
-
-        query_args = CurrentStateTable.EntryType(
-            pdu_id=pdu_id,
-            origin=origin,
-            context=context,
-            pdu_type=pdu_type,
-            state_key=state_key
-        )
-
-        txn.execute(query, query_args)
-
-    def get_current_state_pdu(self, context, pdu_type, state_key):
-        """For a given context, pdu_type, state_key 3-tuple, return what is
-        currently considered the current state.
-
-        Args:
-            txn
-            context (str)
-            pdu_type (str)
-            state_key (str)
-
-        Returns:
-            PduEntry
-        """
-
-        return self.runInteraction(
-            self._get_current_state_pdu, context, pdu_type, state_key
-        )
-
-    def _get_current_state_pdu(self, txn, context, pdu_type, state_key):
-        return self._get_current_interaction(txn, context, pdu_type, state_key)
-
-    def _get_current_interaction(self, txn, context, pdu_type, state_key):
-        logger.debug(
-            "_get_current_interaction %s %s %s",
-            context, pdu_type, state_key
-        )
-
-        fields = _pdu_state_joiner.get_fields(
-            PdusTable="p", StatePdusTable="s")
-
-        current_query = (
-            "SELECT %(fields)s FROM %(state)s as s "
-            "INNER JOIN %(pdus)s as p "
-            "ON s.pdu_id = p.pdu_id AND s.origin = p.origin "
-            "INNER JOIN %(curr)s as c "
-            "ON s.pdu_id = c.pdu_id AND s.origin = c.origin "
-            "WHERE s.context = ? AND s.pdu_type = ? AND s.state_key = ? "
-        ) % {
-            "fields": fields,
-            "curr": CurrentStateTable.table_name,
-            "state": StatePdusTable.table_name,
-            "pdus": PdusTable.table_name,
-        }
-
-        txn.execute(
-            current_query,
-            (context, pdu_type, state_key)
-        )
-
-        row = txn.fetchone()
-
-        result = PduEntry(*row) if row else None
-
-        if not result:
-            logger.debug("_get_current_interaction not found")
-        else:
-            logger.debug(
-                "_get_current_interaction found %s %s",
-                result.pdu_id, result.origin
-            )
-
-        return result
-
-    def handle_new_state(self, new_pdu):
-        """Actually perform conflict resolution on the new_pdu on the
-        assumption we have all the pdus required to perform it.
-
-        Args:
-            new_pdu
-
-        Returns:
-            bool: True if the new_pdu clobbered the current state, False if not
-        """
-        return self.runInteraction(
-            self._handle_new_state, new_pdu
-        )
-
-    def _handle_new_state(self, txn, new_pdu):
-        logger.debug(
-            "handle_new_state %s %s",
-            new_pdu.pdu_id, new_pdu.origin
-        )
-
-        current = self._get_current_interaction(
-            txn,
-            new_pdu.context, new_pdu.pdu_type, new_pdu.state_key
-        )
-
-        is_current = False
-
-        if (not current or not current.prev_state_id
-                or not current.prev_state_origin):
-            # Oh, we don't have any state for this yet.
-            is_current = True
-        elif (current.pdu_id == new_pdu.prev_state_id
-                and current.origin == new_pdu.prev_state_origin):
-            # Oh! A direct clobber. Just do it.
-            is_current = True
-        else:
-            ##
-            # Ok, now loop through until we get to a common ancestor.
-            max_new = int(new_pdu.power_level)
-            max_current = int(current.power_level)
-
-            enum_branches = self._enumerate_state_branches(
-                txn, new_pdu, current
-            )
-            for branch, prev_state, state in enum_branches:
-                if not state:
-                    raise RuntimeError(
-                        "Could not find state_pdu %s %s" %
-                        (
-                            prev_state.prev_state_id,
-                            prev_state.prev_state_origin
-                        )
-                    )
-
-                if branch == 0:
-                    max_new = max(int(state.depth), max_new)
-                else:
-                    max_current = max(int(state.depth), max_current)
-
-            is_current = max_new > max_current
-
-        if is_current:
-            logger.debug("handle_new_state make current")
-
-            # Right, this is a new thing, so woo, just insert it.
-            txn.execute(
-                "INSERT OR REPLACE INTO %(curr)s (%(fields)s) VALUES (%(qs)s)"
-                % {
-                    "curr": CurrentStateTable.table_name,
-                    "fields": CurrentStateTable.get_fields_string(),
-                    "qs": ", ".join(["?"] * len(CurrentStateTable.fields))
-                },
-                CurrentStateTable.EntryType(
-                    *(new_pdu.__dict__[k] for k in CurrentStateTable.fields)
-                )
-            )
-        else:
-            logger.debug("handle_new_state not current")
-
-        logger.debug("handle_new_state done")
-
-        return is_current
-
-    @log_function
-    def _enumerate_state_branches(self, txn, pdu_a, pdu_b):
-        branch_a = pdu_a
-        branch_b = pdu_b
-
-        while True:
-            if (branch_a.pdu_id == branch_b.pdu_id
-                    and branch_a.origin == branch_b.origin):
-                # Woo! We found a common ancestor
-                logger.debug("_enumerate_state_branches Found common ancestor")
-                break
-
-            do_branch_a = (
-                hasattr(branch_a, "prev_state_id") and
-                branch_a.prev_state_id
-            )
-
-            do_branch_b = (
-                hasattr(branch_b, "prev_state_id") and
-                branch_b.prev_state_id
-            )
-
-            logger.debug(
-                "do_branch_a=%s, do_branch_b=%s",
-                do_branch_a, do_branch_b
-            )
-
-            if do_branch_a and do_branch_b:
-                do_branch_a = int(branch_a.depth) > int(branch_b.depth)
-
-            if do_branch_a:
-                pdu_tuple = PduIdTuple(
-                    branch_a.prev_state_id,
-                    branch_a.prev_state_origin
-                )
-
-                prev_branch = branch_a
-
-                logger.debug("getting branch_a prev %s", pdu_tuple)
-                branch_a = self._get_pdu_tuple(txn, *pdu_tuple)
-                if branch_a:
-                    branch_a = Pdu.from_pdu_tuple(branch_a)
-
-                logger.debug("branch_a=%s", branch_a)
-
-                yield (0, prev_branch, branch_a)
-
-                if not branch_a:
-                    break
-            elif do_branch_b:
-                pdu_tuple = PduIdTuple(
-                    branch_b.prev_state_id,
-                    branch_b.prev_state_origin
-                )
-
-                prev_branch = branch_b
-
-                logger.debug("getting branch_b prev %s", pdu_tuple)
-                branch_b = self._get_pdu_tuple(txn, *pdu_tuple)
-                if branch_b:
-                    branch_b = Pdu.from_pdu_tuple(branch_b)
-
-                logger.debug("branch_b=%s", branch_b)
-
-                yield (1, prev_branch, branch_b)
-
-                if not branch_b:
-                    break
-            else:
-                break
-
-
-class PdusTable(Table):
-    table_name = "pdus"
-
-    fields = [
-        "pdu_id",
-        "origin",
-        "context",
-        "pdu_type",
-        "ts",
-        "depth",
-        "is_state",
-        "content_json",
-        "unrecognized_keys",
-        "outlier",
-        "have_processed",
-    ]
-
-    EntryType = namedtuple("PdusEntry", fields)
-
-
-class PduDestinationsTable(Table):
-    table_name = "pdu_destinations"
-
-    fields = [
-        "pdu_id",
-        "origin",
-        "destination",
-        "delivered_ts",
-    ]
-
-    EntryType = namedtuple("PduDestinationsEntry", fields)
-
-
-class PduEdgesTable(Table):
-    table_name = "pdu_edges"
-
-    fields = [
-        "pdu_id",
-        "origin",
-        "prev_pdu_id",
-        "prev_origin",
-        "context"
-    ]
-
-    EntryType = namedtuple("PduEdgesEntry", fields)
-
-
-class PduForwardExtremitiesTable(Table):
-    table_name = "pdu_forward_extremities"
-
-    fields = [
-        "pdu_id",
-        "origin",
-        "context",
-    ]
-
-    EntryType = namedtuple("PduForwardExtremitiesEntry", fields)
-
-
-class PduBackwardExtremitiesTable(Table):
-    table_name = "pdu_backward_extremities"
-
-    fields = [
-        "pdu_id",
-        "origin",
-        "context",
-    ]
-
-    EntryType = namedtuple("PduBackwardExtremitiesEntry", fields)
-
-
-class ContextDepthTable(Table):
-    table_name = "context_depth"
-
-    fields = [
-        "context",
-        "min_depth",
-    ]
-
-    EntryType = namedtuple("ContextDepthEntry", fields)
-
-
-class StatePdusTable(Table):
-    table_name = "state_pdus"
-
-    fields = [
-        "pdu_id",
-        "origin",
-        "context",
-        "pdu_type",
-        "state_key",
-        "power_level",
-        "prev_state_id",
-        "prev_state_origin",
-    ]
-
-    EntryType = namedtuple("StatePdusEntry", fields)
-
-
-class CurrentStateTable(Table):
-    table_name = "current_state"
-
-    fields = [
-        "pdu_id",
-        "origin",
-        "context",
-        "pdu_type",
-        "state_key",
-    ]
-
-    EntryType = namedtuple("CurrentStateEntry", fields)
-
-_pdu_state_joiner = JoinHelper(PdusTable, StatePdusTable)
-
-
-# TODO: These should probably be put somewhere more sensible
-PduIdTuple = namedtuple("PduIdTuple", ("pdu_id", "origin"))
-
-PduEntry = _pdu_state_joiner.EntryType
-""" We are always interested in the join of the PdusTable and StatePdusTable,
-rather than just the PdusTable.
-
-This does not include a prev_pdus key.
-"""
-
-PduTuple = namedtuple(
-    "PduTuple",
-    ("pdu_entry", "prev_pdu_list")
-)
-""" 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/registration.py b/synapse/storage/registration.py
index 719806f82b..a2ca6f9a69 100644
--- a/synapse/storage/registration.py
+++ b/synapse/storage/registration.py
@@ -62,8 +62,10 @@ class RegistrationStore(SQLBaseStore):
         Raises:
             StoreError if the user_id could not be registered.
         """
-        yield self.runInteraction(self._register, user_id, token,
-                                           password_hash)
+        yield self.runInteraction(
+            "register",
+            self._register, user_id, token, password_hash
+        )
 
     def _register(self, txn, user_id, token, password_hash):
         now = int(self.clock.time())
@@ -100,6 +102,7 @@ class RegistrationStore(SQLBaseStore):
             StoreError if no user was found.
         """
         return self.runInteraction(
+            "get_user_by_token",
             self._query_for_auth,
             token
         )
diff --git a/synapse/storage/room.py b/synapse/storage/room.py
index 8cd46334cf..7e48ce9cc3 100644
--- a/synapse/storage/room.py
+++ b/synapse/storage/room.py
@@ -150,6 +150,7 @@ class RoomStore(SQLBaseStore):
 
     def get_power_level(self, room_id, user_id):
         return self.runInteraction(
+            "get_power_level",
             self._get_power_level,
             room_id, user_id,
         )
@@ -183,6 +184,7 @@ class RoomStore(SQLBaseStore):
 
     def get_ops_levels(self, room_id):
         return self.runInteraction(
+            "get_ops_levels",
             self._get_ops_levels,
             room_id,
         )
diff --git a/synapse/storage/schema/edge_pdus.sql b/synapse/storage/schema/edge_pdus.sql
deleted file mode 100644
index 8a00868065..0000000000
--- a/synapse/storage/schema/edge_pdus.sql
+++ /dev/null
@@ -1,31 +0,0 @@
-/* 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.
- */
-CREATE TABLE IF NOT EXISTS context_edge_pdus(
-    id INTEGER PRIMARY KEY AUTOINCREMENT, -- twistar requires this
-    pdu_id TEXT, 
-    origin TEXT,
-    context TEXT, 
-    CONSTRAINT context_edge_pdu_id_origin UNIQUE (pdu_id, origin)
-);
-
-CREATE TABLE IF NOT EXISTS origin_edge_pdus(
-    id INTEGER PRIMARY KEY AUTOINCREMENT, -- twistar requires this
-    pdu_id TEXT,
-    origin TEXT,
-    CONSTRAINT origin_edge_pdu_id_origin UNIQUE (pdu_id, origin)
-);
-
-CREATE INDEX IF NOT EXISTS context_edge_pdu_id ON context_edge_pdus(pdu_id, origin); 
-CREATE INDEX IF NOT EXISTS origin_edge_pdu_id ON origin_edge_pdus(pdu_id, origin);
diff --git a/synapse/storage/schema/event_edges.sql b/synapse/storage/schema/event_edges.sql
new file mode 100644
index 0000000000..e5f768c705
--- /dev/null
+++ b/synapse/storage/schema/event_edges.sql
@@ -0,0 +1,49 @@
+
+CREATE TABLE IF NOT EXISTS event_forward_extremities(
+    event_id TEXT,
+    room_id TEXT,
+    CONSTRAINT uniqueness UNIQUE (event_id, room_id) ON CONFLICT REPLACE
+);
+
+CREATE INDEX IF NOT EXISTS ev_extrem_room ON event_forward_extremities(room_id);
+CREATE INDEX IF NOT EXISTS ev_extrem_id ON event_forward_extremities(event_id);
+
+
+CREATE TABLE IF NOT EXISTS event_backward_extremities(
+    event_id TEXT,
+    room_id TEXT,
+    CONSTRAINT uniqueness UNIQUE (event_id, room_id) ON CONFLICT REPLACE
+);
+
+CREATE INDEX IF NOT EXISTS ev_b_extrem_room ON event_backward_extremities(room_id);
+CREATE INDEX IF NOT EXISTS ev_b_extrem_id ON event_backward_extremities(event_id);
+
+
+CREATE TABLE IF NOT EXISTS event_edges(
+    event_id TEXT,
+    prev_event_id TEXT,
+    room_id TEXT,
+    CONSTRAINT uniqueness UNIQUE (event_id, prev_event_id, room_id)
+);
+
+CREATE INDEX IF NOT EXISTS ev_edges_id ON event_edges(event_id);
+CREATE INDEX IF NOT EXISTS ev_edges_prev_id ON event_edges(prev_event_id);
+
+
+CREATE TABLE IF NOT EXISTS room_depth(
+    room_id TEXT,
+    min_depth INTEGER,
+    CONSTRAINT uniqueness UNIQUE (room_id)
+);
+
+CREATE INDEX IF NOT EXISTS room_depth_room ON room_depth(room_id);
+
+
+create TABLE IF NOT EXISTS event_destinations(
+    event_id TEXT,
+    destination TEXT,
+    delivered_ts INTEGER DEFAULT 0, -- or 0 if not delivered
+    CONSTRAINT uniqueness UNIQUE (event_id, destination) ON CONFLICT REPLACE
+);
+
+CREATE INDEX IF NOT EXISTS event_destinations_id ON event_destinations(event_id);
diff --git a/synapse/storage/schema/event_signatures.sql b/synapse/storage/schema/event_signatures.sql
new file mode 100644
index 0000000000..5491c7ecec
--- /dev/null
+++ b/synapse/storage/schema/event_signatures.sql
@@ -0,0 +1,65 @@
+/* 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.
+ */
+
+CREATE TABLE IF NOT EXISTS event_content_hashes (
+    event_id TEXT,
+    algorithm TEXT,
+    hash BLOB,
+    CONSTRAINT uniqueness UNIQUE (event_id, algorithm)
+);
+
+CREATE INDEX IF NOT EXISTS event_content_hashes_id ON event_content_hashes(
+    event_id
+);
+
+
+CREATE TABLE IF NOT EXISTS event_reference_hashes (
+    event_id TEXT,
+    algorithm TEXT,
+    hash BLOB,
+    CONSTRAINT uniqueness UNIQUE (event_id, algorithm)
+);
+
+CREATE INDEX IF NOT EXISTS event_reference_hashes_id ON event_reference_hashes (
+    event_id
+);
+
+
+CREATE TABLE IF NOT EXISTS event_origin_signatures (
+    event_id TEXT,
+    origin TEXT,
+    key_id TEXT,
+    signature BLOB,
+    CONSTRAINT uniqueness UNIQUE (event_id, key_id)
+);
+
+CREATE INDEX IF NOT EXISTS event_origin_signatures_id ON event_origin_signatures (
+    event_id
+);
+
+
+CREATE TABLE IF NOT EXISTS event_edge_hashes(
+    event_id TEXT,
+    prev_event_id TEXT,
+    algorithm TEXT,
+    hash BLOB,
+    CONSTRAINT uniqueness UNIQUE (
+        event_id, prev_event_id, algorithm
+    )
+);
+
+CREATE INDEX IF NOT EXISTS event_edge_hashes_id ON event_edge_hashes(
+    event_id
+);
diff --git a/synapse/storage/schema/im.sql b/synapse/storage/schema/im.sql
index 3aa83f5c8c..8d6f655993 100644
--- a/synapse/storage/schema/im.sql
+++ b/synapse/storage/schema/im.sql
@@ -23,6 +23,7 @@ CREATE TABLE IF NOT EXISTS events(
     unrecognized_keys TEXT,
     processed BOOL NOT NULL,
     outlier BOOL NOT NULL,
+    depth INTEGER DEFAULT 0 NOT NULL,
     CONSTRAINT ev_uniq UNIQUE (event_id)
 );
 
diff --git a/synapse/storage/schema/pdu.sql b/synapse/storage/schema/pdu.sql
deleted file mode 100644
index 16e111a56c..0000000000
--- a/synapse/storage/schema/pdu.sql
+++ /dev/null
@@ -1,106 +0,0 @@
-/* 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.
- */
--- Stores pdus and their content
-CREATE TABLE IF NOT EXISTS pdus(
-    pdu_id TEXT, 
-    origin TEXT, 
-    context TEXT,
-    pdu_type TEXT,
-    ts INTEGER,
-    depth INTEGER DEFAULT 0 NOT NULL,
-    is_state BOOL, 
-    content_json TEXT,
-    unrecognized_keys TEXT,
-    outlier BOOL NOT NULL,
-    have_processed BOOL, 
-    CONSTRAINT pdu_id_origin UNIQUE (pdu_id, origin)
-);
-
--- Stores what the current state pdu is for a given (context, pdu_type, key) tuple
-CREATE TABLE IF NOT EXISTS state_pdus(
-    pdu_id TEXT,
-    origin TEXT,
-    context TEXT,
-    pdu_type TEXT,
-    state_key TEXT,
-    power_level TEXT,
-    prev_state_id TEXT,
-    prev_state_origin TEXT,
-    CONSTRAINT pdu_id_origin UNIQUE (pdu_id, origin)
-    CONSTRAINT prev_pdu_id_origin UNIQUE (prev_state_id, prev_state_origin)
-);
-
-CREATE TABLE IF NOT EXISTS current_state(
-    pdu_id TEXT,
-    origin TEXT,
-    context TEXT,
-    pdu_type TEXT,
-    state_key TEXT,
-    CONSTRAINT pdu_id_origin UNIQUE (pdu_id, origin)
-    CONSTRAINT uniqueness UNIQUE (context, pdu_type, state_key) ON CONFLICT REPLACE
-);
-
--- Stores where each pdu we want to send should be sent and the delivery status.
-create TABLE IF NOT EXISTS pdu_destinations(
-    pdu_id TEXT,
-    origin TEXT,
-    destination TEXT,
-    delivered_ts INTEGER DEFAULT 0, -- or 0 if not delivered
-    CONSTRAINT uniqueness UNIQUE (pdu_id, origin, destination) ON CONFLICT REPLACE
-);
-
-CREATE TABLE IF NOT EXISTS pdu_forward_extremities(
-    pdu_id TEXT,
-    origin TEXT,
-    context TEXT,
-    CONSTRAINT uniqueness UNIQUE (pdu_id, origin, context) ON CONFLICT REPLACE
-);
-
-CREATE TABLE IF NOT EXISTS pdu_backward_extremities(
-    pdu_id TEXT,
-    origin TEXT,
-    context TEXT,
-    CONSTRAINT uniqueness UNIQUE (pdu_id, origin, context) ON CONFLICT REPLACE
-);
-
-CREATE TABLE IF NOT EXISTS pdu_edges(
-    pdu_id TEXT,
-    origin TEXT,
-    prev_pdu_id TEXT,
-    prev_origin TEXT,
-    context TEXT,
-    CONSTRAINT uniqueness UNIQUE (pdu_id, origin, prev_pdu_id, prev_origin, context)
-);
-
-CREATE TABLE IF NOT EXISTS context_depth(
-    context TEXT,
-    min_depth INTEGER,
-    CONSTRAINT uniqueness UNIQUE (context)
-);
-
-CREATE INDEX IF NOT EXISTS context_depth_context ON context_depth(context);
-
-
-CREATE INDEX IF NOT EXISTS pdu_id ON pdus(pdu_id, origin);
-
-CREATE INDEX IF NOT EXISTS dests_id ON pdu_destinations (pdu_id, origin);
--- CREATE INDEX IF NOT EXISTS dests ON pdu_destinations (destination);
-
-CREATE INDEX IF NOT EXISTS pdu_extrem_context ON pdu_forward_extremities(context);
-CREATE INDEX IF NOT EXISTS pdu_extrem_id ON pdu_forward_extremities(pdu_id, origin);
-
-CREATE INDEX IF NOT EXISTS pdu_edges_id ON pdu_edges(pdu_id, origin);
-
-CREATE INDEX IF NOT EXISTS pdu_b_extrem_context ON pdu_backward_extremities(context);
diff --git a/synapse/storage/schema/state.sql b/synapse/storage/schema/state.sql
new file mode 100644
index 0000000000..b44c56b519
--- /dev/null
+++ b/synapse/storage/schema/state.sql
@@ -0,0 +1,33 @@
+/* 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.
+ */
+
+CREATE TABLE IF NOT EXISTS state_groups(
+    id INTEGER PRIMARY KEY,
+    room_id TEXT NOT NULL,
+    event_id TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS state_groups_state(
+    state_group INTEGER NOT NULL,
+    room_id TEXT NOT NULL,
+    type TEXT NOT NULL,
+    state_key TEXT NOT NULL,
+    event_id TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS event_to_state_groups(
+    event_id TEXT NOT NULL,
+    state_group INTEGER NOT NULL
+);
\ No newline at end of file
diff --git a/synapse/storage/signatures.py b/synapse/storage/signatures.py
new file mode 100644
index 0000000000..b4b3d5d7ea
--- /dev/null
+++ b/synapse/storage/signatures.py
@@ -0,0 +1,165 @@
+# -*- 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 _base import SQLBaseStore
+
+
+class SignatureStore(SQLBaseStore):
+    """Persistence for event signatures and hashes"""
+
+    def _get_event_content_hashes_txn(self, txn, event_id):
+        """Get all the hashes for a given Event.
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+        Returns:
+            A dict of algorithm -> hash.
+        """
+        query = (
+            "SELECT algorithm, hash"
+            " FROM event_content_hashes"
+            " WHERE event_id = ?"
+        )
+        txn.execute(query, (event_id, ))
+        return dict(txn.fetchall())
+
+    def _store_event_content_hash_txn(self, txn, event_id, algorithm,
+                                    hash_bytes):
+        """Store a hash for a Event
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+            algorithm (str): Hashing algorithm.
+            hash_bytes (bytes): Hash function output bytes.
+        """
+        self._simple_insert_txn(
+            txn,
+            "event_content_hashes",
+            {
+                "event_id": event_id,
+                "algorithm": algorithm,
+                "hash": buffer(hash_bytes),
+            },
+            or_ignore=True,
+        )
+
+    def _get_event_reference_hashes_txn(self, txn, event_id):
+        """Get all the hashes for a given PDU.
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+        Returns:
+            A dict of algorithm -> hash.
+        """
+        query = (
+            "SELECT algorithm, hash"
+            " FROM event_reference_hashes"
+            " WHERE event_id = ?"
+        )
+        txn.execute(query, (event_id, ))
+        return dict(txn.fetchall())
+
+    def _store_event_reference_hash_txn(self, txn, event_id, algorithm,
+                                      hash_bytes):
+        """Store a hash for a PDU
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+            algorithm (str): Hashing algorithm.
+            hash_bytes (bytes): Hash function output bytes.
+        """
+        self._simple_insert_txn(
+            txn,
+            "event_reference_hashes",
+            {
+                "event_id": event_id,
+                "algorithm": algorithm,
+                "hash": buffer(hash_bytes),
+            },
+            or_ignore=True,
+        )
+
+
+    def _get_event_origin_signatures_txn(self, txn, event_id):
+        """Get all the signatures for a given PDU.
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+        Returns:
+            A dict of key_id -> signature_bytes.
+        """
+        query = (
+            "SELECT key_id, signature"
+            " FROM event_origin_signatures"
+            " WHERE event_id = ? "
+        )
+        txn.execute(query, (event_id, ))
+        return dict(txn.fetchall())
+
+    def _store_event_origin_signature_txn(self, txn, event_id, origin, key_id,
+                                          signature_bytes):
+        """Store a signature from the origin server for a PDU.
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+            origin (str): origin of the Event.
+            key_id (str): Id for the signing key.
+            signature (bytes): The signature.
+        """
+        self._simple_insert_txn(
+            txn,
+            "event_origin_signatures",
+            {
+                "event_id": event_id,
+                "origin": origin,
+                "key_id": key_id,
+                "signature": buffer(signature_bytes),
+            },
+            or_ignore=True,
+        )
+
+    def _get_prev_event_hashes_txn(self, txn, event_id):
+        """Get all the hashes for previous PDUs of a PDU
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+        Returns:
+            dict of (pdu_id, origin) -> dict of algorithm -> hash_bytes.
+        """
+        query = (
+            "SELECT prev_event_id, algorithm, hash"
+            " FROM event_edge_hashes"
+            " WHERE event_id = ?"
+        )
+        txn.execute(query, (event_id, ))
+        results = {}
+        for prev_event_id, algorithm, hash_bytes in txn.fetchall():
+            hashes = results.setdefault(prev_event_id, {})
+            hashes[algorithm] = hash_bytes
+        return results
+
+    def _store_prev_event_hash_txn(self, txn, event_id, prev_event_id,
+                                 algorithm, hash_bytes):
+        self._simple_insert_txn(
+            txn,
+            "event_edge_hashes",
+            {
+                "event_id": event_id,
+                "prev_event_id": prev_event_id,
+                "algorithm": algorithm,
+                "hash": buffer(hash_bytes),
+            },
+            or_ignore=True,
+        )
\ No newline at end of file
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
new file mode 100644
index 0000000000..e08acd6404
--- /dev/null
+++ b/synapse/storage/state.py
@@ -0,0 +1,101 @@
+# -*- 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 ._base import SQLBaseStore
+from twisted.internet import defer
+
+from collections import namedtuple
+
+
+StateGroup = namedtuple("StateGroup", ("group", "state"))
+
+
+class StateStore(SQLBaseStore):
+
+    @defer.inlineCallbacks
+    def get_state_groups(self, event_ids):
+        groups = set()
+        for event_id in event_ids:
+            group = yield self._simple_select_one_onecol(
+                table="event_to_state_groups",
+                keyvalues={"event_id": event_id},
+                retcol="state_group",
+                allow_none=True,
+            )
+            if group:
+                groups.add(group)
+
+        res = []
+        for group in groups:
+            state_ids = yield self._simple_select_onecol(
+                table="state_groups_state",
+                keyvalues={"state_group": group},
+                retcol="event_id",
+            )
+            state = []
+            for state_id in state_ids:
+                s = yield self.get_event(
+                    state_id,
+                    allow_none=True,
+                )
+                if s:
+                    state.append(s)
+
+            res.append(StateGroup(group, state))
+
+        defer.returnValue(res)
+
+    def store_state_groups(self, event):
+        return self.runInteraction(
+            "store_state_groups",
+            self._store_state_groups_txn, event
+        )
+
+    def _store_state_groups_txn(self, txn, event):
+        if not event.state_events:
+            return
+
+        state_group = event.state_group
+        if not state_group:
+            state_group = self._simple_insert_txn(
+                txn,
+                table="state_groups",
+                values={
+                    "room_id": event.room_id,
+                    "event_id": event.event_id,
+                }
+            )
+
+            for state in event.state_events.values():
+                self._simple_insert_txn(
+                    txn,
+                    table="state_groups_state",
+                    values={
+                        "state_group": state_group,
+                        "room_id": state.room_id,
+                        "type": state.type,
+                        "state_key": state.state_key,
+                        "event_id": state.event_id,
+                    }
+                )
+
+        self._simple_insert_txn(
+            txn,
+            table="event_to_state_groups",
+            values={
+                "state_group": state_group,
+                "event_id": event.event_id,
+            }
+        )
diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py
index d61f909939..8f7f61d29d 100644
--- a/synapse/storage/stream.py
+++ b/synapse/storage/stream.py
@@ -309,7 +309,10 @@ class StreamStore(SQLBaseStore):
         defer.returnValue(ret)
 
     def get_room_events_max_id(self):
-        return self.runInteraction(self._get_room_events_max_id_txn)
+        return self.runInteraction(
+            "get_room_events_max_id",
+            self._get_room_events_max_id_txn
+        )
 
     def _get_room_events_max_id_txn(self, txn):
         txn.execute(
diff --git a/synapse/storage/transactions.py b/synapse/storage/transactions.py
index 2ba8e30efe..ea67900788 100644
--- a/synapse/storage/transactions.py
+++ b/synapse/storage/transactions.py
@@ -14,7 +14,6 @@
 # limitations under the License.
 
 from ._base import SQLBaseStore, Table
-from .pdu import PdusTable
 
 from collections import namedtuple
 
@@ -42,6 +41,7 @@ class TransactionStore(SQLBaseStore):
         """
 
         return self.runInteraction(
+            "get_received_txn_response",
             self._get_received_txn_response, transaction_id, origin
         )
 
@@ -73,6 +73,7 @@ class TransactionStore(SQLBaseStore):
         """
 
         return self.runInteraction(
+            "set_received_txn_response",
             self._set_received_txn_response,
             transaction_id, origin, code, response_dict
         )
@@ -106,6 +107,7 @@ class TransactionStore(SQLBaseStore):
         """
 
         return self.runInteraction(
+            "prep_send_transaction",
             self._prep_send_transaction,
             transaction_id, destination, origin_server_ts, pdu_list
         )
@@ -139,15 +141,15 @@ class TransactionStore(SQLBaseStore):
 
         # Update the tx id -> pdu id mapping
 
-        values = [
-            (transaction_id, destination, pdu[0], pdu[1])
-            for pdu in pdu_list
-        ]
-
-        logger.debug("Inserting: %s", repr(values))
-
-        query = TransactionsToPduTable.insert_statement()
-        txn.executemany(query, values)
+        # values = [
+        #     (transaction_id, destination, pdu[0], pdu[1])
+        #     for pdu in pdu_list
+        # ]
+        #
+        # logger.debug("Inserting: %s", repr(values))
+        #
+        # query = TransactionsToPduTable.insert_statement()
+        # txn.executemany(query, values)
 
         return prev_txns
 
@@ -161,6 +163,7 @@ class TransactionStore(SQLBaseStore):
             response_json (str)
         """
         return self.runInteraction(
+            "delivered_txn",
             self._delivered_txn,
             transaction_id, destination, code, response_dict
         )
@@ -186,6 +189,7 @@ class TransactionStore(SQLBaseStore):
             list: A list of `ReceivedTransactionsTable.EntryType`
         """
         return self.runInteraction(
+            "get_transactions_after",
             self._get_transactions_after, transaction_id, destination
         )
 
@@ -202,49 +206,6 @@ class TransactionStore(SQLBaseStore):
 
         return ReceivedTransactionsTable.decode_results(txn.fetchall())
 
-    def get_pdus_after_transaction(self, transaction_id, destination):
-        """For a given local transaction_id that we sent to a given destination
-        home server, return a list of PDUs that were sent to that destination
-        after it.
-
-        Args:
-            txn
-            transaction_id (str)
-            destination (str)
-
-        Returns
-            list: A list of PduTuple
-        """
-        return self.runInteraction(
-            self._get_pdus_after_transaction,
-            transaction_id, destination
-        )
-
-    def _get_pdus_after_transaction(self, txn, transaction_id, destination):
-
-        # Query that first get's all transaction_ids with an id greater than
-        # the one given from the `sent_transactions` table. Then JOIN on this
-        # from the `tx->pdu` table to get a list of (pdu_id, origin) that
-        # specify the pdus that were sent in those transactions.
-        query = (
-            "SELECT pdu_id, pdu_origin FROM %(tx_pdu)s as tp "
-            "INNER JOIN %(sent_tx)s as st "
-            "ON tp.transaction_id = st.transaction_id "
-            "AND tp.destination = st.destination "
-            "WHERE st.id > ("
-            "SELECT id FROM %(sent_tx)s "
-            "WHERE transaction_id = ? AND destination = ?"
-        ) % {
-            "tx_pdu": TransactionsToPduTable.table_name,
-            "sent_tx": SentTransactions.table_name,
-        }
-
-        txn.execute(query, (transaction_id, destination))
-
-        pdus = PdusTable.decode_results(txn.fetchall())
-
-        return self._get_pdu_tuples(txn, pdus)
-
 
 class ReceivedTransactionsTable(Table):
     table_name = "received_transactions"
diff --git a/synapse/types.py b/synapse/types.py
index c51bc8e4f2..649ff2f7d7 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -78,6 +78,11 @@ class DomainSpecificString(
         """Create a structure on the local domain"""
         return cls(localpart=localpart, domain=hs.hostname, is_mine=True)
 
+    @classmethod
+    def create(cls, localpart, domain, hs):
+        is_mine = domain == hs.hostname
+        return cls(localpart=localpart, domain=domain, is_mine=is_mine)
+
 
 class UserID(DomainSpecificString):
     """Structure representing a user ID."""
@@ -94,6 +99,11 @@ class RoomID(DomainSpecificString):
     SIGIL = "!"
 
 
+class EventID(DomainSpecificString):
+    """Structure representing an event id. """
+    SIGIL = "$"
+
+
 class StreamToken(
     namedtuple(
         "Token",
diff --git a/synapse/util/async.py b/synapse/util/async.py
index 647ea6142c..bf578f8bfb 100644
--- a/synapse/util/async.py
+++ b/synapse/util/async.py
@@ -21,3 +21,10 @@ def sleep(seconds):
     d = defer.Deferred()
     reactor.callLater(seconds, d.callback, seconds)
     return d
+
+
+def run_on_reactor():
+    """ This will cause the rest of the function to be invoked upon the next
+    iteration of the main loop
+    """
+    return sleep(0)
\ No newline at end of file