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-rw-r--r--synapse/handlers/e2e_keys.py304
-rw-r--r--synapse/rest/client/v2_alpha/keys.py53
-rw-r--r--synapse/storage/end_to_end_keys.py32
-rw-r--r--tests/handlers/test_e2e_keys.py295
4 files changed, 682 insertions, 2 deletions
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index 997ad66f8f..95f3cc891b 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -20,7 +20,9 @@ import logging
 from six import iteritems
 
 from canonicaljson import encode_canonical_json, json
+from signedjson.key import decode_verify_key_bytes
 from signedjson.sign import SignatureVerifyException, verify_signed_json
+from unpaddedbase64 import decode_base64
 
 from twisted.internet import defer
 
@@ -608,6 +610,257 @@ class E2eKeysHandler(object):
 
         return {}
 
+    @defer.inlineCallbacks
+    def upload_signatures_for_device_keys(self, user_id, signatures):
+        """Upload device signatures for cross-signing
+
+        Args:
+            user_id (string): the user uploading the signatures
+            signatures (dict[string, dict[string, dict]]): map of users to
+                devices to signed keys
+        """
+        failures = {}
+
+        # signatures to be stored.  Each item will be a tuple of
+        # (signing_key_id, target_user_id, target_device_id, signature)
+        signature_list = []
+
+        # split between checking signatures for own user and signatures for
+        # other users, since we verify them with different keys
+        self_signatures = signatures.get(user_id, {})
+        other_signatures = {k: v for k, v in signatures.items() if k != user_id}
+
+        self_signature_list, self_failures = yield self._process_self_signatures(
+            user_id, self_signatures
+        )
+        signature_list.extend(self_signature_list)
+        failures.update(self_failures)
+
+        other_signature_list, other_failures = yield self._process_other_signatures(
+            user_id, other_signatures
+        )
+        signature_list.extend(other_signature_list)
+        failures.update(other_failures)
+
+        # store the signature, and send the appropriate notifications for sync
+        logger.debug("upload signature failures: %r", failures)
+        yield self.store.store_e2e_cross_signing_signatures(user_id, signature_list)
+
+        self_device_ids = [device_id for (_, _, device_id, _) in self_signature_list]
+        if self_device_ids:
+            yield self.device_handler.notify_device_update(user_id, self_device_ids)
+        signed_users = [user_id for (_, user_id, _, _) in other_signature_list]
+        if signed_users:
+            yield self.device_handler.notify_user_signature_update(
+                user_id, signed_users
+            )
+
+        return {"failures": failures}
+
+    @defer.inlineCallbacks
+    def _process_self_signatures(self, user_id, signatures):
+        signature_list = []
+        failures = {}
+        if not signatures:
+            return signature_list, failures
+
+        try:
+            # get our self-signing key to verify the signatures
+            self_signing_key, self_signing_key_id, self_signing_verify_key = yield self._get_e2e_cross_signing_verify_key(
+                user_id, "self_signing"
+            )
+
+            # get our master key, since it may be signed
+            master_key, master_key_id, master_verify_key = yield self._get_e2e_cross_signing_verify_key(
+                user_id, "master"
+            )
+
+            # fetch our stored devices.  This is used to 1. verify
+            # signatures on the master key, and 2. to can compare with what
+            # was sent if the device was signed
+            devices = yield self.store.get_e2e_device_keys([(user_id, None)])
+
+            if user_id not in devices:
+                raise SynapseError(404, "No device keys found", Codes.NOT_FOUND)
+
+            devices = devices[user_id]
+        except SynapseError as e:
+            failures[user_id] = {
+                device: _exception_to_failure(e) for device in signatures.keys()
+            }
+            return signature_list, failures
+
+        for device_id, device in signatures.items():
+            try:
+                if "signatures" not in device or user_id not in device["signatures"]:
+                    # no signature was sent
+                    raise SynapseError(
+                        400, "Invalid signature", Codes.INVALID_SIGNATURE
+                    )
+
+                if device_id == master_verify_key.version:
+                    # we have master key signed by devices: for each
+                    # device that signed, check the signature.  Since
+                    # the "failures" property in the response only has
+                    # granularity up to the signed device, either all
+                    # of the signatures on the master key succeed, or
+                    # all fail.  So loop over the signatures and add
+                    # them to a separate signature list.  If everything
+                    # works out, then add them all to the main
+                    # signature list.  (In practice, we're likely to
+                    # only have only one signature anyways.)
+                    master_key_signature_list = []
+                    sigs = device["signatures"]
+                    for signing_key_id, signature in sigs[user_id].items():
+                        alg, signing_device_id = signing_key_id.split(":", 1)
+                        if (
+                            signing_device_id not in devices
+                            or signing_key_id
+                            not in devices[signing_device_id]["keys"]["keys"]
+                        ):
+                            # signed by an unknown device, or the
+                            # device does not have the key
+                            raise SynapseError(
+                                400, "Invalid signature", Codes.INVALID_SIGNATURE
+                            )
+
+                        # get the key and check the signature
+                        pubkey = devices[signing_device_id]["keys"]["keys"][
+                            signing_key_id
+                        ]
+                        verify_key = decode_verify_key_bytes(
+                            signing_key_id, decode_base64(pubkey)
+                        )
+                        _check_device_signature(user_id, verify_key, device, master_key)
+                        device["signatures"] = sigs
+
+                        master_key_signature_list.append(
+                            (signing_key_id, user_id, device_id, signature)
+                        )
+
+                    signature_list.extend(master_key_signature_list)
+                    continue
+
+                # at this point, we have a device that should be signed
+                # by the self-signing key
+                if self_signing_key_id not in device["signatures"][user_id]:
+                    # no signature was sent
+                    raise SynapseError(
+                        400, "Invalid signature", Codes.INVALID_SIGNATURE
+                    )
+
+                stored_device = None
+                try:
+                    stored_device = devices[device_id]["keys"]
+                except KeyError:
+                    raise SynapseError(404, "Unknown device", Codes.NOT_FOUND)
+                if self_signing_key_id in stored_device.get("signatures", {}).get(
+                    user_id, {}
+                ):
+                    # we already have a signature on this device, so we
+                    # can skip it, since it should be exactly the same
+                    continue
+
+                _check_device_signature(
+                    user_id, self_signing_verify_key, device, stored_device
+                )
+
+                signature = device["signatures"][user_id][self_signing_key_id]
+                signature_list.append(
+                    (self_signing_key_id, user_id, device_id, signature)
+                )
+            except SynapseError as e:
+                failures.setdefault(user_id, {})[device_id] = _exception_to_failure(e)
+
+        return signature_list, failures
+
+    @defer.inlineCallbacks
+    def _process_other_signatures(self, user_id, signatures):
+        # now check non-self signatures.  These signatures will be signed
+        # by the user-signing key
+        signature_list = []
+        failures = {}
+        if not signatures:
+            return signature_list, failures
+
+        try:
+            # get our user-signing key to verify the signatures
+            user_signing_key, user_signing_key_id, user_signing_verify_key = yield self._get_e2e_cross_signing_verify_key(
+                user_id, "user_signing"
+            )
+        except SynapseError as e:
+            failure = _exception_to_failure(e)
+            for user, devicemap in signatures.items():
+                failures[user] = {device_id: failure for device_id in devicemap.keys()}
+            return signature_list, failures
+
+        for user, devicemap in signatures.items():
+            device_id = None
+            try:
+                # get the user's master key, to make sure it matches
+                # what was sent
+                stored_key, stored_key_id, _ = yield self._get_e2e_cross_signing_verify_key(
+                    user, "master", user_id
+                )
+
+                # make sure that the user's master key is the one that
+                # was signed (and no others)
+                device_id = stored_key_id.split(":", 1)[1]
+                if device_id not in devicemap:
+                    logger.error(
+                        "upload signature: could not find signature for device %s",
+                        device_id,
+                    )
+                    # set device to None so that the failure gets
+                    # marked on all the signatures
+                    device_id = None
+                    raise SynapseError(404, "Unknown device", Codes.NOT_FOUND)
+                key = devicemap[device_id]
+                other_devices = [k for k in devicemap.keys() if k != device_id]
+                if other_devices:
+                    # other devices were signed -- mark those as failures
+                    logger.error("upload signature: too many devices specified")
+                    failure = _exception_to_failure(
+                        SynapseError(404, "Unknown device", Codes.NOT_FOUND)
+                    )
+                    failures[user] = {device: failure for device in other_devices}
+
+                if user_signing_key_id in stored_key.get("signatures", {}).get(
+                    user_id, {}
+                ):
+                    # we already have the signature, so we can skip it
+                    continue
+
+                _check_device_signature(
+                    user_id, user_signing_verify_key, key, stored_key
+                )
+
+                signature = key["signatures"][user_id][user_signing_key_id]
+                signature_list.append((user_signing_key_id, user, device_id, signature))
+            except SynapseError as e:
+                failure = _exception_to_failure(e)
+                if device_id is None:
+                    failures[user] = {
+                        device_id: failure for device_id in devicemap.keys()
+                    }
+                else:
+                    failures.setdefault(user, {})[device_id] = failure
+
+        return signature_list, failures
+
+    @defer.inlineCallbacks
+    def _get_e2e_cross_signing_verify_key(self, user_id, key_type, from_user_id=None):
+        key = yield self.store.get_e2e_cross_signing_key(
+            user_id, key_type, from_user_id
+        )
+        if key is None:
+            logger.error("no %s key found for %s", key_type, user_id)
+            raise SynapseError(
+                404, "No %s key found for %s" % (key_type, user_id), Codes.NOT_FOUND
+            )
+        key_id, verify_key = get_verify_key_from_cross_signing_key(key)
+        return key, key_id, verify_key
+
 
 def _check_cross_signing_key(key, user_id, key_type, signing_key=None):
     """Check a cross-signing key uploaded by a user.  Performs some basic sanity
@@ -636,7 +889,58 @@ def _check_cross_signing_key(key, user_id, key_type, signing_key=None):
             )
 
 
+def _check_device_signature(user_id, verify_key, signed_device, stored_device):
+    """Check that a device signature is correct and matches the copy of the device
+    that we have.  Throws an exception if an error is detected.
+
+    Args:
+        user_id (str): the user ID whose signature is being checked
+        verify_key (VerifyKey): the key to verify the device with
+        signed_device (dict): the signed device data
+        stored_device (dict): our previous copy of the device
+    """
+
+    key_id = "%s:%s" % (verify_key.alg, verify_key.version)
+
+    # make sure the device is signed
+    if (
+        "signatures" not in signed_device
+        or user_id not in signed_device["signatures"]
+        or key_id not in signed_device["signatures"][user_id]
+    ):
+        logger.error("upload signature: user not found in signatures")
+        raise SynapseError(400, "Invalid signature", Codes.INVALID_SIGNATURE)
+
+    signature = signed_device["signatures"][user_id][key_id]
+
+    # make sure that the device submitted matches what we have stored
+    del signed_device["signatures"]
+    # use pop to avoid exception if key doesn't exist
+    signed_device.pop("unsigned", None)
+    stored_device.pop("signatures", None)
+    stored_device.pop("unsigned", None)
+    if signed_device != stored_device:
+        logger.error(
+            "upload signatures: key does not match %s vs %s",
+            signed_device,
+            stored_device,
+        )
+        raise SynapseError(400, "Key does not match")
+
+    # check the signature
+    signed_device["signatures"] = {user_id: {key_id: signature}}
+
+    try:
+        verify_signed_json(signed_device, user_id, verify_key)
+    except SignatureVerifyException:
+        logger.error("invalid signature on key")
+        raise SynapseError(400, "Invalid signature", Codes.INVALID_SIGNATURE)
+
+
 def _exception_to_failure(e):
+    if isinstance(e, SynapseError):
+        return {"status": e.code, "errcode": e.errcode, "message": str(e)}
+
     if isinstance(e, CodeMessageException):
         return {"status": e.code, "message": str(e)}
 
diff --git a/synapse/rest/client/v2_alpha/keys.py b/synapse/rest/client/v2_alpha/keys.py
index 151a70d449..341567ae21 100644
--- a/synapse/rest/client/v2_alpha/keys.py
+++ b/synapse/rest/client/v2_alpha/keys.py
@@ -274,7 +274,57 @@ class SigningKeyUploadServlet(RestServlet):
         )
 
         result = yield self.e2e_keys_handler.upload_signing_keys_for_user(user_id, body)
-        return (200, result)
+        return 200, result
+
+
+class SignaturesUploadServlet(RestServlet):
+    """
+    POST /keys/signatures/upload HTTP/1.1
+    Content-Type: application/json
+
+    {
+      "@alice:example.com": {
+        "<device_id>": {
+          "user_id": "<user_id>",
+          "device_id": "<device_id>",
+          "algorithms": [
+            "m.olm.curve25519-aes-sha256",
+            "m.megolm.v1.aes-sha"
+          ],
+          "keys": {
+            "<algorithm>:<device_id>": "<key_base64>",
+          },
+          "signatures": {
+            "<signing_user_id>": {
+              "<algorithm>:<signing_key_base64>": "<signature_base64>>"
+            }
+          }
+        }
+      }
+    }
+    """
+
+    PATTERNS = client_patterns("/keys/signatures/upload$")
+
+    def __init__(self, hs):
+        """
+        Args:
+            hs (synapse.server.HomeServer): server
+        """
+        super(SignaturesUploadServlet, self).__init__()
+        self.auth = hs.get_auth()
+        self.e2e_keys_handler = hs.get_e2e_keys_handler()
+
+    @defer.inlineCallbacks
+    def on_POST(self, request):
+        requester = yield self.auth.get_user_by_req(request, allow_guest=True)
+        user_id = requester.user.to_string()
+        body = parse_json_object_from_request(request)
+
+        result = yield self.e2e_keys_handler.upload_signatures_for_device_keys(
+            user_id, body
+        )
+        return 200, result
 
 
 def register_servlets(hs, http_server):
@@ -283,3 +333,4 @@ def register_servlets(hs, http_server):
     KeyChangesServlet(hs).register(http_server)
     OneTimeKeyServlet(hs).register(http_server)
     SigningKeyUploadServlet(hs).register(http_server)
+    SignaturesUploadServlet(hs).register(http_server)
diff --git a/synapse/storage/end_to_end_keys.py b/synapse/storage/end_to_end_keys.py
index 8ce5dd8bf9..258e8dcb47 100644
--- a/synapse/storage/end_to_end_keys.py
+++ b/synapse/storage/end_to_end_keys.py
@@ -59,6 +59,12 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
         for user_id, device_keys in iteritems(results):
             for device_id, device_info in iteritems(device_keys):
                 device_info["keys"] = db_to_json(device_info.pop("key_json"))
+                # add cross-signing signatures to the keys
+                if "signatures" in device_info:
+                    for sig_user_id, sigs in device_info["signatures"].items():
+                        device_info["keys"].setdefault("signatures", {}).setdefault(
+                            sig_user_id, {}
+                        ).update(sigs)
 
         return results
 
@@ -71,6 +77,8 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
 
         query_clauses = []
         query_params = []
+        signature_query_clauses = []
+        signature_query_params = []
 
         if include_all_devices is False:
             include_deleted_devices = False
@@ -81,12 +89,20 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
         for (user_id, device_id) in query_list:
             query_clause = "user_id = ?"
             query_params.append(user_id)
+            signature_query_clause = "target_user_id = ?"
+            signature_query_params.append(user_id)
 
             if device_id is not None:
                 query_clause += " AND device_id = ?"
                 query_params.append(device_id)
+                signature_query_clause += " AND target_device_id = ?"
+                signature_query_params.append(device_id)
+
+            signature_query_clause += " AND user_id = ?"
+            signature_query_params.append(user_id)
 
             query_clauses.append(query_clause)
+            signature_query_clauses.append(signature_query_clause)
 
         sql = (
             "SELECT user_id, device_id, "
@@ -113,6 +129,22 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
             for user_id, device_id in deleted_devices:
                 result.setdefault(user_id, {})[device_id] = None
 
+        # get signatures on the device
+        signature_sql = (
+            "SELECT * " "  FROM e2e_cross_signing_signatures " " WHERE %s"
+        ) % (" OR ".join("(" + q + ")" for q in signature_query_clauses))
+
+        txn.execute(signature_sql, signature_query_params)
+        rows = self.cursor_to_dict(txn)
+
+        for row in rows:
+            target_user_id = row["target_user_id"]
+            target_device_id = row["target_device_id"]
+            if target_user_id in result and target_device_id in result[target_user_id]:
+                result[target_user_id][target_device_id].setdefault(
+                    "signatures", {}
+                ).setdefault(row["user_id"], {})[row["key_id"]] = row["signature"]
+
         log_kv(result)
         return result
 
diff --git a/tests/handlers/test_e2e_keys.py b/tests/handlers/test_e2e_keys.py
index a62c52eefa..854eb6c024 100644
--- a/tests/handlers/test_e2e_keys.py
+++ b/tests/handlers/test_e2e_keys.py
@@ -17,9 +17,11 @@
 
 import mock
 
+import signedjson.key as key
+import signedjson.sign as sign
+
 from twisted.internet import defer
 
-import synapse.api.errors
 import synapse.handlers.e2e_keys
 import synapse.storage
 from synapse.api import errors
@@ -182,6 +184,96 @@ class E2eKeysHandlerTestCase(unittest.TestCase):
         self.assertDictEqual(devices["master_keys"], {local_user: keys2["master_key"]})
 
     @defer.inlineCallbacks
+    def test_reupload_signatures(self):
+        """re-uploading a signature should not fail"""
+        local_user = "@boris:" + self.hs.hostname
+        keys1 = {
+            "master_key": {
+                # private key: HvQBbU+hc2Zr+JP1sE0XwBe1pfZZEYtJNPJLZJtS+F8
+                "user_id": local_user,
+                "usage": ["master"],
+                "keys": {
+                    "ed25519:EmkqvokUn8p+vQAGZitOk4PWjp7Ukp3txV2TbMPEiBQ": "EmkqvokUn8p+vQAGZitOk4PWjp7Ukp3txV2TbMPEiBQ"
+                },
+            },
+            "self_signing_key": {
+                # private key: 2lonYOM6xYKdEsO+6KrC766xBcHnYnim1x/4LFGF8B0
+                "user_id": local_user,
+                "usage": ["self_signing"],
+                "keys": {
+                    "ed25519:nqOvzeuGWT/sRx3h7+MHoInYj3Uk2LD/unI9kDYcHwk": "nqOvzeuGWT/sRx3h7+MHoInYj3Uk2LD/unI9kDYcHwk"
+                },
+            },
+        }
+        master_signing_key = key.decode_signing_key_base64(
+            "ed25519",
+            "EmkqvokUn8p+vQAGZitOk4PWjp7Ukp3txV2TbMPEiBQ",
+            "HvQBbU+hc2Zr+JP1sE0XwBe1pfZZEYtJNPJLZJtS+F8",
+        )
+        sign.sign_json(keys1["self_signing_key"], local_user, master_signing_key)
+        signing_key = key.decode_signing_key_base64(
+            "ed25519",
+            "nqOvzeuGWT/sRx3h7+MHoInYj3Uk2LD/unI9kDYcHwk",
+            "2lonYOM6xYKdEsO+6KrC766xBcHnYnim1x/4LFGF8B0",
+        )
+        yield self.handler.upload_signing_keys_for_user(local_user, keys1)
+
+        # upload two device keys, which will be signed later by the self-signing key
+        device_key_1 = {
+            "user_id": local_user,
+            "device_id": "abc",
+            "algorithms": ["m.olm.curve25519-aes-sha256", "m.megolm.v1.aes-sha"],
+            "keys": {
+                "ed25519:abc": "base64+ed25519+key",
+                "curve25519:abc": "base64+curve25519+key",
+            },
+            "signatures": {local_user: {"ed25519:abc": "base64+signature"}},
+        }
+        device_key_2 = {
+            "user_id": local_user,
+            "device_id": "def",
+            "algorithms": ["m.olm.curve25519-aes-sha256", "m.megolm.v1.aes-sha"],
+            "keys": {
+                "ed25519:def": "base64+ed25519+key",
+                "curve25519:def": "base64+curve25519+key",
+            },
+            "signatures": {local_user: {"ed25519:def": "base64+signature"}},
+        }
+
+        yield self.handler.upload_keys_for_user(
+            local_user, "abc", {"device_keys": device_key_1}
+        )
+        yield self.handler.upload_keys_for_user(
+            local_user, "def", {"device_keys": device_key_2}
+        )
+
+        # sign the first device key and upload it
+        del device_key_1["signatures"]
+        sign.sign_json(device_key_1, local_user, signing_key)
+        yield self.handler.upload_signatures_for_device_keys(
+            local_user, {local_user: {"abc": device_key_1}}
+        )
+
+        # sign the second device key and upload both device keys.  The server
+        # should ignore the first device key since it already has a valid
+        # signature for it
+        del device_key_2["signatures"]
+        sign.sign_json(device_key_2, local_user, signing_key)
+        yield self.handler.upload_signatures_for_device_keys(
+            local_user, {local_user: {"abc": device_key_1, "def": device_key_2}}
+        )
+
+        device_key_1["signatures"][local_user]["ed25519:abc"] = "base64+signature"
+        device_key_2["signatures"][local_user]["ed25519:def"] = "base64+signature"
+        devices = yield self.handler.query_devices(
+            {"device_keys": {local_user: []}}, 0, local_user
+        )
+        del devices["device_keys"][local_user]["abc"]["unsigned"]
+        del devices["device_keys"][local_user]["def"]["unsigned"]
+        self.assertDictEqual(devices["device_keys"][local_user]["abc"], device_key_1)
+        self.assertDictEqual(devices["device_keys"][local_user]["def"], device_key_2)
+
+    @defer.inlineCallbacks
     def test_self_signing_key_doesnt_show_up_as_device(self):
         """signing keys should be hidden when fetching a user's devices"""
         local_user = "@boris:" + self.hs.hostname
@@ -210,3 +302,204 @@ class E2eKeysHandlerTestCase(unittest.TestCase):
 
         res = yield self.handler.query_local_devices({local_user: None})
         self.assertDictEqual(res, {local_user: {}})
+
+    @defer.inlineCallbacks
+    def test_upload_signatures(self):
+        """should check signatures that are uploaded"""
+        # set up a user with cross-signing keys and a device.  This user will
+        # try uploading signatures
+        local_user = "@boris:" + self.hs.hostname
+        device_id = "xyz"
+        # private key: OMkooTr76ega06xNvXIGPbgvvxAOzmQncN8VObS7aBA
+        device_pubkey = "NnHhnqiMFQkq969szYkooLaBAXW244ZOxgukCvm2ZeY"
+        device_key = {
+            "user_id": local_user,
+            "device_id": device_id,
+            "algorithms": ["m.olm.curve25519-aes-sha256", "m.megolm.v1.aes-sha"],
+            "keys": {"curve25519:xyz": "curve25519+key", "ed25519:xyz": device_pubkey},
+            "signatures": {local_user: {"ed25519:xyz": "something"}},
+        }
+        device_signing_key = key.decode_signing_key_base64(
+            "ed25519", "xyz", "OMkooTr76ega06xNvXIGPbgvvxAOzmQncN8VObS7aBA"
+        )
+
+        yield self.handler.upload_keys_for_user(
+            local_user, device_id, {"device_keys": device_key}
+        )
+
+        # private key: 2lonYOM6xYKdEsO+6KrC766xBcHnYnim1x/4LFGF8B0
+        master_pubkey = "nqOvzeuGWT/sRx3h7+MHoInYj3Uk2LD/unI9kDYcHwk"
+        master_key = {
+            "user_id": local_user,
+            "usage": ["master"],
+            "keys": {"ed25519:" + master_pubkey: master_pubkey},
+        }
+        master_signing_key = key.decode_signing_key_base64(
+            "ed25519", master_pubkey, "2lonYOM6xYKdEsO+6KrC766xBcHnYnim1x/4LFGF8B0"
+        )
+        usersigning_pubkey = "Hq6gL+utB4ET+UvD5ci0kgAwsX6qP/zvf8v6OInU5iw"
+        usersigning_key = {
+            # private key: 4TL4AjRYwDVwD3pqQzcor+ez/euOB1/q78aTJ+czDNs
+            "user_id": local_user,
+            "usage": ["user_signing"],
+            "keys": {"ed25519:" + usersigning_pubkey: usersigning_pubkey},
+        }
+        usersigning_signing_key = key.decode_signing_key_base64(
+            "ed25519", usersigning_pubkey, "4TL4AjRYwDVwD3pqQzcor+ez/euOB1/q78aTJ+czDNs"
+        )
+        sign.sign_json(usersigning_key, local_user, master_signing_key)
+        # private key: HvQBbU+hc2Zr+JP1sE0XwBe1pfZZEYtJNPJLZJtS+F8
+        selfsigning_pubkey = "EmkqvokUn8p+vQAGZitOk4PWjp7Ukp3txV2TbMPEiBQ"
+        selfsigning_key = {
+            "user_id": local_user,
+            "usage": ["self_signing"],
+            "keys": {"ed25519:" + selfsigning_pubkey: selfsigning_pubkey},
+        }
+        selfsigning_signing_key = key.decode_signing_key_base64(
+            "ed25519", selfsigning_pubkey, "HvQBbU+hc2Zr+JP1sE0XwBe1pfZZEYtJNPJLZJtS+F8"
+        )
+        sign.sign_json(selfsigning_key, local_user, master_signing_key)
+        cross_signing_keys = {
+            "master_key": master_key,
+            "user_signing_key": usersigning_key,
+            "self_signing_key": selfsigning_key,
+        }
+        yield self.handler.upload_signing_keys_for_user(local_user, cross_signing_keys)
+
+        # set up another user with a master key.  This user will be signed by
+        # the first user
+        other_user = "@otherboris:" + self.hs.hostname
+        other_master_pubkey = "fHZ3NPiKxoLQm5OoZbKa99SYxprOjNs4TwJUKP+twCM"
+        other_master_key = {
+            # private key: oyw2ZUx0O4GifbfFYM0nQvj9CL0b8B7cyN4FprtK8OI
+            "user_id": other_user,
+            "usage": ["master"],
+            "keys": {"ed25519:" + other_master_pubkey: other_master_pubkey},
+        }
+        yield self.handler.upload_signing_keys_for_user(
+            other_user, {"master_key": other_master_key}
+        )
+
+        # test various signature failures (see below)
+        ret = yield self.handler.upload_signatures_for_device_keys(
+            local_user,
+            {
+                local_user: {
+                    # fails because the signature is invalid
+                    # should fail with INVALID_SIGNATURE
+                    device_id: {
+                        "user_id": local_user,
+                        "device_id": device_id,
+                        "algorithms": [
+                            "m.olm.curve25519-aes-sha256",
+                            "m.megolm.v1.aes-sha",
+                        ],
+                        "keys": {
+                            "curve25519:xyz": "curve25519+key",
+                            # private key: OMkooTr76ega06xNvXIGPbgvvxAOzmQncN8VObS7aBA
+                            "ed25519:xyz": device_pubkey,
+                        },
+                        "signatures": {
+                            local_user: {"ed25519:" + selfsigning_pubkey: "something"}
+                        },
+                    },
+                    # fails because device is unknown
+                    # should fail with NOT_FOUND
+                    "unknown": {
+                        "user_id": local_user,
+                        "device_id": "unknown",
+                        "signatures": {
+                            local_user: {"ed25519:" + selfsigning_pubkey: "something"}
+                        },
+                    },
+                    # fails because the signature is invalid
+                    # should fail with INVALID_SIGNATURE
+                    master_pubkey: {
+                        "user_id": local_user,
+                        "usage": ["master"],
+                        "keys": {"ed25519:" + master_pubkey: master_pubkey},
+                        "signatures": {
+                            local_user: {"ed25519:" + device_pubkey: "something"}
+                        },
+                    },
+                },
+                other_user: {
+                    # fails because the device is not the user's master-signing key
+                    # should fail with NOT_FOUND
+                    "unknown": {
+                        "user_id": other_user,
+                        "device_id": "unknown",
+                        "signatures": {
+                            local_user: {"ed25519:" + usersigning_pubkey: "something"}
+                        },
+                    },
+                    other_master_pubkey: {
+                        # fails because the key doesn't match what the server has
+                        # should fail with UNKNOWN
+                        "user_id": other_user,
+                        "usage": ["master"],
+                        "keys": {"ed25519:" + other_master_pubkey: other_master_pubkey},
+                        "something": "random",
+                        "signatures": {
+                            local_user: {"ed25519:" + usersigning_pubkey: "something"}
+                        },
+                    },
+                },
+            },
+        )
+
+        user_failures = ret["failures"][local_user]
+        self.assertEqual(
+            user_failures[device_id]["errcode"], errors.Codes.INVALID_SIGNATURE
+        )
+        self.assertEqual(
+            user_failures[master_pubkey]["errcode"], errors.Codes.INVALID_SIGNATURE
+        )
+        self.assertEqual(user_failures["unknown"]["errcode"], errors.Codes.NOT_FOUND)
+
+        other_user_failures = ret["failures"][other_user]
+        self.assertEqual(
+            other_user_failures["unknown"]["errcode"], errors.Codes.NOT_FOUND
+        )
+        self.assertEqual(
+            other_user_failures[other_master_pubkey]["errcode"], errors.Codes.UNKNOWN
+        )
+
+        # test successful signatures
+        del device_key["signatures"]
+        sign.sign_json(device_key, local_user, selfsigning_signing_key)
+        sign.sign_json(master_key, local_user, device_signing_key)
+        sign.sign_json(other_master_key, local_user, usersigning_signing_key)
+        ret = yield self.handler.upload_signatures_for_device_keys(
+            local_user,
+            {
+                local_user: {device_id: device_key, master_pubkey: master_key},
+                other_user: {other_master_pubkey: other_master_key},
+            },
+        )
+
+        self.assertEqual(ret["failures"], {})
+
+        # fetch the signed keys/devices and make sure that the signatures are there
+        ret = yield self.handler.query_devices(
+            {"device_keys": {local_user: [], other_user: []}}, 0, local_user
+        )
+
+        self.assertEqual(
+            ret["device_keys"][local_user]["xyz"]["signatures"][local_user][
+                "ed25519:" + selfsigning_pubkey
+            ],
+            device_key["signatures"][local_user]["ed25519:" + selfsigning_pubkey],
+        )
+        self.assertEqual(
+            ret["master_keys"][local_user]["signatures"][local_user][
+                "ed25519:" + device_id
+            ],
+            master_key["signatures"][local_user]["ed25519:" + device_id],
+        )
+        self.assertEqual(
+            ret["master_keys"][other_user]["signatures"][local_user][
+                "ed25519:" + usersigning_pubkey
+            ],
+            other_master_key["signatures"][local_user]["ed25519:" + usersigning_pubkey],
+        )