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implement device signature uploading/fetching
This commit is contained in:
Hubert Chathi
parent
a22d58c96c
commit
4bb4544784
3 changed files with 338 additions and 0 deletions
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@ -608,6 +608,194 @@ class E2eKeysHandler(object):
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return {}
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@defer.inlineCallbacks
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def upload_signatures_for_device_keys(self, user_id, signatures):
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"""Upload device signatures for cross-signing
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Args:
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user_id (string): the user uploading the signatures
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signatures (dict[string, dict[string, dict]]): map of users to
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devices to signed keys
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"""
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failures = {}
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signature_list = [] # signatures to be stored
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self_device_ids = [] # what devices have been updated, for notifying
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# split between checking signatures for own user and signatures for
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# other users, since we verify them with different keys
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if user_id in signatures:
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self_signatures = signatures[user_id]
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del signatures[user_id]
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self_device_ids = list(self_signatures.keys())
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try:
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# get our self-signing key to verify the signatures
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self_signing_key = yield self.store.get_e2e_cross_signing_key(
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user_id, "self_signing"
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)
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if self_signing_key is None:
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raise SynapseError(
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404,
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"No self-signing key found",
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Codes.NOT_FOUND
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)
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self_signing_key_id, self_signing_verify_key \
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= get_verify_key_from_cross_signing_key(self_signing_key)
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# fetch our stored devices so that we can compare with what was sent
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user_devices = []
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for device in self_signatures.keys():
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user_devices.append((user_id, device))
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devices = yield self.store.get_e2e_device_keys(user_devices)
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if user_id not in devices:
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raise SynapseError(
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404,
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"No device key found",
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Codes.NOT_FOUND
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)
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devices = devices[user_id]
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for device_id, device in self_signatures.items():
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try:
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if ("signatures" not in device or
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user_id not in device["signatures"] or
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self_signing_key_id not in device["signatures"][user_id]):
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# no signature was sent
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raise SynapseError(
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400,
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"Invalid signature",
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Codes.INVALID_SIGNATURE
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)
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stored_device = devices[device_id]["keys"]
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if self_signing_key_id in stored_device.get("signatures", {}) \
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.get(user_id, {}):
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# we already have a signature on this device, so we
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# can skip it, since it should be exactly the same
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continue
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_check_device_signature(
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user_id, self_signing_verify_key, device, stored_device
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)
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signature = device["signatures"][user_id][self_signing_key_id]
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signature_list.append(
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(self_signing_key_id, user_id, device_id, signature)
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)
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except SynapseError as e:
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failures.setdefault(user_id, {})[device_id] \
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= _exception_to_failure(e)
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except SynapseError as e:
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failures[user_id] = {
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device: _exception_to_failure(e)
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for device in self_signatures.keys()
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}
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signed_users = [] # what user have been signed, for notifying
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if len(signatures):
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# if signatures isn't empty, then we have signatures for other
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# users. These signatures will be signed by the user signing key
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# get our user-signing key to verify the signatures
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user_signing_key = yield self.store.get_e2e_cross_signing_key(
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user_id, "user_signing"
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)
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if user_signing_key is None:
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for user, devicemap in signatures.items():
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failures[user] = {
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device: _exception_to_failure(SynapseError(
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404,
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"No user-signing key found",
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Codes.NOT_FOUND
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))
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for device in devicemap.keys()
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}
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else:
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user_signing_key_id, user_signing_verify_key \
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= get_verify_key_from_cross_signing_key(user_signing_key)
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for user, devicemap in signatures.items():
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device_id = None
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try:
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# get the user's master key, to make sure it matches
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# what was sent
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stored_key = yield self.store.get_e2e_cross_signing_key(
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user, "master", user_id
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)
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if stored_key is None:
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logger.error(
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"upload signature: no user key found for %s", user
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)
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raise SynapseError(
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404,
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"User's master key not found",
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Codes.NOT_FOUND
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)
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# make sure that the user's master key is the one that
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# was signed (and no others)
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device_id = get_verify_key_from_cross_signing_key(stored_key)[0] \
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.split(":", 1)[1]
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if device_id not in devicemap:
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logger.error(
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"upload signature: wrong device: %s vs %s",
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device, devicemap
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)
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raise SynapseError(
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404,
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"Unknown device",
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Codes.NOT_FOUND
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)
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if len(devicemap) > 1:
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logger.error("upload signature: too many devices specified")
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failures[user] = {
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device: _exception_to_failure(SynapseError(
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404,
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"Unknown device",
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Codes.NOT_FOUND
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))
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for device in devicemap.keys()
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}
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key = devicemap[device_id]
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if user_signing_key_id in stored_key.get("signatures", {}) \
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.get(user_id, {}):
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# we already have the signature, so we can skip it
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continue
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_check_device_signature(
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user_id, user_signing_verify_key, key, stored_key
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)
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signature = key["signatures"][user_id][user_signing_key_id]
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signed_users.append(user)
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signature_list.append(
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(user_signing_key_id, user, device_id, signature)
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)
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except SynapseError as e:
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if device_id is None:
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failures[user] = {
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device_id: _exception_to_failure(e)
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for device_id in devicemap.keys()
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}
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else:
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failures.setdefault(user, {})[device_id] \
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= _exception_to_failure(e)
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# store the signature, and send the appropriate notifications for sync
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logger.debug("upload signature failures: %r", failures)
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yield self.store.store_e2e_device_signatures(user_id, signature_list)
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if len(self_device_ids):
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yield self.device_handler.notify_device_update(user_id, self_device_ids)
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if len(signed_users):
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yield self.device_handler.notify_user_signature_update(user_id, signed_users)
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defer.returnValue({"failures": failures})
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def _check_cross_signing_key(key, user_id, key_type, signing_key=None):
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"""Check a cross-signing key uploaded by a user. Performs some basic sanity
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@ -636,6 +824,68 @@ def _check_cross_signing_key(key, user_id, key_type, signing_key=None):
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)
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def _check_device_signature(user_id, verify_key, signed_device, stored_device):
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"""Check that a device signature is correct and matches the copy of the device
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that we have. Throws an exception if an error is detected.
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Args:
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user_id (str): the user ID whose signature is being checked
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verify_key (VerifyKey): the key to verify the device with
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signed_device (dict): the signed device data
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stored_device (dict): our previous copy of the device
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"""
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key_id = "%s:%s" % (verify_key.alg, verify_key.version)
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# make sure the device is signed
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if ("signatures" not in signed_device or user_id not in signed_device["signatures"]
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or key_id not in signed_device["signatures"][user_id]):
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logger.error("upload signature: user not found in signatures")
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raise SynapseError(
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400,
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"Invalid signature",
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Codes.INVALID_SIGNATURE
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)
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signature = signed_device["signatures"][user_id][key_id]
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# make sure that the device submitted matches what we have stored
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del signed_device["signatures"]
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if "unsigned" in signed_device:
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del signed_device["unsigned"]
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if "signatures" in stored_device:
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del stored_device["signatures"]
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if "unsigned" in stored_device:
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del stored_device["unsigned"]
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if signed_device != stored_device:
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logger.error(
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"upload signatures: key does not match %s vs %s",
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signed_device, stored_device
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)
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raise SynapseError(
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400,
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"Key does not match",
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"M_MISMATCHED_KEY"
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)
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# check the signature
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signed_device["signatures"] = {
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user_id: {
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key_id: signature
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}
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}
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try:
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verify_signed_json(signed_device, user_id, verify_key)
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except SignatureVerifyException:
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logger.error("invalid signature on key")
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raise SynapseError(
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400,
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"Invalid signature",
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Codes.INVALID_SIGNATURE
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)
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def _exception_to_failure(e):
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if isinstance(e, CodeMessageException):
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return {"status": e.code, "message": str(e)}
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