230 lines
8.8 KiB
Python
230 lines
8.8 KiB
Python
# Copyright 2015, 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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from typing import Dict
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from signedjson.sign import sign_json
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from synapse.api.errors import Codes, SynapseError
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from synapse.crypto.keyring import ServerKeyFetcher
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from synapse.http.server import DirectServeJsonResource, respond_with_json
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from synapse.http.servlet import parse_integer, parse_json_object_from_request
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from synapse.util import json_decoder
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logger = logging.getLogger(__name__)
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class RemoteKey(DirectServeJsonResource):
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"""HTTP resource for retrieving the TLS certificate and NACL signature
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verification keys for a collection of servers. Checks that the reported
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X.509 TLS certificate matches the one used in the HTTPS connection. Checks
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that the NACL signature for the remote server is valid. Returns a dict of
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JSON signed by both the remote server and by this server.
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Supports individual GET APIs and a bulk query POST API.
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Requests:
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GET /_matrix/key/v2/query/remote.server.example.com HTTP/1.1
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GET /_matrix/key/v2/query/remote.server.example.com/a.key.id HTTP/1.1
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POST /_matrix/v2/query HTTP/1.1
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Content-Type: application/json
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{
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"server_keys": {
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"remote.server.example.com": {
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"a.key.id": {
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"minimum_valid_until_ts": 1234567890123
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}
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}
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}
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}
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Response:
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HTTP/1.1 200 OK
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Content-Type: application/json
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{
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"server_keys": [
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{
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"server_name": "remote.server.example.com"
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"valid_until_ts": # posix timestamp
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"verify_keys": {
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"a.key.id": { # The identifier for a key.
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key: "" # base64 encoded verification key.
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}
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}
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"old_verify_keys": {
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"an.old.key.id": { # The identifier for an old key.
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key: "", # base64 encoded key
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"expired_ts": 0, # when the key stop being used.
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}
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}
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"tls_fingerprints": [
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{ "sha256": # fingerprint }
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]
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"signatures": {
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"remote.server.example.com": {...}
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"this.server.example.com": {...}
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}
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}
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]
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}
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"""
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isLeaf = True
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def __init__(self, hs):
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super().__init__()
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self.fetcher = ServerKeyFetcher(hs)
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self.store = hs.get_datastore()
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self.clock = hs.get_clock()
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self.federation_domain_whitelist = hs.config.federation_domain_whitelist
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self.config = hs.config
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async def _async_render_GET(self, request):
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if len(request.postpath) == 1:
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(server,) = request.postpath
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query = {server.decode("ascii"): {}} # type: dict
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elif len(request.postpath) == 2:
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server, key_id = request.postpath
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minimum_valid_until_ts = parse_integer(request, "minimum_valid_until_ts")
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arguments = {}
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if minimum_valid_until_ts is not None:
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arguments["minimum_valid_until_ts"] = minimum_valid_until_ts
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query = {server.decode("ascii"): {key_id.decode("ascii"): arguments}}
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else:
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raise SynapseError(404, "Not found %r" % request.postpath, Codes.NOT_FOUND)
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await self.query_keys(request, query, query_remote_on_cache_miss=True)
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async def _async_render_POST(self, request):
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content = parse_json_object_from_request(request)
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query = content["server_keys"]
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await self.query_keys(request, query, query_remote_on_cache_miss=True)
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async def query_keys(self, request, query, query_remote_on_cache_miss=False):
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logger.info("Handling query for keys %r", query)
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store_queries = []
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for server_name, key_ids in query.items():
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if (
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self.federation_domain_whitelist is not None
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and server_name not in self.federation_domain_whitelist
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):
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logger.debug("Federation denied with %s", server_name)
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continue
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if not key_ids:
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key_ids = (None,)
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for key_id in key_ids:
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store_queries.append((server_name, key_id, None))
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cached = await self.store.get_server_keys_json(store_queries)
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json_results = set()
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time_now_ms = self.clock.time_msec()
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# Note that the value is unused.
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cache_misses = {} # type: Dict[str, Dict[str, int]]
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for (server_name, key_id, _), results in cached.items():
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results = [(result["ts_added_ms"], result) for result in results]
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if not results and key_id is not None:
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cache_misses.setdefault(server_name, {})[key_id] = 0
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continue
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if key_id is not None:
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ts_added_ms, most_recent_result = max(results)
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ts_valid_until_ms = most_recent_result["ts_valid_until_ms"]
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req_key = query.get(server_name, {}).get(key_id, {})
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req_valid_until = req_key.get("minimum_valid_until_ts")
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miss = False
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if req_valid_until is not None:
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if ts_valid_until_ms < req_valid_until:
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logger.debug(
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"Cached response for %r/%r is older than requested"
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": valid_until (%r) < minimum_valid_until (%r)",
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server_name,
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key_id,
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ts_valid_until_ms,
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req_valid_until,
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)
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miss = True
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else:
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logger.debug(
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"Cached response for %r/%r is newer than requested"
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": valid_until (%r) >= minimum_valid_until (%r)",
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server_name,
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key_id,
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ts_valid_until_ms,
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req_valid_until,
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)
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elif (ts_added_ms + ts_valid_until_ms) / 2 < time_now_ms:
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logger.debug(
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"Cached response for %r/%r is too old"
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": (added (%r) + valid_until (%r)) / 2 < now (%r)",
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server_name,
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key_id,
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ts_added_ms,
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ts_valid_until_ms,
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time_now_ms,
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)
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# We more than half way through the lifetime of the
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# response. We should fetch a fresh copy.
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miss = True
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else:
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logger.debug(
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"Cached response for %r/%r is still valid"
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": (added (%r) + valid_until (%r)) / 2 < now (%r)",
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server_name,
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key_id,
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ts_added_ms,
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ts_valid_until_ms,
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time_now_ms,
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)
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if miss:
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cache_misses.setdefault(server_name, {})[key_id] = 0
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# Cast to bytes since postgresql returns a memoryview.
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json_results.add(bytes(most_recent_result["key_json"]))
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else:
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for _, result in results:
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# Cast to bytes since postgresql returns a memoryview.
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json_results.add(bytes(result["key_json"]))
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# If there is a cache miss, request the missing keys, then recurse (and
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# ensure the result is sent).
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if cache_misses and query_remote_on_cache_miss:
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await self.fetcher.get_keys(cache_misses)
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await self.query_keys(request, query, query_remote_on_cache_miss=False)
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else:
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signed_keys = []
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for key_json in json_results:
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key_json = json_decoder.decode(key_json.decode("utf-8"))
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for signing_key in self.config.key_server_signing_keys:
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key_json = sign_json(key_json, self.config.server_name, signing_key)
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signed_keys.append(key_json)
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results = {"server_keys": signed_keys}
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respond_with_json(request, 200, results, canonical_json=True)
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