Add an export_signing_key script (#6546)

I want to do some key rotation, and it is silly that we don't have a way to do
this.

1 files changed, 94 insertions, 0 deletions

diff --git a/scripts/export_signing_key b/scripts/export_signing_key
new file mode 100755
index 0000000000..8aec9d802b
--- /dev/null
+++ b/scripts/export_signing_key
@@ -0,0 +1,94 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+#
+# 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.
+import argparse
+import sys
+import time
+from typing import Optional
+
+import nacl.signing
+from signedjson.key import encode_verify_key_base64, get_verify_key, read_signing_keys
+
+
+def exit(status: int = 0, message: Optional[str] = None):
+    if message:
+        print(message, file=sys.stderr)
+    sys.exit(status)
+
+
+def format_plain(public_key: nacl.signing.VerifyKey):
+    print(
+        "%s:%s %s"
+        % (public_key.alg, public_key.version, encode_verify_key_base64(public_key),)
+    )
+
+
+def format_for_config(public_key: nacl.signing.VerifyKey, expiry_ts: int):
+    print(
+        '  "%s:%s": { key: "%s", expired_ts: %i }'
+        % (
+            public_key.alg,
+            public_key.version,
+            encode_verify_key_base64(public_key),
+            expiry_ts,
+        )
+    )
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument(
+        "key_file", nargs="+", type=argparse.FileType("r"), help="The key file to read",
+    )
+
+    parser.add_argument(
+        "-x",
+        action="store_true",
+        dest="for_config",
+        help="format the output for inclusion in the old_signing_keys config setting",
+    )
+
+    parser.add_argument(
+        "--expiry-ts",
+        type=int,
+        default=int(time.time() * 1000) + 6*3600000,
+        help=(
+            "The expiry time to use for -x, in milliseconds since 1970. The default "
+            "is (now+6h)."
+        ),
+    )
+
+    args = parser.parse_args()
+
+    formatter = (
+        (lambda k: format_for_config(k, args.expiry_ts))
+        if args.for_config
+        else format_plain
+    )
+
+    keys = []
+    for file in args.key_file:
+        try:
+            res = read_signing_keys(file)
+        except Exception as e:
+            exit(
+                status=1,
+                message="Error reading key from file %s: %s %s"
+                % (file.name, type(e), e),
+            )
+            res = []
+        for key in res:
+            formatter(get_verify_key(key))