Basic itsdangerous infrastructure.

Implement the basic infrastructure for using itsdangerous
in mediagoblin. Usage instructions will follow.

1 files changed, 55 insertions, 0 deletions

diff --git a/mediagoblin/tools/crypto.py b/mediagoblin/tools/crypto.py
new file mode 100644
index 00000000..46752b55
--- /dev/null
+++ b/mediagoblin/tools/crypto.py
@@ -0,0 +1,55 @@
+# GNU MediaGoblin -- federated, autonomous media hosting
+# Copyright (C) 2013 MediaGoblin contributors.  See AUTHORS.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os.path
+import logging
+import random
+import itsdangerous
+from mediagoblin import mg_globals
+
+_log = logging.getLogger(__name__)
+
+
+# Use the system (hardware-based) random number generator if it exists.
+# -- this optimization is lifted from Django
+if hasattr(random, 'SystemRandom'):
+    getrandbits = random.SystemRandom().getrandbits
+else:
+    getrandbits = random.getrandbits
+
+
+__itsda_secret = None
+
+
+def setup_crypto():
+    global __itsda_secret
+    dir = mg_globals.app_config["crypto_path"]
+    if not os.path.isdir(dir):
+        _log.info("Creating %s", dir)
+        os.makedirs(dir)
+    name = os.path.join(dir, "itsdangeroussecret.bin")
+    if os.path.exists(name):
+        __itsda_secret = file(name, "r").read()
+    else:
+        __itsda_secret = str(getrandbits(192))
+        file(name, "w").write(__itsda_secret)
+        _log.info("Created %s", name)
+
+
+def get_timed_signer_url(namespace):
+    assert __itsda_secret is not None
+    return itsdangerous.URLSafeTimedSerializer(__itsda_secret,
+         salt=namespace)