1 files changed, 94 insertions, 0 deletions
diff --git a/src/leap/keymanager/validation.py b/src/leap/keymanager/validation.py
new file mode 100644
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+++ b/src/leap/keymanager/validation.py
@@ -0,0 +1,94 @@
+# -*- coding: utf-8 -*-
+# __init__.py
+# Copyright (C) 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+"""
+Validation levels implementation for key managment.
+
+See:
+    https://lists.riseup.net/www/arc/leap-discuss/2014-09/msg00000.html
+"""
+
+
+from datetime import datetime
+from enum import Enum
+
+
+ValidationLevel = Enum(
+    "Weak_Chain",
+    "Provider_Trust",
+    "Provider_Endorsement",
+    "Third_Party_Endorsement",
+    "Third_Party_Consensus",
+    "Historically_Auditing",
+    "Known_Key",
+    "Fingerprint")
+
+
+def toValidationLevel(value):
+    """
+    Convert a string representation of a validation level into
+    C{ValidationLevel}
+
+    :param value: validation level
+    :type value: str
+    :rtype: ValidationLevel
+    :raises ValueError: if C{value} is not a validation level
+    """
+    for level in ValidationLevel:
+        if value == str(level):
+            return level
+    raise ValueError("Not valid validation level: %s" % (value,))
+
+
+def can_upgrade(new_key, old_key):
+    """
+    :type new_key: EncryptionKey
+    :type old_key: EncryptionKey
+    :rtype: bool
+    """
+    # XXX not succesfully used and strict high validation level (#6211)
+    # XXX implement key signature checking (#6120)
+
+    # First contact
+    if old_key is None:
+        return True
+
+    if new_key.address != old_key.address:
+        # XXX how do we map multiple IDs? (#6212)
+        return False
+
+    # An update of the same key
+    if new_key.fingerprint == old_key.fingerprint:
+        # XXX wich one is newer? is that a downgrade attack? (#6210)
+        return True
+
+    # Manually verified fingerprint
+    if new_key.validation == ValidationLevel.Fingerprint:
+        return True
+
+    # Expired key and higher validation level
+    if old_key.expiry_date:
+        old_expiry_date = datetime.fromtimestamp(int(old_key.expiry_date))
+        if (old_expiry_date < datetime.now() and
+                new_key.validation >= old_key.validation):
+            return True
+
+    # No expiration date and higher validation level
+    elif new_key.validation >= old_key.validation:
+        return True
+
+    return False