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+# -*- coding: utf-8 -*-
+# keys.py
+# Copyright (C) 2013 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/>.
+
+
+"""
+Abstact key type and encryption scheme representations.
+"""
+
+
+try:
+ import simplejson as json
+except ImportError:
+ import json # noqa
+import re
+
+
+from abc import ABCMeta, abstractmethod
+from leap.common.check import leap_assert
+
+
+#
+# Dictionary keys used for storing cryptographic keys.
+#
+
+KEY_ADDRESS_KEY = 'address'
+KEY_TYPE_KEY = 'type'
+KEY_ID_KEY = 'key_id'
+KEY_FINGERPRINT_KEY = 'fingerprint'
+KEY_DATA_KEY = 'key_data'
+KEY_PRIVATE_KEY = 'private'
+KEY_LENGTH_KEY = 'length'
+KEY_EXPIRY_DATE_KEY = 'expiry_date'
+KEY_FIRST_SEEN_AT_KEY = 'first_seen_at'
+KEY_LAST_AUDITED_AT_KEY = 'last_audited_at'
+KEY_VALIDATION_KEY = 'validation'
+KEY_TAGS_KEY = 'tags'
+
+
+#
+# Key storage constants
+#
+
+KEYMANAGER_KEY_TAG = 'keymanager-key'
+
+
+#
+# key indexing constants.
+#
+
+TAGS_PRIVATE_INDEX = 'by-tags-private'
+TAGS_ADDRESS_PRIVATE_INDEX = 'by-tags-address-private'
+INDEXES = {
+ TAGS_PRIVATE_INDEX: [
+ KEY_TAGS_KEY,
+ 'bool(%s)' % KEY_PRIVATE_KEY,
+ ],
+ TAGS_ADDRESS_PRIVATE_INDEX: [
+ KEY_TAGS_KEY,
+ KEY_ADDRESS_KEY,
+ 'bool(%s)' % KEY_PRIVATE_KEY,
+ ]
+}
+
+
+#
+# Key handling utilities
+#
+
+def is_address(address):
+ """
+ Return whether the given C{address} is in the form user@provider.
+
+ :param address: The address to be tested.
+ :type address: str
+ :return: Whether C{address} is in the form user@provider.
+ :rtype: bool
+ """
+ return bool(re.match('[\w.-]+@[\w.-]+', address))
+
+
+def build_key_from_dict(kClass, address, kdict):
+ """
+ Build an C{kClass} key bound to C{address} based on info in C{kdict}.
+
+ :param address: The address bound to the key.
+ :type address: str
+ :param kdict: Dictionary with key data.
+ :type kdict: dict
+ :return: An instance of the key.
+ :rtype: C{kClass}
+ """
+ leap_assert(
+ address == kdict[KEY_ADDRESS_KEY],
+ 'Wrong address in key data.')
+ return kClass(
+ address,
+ key_id=kdict[KEY_ID_KEY],
+ fingerprint=kdict[KEY_FINGERPRINT_KEY],
+ key_data=kdict[KEY_DATA_KEY],
+ private=kdict[KEY_PRIVATE_KEY],
+ length=kdict[KEY_LENGTH_KEY],
+ expiry_date=kdict[KEY_EXPIRY_DATE_KEY],
+ first_seen_at=kdict[KEY_FIRST_SEEN_AT_KEY],
+ last_audited_at=kdict[KEY_LAST_AUDITED_AT_KEY],
+ validation=kdict[KEY_VALIDATION_KEY], # TODO: verify for validation.
+ )
+
+
+#
+# Abstraction for encryption keys
+#
+
+class EncryptionKey(object):
+ """
+ Abstract class for encryption keys.
+
+ A key is "validated" if the nicknym agent has bound the user address to a
+ public key. Nicknym supports three different levels of key validation:
+
+ * Level 3 - path trusted: A path of cryptographic signatures can be traced
+ from a trusted key to the key under evaluation. By default, only the
+ provider key from the user's provider is a "trusted key".
+ * level 2 - provider signed: The key has been signed by a provider key for
+ the same domain, but the provider key is not validated using a trust
+ path (i.e. it is only registered)
+ * level 1 - registered: The key has been encountered and saved, it has no
+ signatures (that are meaningful to the nicknym agent).
+ """
+
+ __metaclass__ = ABCMeta
+
+ def __init__(self, address, key_id=None, fingerprint=None,
+ key_data=None, private=None, length=None, expiry_date=None,
+ validation=None, first_seen_at=None, last_audited_at=None):
+ self.address = address
+ self.key_id = key_id
+ self.fingerprint = fingerprint
+ self.key_data = key_data
+ self.private = private
+ self.length = length
+ self.expiry_date = expiry_date
+ self.validation = validation
+ self.first_seen_at = first_seen_at
+ self.last_audited_at = last_audited_at
+
+ def get_json(self):
+ """
+ Return a JSON string describing this key.
+
+ :return: The JSON string describing this key.
+ :rtype: str
+ """
+ return json.dumps({
+ KEY_ADDRESS_KEY: self.address,
+ KEY_TYPE_KEY: str(self.__class__),
+ KEY_ID_KEY: self.key_id,
+ KEY_FINGERPRINT_KEY: self.fingerprint,
+ KEY_DATA_KEY: self.key_data,
+ KEY_PRIVATE_KEY: self.private,
+ KEY_LENGTH_KEY: self.length,
+ KEY_EXPIRY_DATE_KEY: self.expiry_date,
+ KEY_VALIDATION_KEY: self.validation,
+ KEY_FIRST_SEEN_AT_KEY: self.first_seen_at,
+ KEY_LAST_AUDITED_AT_KEY: self.last_audited_at,
+ KEY_TAGS_KEY: [KEYMANAGER_KEY_TAG],
+ })
+
+ def __repr__(self):
+ """
+ Representation of this class
+ """
+ return u"<%s 0x%s (%s - %s)>" % (
+ self.__class__.__name__,
+ self.key_id,
+ self.address,
+ "priv" if self.private else "publ")
+
+
+#
+# Encryption schemes
+#
+
+class EncryptionScheme(object):
+ """
+ Abstract class for Encryption Schemes.
+
+ A wrapper for a certain encryption schemes should know how to get and put
+ keys in local storage using Soledad, how to generate new keys and how to
+ find out about possibly encrypted content.
+ """
+
+ __metaclass__ = ABCMeta
+
+ def __init__(self, soledad):
+ """
+ Initialize this Encryption Scheme.
+
+ :param soledad: A Soledad instance for local storage of keys.
+ :type soledad: leap.soledad.Soledad
+ """
+ self._soledad = soledad
+ self._init_indexes()
+
+ def _init_indexes(self):
+ """
+ Initialize the database indexes.
+ """
+ # Ask the database for currently existing indexes.
+ db_indexes = dict(self._soledad.list_indexes())
+ # Loop through the indexes we expect to find.
+ for name, expression in INDEXES.items():
+ if name not in db_indexes:
+ # The index does not yet exist.
+ self._soledad.create_index(name, *expression)
+ continue
+ if expression == db_indexes[name]:
+ # The index exists and is up to date.
+ continue
+ # The index exists but the definition is not what expected, so we
+ # delete it and add the proper index expression.
+ self._soledad.delete_index(name)
+ self._soledad.create_index(name, *expression)
+
+ @abstractmethod
+ def get_key(self, address, private=False):
+ """
+ Get key from local storage.
+
+ :param address: The address bound to the key.
+ :type address: str
+ :param private: Look for a private key instead of a public one?
+ :type private: bool
+
+ :return: The key bound to C{address}.
+ :rtype: EncryptionKey
+ @raise KeyNotFound: If the key was not found on local storage.
+ """
+ pass
+
+ @abstractmethod
+ def put_key(self, key):
+ """
+ Put a key in local storage.
+
+ :param key: The key to be stored.
+ :type key: EncryptionKey
+ """
+ pass
+
+ @abstractmethod
+ def gen_key(self, address):
+ """
+ Generate a new key.
+
+ :param address: The address bound to the key.
+ :type address: str
+
+ :return: The key bound to C{address}.
+ :rtype: EncryptionKey
+ """
+ pass
+
+ @abstractmethod
+ def delete_key(self, key):
+ """
+ Remove C{key} from storage.
+
+ :param key: The key to be removed.
+ :type key: EncryptionKey
+ """
+ pass