Source code for keystone.credential.providers.fernet.core

# 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
# 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 hashlib

from cryptography import fernet
from oslo_log import log

from keystone.common import fernet_utils
import keystone.conf
from keystone.credential.providers import core
from keystone import exception
from keystone.i18n import _

CONF = keystone.conf.CONF
LOG = log.getLogger(__name__)

# NOTE(lbragstad): Credential key rotation operates slightly different than
# token key rotation. Each credential holds a hash of the key that encrypted
# it. This is important for credential key rotation because it helps us make
# sure we don't over-rotate credential keys. During a rotation of credential
# keys, if any credential has not been re-encrypted with the current primary
# key, we can abandon the key rotation until all credentials have been migrated
# to the new primary key. If we don't take this step, it is possible that we
# could remove a key used to encrypt credentials, leaving them unrecoverable.
# This also means that we don't need to expose a `[credential] max_active_keys`
# option through configuration. Instead we will use a global variable and share
# that across all places that need to use FernetUtils for credential
# encryption.

[docs]def get_multi_fernet_keys(): key_utils = fernet_utils.FernetUtils( CONF.credential.key_repository, MAX_ACTIVE_KEYS, 'credential') keys = key_utils.load_keys(use_null_key=True) fernet_keys = [fernet.Fernet(key) for key in keys] crypto = fernet.MultiFernet(fernet_keys) return crypto, keys
[docs]def primary_key_hash(keys): """Calculate a hash of the primary key used for encryption.""" if isinstance(keys[0], str): keys[0] = keys[0].encode('utf-8') # NOTE(lhinds) This is marked as #nosec since bandit will see SHA1 which # is marked as insecure. However, this hash function is used alongside # encrypted blobs to implement HMAC-SHA1, which is currently not insecure # but will still trigger when scanned by bandit. return hashlib.sha1(keys[0]).hexdigest() # nosec
[docs]class Provider(core.Provider):
[docs] def encrypt(self, credential): """Attempt to encrypt a plaintext credential. :param credential: a plaintext representation of a credential :returns: an encrypted credential """ crypto, keys = get_multi_fernet_keys() if keys[0] == fernet_utils.NULL_KEY: LOG.warning( 'Encrypting credentials with the null key. Please properly ' 'encrypt credentials using `keystone-manage credential_setup`,' ' `keystone-manage credential_migrate`, and `keystone-manage ' 'credential_rotate`') try: return ( crypto.encrypt(credential.encode('utf-8')), primary_key_hash(keys)) except (TypeError, ValueError) as e: msg = 'Credential could not be encrypted: %s' % str(e) tr_msg = _('Credential could not be encrypted: %s') % str(e) LOG.error(msg) raise exception.CredentialEncryptionError(tr_msg)
[docs] def decrypt(self, credential): """Attempt to decrypt a credential. :param credential: an encrypted credential string :returns: a decrypted credential """ key_utils = fernet_utils.FernetUtils( CONF.credential.key_repository, MAX_ACTIVE_KEYS) keys = key_utils.load_keys(use_null_key=True) fernet_keys = [fernet.Fernet(key) for key in keys] crypto = fernet.MultiFernet(fernet_keys) try: if isinstance(credential, str): credential = credential.encode('utf-8') return crypto.decrypt(credential).decode('utf-8') except (fernet.InvalidToken, TypeError, ValueError): msg = ('Credential could not be decrypted. Please contact the ' 'administrator') tr_msg = _('Credential could not be decrypted. Please contact the ' 'administrator') LOG.error(msg) raise exception.CredentialEncryptionError(tr_msg)