Change use of random to random.SystemRandom

There's no reason to use random directly unless the code really
requires a pseudo-random number generator. This is for security
hardening.

SecImpact
Closes-Bug: 1424089

Change-Id: I2eb0c78af230026de9139363bc05e453d581a700

keystone/common/kvs/backends/memcached.py

@@ -16,7 +16,7 @@
 Keystone Memcached dogpile.cache backend implementation.
 """
 
-import random
+import random as _random
 import time
 
 from dogpile.cache import api
@@ -33,7 +33,7 @@ from keystone.i18n import _
 CONF = cfg.CONF
 LOG = log.getLogger(__name__)
 NO_VALUE = api.NO_VALUE
-
+random = _random.SystemRandom()
 
 VALID_DOGPILE_BACKENDS = dict(
     pylibmc=memcached.PylibmcBackend,

keystone/contrib/oauth1/backends/sql.py

@@ -13,7 +13,7 @@
 # under the License.
 
 import datetime
-import random
+import random as _random
 import uuid
 
 from oslo_serialization import jsonutils
@@ -26,6 +26,9 @@ from keystone import exception
 from keystone.i18n import _
 
 
+random = _random.SystemRandom()
+
+
 class Consumer(sql.ModelBase, sql.DictBase):
     __tablename__ = 'consumer'
     attributes = ['id', 'description', 'secret']