diff --git a/dev-requirements.txt b/dev-requirements.txt
index 4754221d..1922ad28 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -19,7 +19,7 @@ cffi==1.7.0
 pycrypto==2.6.1
 pynacl==1.0.1
 cryptography==1.4.0
-securesystemslib==0.10.1
+securesystemslib==0.10.6
 
 # Testing requirements.  The rest of the testing dependencies available in
 # 'tox.ini'
diff --git a/setup.py b/setup.py
index 4a54bad2..6a926834 100755
--- a/setup.py
+++ b/setup.py
@@ -105,7 +105,7 @@
     'Topic :: Security',
     'Topic :: Software Development'
   ],
-   install_requires = ['iso8601', 'six', 'securesystemslib>=0.10.5'],
+   install_requires = ['iso8601', 'six', 'securesystemslib>=0.10.6'],
   packages = find_packages(exclude=['tests']),
   scripts = [
     'tuf/scripts/basic_client.py',
diff --git a/tests/repository_data/client/test_repository/metadata/current/root.json.gz b/tests/repository_data/client/test_repository/metadata/current/root.json.gz
new file mode 100644
index 00000000..2df907ec
Binary files /dev/null and b/tests/repository_data/client/test_repository/metadata/current/root.json.gz differ
diff --git a/tests/test_exceptions.py b/tests/test_exceptions.py
new file mode 100755
index 00000000..b29b72b8
--- /dev/null
+++ b/tests/test_exceptions.py
@@ -0,0 +1,62 @@
+#!/usr/bin/env python
+
+"""
+<Program Name>
+  test_exceptions.py
+
+<Author>
+  Vladimir Diaz
+
+<Started>
+  July 13, 2017.
+
+<Copyright>
+  See LICENSE for licensing information.
+
+<Purpose>
+  Test cases for exceptions.py (mainly the exceptions defined there).
+"""
+
+# Help with Python 3 compatibility, where the print statement is a function, an
+# implicit relative import is invalid, and the '/' operator performs true
+# division.  Example:  print 'hello world' raises a 'SyntaxError' exception.
+from __future__ import print_function
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import unicode_literals
+
+import unittest
+import logging
+
+import tuf.exceptions
+
+logger = logging.getLogger('test_exceptions')
+
+class TestExceptions(unittest.TestCase):
+  def setUp(self):
+    pass
+
+
+  def tearDown(self):
+    pass
+
+
+  def test_bad_signature_error(self):
+    bad_signature_error = tuf.exceptions.BadSignatureError('bad sig')
+    logger.error(bad_signature_error)
+
+
+  def test_bad_hash_error(self):
+    bad_hash_error = tuf.exceptions.BadHashError('1234', '5678')
+    logger.error(bad_hash_error)
+
+
+  def test_decompression_error(self):
+    download_exception = tuf.exceptions.DownloadError()
+    decompression_error = tuf.exceptions.DecompressionError(download_exception)
+    logger.error(decompression_error)
+
+
+# Run the unit tests.
+if __name__ == '__main__':
+  unittest.main()
diff --git a/tests/test_repository_lib.py b/tests/test_repository_lib.py
index 815ade6f..a3ef34ee 100755
--- a/tests/test_repository_lib.py
+++ b/tests/test_repository_lib.py
@@ -1018,6 +1018,11 @@ def test__load_top_level_metadata(self):
 
     repo_lib.write_metadata_file(signable, root_file, 8, ['gz'], False)
 
+    # Attempt to load a repository that contains a compressed Root file.
+    repository = repo_tool.create_new_repository(repository_directory, repository_name)
+    filenames = repo_lib.get_metadata_filenames(metadata_directory)
+    repo_lib._load_top_level_metadata(repository, filenames, repository_name)
+
     # Remove compressed metadata so that we can test for loading of a
     # repository with no compression enabled.
     for role_file in os.listdir(metadata_directory):
diff --git a/tests/test_repository_tool.py b/tests/test_repository_tool.py
index 4acc4869..d43749c8 100755
--- a/tests/test_repository_tool.py
+++ b/tests/test_repository_tool.py
@@ -84,6 +84,9 @@ def tearDownClass(cls):
 
 
   def setUp(self):
+    tuf.roledb.clear_roledb(clear_all=True)
+    tuf.keydb.clear_keydb(clear_all=True)
+
     tuf.roledb.create_roledb('test_repository')
     tuf.keydb.create_keydb('test_repository')
 
diff --git a/tests/test_unittest_toolbox.py b/tests/test_unittest_toolbox.py
new file mode 100755
index 00000000..18b39b3a
--- /dev/null
+++ b/tests/test_unittest_toolbox.py
@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+
+"""
+<Program Name>
+  test_unittest_toolbox.py
+
+<Author>
+  Vladimir Diaz
+
+<Started>
+  July 14, 2017.
+
+<Copyright>
+  See LICENSE for licensing information.
+
+<Purpose>
+  Test cases for unittest_toolbox.py.
+"""
+
+# Help with Python 3 compatibility, where the print statement is a function, an
+# implicit relative import is invalid, and the '/' operator performs true
+# division.  Example:  print 'hello world' raises a 'SyntaxError' exception.
+from __future__ import print_function
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import unicode_literals
+
+import unittest
+import logging
+import shutil
+
+import tuf.unittest_toolbox as unittest_toolbox
+
+logger = logging.getLogger('test_unittest_toolbox')
+
+
+class TestUnittestToolbox(unittest_toolbox.Modified_TestCase):
+  def setUp(self):
+    unittest_toolbox.Modified_TestCase.setUp(self)
+
+  def tearDown(self):
+    unittest_toolbox.Modified_TestCase.tearDown(self)
+
+
+  def test_tear_down_already_deleted_dir(self):
+    temp_directory = self.make_temp_directory()
+
+    # Delete the temp directory to make sure unittest_toolbox doesn't
+    # complain about the missing temp_directory.
+    shutil.rmtree(temp_directory)
+
+
+# Run the unit tests.
+if __name__ == '__main__':
+  unittest.main()
diff --git a/tests/test_updater.py b/tests/test_updater.py
index 1163afa5..9bfd0ce3 100755
--- a/tests/test_updater.py
+++ b/tests/test_updater.py
@@ -133,6 +133,8 @@ def tearDownClass(cls):
   def setUp(self):
     # We are inheriting from custom class.
     unittest_toolbox.Modified_TestCase.setUp(self)
+    tuf.roledb.clear_roledb(clear_all=True)
+    tuf.keydb.clear_keydb(clear_all=True)
 
     self.repository_name = 'test_repository'
 
@@ -312,6 +314,14 @@ def test_1__load_metadata_from_file(self):
     self.assertEqual(self.repository_updater.metadata['current']['role1'],
                      role1_meta['signed'])
 
+    # Verify that _load_metadata_from_file() doesn't raise an exception for
+    # improperly formatted metadata, and doesn't load the bad file.
+    with open(role1_filepath, 'a') as file_object:
+      file_object.write('bad JSON data')
+
+    self.repository_updater._load_metadata_from_file('current', 'role1')
+    self.assertEqual(len(self.repository_updater.metadata['current']), 5)
+
     # Test if we fail gracefully if we can't deserialize a meta file
     self.repository_updater._load_metadata_from_file('current', 'empty_file')
     self.assertFalse('empty_file' in self.repository_updater.metadata['current'])
@@ -325,29 +335,29 @@ def test_1__load_metadata_from_file(self):
 
 
 
-  """
   def test_1__rebuild_key_and_role_db(self):
     # Setup
     root_roleinfo = tuf.roledb.get_roleinfo('root', self.repository_name)
     root_metadata = self.repository_updater.metadata['current']['root']
     root_threshold = root_metadata['roles']['root']['threshold']
-    print('\nnumber of root keys: ' + str(len(root_metadata['keys'].keys())))
-    print('\nKeys in root metadata: ' + repr(root_metadata['keys'].keys()))
     number_of_root_keys = len(root_metadata['keys'])
 
     self.assertEqual(root_roleinfo['threshold'], root_threshold)
-    # Ensure we add 1 to the number of root keys (actually, the number of root
+
+    # Ensure we add 2 to the number of root keys (actually, the number of root
     # keys multiplied by the number of keyid hash algorithms), to include the
-    # delegated targets key.  The delegated roles of 'targets.json' are also
-    # loaded when the repository object is instantiated.
-    print('\ndifference: ' + repr(list(set(tuf.keydb._keydb_dict[self.repository_name].keys()) - set(root_metadata['keys'].keys()))))
-    self.assertEqual(number_of_root_keys * 2 + 1, len(tuf.keydb._keydb_dict[self.repository_name]))
+    # delegated targets key (+1 for its sha512 keyid).  The delegated roles of
+    # 'targets.json' are also loaded when the repository object is
+    # instantiated.
+
+    self.assertEqual(number_of_root_keys * 2 + 2, len(tuf.keydb._keydb_dict[self.repository_name]))
 
     # Test: normal case.
     self.repository_updater._rebuild_key_and_role_db()
 
     root_roleinfo = tuf.roledb.get_roleinfo('root', self.repository_name)
     self.assertEqual(root_roleinfo['threshold'], root_threshold)
+
     # _rebuild_key_and_role_db() will only rebuild the keys and roles specified
     # in the 'root.json' file, unlike __init__().  Instantiating an updater
     # object calls both _rebuild_key_and_role_db() and _import_delegations().
@@ -363,7 +373,6 @@ def test_1__rebuild_key_and_role_db(self):
     root_roleinfo = tuf.roledb.get_roleinfo('root', self.repository_name)
     self.assertEqual(root_roleinfo['threshold'], 8)
     self.assertEqual(number_of_root_keys * 2 - 2, len(tuf.keydb._keydb_dict[self.repository_name]))
-  """
 
 
 
@@ -459,14 +468,13 @@ def test_2__fileinfo_has_changed(self):
 
 
 
-  """
   def test_2__import_delegations(self):
     # Setup.
     # In order to test '_import_delegations' the parent of the delegation
     # has to be in Repository.metadata['current'], but it has to be inserted
     # there without using '_load_metadata_from_file()' since it calls
     # '_import_delegations()'.
-    repository_name = self.repository_updater.updater_name
+    repository_name = self.repository_updater.repository_name
     tuf.keydb.clear_keydb(repository_name)
     tuf.roledb.clear_roledb(repository_name)
 
@@ -476,10 +484,9 @@ def test_2__import_delegations(self):
     self.repository_updater._rebuild_key_and_role_db()
 
     self.assertEqual(len(tuf.roledb._roledb_dict[repository_name]), 4)
+
     # Take into account the number of keyids algorithms supported by default,
     # which this test condition expects to be two (sha256 and sha512).
-    print('\nkeydb_dict len: ' + repr(len(tuf.keydb._keydb_dict[repository_name].keys())))
-    print('\nkeydb_dict: ' + repr(tuf.keydb._keydb_dict[repository_name].keys()))
     self.assertEqual(4 * 2, len(tuf.keydb._keydb_dict[repository_name]))
 
     # Test: pass a role without delegations.
@@ -497,8 +504,8 @@ def test_2__import_delegations(self):
 
     self.assertEqual(len(tuf.roledb._roledb_dict[repository_name]), 5)
     # The number of root keys (times the number of key hash algorithms) +
-    # delegation's key.
-    self.assertEqual(len(tuf.keydb._keydb_dict[repository_name]), 4 * 2 + 1)
+    # delegation's key (+1 for its sha512 keyid).
+    self.assertEqual(len(tuf.keydb._keydb_dict[repository_name]), 4 * 2 + 2)
 
     # Verify that roledb dictionary was added.
     self.assertTrue('role1' in tuf.roledb._roledb_dict[repository_name])
@@ -526,24 +533,23 @@ def test_2__import_delegations(self):
     self.repository_updater.metadata['current']['targets']\
       ['delegations']['keys'][existing_keyid]['keytype'] = 'ed25519'
 
-    # Verify that _import_delegations() raises an exception if any key in
-    # 'delegations' is improperly formatted (i.e., bad keyid).
-    tuf.keydb.clear_keydb(repository_name)
+    # Verify that _import_delegations() raises an exception if one of the
+    # delegated keys is malformed.
+    valid_keyval = self.repository_updater.metadata['current']['targets']\
+      ['delegations']['keys'][existing_keyid]['keyval']
 
-    self.repository_updater.metadata['current']['targets']['delegations']\
-      ['keys'].update({'123': self.repository_updater.metadata['current']\
-      ['targets']['delegations']['keys'][existing_keyid]})
-    self.assertRaises(securesystemslib.exceptions.Error, self.repository_updater._import_delegations,
-                      'targets')
-
-    # Restore the keyid of 'existing_keyids2'.
     self.repository_updater.metadata['current']['targets']\
-      ['delegations']['keys'][existing_keyid]['keyid'] = existing_keyid
+      ['delegations']['keys'][existing_keyid]['keyval'] = 1
+    self.assertRaises(securesystemslib.exceptions.FormatError, self.repository_updater._import_delegations, 'targets')
 
-    # Verify that _import_delegations() raises an exception if it fails to add
-    # one of the roles loaded from parent role's 'delegations'.
-  """
+    self.repository_updater.metadata['current']['targets']\
+      ['delegations']['keys'][existing_keyid]['keyval'] = valid_keyval
 
+    # Verify that _import_delegations() raises an exception if one of the
+    # delegated roles is malformed.
+    self.repository_updater.metadata['current']['targets']\
+      ['delegations']['roles'][0]['name'] = 1
+    self.assertRaises(securesystemslib.exceptions.FormatError, self.repository_updater._import_delegations, 'targets')
 
 
 
@@ -1393,6 +1399,14 @@ def test_10__soft_check_file_length(self):
                      self.repository_updater._soft_check_file_length,
                      temp_file_object, 1)
 
+    # Verify that an exception is not raised if the file length <= the observed
+    # file length.
+    temp_file_object.seek(0)
+    self.repository_updater._soft_check_file_length(temp_file_object, 3)
+    temp_file_object.seek(0)
+    self.repository_updater._soft_check_file_length(temp_file_object, 4)
+
+
 
 
   def test_10__targets_of_role(self):
diff --git a/tuf/client/updater.py b/tuf/client/updater.py
index 72f9574d..a331ff36 100755
--- a/tuf/client/updater.py
+++ b/tuf/client/updater.py
@@ -540,12 +540,11 @@ def _import_delegations(self, parent_role):
     # Iterate the keys of the delegated roles of 'parent_role' and load them.
     for keyid, keyinfo in six.iteritems(keys_info):
       if keyinfo['keytype'] in ['rsa', 'ed25519']:
-        key, keyids = securesystemslib.keys.format_metadata_to_key(keyinfo)
 
         # We specify the keyid to ensure that it's the correct keyid
         # for the key.
         try:
-          tuf.keydb.add_key(key, keyid, self.repository_name)
+          key, keyids = securesystemslib.keys.format_metadata_to_key(keyinfo)
           for keyid in keyids:
             key['keyid'] = keyid
             tuf.keydb.add_key(key, keyid=None, repository_name=self.repository_name)
@@ -575,7 +574,7 @@ def _import_delegations(self, parent_role):
         logger.warning('Role already exists: ' + rolename)
 
       except:
-        logger.exception('Failed to add delegated role: ' + rolename + '.')
+        logger.exception('Failed to add delegated role: ' + repr(rolename) + '.')
         raise
 
 
diff --git a/tuf/download.py b/tuf/download.py
index 48bd77cd..e1f7ab2e 100755
--- a/tuf/download.py
+++ b/tuf/download.py
@@ -682,10 +682,7 @@ class VerifiedHTTPSConnection(six.moves.http_client.HTTPSConnection):
   def connect(self):
 
     self.connection_kwargs = {}
-
-    # for > py2.5
-    if hasattr(self, 'timeout'):
-      self.connection_kwargs.update(timeout = self.timeout)
+    self.connection_kwargs.update(timeout = self.timeout)
 
     # for >= py2.7
     if hasattr(self, 'source_address'):
diff --git a/tuf/repository_lib.py b/tuf/repository_lib.py
index 0d56fc64..338e5049 100755
--- a/tuf/repository_lib.py
+++ b/tuf/repository_lib.py
@@ -737,7 +737,6 @@ def _load_top_level_metadata(repository, top_level_filenames, repository_name):
       # repository maintainer should have also been made aware of the duplicate
       # key when it was added.
       try:
-        tuf.keydb.add_key(key_object, repository_name=repository_name)
         for keyid in keyids: #pragma: no branch
           key_object['keyid'] = keyid
           tuf.keydb.add_key(key_object, keyid=None,
diff --git a/tuf/repository_tool.py b/tuf/repository_tool.py
index 86a49f19..e236ff29 100755
--- a/tuf/repository_tool.py
+++ b/tuf/repository_tool.py
@@ -3126,9 +3126,12 @@ def load_repository(repository_directory, repository_name='default'):
     # The repository maintainer should have also been made aware of the
     # duplicate key when it was added.
     for key_metadata in six.itervalues(metadata_object['delegations']['keys']):
-      key_object, junk = securesystemslib.keys.format_metadata_to_key(key_metadata)
+      key_object, keyids = securesystemslib.keys.format_metadata_to_key(key_metadata)
       try:
-        tuf.keydb.add_key(key_object, repository_name=repository_name)
+        for keyid in keyids:
+          key_object['keyid'] = keyid
+          tuf.keydb.add_key(key_object, keyid=None,
+              repository_name=repository_name)
 
       except securesystemslib.exceptions.KeyAlreadyExistsError:
         pass
diff --git a/tuf/roledb.py b/tuf/roledb.py
index 1ad93cbd..26403569 100755
--- a/tuf/roledb.py
+++ b/tuf/roledb.py
@@ -810,8 +810,8 @@ def get_role_threshold(rolename, repository_name='default'):
     securesystemslib.exceptions.FormatError, if the arguments do not have the
     correct object format.
 
-    securesystemslib.exceptions.UnknownRoleError, if 'rolename' cannot be found
-    in in the role database.
+    tuf.exceptions.UnknownRoleError, if 'rolename' cannot be found
+    in the role database.
 
     securesystemslib.exceptions.InvalidNameError, if 'rolename' is incorrectly
     formatted, or 'repository_name' does not exist in the role database.
@@ -822,6 +822,7 @@ def get_role_threshold(rolename, repository_name='default'):
   <Returns>
     A threshold integer value.
   """
+
   # Raise 'securesystemslib.exceptions.FormatError' if 'repository_name' is
   # improperly formatted.
   securesystemslib.formats.NAME_SCHEMA.check_match(repository_name)
@@ -885,10 +886,6 @@ def get_role_paths(rolename, repository_name='default'):
   global _roledb_dict
   global _dirty_roles
 
-  if repository_name not in _roledb_dict or repository_name not in _dirty_roles:
-    raise securesystemslib.exceptions.InvalidNameError('Repository name does not' ' exist: ' +
-      repository_name)
-
   roleinfo = _roledb_dict[repository_name][rolename]
 
   # Paths won't exist for non-target roles.
@@ -949,10 +946,6 @@ def get_delegated_rolenames(rolename, repository_name='default'):
   global _roledb_dict
   global _dirty_roles
 
-  if repository_name not in _roledb_dict or repository_name not in _dirty_roles:
-    raise securesystemslib.exceptions.InvalidNameError('Repository name does not'
-      ' exist: ' + repository_name)
-
   # get_roleinfo() raises a 'securesystemslib.exceptions.InvalidNameError' if
   # 'repository_name' does not exist in the role database.
   roleinfo = get_roleinfo(rolename, repository_name)
diff --git a/tuf/sig.py b/tuf/sig.py
index d572f92b..0f3b45c9 100755
--- a/tuf/sig.py
+++ b/tuf/sig.py
@@ -101,7 +101,7 @@ def get_signature_status(signable, role=None, repository_name='default',
     securesystemslib.exceptions.FormatError, if 'signable' does not have the
     correct format.
 
-    securesystemslib.exceptions.UnknownRoleError, if 'role' is not recognized.
+    tuf.exceptions.UnknownRoleError, if 'role' is not recognized.
 
   <Side Effects>
     None.
@@ -188,7 +188,7 @@ def get_signature_status(signable, role=None, repository_name='default',
             continue
 
         # Unknown role, re-raise exception.
-        except securesystemslib.exceptions.UnknownRoleError:
+        except tuf.exceptions.UnknownRoleError:
           raise
 
       # This is an unset role, thus an unknown signature.
@@ -211,7 +211,7 @@ def get_signature_status(signable, role=None, repository_name='default',
       threshold = \
         tuf.roledb.get_role_threshold(role, repository_name=repository_name)
 
-    except securesystemslib.exceptions.UnknownRoleError:
+    except tuf.exceptions.UnknownRoleError:
       raise
 
   else:
diff --git a/tuf/unittest_toolbox.py b/tuf/unittest_toolbox.py
index 67ef7286..b9ced979 100755
--- a/tuf/unittest_toolbox.py
+++ b/tuf/unittest_toolbox.py
@@ -85,7 +85,7 @@ def tearDown(self):
       try:
         # OSError will occur if the directory was already removed.
         cleanup_function()
-      
+
       except OSError:
         pass
 
@@ -93,11 +93,15 @@ def tearDown(self):
 
   def make_temp_directory(self, directory=None):
     """Creates and returns an absolute path of a directory."""
+
     prefix = self.__class__.__name__+'_'
     temp_directory = tempfile.mkdtemp(prefix=prefix, dir=directory)
+
     def _destroy_temp_directory():
       shutil.rmtree(temp_directory)
+
     self._cleanup.append(_destroy_temp_directory)
+
     return temp_directory