diff --git a/tuf/__init__.py b/tuf/__init__.py
index aaa49338..4be6efda 100755
--- a/tuf/__init__.py
+++ b/tuf/__init__.py
@@ -80,7 +80,14 @@ class UnsupportedAlgorithmError(Error):
 
 class BadHashError(Error):
   """Indicate an error while checking the value a hash object."""
-  pass
+
+  def __init__(self, expected_hash, observed_hash):
+    self.expected_hash = expected_hash
+    self.observed_hash = observed_hash
+
+  def __str__(self):
+    return 'Observed hash ('+str(self.observed_hash)+\
+           ') != expected hash ('+str(self.expected_hash)+')'
 
 
 
@@ -120,7 +127,12 @@ class ForbiddenTargetError(RepositoryError):
 
 class ExpiredMetadataError(Error):
   """Indicate that a TUF Metadata file has expired."""
-  pass
+
+  def __init__(self, expiry_time):
+    self.expiry_time = expiry_time # UTC
+
+  def __str__(self):
+    return 'Metadata expired on '+str(self.expiry_time)+'.'
 
 
 
@@ -154,8 +166,12 @@ class CryptoError(Error):
 
 class BadSignatureError(CryptoError):
   """Indicate that some metadata file had a bad signature."""
-  pass
 
+  def __init__(self, metadata_role_name):
+    self.metadata_role_name = metadata_role_name
+
+  def __str__(self):
+    return str(self.metadata_role_name)+' metadata bad signature!'
 
 
 
diff --git a/tuf/client/updater.py b/tuf/client/updater.py
index fc1f9d3c..3b875fb3 100755
--- a/tuf/client/updater.py
+++ b/tuf/client/updater.py
@@ -627,8 +627,7 @@ def __check_hashes(self, file_object, trusted_hashes):
       digest_object.update(file_object.read())
       computed_hash = digest_object.hexdigest()
       if trusted_hash != computed_hash:
-        raise tuf.BadHashError('Hashes do not match! Expected '+
-                               trusted_hash+' got '+computed_hash)
+        raise tuf.BadHashError(trusted_hash, computed_hash)
       else:
         logger.info('The file\'s '+algorithm+' hash is correct: '+trusted_hash)
 
@@ -835,7 +834,7 @@ def __verify_uncompressed_metadata_file(self, metadata_file_object,
     # Verify the signature on the downloaded metadata object.
     valid = tuf.sig.verify(metadata_signable, metadata_role)
     if not valid:
-      raise tuf.BadSignatureError()
+      raise tuf.BadSignatureError(metadata_role)
 
 
 
@@ -1742,10 +1741,11 @@ def _ensure_not_expired(self, metadata_role):
     # an exception.  'expires' is in YYYY-MM-DD HH:MM:SS format, so
     # convert it to seconds since the epoch, which is the time format
     # returned by time.time() (i.e., current time), before comparing.
-    if tuf.formats.parse_time(expires) < time.time():
-      message = 'Metadata '+repr(rolepath)+' expired on '+repr(expires)+'.'
-      logger.error(message)
-      raise tuf.ExpiredMetadataError(message)
+    current_time = time.time()
+    expiry_time = tuf.formats.parse_time(expires)
+    if expiry_time < current_time:
+      logger.error('Metadata '+repr(rolepath)+' expired on '+repr(expires)+'.')
+      raise tuf.ExpiredMetadataError(expires)