Updater: clean up _check_hashes() comments

Remove duplicate/obvious comments, tighten other comments and a logline

Signed-off-by: Jussi Kukkonen <[email protected]>

Author: Jussi Kukkonen

tuf/client/updater.py

@@ -1167,11 +1167,7 @@ def neither_403_nor_404(mirror_error):
   def _check_hashes(self, file_object, trusted_hashes):
     """
     <Purpose>
-      Non-public method that verifies multiple secure hashes of the downloaded
-      file 'file_object'.  If any of these fail it raises an exception.  This is
-      to conform with the TUF spec, which support clients with different hashing
-      algorithms. The 'hash.py' module is used to compute the hashes of
-      'file_object'.
+      Non-public method that verifies multiple secure hashes of 'file_object'.
 
     <Arguments>
       file_object:
@@ -1193,21 +1189,18 @@ def _check_hashes(self, file_object, trusted_hashes):
       None.
     """
 
-    # Verify each trusted hash of 'trusted_hashes'.  If all are valid, simply
-    # return.
+    # Verify each hash, raise an exception if any hash fails to verify
     for algorithm, trusted_hash in six.iteritems(trusted_hashes):
       digest_object = securesystemslib.hash.digest_fileobject(file_object,
           algorithm)
       computed_hash = digest_object.hexdigest()
 
-      # Raise an exception if any of the hashes are incorrect.
       if trusted_hash != computed_hash:
         raise securesystemslib.exceptions.BadHashError(trusted_hash,
             computed_hash)
 
       else:
-        logger.info('The file\'s ' + algorithm + ' hash is'
-            ' correct: ' + trusted_hash)
+        logger.info('Verified ' + algorithm + ' hash: ' + trusted_hash)