remove IV validation step from RestoreHelper

Since the same decryption context is carried over between the Tar
volumes of one backup set, the built-in IV uniqueness checks
suffice. Between multiple backup sets, the salt and IV fixed
parts change, so there is no occasion for conflict. The IVs of
auxiliary files are unique anyways.

diff --git a/deltatar/deltatar.py b/deltatar/deltatar.py
index b5a73a2..d0d6b4e 100644 (file)
--- a/deltatar/deltatar.py
+++ b/deltatar/deltatar.py
@@ -1413,7 +1413,6 @@ class DeltaTar(object):
         index_it.release()
         os.chdir(cwd)
         helper.cleanup()
-        helper.validate()
 
     def _parse_json_line(self, f, l_no):
         '''
@@ -1533,23 +1532,6 @@ class RestoreHelper(object):
             self._data.append(s)
 
 
-    def validate (self):
-        """If encryption was used, verify post-conditions."""
-        if len (self._decryptors) == 0:
-            return
-        acc = None
-        for dec in self._decryptors:
-            if acc is None:
-                acc = dec.used_ivs.copy ()
-            else:
-                used_ivs  = dec.used_ivs
-                intersect = used_ivs & acc
-                if len (intersect) > 0:
-                    raise Exception ("ERROR: %d duplicate IVs found during "
-                                     "decryption" % len (intersect))
-                acc |= used_ivs
-
-
     def cleanup(self):
         '''
         Closes all open files