diff --git a/PyNDN/Data.py b/PyNDN/Data.py
index 7e8dd56..5369380 100644
--- a/PyNDN/Data.py
+++ b/PyNDN/Data.py
@@ -101,7 +101,7 @@
                     # ?
                     pass
                 if value.freshnessSeconds:
-                    self._data.SetFreshness (ns.core.Seconds (value))
+                    self._data.SetFreshness (ns.core.Seconds (value.freshnessSeconds))
                 if value.keyLocator:
                     self._data.SetKeyLocator (value._name)
             else:
diff --git a/PyNDN/Key.py b/PyNDN/Key.py
index 2dc562a..842024b 100644
--- a/PyNDN/Key.py
+++ b/PyNDN/Key.py
@@ -23,8 +23,8 @@
 
 class Key (object):
     def __init__ (self):
-        # self.publicKeyID = None # SHA256 hash
-        self.fakeKey = None
+        self.publicKeyID = None # SHA256 hash
+        self.fakeKey = 0
 
     def generateRSA(self, numbits):
         randVar = ns.core.UniformVariable ()
@@ -49,19 +49,19 @@
 
     def fromDER(self, private = None, public = None):
         if private:
-            self.fakeKey = private
+            self.fakeKey = hash(private)
         elif public:
-            self.fakeKey = public
+            self.fakeKey = hash(public)
 
     def fromPEM(self, filename = None, private = None, public = None, password = None):
         if filename:
             f = open(filename, 'r')
-            self.fakeKey = f.read ()
+            self.fakeKey = hash(f.read ())
             f.close()
         elif private:
-            self.fakeKey = private
+            self.fakeKey = hash(private)
         elif public:
-            self.fakeKey = public
+            self.fakeKey = hash(public)
 
     @staticmethod
     def createFromDER (private = None, public = None):
diff --git a/PyNDN/SignedInfo.py b/PyNDN/SignedInfo.py
index cadf1e7..84941ad 100644
--- a/PyNDN/SignedInfo.py
+++ b/PyNDN/SignedInfo.py
@@ -30,13 +30,16 @@
 CONTENT_NACK = ContentType.new_flag('CONTENT_NACK', 0x34008A)
 
 class SignedInfo (object):
-    def __init__(self, keyLocator = None, freshness = None, timestamp = None, type = CONTENT_DATA):
+    def __init__(self, keyLocator = None, freshness = None,
+                 timestamp = None, type = CONTENT_DATA, *kw, **kwargs):
 
         self.timestamp = timestamp
         self.freshnessSeconds = freshness
         self.keyLocator = keyLocator
         self.type = type
 
+        # all other parameters are silently ignored
+
     def __repr__(self):
         args = []