diff --git a/src/saml2/server.py b/src/saml2/server.py
index 94b1136..f8623d9 100644
--- a/src/saml2/server.py
+++ b/src/saml2/server.py
@@ -48,13 +48,22 @@ class UnknownVO(Exception):
     
 class Identifier(object):
     """ A class that handles identifiers of objects """
-    def __init__(self, dbname, entityid, voconf=None, debug=0, log=None):
+    def __init__(self, dbname, voconf=None, debug=0, log=None):
         self.map = shelve.open(dbname, writeback=True)
-        self.entityid = entityid
         self.voconf = voconf
         self.debug = debug
         self.log = log
         
+    def _store(self, typ, entity_id, local, remote):
+        self.map["|".join([typ, entity_id, "f", local])] = remote
+        self.map["|".join([typ, entity_id, "b", remote])] = local
+    
+    def _get_remote(self, typ, entity_id, local):
+        return self.map["|".join([typ, entity_id, "f", local])]
+
+    def _get_local(self, typ, entity_id, remote):
+        return self.map["|".join([typ, entity_id, "b", remote])]
+        
     def persistent(self, entity_id, subject_id):
         """ Keeps the link between a permanent identifier and a 
         temporary/pseudo-temporary identifier for a subject
@@ -68,26 +77,16 @@ class Identifier(object):
         :return: An arbitrary identifier for the subject unique to the
             service/group of services/VO with a given entity_id
         """
-        if self.debug:
-            self.log and self.log.debug("Id map keys: %s" % self.map.keys())
-            
         try:
-            emap = self.map[entity_id]
-        except KeyError:
-            emap = self.map[entity_id] = {"forward":{}, "backward":{}}
-
-        try:
-            if self.debug:
-                self.log.debug("map forward keys: %s" % emap["forward"].keys())
-            return emap["forward"][subject_id]
+            return self._get_remote("persistent", entity_id, subject_id)
         except KeyError:
             while True:
                 temp_id = sid()
-                if temp_id not in emap["backward"]:
+                try:
+                    l = self._get_local("persistent", entity_id, temp_id)
+                except KeyError:
                     break
-            emap["forward"][subject_id] = temp_id
-            emap["backward"][temp_id] = subject_id
-            self.map[entity_id] = emap
+            self._store("persistent", entity_id, subject_id, temp_id)
             self.map.sync()
             
             return temp_id
@@ -113,8 +112,6 @@ class Identifier(object):
         return saml.NameID(format=nameid_format,
                             sp_name_qualifier=sp_name_qualifier,
                             text=subj_id)
-        # return args2dict(subj_id, format=nameid_format,
-        #                     sp_name_qualifier=sp_name_qualifier)
     
     def persistent_nameid(self, sp_name_qualifier, userid):
         """ Get or create a persistent identifier for this object to be used
@@ -128,15 +125,20 @@ class Identifier(object):
         return saml.NameID(format=saml.NAMEID_FORMAT_PERSISTENT,
                             sp_name_qualifier=sp_name_qualifier,
                             text=subj_id)
-                                
-        # return args2dict(subj_id, format=saml.NAMEID_FORMAT_PERSISTENT,
-        #                         sp_name_qualifier=sp_name_qualifier)    
 
-    def temporary_nameid(self):
+    def transient_nameid(self, sp_name_qualifier, userid):
         """ Returns a random one-time identifier """
+        while True:
+            temp_id = sid()
+            try:
+                l = self._get_local("transient", sp_name_qualifier, temp_id)
+            except KeyError:
+                break
+        self._store("transient", sp_name_qualifier, userid, temp_id)
+        self.map.sync()
+
         return saml.NameID(format=saml.NAMEID_FORMAT_TRANSIENT,
-                             text=sid())
-        #return args2dict(sid(), format=saml.NAMEID_FORMAT_TRANSIENT)
+                             text=temp_id)
 
     def construct_nameid(self, local_policy, userid, sp_entity_id,
                         identity=None, name_id_policy=None):
@@ -157,11 +159,24 @@ class Identifier(object):
         else:
             nameid_format = local_policy.get_nameid_format(sp_entity_id)
             if nameid_format == saml.NAMEID_FORMAT_PERSISTENT:
-                return self.persistent_nameid(self.entityid, userid)
+                return self.persistent_nameid(sp_entity_id, userid)
             elif nameid_format == saml.NAMEID_FORMAT_TRANSIENT:
-                return self.temporary_nameid()
+                return self.transient_nameid(sp_entity_id, userid)
                 
+    def local_name(self, entity_id, remote_id):
+        """ Only works for persistent names
         
+        :param entity_id: The identifier of the entity that got the remote id
+        :param remote_id: The identifier that was exported
+        :return: Local identifier
+        """
+        try:
+            return self._get_local("persistent", entity_id, remote_id)
+        except KeyError:
+            try:
+                return self._get_local("transient", entity_id, remote_id)
+            except KeyError:
+                return None
         
 class Server(object):
     """ A class that does things that IdPs or AAs do """
@@ -192,7 +207,7 @@ class Server(object):
         self.conf.load_file(config_file)
         if "subject_data" in self.conf:
             self.ident = Identifier(self.conf["subject_data"], 
-                                    self.conf["entityid"], self.conf.vo_conf,
+                                    self.conf.vo_conf,
                                     self.debug, self.log)
         else:
             self.ident = None